1 //===- SimplifyLibCalls.cpp - Optimize specific well-known library calls --===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements a simple pass that applies a variety of small
11 // optimizations for calls to specific well-known function calls (e.g. runtime
12 // library functions). For example, a call to the function "exit(3)" that
13 // occurs within the main() function can be transformed into a simple "return 3"
14 // instruction. Any optimization that takes this form (replace call to library
15 // function with simpler code that provides the same result) belongs in this
18 //===----------------------------------------------------------------------===//
20 #define DEBUG_TYPE "simplify-libcalls"
21 #include "llvm/Transforms/Scalar.h"
22 #include "llvm/Intrinsics.h"
23 #include "llvm/Module.h"
24 #include "llvm/Pass.h"
25 #include "llvm/Support/IRBuilder.h"
26 #include "llvm/Target/TargetData.h"
27 #include "llvm/ADT/SmallPtrSet.h"
28 #include "llvm/ADT/StringMap.h"
29 #include "llvm/ADT/Statistic.h"
30 #include "llvm/Support/Compiler.h"
31 #include "llvm/Support/Debug.h"
32 #include "llvm/Config/config.h"
35 STATISTIC(NumSimplified, "Number of library calls simplified");
37 //===----------------------------------------------------------------------===//
38 // Optimizer Base Class
39 //===----------------------------------------------------------------------===//
41 /// This class is the abstract base class for the set of optimizations that
42 /// corresponds to one library call.
44 class VISIBILITY_HIDDEN LibCallOptimization {
49 LibCallOptimization() { }
50 virtual ~LibCallOptimization() {}
52 /// CallOptimizer - This pure virtual method is implemented by base classes to
53 /// do various optimizations. If this returns null then no transformation was
54 /// performed. If it returns CI, then it transformed the call and CI is to be
55 /// deleted. If it returns something else, replace CI with the new value and
57 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) =0;
59 Value *OptimizeCall(CallInst *CI, const TargetData &TD, IRBuilder &B) {
60 Caller = CI->getParent()->getParent();
62 return CallOptimizer(CI->getCalledFunction(), CI, B);
65 /// CastToCStr - Return V if it is an i8*, otherwise cast it to i8*.
66 Value *CastToCStr(Value *V, IRBuilder &B);
68 /// EmitStrLen - Emit a call to the strlen function to the builder, for the
69 /// specified pointer. Ptr is required to be some pointer type, and the
70 /// return value has 'intptr_t' type.
71 Value *EmitStrLen(Value *Ptr, IRBuilder &B);
73 /// EmitMemCpy - Emit a call to the memcpy function to the builder. This
74 /// always expects that the size has type 'intptr_t' and Dst/Src are pointers.
75 Value *EmitMemCpy(Value *Dst, Value *Src, Value *Len,
76 unsigned Align, IRBuilder &B);
78 /// EmitMemChr - Emit a call to the memchr function. This assumes that Ptr is
79 /// a pointer, Val is an i32 value, and Len is an 'intptr_t' value.
80 Value *EmitMemChr(Value *Ptr, Value *Val, Value *Len, IRBuilder &B);
82 /// EmitUnaryFloatFnCall - Emit a call to the unary function named 'Name' (e.g.
83 /// 'floor'). This function is known to take a single of type matching 'Op'
84 /// and returns one value with the same type. If 'Op' is a long double, 'l'
85 /// is added as the suffix of name, if 'Op' is a float, we add a 'f' suffix.
86 Value *EmitUnaryFloatFnCall(Value *Op, const char *Name, IRBuilder &B);
88 /// EmitPutChar - Emit a call to the putchar function. This assumes that Char
90 void EmitPutChar(Value *Char, IRBuilder &B);
92 /// EmitPutS - Emit a call to the puts function. This assumes that Str is
94 void EmitPutS(Value *Str, IRBuilder &B);
96 /// EmitFPutC - Emit a call to the fputc function. This assumes that Char is
97 /// an i32, and File is a pointer to FILE.
98 void EmitFPutC(Value *Char, Value *File, IRBuilder &B);
100 /// EmitFPutS - Emit a call to the puts function. Str is required to be a
101 /// pointer and File is a pointer to FILE.
102 void EmitFPutS(Value *Str, Value *File, IRBuilder &B);
104 /// EmitFWrite - Emit a call to the fwrite function. This assumes that Ptr is
105 /// a pointer, Size is an 'intptr_t', and File is a pointer to FILE.
106 void EmitFWrite(Value *Ptr, Value *Size, Value *File, IRBuilder &B);
109 } // End anonymous namespace.
111 /// CastToCStr - Return V if it is an i8*, otherwise cast it to i8*.
112 Value *LibCallOptimization::CastToCStr(Value *V, IRBuilder &B) {
113 return B.CreateBitCast(V, PointerType::getUnqual(Type::Int8Ty), "cstr");
116 /// EmitStrLen - Emit a call to the strlen function to the builder, for the
117 /// specified pointer. This always returns an integer value of size intptr_t.
118 Value *LibCallOptimization::EmitStrLen(Value *Ptr, IRBuilder &B) {
119 Module *M = Caller->getParent();
120 Constant *StrLen =M->getOrInsertFunction("strlen", TD->getIntPtrType(),
121 PointerType::getUnqual(Type::Int8Ty),
123 return B.CreateCall(StrLen, CastToCStr(Ptr, B), "strlen");
126 /// EmitMemCpy - Emit a call to the memcpy function to the builder. This always
127 /// expects that the size has type 'intptr_t' and Dst/Src are pointers.
128 Value *LibCallOptimization::EmitMemCpy(Value *Dst, Value *Src, Value *Len,
129 unsigned Align, IRBuilder &B) {
130 Module *M = Caller->getParent();
131 Intrinsic::ID IID = TD->getIntPtrType() == Type::Int32Ty ?
132 Intrinsic::memcpy_i32 : Intrinsic::memcpy_i64;
133 Value *MemCpy = Intrinsic::getDeclaration(M, IID);
134 return B.CreateCall4(MemCpy, CastToCStr(Dst, B), CastToCStr(Src, B), Len,
135 ConstantInt::get(Type::Int32Ty, Align));
138 /// EmitMemChr - Emit a call to the memchr function. This assumes that Ptr is
139 /// a pointer, Val is an i32 value, and Len is an 'intptr_t' value.
140 Value *LibCallOptimization::EmitMemChr(Value *Ptr, Value *Val,
141 Value *Len, IRBuilder &B) {
142 Module *M = Caller->getParent();
143 Value *MemChr = M->getOrInsertFunction("memchr",
144 PointerType::getUnqual(Type::Int8Ty),
145 PointerType::getUnqual(Type::Int8Ty),
146 Type::Int32Ty, TD->getIntPtrType(),
148 return B.CreateCall3(MemChr, CastToCStr(Ptr, B), Val, Len, "memchr");
151 /// EmitUnaryFloatFnCall - Emit a call to the unary function named 'Name' (e.g.
152 /// 'floor'). This function is known to take a single of type matching 'Op' and
153 /// returns one value with the same type. If 'Op' is a long double, 'l' is
154 /// added as the suffix of name, if 'Op' is a float, we add a 'f' suffix.
155 Value *LibCallOptimization::EmitUnaryFloatFnCall(Value *Op, const char *Name,
158 if (Op->getType() != Type::DoubleTy) {
159 // If we need to add a suffix, copy into NameBuffer.
160 unsigned NameLen = strlen(Name);
161 assert(NameLen < sizeof(NameBuffer)-2);
162 memcpy(NameBuffer, Name, NameLen);
163 if (Op->getType() == Type::FloatTy)
164 NameBuffer[NameLen] = 'f'; // floorf
166 NameBuffer[NameLen] = 'l'; // floorl
167 NameBuffer[NameLen+1] = 0;
171 Module *M = Caller->getParent();
172 Value *Callee = M->getOrInsertFunction(Name, Op->getType(),
173 Op->getType(), NULL);
174 return B.CreateCall(Callee, Op, Name);
177 /// EmitPutChar - Emit a call to the putchar function. This assumes that Char
179 void LibCallOptimization::EmitPutChar(Value *Char, IRBuilder &B) {
180 Module *M = Caller->getParent();
181 Value *F = M->getOrInsertFunction("putchar", Type::Int32Ty,
182 Type::Int32Ty, NULL);
183 B.CreateCall(F, B.CreateIntCast(Char, Type::Int32Ty, "chari"), "putchar");
186 /// EmitPutS - Emit a call to the puts function. This assumes that Str is
188 void LibCallOptimization::EmitPutS(Value *Str, IRBuilder &B) {
189 Module *M = Caller->getParent();
190 Value *F = M->getOrInsertFunction("puts", Type::Int32Ty,
191 PointerType::getUnqual(Type::Int8Ty), NULL);
192 B.CreateCall(F, CastToCStr(Str, B), "puts");
195 /// EmitFPutC - Emit a call to the fputc function. This assumes that Char is
196 /// an integer and File is a pointer to FILE.
197 void LibCallOptimization::EmitFPutC(Value *Char, Value *File, IRBuilder &B) {
198 Module *M = Caller->getParent();
199 Constant *F = M->getOrInsertFunction("fputc", Type::Int32Ty, Type::Int32Ty,
200 File->getType(), NULL);
201 Char = B.CreateIntCast(Char, Type::Int32Ty, "chari");
202 B.CreateCall2(F, Char, File, "fputc");
205 /// EmitFPutS - Emit a call to the puts function. Str is required to be a
206 /// pointer and File is a pointer to FILE.
207 void LibCallOptimization::EmitFPutS(Value *Str, Value *File, IRBuilder &B) {
208 Module *M = Caller->getParent();
209 Constant *F = M->getOrInsertFunction("fputs", Type::Int32Ty,
210 PointerType::getUnqual(Type::Int8Ty),
211 File->getType(), NULL);
212 B.CreateCall2(F, CastToCStr(Str, B), File, "fputs");
215 /// EmitFWrite - Emit a call to the fwrite function. This assumes that Ptr is
216 /// a pointer, Size is an 'intptr_t', and File is a pointer to FILE.
217 void LibCallOptimization::EmitFWrite(Value *Ptr, Value *Size, Value *File,
219 Module *M = Caller->getParent();
220 Constant *F = M->getOrInsertFunction("fwrite", TD->getIntPtrType(),
221 PointerType::getUnqual(Type::Int8Ty),
222 TD->getIntPtrType(), TD->getIntPtrType(),
223 File->getType(), NULL);
224 B.CreateCall4(F, CastToCStr(Ptr, B), Size,
225 ConstantInt::get(TD->getIntPtrType(), 1), File);
228 //===----------------------------------------------------------------------===//
230 //===----------------------------------------------------------------------===//
232 /// GetConstantStringInfo - This function computes the length of a
233 /// null-terminated C string pointed to by V. If successful, it returns true
234 /// and returns the string in Str. If unsuccessful, it returns false.
235 static bool GetConstantStringInfo(Value *V, std::string &Str) {
236 // Look bitcast instructions.
237 if (BitCastInst *BCI = dyn_cast<BitCastInst>(V))
238 return GetConstantStringInfo(BCI->getOperand(0), Str);
240 // If the value is not a GEP instruction nor a constant expression with a
241 // GEP instruction, then return false because ConstantArray can't occur
244 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
246 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
247 if (CE->getOpcode() != Instruction::GetElementPtr)
254 // Make sure the GEP has exactly three arguments.
255 if (GEP->getNumOperands() != 3)
258 // Check to make sure that the first operand of the GEP is an integer and
259 // has value 0 so that we are sure we're indexing into the initializer.
260 if (ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
266 // If the second index isn't a ConstantInt, then this is a variable index
267 // into the array. If this occurs, we can't say anything meaningful about
269 uint64_t StartIdx = 0;
270 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
271 StartIdx = CI->getZExtValue();
275 // The GEP instruction, constant or instruction, must reference a global
276 // variable that is a constant and is initialized. The referenced constant
277 // initializer is the array that we'll use for optimization.
278 GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
279 if (!GV || !GV->isConstant() || !GV->hasInitializer())
281 Constant *GlobalInit = GV->getInitializer();
283 // Handle the ConstantAggregateZero case
284 if (isa<ConstantAggregateZero>(GlobalInit)) {
285 // This is a degenerate case. The initializer is constant zero so the
286 // length of the string must be zero.
291 // Must be a Constant Array
292 ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
293 if (Array == 0 || Array->getType()->getElementType() != Type::Int8Ty)
296 // Get the number of elements in the array
297 uint64_t NumElts = Array->getType()->getNumElements();
299 // Traverse the constant array from StartIdx (derived above) which is
300 // the place the GEP refers to in the array.
301 for (unsigned i = StartIdx; i < NumElts; ++i) {
302 Constant *Elt = Array->getOperand(i);
303 ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
304 if (!CI) // This array isn't suitable, non-int initializer.
307 return true; // we found end of string, success!
308 Str += (char)CI->getZExtValue();
311 return false; // The array isn't null terminated.
314 /// GetStringLengthH - If we can compute the length of the string pointed to by
315 /// the specified pointer, return 'len+1'. If we can't, return 0.
316 static uint64_t GetStringLengthH(Value *V, SmallPtrSet<PHINode*, 32> &PHIs) {
317 // Look through noop bitcast instructions.
318 if (BitCastInst *BCI = dyn_cast<BitCastInst>(V))
319 return GetStringLengthH(BCI->getOperand(0), PHIs);
321 // If this is a PHI node, there are two cases: either we have already seen it
323 if (PHINode *PN = dyn_cast<PHINode>(V)) {
324 if (!PHIs.insert(PN))
325 return ~0ULL; // already in the set.
327 // If it was new, see if all the input strings are the same length.
328 uint64_t LenSoFar = ~0ULL;
329 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
330 uint64_t Len = GetStringLengthH(PN->getIncomingValue(i), PHIs);
331 if (Len == 0) return 0; // Unknown length -> unknown.
333 if (Len == ~0ULL) continue;
335 if (Len != LenSoFar && LenSoFar != ~0ULL)
336 return 0; // Disagree -> unknown.
340 // Success, all agree.
344 // strlen(select(c,x,y)) -> strlen(x) ^ strlen(y)
345 if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
346 uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs);
347 if (Len1 == 0) return 0;
348 uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs);
349 if (Len2 == 0) return 0;
350 if (Len1 == ~0ULL) return Len2;
351 if (Len2 == ~0ULL) return Len1;
352 if (Len1 != Len2) return 0;
356 // If the value is not a GEP instruction nor a constant expression with a
357 // GEP instruction, then return unknown.
359 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
361 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
362 if (CE->getOpcode() != Instruction::GetElementPtr)
369 // Make sure the GEP has exactly three arguments.
370 if (GEP->getNumOperands() != 3)
373 // Check to make sure that the first operand of the GEP is an integer and
374 // has value 0 so that we are sure we're indexing into the initializer.
375 if (ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
381 // If the second index isn't a ConstantInt, then this is a variable index
382 // into the array. If this occurs, we can't say anything meaningful about
384 uint64_t StartIdx = 0;
385 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
386 StartIdx = CI->getZExtValue();
390 // The GEP instruction, constant or instruction, must reference a global
391 // variable that is a constant and is initialized. The referenced constant
392 // initializer is the array that we'll use for optimization.
393 GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
394 if (!GV || !GV->isConstant() || !GV->hasInitializer())
396 Constant *GlobalInit = GV->getInitializer();
398 // Handle the ConstantAggregateZero case, which is a degenerate case. The
399 // initializer is constant zero so the length of the string must be zero.
400 if (isa<ConstantAggregateZero>(GlobalInit))
401 return 1; // Len = 0 offset by 1.
403 // Must be a Constant Array
404 ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
405 if (!Array || Array->getType()->getElementType() != Type::Int8Ty)
408 // Get the number of elements in the array
409 uint64_t NumElts = Array->getType()->getNumElements();
411 // Traverse the constant array from StartIdx (derived above) which is
412 // the place the GEP refers to in the array.
413 for (unsigned i = StartIdx; i != NumElts; ++i) {
414 Constant *Elt = Array->getOperand(i);
415 ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
416 if (!CI) // This array isn't suitable, non-int initializer.
419 return i-StartIdx+1; // We found end of string, success!
422 return 0; // The array isn't null terminated, conservatively return 'unknown'.
425 /// GetStringLength - If we can compute the length of the string pointed to by
426 /// the specified pointer, return 'len+1'. If we can't, return 0.
427 static uint64_t GetStringLength(Value *V) {
428 if (!isa<PointerType>(V->getType())) return 0;
430 SmallPtrSet<PHINode*, 32> PHIs;
431 uint64_t Len = GetStringLengthH(V, PHIs);
432 // If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return
433 // an empty string as a length.
434 return Len == ~0ULL ? 1 : Len;
437 /// IsOnlyUsedInZeroEqualityComparison - Return true if it only matters that the
438 /// value is equal or not-equal to zero.
439 static bool IsOnlyUsedInZeroEqualityComparison(Value *V) {
440 for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
442 if (ICmpInst *IC = dyn_cast<ICmpInst>(*UI))
443 if (IC->isEquality())
444 if (Constant *C = dyn_cast<Constant>(IC->getOperand(1)))
445 if (C->isNullValue())
447 // Unknown instruction.
453 //===----------------------------------------------------------------------===//
454 // Miscellaneous LibCall Optimizations
455 //===----------------------------------------------------------------------===//
457 //===---------------------------------------===//
458 // 'exit' Optimizations
460 /// ExitOpt - int main() { exit(4); } --> int main() { return 4; }
461 struct VISIBILITY_HIDDEN ExitOpt : public LibCallOptimization {
462 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
463 // Verify we have a reasonable prototype for exit.
464 if (Callee->arg_size() == 0 || !CI->use_empty())
467 // Verify the caller is main, and that the result type of main matches the
468 // argument type of exit.
469 if (!Caller->isName("main") || !Caller->hasExternalLinkage() ||
470 Caller->getReturnType() != CI->getOperand(1)->getType())
473 TerminatorInst *OldTI = CI->getParent()->getTerminator();
475 // Create the return after the call.
476 ReturnInst *RI = B.CreateRet(CI->getOperand(1));
478 // Drop all successor phi node entries.
479 for (unsigned i = 0, e = OldTI->getNumSuccessors(); i != e; ++i)
480 OldTI->getSuccessor(i)->removePredecessor(CI->getParent());
482 // Erase all instructions from after our return instruction until the end of
484 BasicBlock::iterator FirstDead = RI; ++FirstDead;
485 CI->getParent()->getInstList().erase(FirstDead, CI->getParent()->end());
490 //===----------------------------------------------------------------------===//
491 // String and Memory LibCall Optimizations
492 //===----------------------------------------------------------------------===//
494 //===---------------------------------------===//
495 // 'strcat' Optimizations
497 struct VISIBILITY_HIDDEN StrCatOpt : public LibCallOptimization {
498 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
499 // Verify the "strcat" function prototype.
500 const FunctionType *FT = Callee->getFunctionType();
501 if (FT->getNumParams() != 2 ||
502 FT->getReturnType() != PointerType::getUnqual(Type::Int8Ty) ||
503 FT->getParamType(0) != FT->getReturnType() ||
504 FT->getParamType(1) != FT->getReturnType())
507 // Extract some information from the instruction
508 Value *Dst = CI->getOperand(1);
509 Value *Src = CI->getOperand(2);
511 // See if we can get the length of the input string.
512 uint64_t Len = GetStringLength(Src);
513 if (Len == 0) return 0;
514 --Len; // Unbias length.
516 // Handle the simple, do-nothing case: strcat(x, "") -> x
520 // We need to find the end of the destination string. That's where the
521 // memory is to be moved to. We just generate a call to strlen.
522 Value *DstLen = EmitStrLen(Dst, B);
524 // Now that we have the destination's length, we must index into the
525 // destination's pointer to get the actual memcpy destination (end of
526 // the string .. we're concatenating).
527 Dst = B.CreateGEP(Dst, DstLen, "endptr");
529 // We have enough information to now generate the memcpy call to do the
530 // concatenation for us. Make a memcpy to copy the nul byte with align = 1.
531 EmitMemCpy(Dst, Src, ConstantInt::get(TD->getIntPtrType(), Len+1), 1, B);
536 //===---------------------------------------===//
537 // 'strchr' Optimizations
539 struct VISIBILITY_HIDDEN StrChrOpt : public LibCallOptimization {
540 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
541 // Verify the "strchr" function prototype.
542 const FunctionType *FT = Callee->getFunctionType();
543 if (FT->getNumParams() != 2 ||
544 FT->getReturnType() != PointerType::getUnqual(Type::Int8Ty) ||
545 FT->getParamType(0) != FT->getReturnType())
548 Value *SrcStr = CI->getOperand(1);
550 // If the second operand is non-constant, see if we can compute the length
551 // of the input string and turn this into memchr.
552 ConstantInt *CharC = dyn_cast<ConstantInt>(CI->getOperand(2));
554 uint64_t Len = GetStringLength(SrcStr);
555 if (Len == 0 || FT->getParamType(1) != Type::Int32Ty) // memchr needs i32.
558 return EmitMemChr(SrcStr, CI->getOperand(2), // include nul.
559 ConstantInt::get(TD->getIntPtrType(), Len), B);
562 // Otherwise, the character is a constant, see if the first argument is
563 // a string literal. If so, we can constant fold.
565 if (!GetConstantStringInfo(SrcStr, Str))
568 // strchr can find the nul character.
570 char CharValue = CharC->getSExtValue();
572 // Compute the offset.
575 if (i == Str.size()) // Didn't find the char. strchr returns null.
576 return Constant::getNullValue(CI->getType());
577 // Did we find our match?
578 if (Str[i] == CharValue)
583 // strchr(s+n,c) -> gep(s+n+i,c)
584 Value *Idx = ConstantInt::get(Type::Int64Ty, i);
585 return B.CreateGEP(SrcStr, Idx, "strchr");
589 //===---------------------------------------===//
590 // 'strcmp' Optimizations
592 struct VISIBILITY_HIDDEN StrCmpOpt : public LibCallOptimization {
593 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
594 // Verify the "strcmp" function prototype.
595 const FunctionType *FT = Callee->getFunctionType();
596 if (FT->getNumParams() != 2 || FT->getReturnType() != Type::Int32Ty ||
597 FT->getParamType(0) != FT->getParamType(1) ||
598 FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty))
601 Value *Str1P = CI->getOperand(1), *Str2P = CI->getOperand(2);
602 if (Str1P == Str2P) // strcmp(x,x) -> 0
603 return ConstantInt::get(CI->getType(), 0);
605 std::string Str1, Str2;
606 bool HasStr1 = GetConstantStringInfo(Str1P, Str1);
607 bool HasStr2 = GetConstantStringInfo(Str2P, Str2);
609 if (HasStr1 && Str1.empty()) // strcmp("", x) -> *x
610 return B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType());
612 if (HasStr2 && Str2.empty()) // strcmp(x,"") -> *x
613 return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType());
615 // strcmp(x, y) -> cnst (if both x and y are constant strings)
616 if (HasStr1 && HasStr2)
617 return ConstantInt::get(CI->getType(), strcmp(Str1.c_str(),Str2.c_str()));
622 //===---------------------------------------===//
623 // 'strncmp' Optimizations
625 struct VISIBILITY_HIDDEN StrNCmpOpt : public LibCallOptimization {
626 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
627 // Verify the "strncmp" function prototype.
628 const FunctionType *FT = Callee->getFunctionType();
629 if (FT->getNumParams() != 3 || FT->getReturnType() != Type::Int32Ty ||
630 FT->getParamType(0) != FT->getParamType(1) ||
631 FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty) ||
632 !isa<IntegerType>(FT->getParamType(2)))
635 Value *Str1P = CI->getOperand(1), *Str2P = CI->getOperand(2);
636 if (Str1P == Str2P) // strncmp(x,x,n) -> 0
637 return ConstantInt::get(CI->getType(), 0);
639 // Get the length argument if it is constant.
641 if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(CI->getOperand(3)))
642 Length = LengthArg->getZExtValue();
646 if (Length == 0) // strncmp(x,y,0) -> 0
647 return ConstantInt::get(CI->getType(), 0);
649 std::string Str1, Str2;
650 bool HasStr1 = GetConstantStringInfo(Str1P, Str1);
651 bool HasStr2 = GetConstantStringInfo(Str2P, Str2);
653 if (HasStr1 && Str1.empty()) // strncmp("", x, n) -> *x
654 return B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType());
656 if (HasStr2 && Str2.empty()) // strncmp(x, "", n) -> *x
657 return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType());
659 // strncmp(x, y) -> cnst (if both x and y are constant strings)
660 if (HasStr1 && HasStr2)
661 return ConstantInt::get(CI->getType(),
662 strncmp(Str1.c_str(), Str2.c_str(), Length));
668 //===---------------------------------------===//
669 // 'strcpy' Optimizations
671 struct VISIBILITY_HIDDEN StrCpyOpt : public LibCallOptimization {
672 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
673 // Verify the "strcpy" function prototype.
674 const FunctionType *FT = Callee->getFunctionType();
675 if (FT->getNumParams() != 2 || FT->getReturnType() != FT->getParamType(0) ||
676 FT->getParamType(0) != FT->getParamType(1) ||
677 FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty))
680 Value *Dst = CI->getOperand(1), *Src = CI->getOperand(2);
681 if (Dst == Src) // strcpy(x,x) -> x
684 // See if we can get the length of the input string.
685 uint64_t Len = GetStringLength(Src);
686 if (Len == 0) return 0;
688 // We have enough information to now generate the memcpy call to do the
689 // concatenation for us. Make a memcpy to copy the nul byte with align = 1.
690 EmitMemCpy(Dst, Src, ConstantInt::get(TD->getIntPtrType(), Len), 1, B);
697 //===---------------------------------------===//
698 // 'strlen' Optimizations
700 struct VISIBILITY_HIDDEN StrLenOpt : public LibCallOptimization {
701 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
702 const FunctionType *FT = Callee->getFunctionType();
703 if (FT->getNumParams() != 1 ||
704 FT->getParamType(0) != PointerType::getUnqual(Type::Int8Ty) ||
705 !isa<IntegerType>(FT->getReturnType()))
708 Value *Src = CI->getOperand(1);
710 // Constant folding: strlen("xyz") -> 3
711 if (uint64_t Len = GetStringLength(Src))
712 return ConstantInt::get(CI->getType(), Len-1);
714 // Handle strlen(p) != 0.
715 if (!IsOnlyUsedInZeroEqualityComparison(CI)) return 0;
717 // strlen(x) != 0 --> *x != 0
718 // strlen(x) == 0 --> *x == 0
719 return B.CreateZExt(B.CreateLoad(Src, "strlenfirst"), CI->getType());
723 //===---------------------------------------===//
724 // 'memcmp' Optimizations
726 struct VISIBILITY_HIDDEN MemCmpOpt : public LibCallOptimization {
727 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
728 const FunctionType *FT = Callee->getFunctionType();
729 if (FT->getNumParams() != 3 || !isa<PointerType>(FT->getParamType(0)) ||
730 !isa<PointerType>(FT->getParamType(1)) ||
731 FT->getReturnType() != Type::Int32Ty)
734 Value *LHS = CI->getOperand(1), *RHS = CI->getOperand(2);
736 if (LHS == RHS) // memcmp(s,s,x) -> 0
737 return Constant::getNullValue(CI->getType());
739 // Make sure we have a constant length.
740 ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getOperand(3));
742 uint64_t Len = LenC->getZExtValue();
744 if (Len == 0) // memcmp(s1,s2,0) -> 0
745 return Constant::getNullValue(CI->getType());
747 if (Len == 1) { // memcmp(S1,S2,1) -> *LHS - *RHS
748 Value *LHSV = B.CreateLoad(CastToCStr(LHS, B), "lhsv");
749 Value *RHSV = B.CreateLoad(CastToCStr(RHS, B), "rhsv");
750 return B.CreateZExt(B.CreateSub(LHSV, RHSV, "chardiff"), CI->getType());
753 // memcmp(S1,S2,2) != 0 -> (*(short*)LHS ^ *(short*)RHS) != 0
754 // memcmp(S1,S2,4) != 0 -> (*(int*)LHS ^ *(int*)RHS) != 0
755 if ((Len == 2 || Len == 4) && IsOnlyUsedInZeroEqualityComparison(CI)) {
756 LHS = B.CreateBitCast(LHS, PointerType::getUnqual(Type::Int16Ty), "tmp");
757 RHS = B.CreateBitCast(RHS, LHS->getType(), "tmp");
758 LoadInst *LHSV = B.CreateLoad(LHS, "lhsv");
759 LoadInst *RHSV = B.CreateLoad(RHS, "rhsv");
760 LHSV->setAlignment(1); RHSV->setAlignment(1); // Unaligned loads.
761 return B.CreateZExt(B.CreateXor(LHSV, RHSV, "shortdiff"), CI->getType());
768 //===---------------------------------------===//
769 // 'memcpy' Optimizations
771 struct VISIBILITY_HIDDEN MemCpyOpt : public LibCallOptimization {
772 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
773 const FunctionType *FT = Callee->getFunctionType();
774 if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
775 !isa<PointerType>(FT->getParamType(0)) ||
776 !isa<PointerType>(FT->getParamType(1)) ||
777 FT->getParamType(2) != TD->getIntPtrType())
780 // memcpy(x, y, n) -> llvm.memcpy(x, y, n, 1)
781 EmitMemCpy(CI->getOperand(1), CI->getOperand(2), CI->getOperand(3), 1, B);
782 return CI->getOperand(1);
786 //===----------------------------------------------------------------------===//
787 // Math Library Optimizations
788 //===----------------------------------------------------------------------===//
790 //===---------------------------------------===//
791 // 'pow*' Optimizations
793 struct VISIBILITY_HIDDEN PowOpt : public LibCallOptimization {
794 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
795 const FunctionType *FT = Callee->getFunctionType();
796 // Just make sure this has 2 arguments of the same FP type, which match the
798 if (FT->getNumParams() != 2 || FT->getReturnType() != FT->getParamType(0) ||
799 FT->getParamType(0) != FT->getParamType(1) ||
800 !FT->getParamType(0)->isFloatingPoint())
803 Value *Op1 = CI->getOperand(1), *Op2 = CI->getOperand(2);
804 if (ConstantFP *Op1C = dyn_cast<ConstantFP>(Op1)) {
805 if (Op1C->isExactlyValue(1.0)) // pow(1.0, x) -> 1.0
807 if (Op1C->isExactlyValue(2.0)) // pow(2.0, x) -> exp2(x)
808 return EmitUnaryFloatFnCall(Op2, "exp2", B);
811 ConstantFP *Op2C = dyn_cast<ConstantFP>(Op2);
812 if (Op2C == 0) return 0;
814 if (Op2C->getValueAPF().isZero()) // pow(x, 0.0) -> 1.0
815 return ConstantFP::get(CI->getType(), 1.0);
817 if (Op2C->isExactlyValue(0.5)) {
818 // FIXME: This is not safe for -0.0 and -inf. This can only be done when
819 // 'unsafe' math optimizations are allowed.
820 // x pow(x, 0.5) sqrt(x)
821 // ---------------------------------------------
825 // pow(x, 0.5) -> sqrt(x)
826 return B.CreateCall(get_sqrt(), Op1, "sqrt");
830 if (Op2C->isExactlyValue(1.0)) // pow(x, 1.0) -> x
832 if (Op2C->isExactlyValue(2.0)) // pow(x, 2.0) -> x*x
833 return B.CreateMul(Op1, Op1, "pow2");
834 if (Op2C->isExactlyValue(-1.0)) // pow(x, -1.0) -> 1.0/x
835 return B.CreateFDiv(ConstantFP::get(CI->getType(), 1.0), Op1, "powrecip");
840 //===---------------------------------------===//
841 // 'exp2' Optimizations
843 struct VISIBILITY_HIDDEN Exp2Opt : public LibCallOptimization {
844 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
845 const FunctionType *FT = Callee->getFunctionType();
846 // Just make sure this has 1 argument of FP type, which matches the
848 if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) ||
849 !FT->getParamType(0)->isFloatingPoint())
852 Value *Op = CI->getOperand(1);
853 // Turn exp2(sitofp(x)) -> ldexp(1.0, sext(x)) if sizeof(x) <= 32
854 // Turn exp2(uitofp(x)) -> ldexp(1.0, zext(x)) if sizeof(x) < 32
856 if (SIToFPInst *OpC = dyn_cast<SIToFPInst>(Op)) {
857 if (OpC->getOperand(0)->getType()->getPrimitiveSizeInBits() <= 32)
858 LdExpArg = B.CreateSExt(OpC->getOperand(0), Type::Int32Ty, "tmp");
859 } else if (UIToFPInst *OpC = dyn_cast<UIToFPInst>(Op)) {
860 if (OpC->getOperand(0)->getType()->getPrimitiveSizeInBits() < 32)
861 LdExpArg = B.CreateZExt(OpC->getOperand(0), Type::Int32Ty, "tmp");
866 if (Op->getType() == Type::FloatTy)
868 else if (Op->getType() == Type::DoubleTy)
873 Constant *One = ConstantFP::get(APFloat(1.0f));
874 if (Op->getType() != Type::FloatTy)
875 One = ConstantExpr::getFPExtend(One, Op->getType());
877 Module *M = Caller->getParent();
878 Value *Callee = M->getOrInsertFunction(Name, Op->getType(),
879 Op->getType(), Type::Int32Ty,NULL);
880 return B.CreateCall2(Callee, One, LdExpArg);
887 //===---------------------------------------===//
888 // Double -> Float Shrinking Optimizations for Unary Functions like 'floor'
890 struct VISIBILITY_HIDDEN UnaryDoubleFPOpt : public LibCallOptimization {
891 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
892 const FunctionType *FT = Callee->getFunctionType();
893 if (FT->getNumParams() != 1 || FT->getReturnType() != Type::DoubleTy ||
894 FT->getParamType(0) != Type::DoubleTy)
897 // If this is something like 'floor((double)floatval)', convert to floorf.
898 FPExtInst *Cast = dyn_cast<FPExtInst>(CI->getOperand(1));
899 if (Cast == 0 || Cast->getOperand(0)->getType() != Type::FloatTy)
902 // floor((double)floatval) -> (double)floorf(floatval)
903 Value *V = Cast->getOperand(0);
904 V = EmitUnaryFloatFnCall(V, Callee->getNameStart(), B);
905 return B.CreateFPExt(V, Type::DoubleTy);
909 //===----------------------------------------------------------------------===//
910 // Integer Optimizations
911 //===----------------------------------------------------------------------===//
913 //===---------------------------------------===//
914 // 'ffs*' Optimizations
916 struct VISIBILITY_HIDDEN FFSOpt : public LibCallOptimization {
917 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
918 const FunctionType *FT = Callee->getFunctionType();
919 // Just make sure this has 2 arguments of the same FP type, which match the
921 if (FT->getNumParams() != 1 || FT->getReturnType() != Type::Int32Ty ||
922 !isa<IntegerType>(FT->getParamType(0)))
925 Value *Op = CI->getOperand(1);
928 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op)) {
929 if (CI->getValue() == 0) // ffs(0) -> 0.
930 return Constant::getNullValue(CI->getType());
931 return ConstantInt::get(Type::Int32Ty, // ffs(c) -> cttz(c)+1
932 CI->getValue().countTrailingZeros()+1);
935 // ffs(x) -> x != 0 ? (i32)llvm.cttz(x)+1 : 0
936 const Type *ArgType = Op->getType();
937 Value *F = Intrinsic::getDeclaration(Callee->getParent(),
938 Intrinsic::cttz, &ArgType, 1);
939 Value *V = B.CreateCall(F, Op, "cttz");
940 V = B.CreateAdd(V, ConstantInt::get(Type::Int32Ty, 1), "tmp");
941 V = B.CreateIntCast(V, Type::Int32Ty, false, "tmp");
943 Value *Cond = B.CreateICmpNE(Op, Constant::getNullValue(ArgType), "tmp");
944 return B.CreateSelect(Cond, V, ConstantInt::get(Type::Int32Ty, 0));
948 //===---------------------------------------===//
949 // 'isdigit' Optimizations
951 struct VISIBILITY_HIDDEN IsDigitOpt : public LibCallOptimization {
952 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
953 const FunctionType *FT = Callee->getFunctionType();
954 // We require integer(i32)
955 if (FT->getNumParams() != 1 || !isa<IntegerType>(FT->getReturnType()) ||
956 FT->getParamType(0) != Type::Int32Ty)
959 // isdigit(c) -> (c-'0') <u 10
960 Value *Op = CI->getOperand(1);
961 Op = B.CreateSub(Op, ConstantInt::get(Type::Int32Ty, '0'), "isdigittmp");
962 Op = B.CreateICmpULT(Op, ConstantInt::get(Type::Int32Ty, 10), "isdigit");
963 return B.CreateZExt(Op, CI->getType());
967 //===---------------------------------------===//
968 // 'isascii' Optimizations
970 struct VISIBILITY_HIDDEN IsAsciiOpt : public LibCallOptimization {
971 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
972 const FunctionType *FT = Callee->getFunctionType();
973 // We require integer(i32)
974 if (FT->getNumParams() != 1 || !isa<IntegerType>(FT->getReturnType()) ||
975 FT->getParamType(0) != Type::Int32Ty)
978 // isascii(c) -> c <u 128
979 Value *Op = CI->getOperand(1);
980 Op = B.CreateICmpULT(Op, ConstantInt::get(Type::Int32Ty, 128), "isascii");
981 return B.CreateZExt(Op, CI->getType());
985 //===---------------------------------------===//
986 // 'toascii' Optimizations
988 struct VISIBILITY_HIDDEN ToAsciiOpt : public LibCallOptimization {
989 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
990 const FunctionType *FT = Callee->getFunctionType();
991 // We require i32(i32)
992 if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) ||
993 FT->getParamType(0) != Type::Int32Ty)
996 // isascii(c) -> c & 0x7f
997 return B.CreateAnd(CI->getOperand(1), ConstantInt::get(CI->getType(),0x7F));
1001 //===----------------------------------------------------------------------===//
1002 // Formatting and IO Optimizations
1003 //===----------------------------------------------------------------------===//
1005 //===---------------------------------------===//
1006 // 'printf' Optimizations
1008 struct VISIBILITY_HIDDEN PrintFOpt : public LibCallOptimization {
1009 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
1010 // Require one fixed pointer argument and an integer/void result.
1011 const FunctionType *FT = Callee->getFunctionType();
1012 if (FT->getNumParams() < 1 || !isa<PointerType>(FT->getParamType(0)) ||
1013 !(isa<IntegerType>(FT->getReturnType()) ||
1014 FT->getReturnType() == Type::VoidTy))
1017 // Check for a fixed format string.
1018 std::string FormatStr;
1019 if (!GetConstantStringInfo(CI->getOperand(1), FormatStr))
1022 // Empty format string -> noop.
1023 if (FormatStr.empty()) // Tolerate printf's declared void.
1024 return CI->use_empty() ? (Value*)CI : ConstantInt::get(CI->getType(), 0);
1026 // printf("x") -> putchar('x'), even for '%'.
1027 if (FormatStr.size() == 1) {
1028 EmitPutChar(ConstantInt::get(Type::Int32Ty, FormatStr[0]), B);
1029 return CI->use_empty() ? (Value*)CI : ConstantInt::get(CI->getType(), 1);
1032 // printf("foo\n") --> puts("foo")
1033 if (FormatStr[FormatStr.size()-1] == '\n' &&
1034 FormatStr.find('%') == std::string::npos) { // no format characters.
1035 // Create a string literal with no \n on it. We expect the constant merge
1036 // pass to be run after this pass, to merge duplicate strings.
1037 FormatStr.erase(FormatStr.end()-1);
1038 Constant *C = ConstantArray::get(FormatStr, true);
1039 C = new GlobalVariable(C->getType(), true,GlobalVariable::InternalLinkage,
1040 C, "str", Callee->getParent());
1042 return CI->use_empty() ? (Value*)CI :
1043 ConstantInt::get(CI->getType(), FormatStr.size()+1);
1046 // Optimize specific format strings.
1047 // printf("%c", chr) --> putchar(*(i8*)dst)
1048 if (FormatStr == "%c" && CI->getNumOperands() > 2 &&
1049 isa<IntegerType>(CI->getOperand(2)->getType())) {
1050 EmitPutChar(CI->getOperand(2), B);
1051 return CI->use_empty() ? (Value*)CI : ConstantInt::get(CI->getType(), 1);
1054 // printf("%s\n", str) --> puts(str)
1055 if (FormatStr == "%s\n" && CI->getNumOperands() > 2 &&
1056 isa<PointerType>(CI->getOperand(2)->getType()) &&
1058 EmitPutS(CI->getOperand(2), B);
1065 //===---------------------------------------===//
1066 // 'sprintf' Optimizations
1068 struct VISIBILITY_HIDDEN SPrintFOpt : public LibCallOptimization {
1069 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
1070 // Require two fixed pointer arguments and an integer result.
1071 const FunctionType *FT = Callee->getFunctionType();
1072 if (FT->getNumParams() != 2 || !isa<PointerType>(FT->getParamType(0)) ||
1073 !isa<PointerType>(FT->getParamType(1)) ||
1074 !isa<IntegerType>(FT->getReturnType()))
1077 // Check for a fixed format string.
1078 std::string FormatStr;
1079 if (!GetConstantStringInfo(CI->getOperand(2), FormatStr))
1082 // If we just have a format string (nothing else crazy) transform it.
1083 if (CI->getNumOperands() == 3) {
1084 // Make sure there's no % in the constant array. We could try to handle
1085 // %% -> % in the future if we cared.
1086 for (unsigned i = 0, e = FormatStr.size(); i != e; ++i)
1087 if (FormatStr[i] == '%')
1088 return 0; // we found a format specifier, bail out.
1090 // sprintf(str, fmt) -> llvm.memcpy(str, fmt, strlen(fmt)+1, 1)
1091 EmitMemCpy(CI->getOperand(1), CI->getOperand(2), // Copy the nul byte.
1092 ConstantInt::get(TD->getIntPtrType(), FormatStr.size()+1),1,B);
1093 return ConstantInt::get(CI->getType(), FormatStr.size());
1096 // The remaining optimizations require the format string to be "%s" or "%c"
1097 // and have an extra operand.
1098 if (FormatStr.size() != 2 || FormatStr[0] != '%' || CI->getNumOperands() <4)
1101 // Decode the second character of the format string.
1102 if (FormatStr[1] == 'c') {
1103 // sprintf(dst, "%c", chr) --> *(i8*)dst = chr; *((i8*)dst+1) = 0
1104 if (!isa<IntegerType>(CI->getOperand(3)->getType())) return 0;
1105 Value *V = B.CreateTrunc(CI->getOperand(3), Type::Int8Ty, "char");
1106 Value *Ptr = CastToCStr(CI->getOperand(1), B);
1107 B.CreateStore(V, Ptr);
1108 Ptr = B.CreateGEP(Ptr, ConstantInt::get(Type::Int32Ty, 1), "nul");
1109 B.CreateStore(Constant::getNullValue(Type::Int8Ty), Ptr);
1111 return ConstantInt::get(CI->getType(), 1);
1114 if (FormatStr[1] == 's') {
1115 // sprintf(dest, "%s", str) -> llvm.memcpy(dest, str, strlen(str)+1, 1)
1116 if (!isa<PointerType>(CI->getOperand(3)->getType())) return 0;
1118 Value *Len = EmitStrLen(CI->getOperand(3), B);
1119 Value *IncLen = B.CreateAdd(Len, ConstantInt::get(Len->getType(), 1),
1121 EmitMemCpy(CI->getOperand(1), CI->getOperand(3), IncLen, 1, B);
1123 // The sprintf result is the unincremented number of bytes in the string.
1124 return B.CreateIntCast(Len, CI->getType(), false);
1130 //===---------------------------------------===//
1131 // 'fwrite' Optimizations
1133 struct VISIBILITY_HIDDEN FWriteOpt : public LibCallOptimization {
1134 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
1135 // Require a pointer, an integer, an integer, a pointer, returning integer.
1136 const FunctionType *FT = Callee->getFunctionType();
1137 if (FT->getNumParams() != 4 || !isa<PointerType>(FT->getParamType(0)) ||
1138 !isa<IntegerType>(FT->getParamType(1)) ||
1139 !isa<IntegerType>(FT->getParamType(2)) ||
1140 !isa<PointerType>(FT->getParamType(3)) ||
1141 !isa<IntegerType>(FT->getReturnType()))
1144 // Get the element size and count.
1145 ConstantInt *SizeC = dyn_cast<ConstantInt>(CI->getOperand(2));
1146 ConstantInt *CountC = dyn_cast<ConstantInt>(CI->getOperand(3));
1147 if (!SizeC || !CountC) return 0;
1148 uint64_t Bytes = SizeC->getZExtValue()*CountC->getZExtValue();
1150 // If this is writing zero records, remove the call (it's a noop).
1152 return ConstantInt::get(CI->getType(), 0);
1154 // If this is writing one byte, turn it into fputc.
1155 if (Bytes == 1) { // fwrite(S,1,1,F) -> fputc(S[0],F)
1156 Value *Char = B.CreateLoad(CastToCStr(CI->getOperand(1), B), "char");
1157 EmitFPutC(Char, CI->getOperand(4), B);
1158 return ConstantInt::get(CI->getType(), 1);
1165 //===---------------------------------------===//
1166 // 'fputs' Optimizations
1168 struct VISIBILITY_HIDDEN FPutsOpt : public LibCallOptimization {
1169 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
1170 // Require two pointers. Also, we can't optimize if return value is used.
1171 const FunctionType *FT = Callee->getFunctionType();
1172 if (FT->getNumParams() != 2 || !isa<PointerType>(FT->getParamType(0)) ||
1173 !isa<PointerType>(FT->getParamType(1)) ||
1177 // fputs(s,F) --> fwrite(s,1,strlen(s),F)
1178 uint64_t Len = GetStringLength(CI->getOperand(1));
1180 EmitFWrite(CI->getOperand(1), ConstantInt::get(TD->getIntPtrType(), Len-1),
1181 CI->getOperand(2), B);
1182 return CI; // Known to have no uses (see above).
1186 //===---------------------------------------===//
1187 // 'fprintf' Optimizations
1189 struct VISIBILITY_HIDDEN FPrintFOpt : public LibCallOptimization {
1190 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder &B) {
1191 // Require two fixed paramters as pointers and integer result.
1192 const FunctionType *FT = Callee->getFunctionType();
1193 if (FT->getNumParams() != 2 || !isa<PointerType>(FT->getParamType(0)) ||
1194 !isa<PointerType>(FT->getParamType(1)) ||
1195 !isa<IntegerType>(FT->getReturnType()))
1198 // All the optimizations depend on the format string.
1199 std::string FormatStr;
1200 if (!GetConstantStringInfo(CI->getOperand(2), FormatStr))
1203 // fprintf(F, "foo") --> fwrite("foo", 3, 1, F)
1204 if (CI->getNumOperands() == 3) {
1205 for (unsigned i = 0, e = FormatStr.size(); i != e; ++i)
1206 if (FormatStr[i] == '%') // Could handle %% -> % if we cared.
1207 return 0; // We found a format specifier.
1209 EmitFWrite(CI->getOperand(2), ConstantInt::get(TD->getIntPtrType(),
1211 CI->getOperand(1), B);
1212 return ConstantInt::get(CI->getType(), FormatStr.size());
1215 // The remaining optimizations require the format string to be "%s" or "%c"
1216 // and have an extra operand.
1217 if (FormatStr.size() != 2 || FormatStr[0] != '%' || CI->getNumOperands() <4)
1220 // Decode the second character of the format string.
1221 if (FormatStr[1] == 'c') {
1222 // fprintf(F, "%c", chr) --> *(i8*)dst = chr
1223 if (!isa<IntegerType>(CI->getOperand(3)->getType())) return 0;
1224 EmitFPutC(CI->getOperand(3), CI->getOperand(1), B);
1225 return ConstantInt::get(CI->getType(), 1);
1228 if (FormatStr[1] == 's') {
1229 // fprintf(F, "%s", str) -> fputs(str, F)
1230 if (!isa<PointerType>(CI->getOperand(3)->getType()) || !CI->use_empty())
1232 EmitFPutS(CI->getOperand(3), CI->getOperand(1), B);
1240 //===----------------------------------------------------------------------===//
1241 // SimplifyLibCalls Pass Implementation
1242 //===----------------------------------------------------------------------===//
1245 /// This pass optimizes well known library functions from libc and libm.
1247 class VISIBILITY_HIDDEN SimplifyLibCalls : public FunctionPass {
1248 StringMap<LibCallOptimization*> Optimizations;
1249 // Miscellaneous LibCall Optimizations
1251 // String and Memory LibCall Optimizations
1252 StrCatOpt StrCat; StrChrOpt StrChr; StrCmpOpt StrCmp; StrNCmpOpt StrNCmp;
1253 StrCpyOpt StrCpy; StrLenOpt StrLen; MemCmpOpt MemCmp; MemCpyOpt MemCpy;
1254 // Math Library Optimizations
1255 PowOpt Pow; Exp2Opt Exp2; UnaryDoubleFPOpt UnaryDoubleFP;
1256 // Integer Optimizations
1257 FFSOpt FFS; IsDigitOpt IsDigit; IsAsciiOpt IsAscii; ToAsciiOpt ToAscii;
1258 // Formatting and IO Optimizations
1259 SPrintFOpt SPrintF; PrintFOpt PrintF;
1260 FWriteOpt FWrite; FPutsOpt FPuts; FPrintFOpt FPrintF;
1262 static char ID; // Pass identification
1263 SimplifyLibCalls() : FunctionPass((intptr_t)&ID) {}
1265 void InitOptimizations();
1266 bool runOnFunction(Function &F);
1268 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
1269 AU.addRequired<TargetData>();
1272 char SimplifyLibCalls::ID = 0;
1273 } // end anonymous namespace.
1275 static RegisterPass<SimplifyLibCalls>
1276 X("simplify-libcalls", "Simplify well-known library calls");
1278 // Public interface to the Simplify LibCalls pass.
1279 FunctionPass *llvm::createSimplifyLibCallsPass() {
1280 return new SimplifyLibCalls();
1283 /// Optimizations - Populate the Optimizations map with all the optimizations
1285 void SimplifyLibCalls::InitOptimizations() {
1286 // Miscellaneous LibCall Optimizations
1287 Optimizations["exit"] = &Exit;
1289 // String and Memory LibCall Optimizations
1290 Optimizations["strcat"] = &StrCat;
1291 Optimizations["strchr"] = &StrChr;
1292 Optimizations["strcmp"] = &StrCmp;
1293 Optimizations["strncmp"] = &StrNCmp;
1294 Optimizations["strcpy"] = &StrCpy;
1295 Optimizations["strlen"] = &StrLen;
1296 Optimizations["memcmp"] = &MemCmp;
1297 Optimizations["memcpy"] = &MemCpy;
1299 // Math Library Optimizations
1300 Optimizations["powf"] = &Pow;
1301 Optimizations["pow"] = &Pow;
1302 Optimizations["powl"] = &Pow;
1303 Optimizations["exp2l"] = &Exp2;
1304 Optimizations["exp2"] = &Exp2;
1305 Optimizations["exp2f"] = &Exp2;
1308 Optimizations["floor"] = &UnaryDoubleFP;
1311 Optimizations["ceil"] = &UnaryDoubleFP;
1314 Optimizations["round"] = &UnaryDoubleFP;
1317 Optimizations["rint"] = &UnaryDoubleFP;
1319 #ifdef HAVE_NEARBYINTF
1320 Optimizations["nearbyint"] = &UnaryDoubleFP;
1323 // Integer Optimizations
1324 Optimizations["ffs"] = &FFS;
1325 Optimizations["ffsl"] = &FFS;
1326 Optimizations["ffsll"] = &FFS;
1327 Optimizations["isdigit"] = &IsDigit;
1328 Optimizations["isascii"] = &IsAscii;
1329 Optimizations["toascii"] = &ToAscii;
1331 // Formatting and IO Optimizations
1332 Optimizations["sprintf"] = &SPrintF;
1333 Optimizations["printf"] = &PrintF;
1334 Optimizations["fwrite"] = &FWrite;
1335 Optimizations["fputs"] = &FPuts;
1336 Optimizations["fprintf"] = &FPrintF;
1340 /// runOnFunction - Top level algorithm.
1342 bool SimplifyLibCalls::runOnFunction(Function &F) {
1343 if (Optimizations.empty())
1344 InitOptimizations();
1346 const TargetData &TD = getAnalysis<TargetData>();
1350 bool Changed = false;
1351 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
1352 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
1353 // Ignore non-calls.
1354 CallInst *CI = dyn_cast<CallInst>(I++);
1357 // Ignore indirect calls and calls to non-external functions.
1358 Function *Callee = CI->getCalledFunction();
1359 if (Callee == 0 || !Callee->isDeclaration() ||
1360 !(Callee->hasExternalLinkage() || Callee->hasDLLImportLinkage()))
1363 // Ignore unknown calls.
1364 const char *CalleeName = Callee->getNameStart();
1365 StringMap<LibCallOptimization*>::iterator OMI =
1366 Optimizations.find(CalleeName, CalleeName+Callee->getNameLen());
1367 if (OMI == Optimizations.end()) continue;
1369 // Set the builder to the instruction after the call.
1370 Builder.SetInsertPoint(BB, I);
1372 // Try to optimize this call.
1373 Value *Result = OMI->second->OptimizeCall(CI, TD, Builder);
1374 if (Result == 0) continue;
1376 DEBUG(DOUT << "SimplifyLibCalls simplified: " << *CI;
1377 DOUT << " into: " << *Result << "\n");
1379 // Something changed!
1383 // Inspect the instruction after the call (which was potentially just
1387 if (CI != Result && !CI->use_empty()) {
1388 CI->replaceAllUsesWith(Result);
1389 if (!Result->hasName())
1390 Result->takeName(CI);
1392 CI->eraseFromParent();
1400 // Additional cases that we need to add to this file:
1403 // * cbrt(expN(X)) -> expN(x/3)
1404 // * cbrt(sqrt(x)) -> pow(x,1/6)
1405 // * cbrt(sqrt(x)) -> pow(x,1/9)
1408 // * cos(-x) -> cos(x)
1411 // * exp(log(x)) -> x
1414 // * log(exp(x)) -> x
1415 // * log(x**y) -> y*log(x)
1416 // * log(exp(y)) -> y*log(e)
1417 // * log(exp2(y)) -> y*log(2)
1418 // * log(exp10(y)) -> y*log(10)
1419 // * log(sqrt(x)) -> 0.5*log(x)
1420 // * log(pow(x,y)) -> y*log(x)
1422 // lround, lroundf, lroundl:
1423 // * lround(cnst) -> cnst'
1426 // * memcmp(x,y,l) -> cnst
1427 // (if all arguments are constant and strlen(x) <= l and strlen(y) <= l)
1430 // * memmove(d,s,l,a) -> memcpy(d,s,l,a)
1431 // (if s is a global constant array)
1434 // * pow(exp(x),y) -> exp(x*y)
1435 // * pow(sqrt(x),y) -> pow(x,y*0.5)
1436 // * pow(pow(x,y),z)-> pow(x,y*z)
1439 // * puts("") -> putchar("\n")
1441 // round, roundf, roundl:
1442 // * round(cnst) -> cnst'
1445 // * signbit(cnst) -> cnst'
1446 // * signbit(nncst) -> 0 (if pstv is a non-negative constant)
1448 // sqrt, sqrtf, sqrtl:
1449 // * sqrt(expN(x)) -> expN(x*0.5)
1450 // * sqrt(Nroot(x)) -> pow(x,1/(2*N))
1451 // * sqrt(pow(x,y)) -> pow(|x|,y*0.5)
1454 // * stpcpy(str, "literal") ->
1455 // llvm.memcpy(str,"literal",strlen("literal")+1,1)
1457 // * strrchr(s,c) -> reverse_offset_of_in(c,s)
1458 // (if c is a constant integer and s is a constant string)
1459 // * strrchr(s1,0) -> strchr(s1,0)
1462 // * strncat(x,y,0) -> x
1463 // * strncat(x,y,0) -> x (if strlen(y) = 0)
1464 // * strncat(x,y,l) -> strcat(x,y) (if y and l are constants an l > strlen(y))
1467 // * strncpy(d,s,0) -> d
1468 // * strncpy(d,s,l) -> memcpy(d,s,l,1)
1469 // (if s and l are constants)
1472 // * strpbrk(s,a) -> offset_in_for(s,a)
1473 // (if s and a are both constant strings)
1474 // * strpbrk(s,"") -> 0
1475 // * strpbrk(s,a) -> strchr(s,a[0]) (if a is constant string of length 1)
1478 // * strspn(s,a) -> const_int (if both args are constant)
1479 // * strspn("",a) -> 0
1480 // * strspn(s,"") -> 0
1481 // * strcspn(s,a) -> const_int (if both args are constant)
1482 // * strcspn("",a) -> 0
1483 // * strcspn(s,"") -> strlen(a)
1486 // * strstr(x,x) -> x
1487 // * strstr(s1,s2) -> offset_of_s2_in(s1)
1488 // (if s1 and s2 are constant strings)
1491 // * tan(atan(x)) -> x
1493 // trunc, truncf, truncl:
1494 // * trunc(cnst) -> cnst'