//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Intrinsics.h"
+#include "llvm/IntrinsicInst.h"
#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Target/TargetData.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
#include <cerrno>
-#include <cmath>
using namespace llvm;
//===----------------------------------------------------------------------===//
/// doConstantPropagation - If an instruction references constants, try to fold
/// them together...
///
-bool llvm::doConstantPropagation(BasicBlock::iterator &II) {
- if (Constant *C = ConstantFoldInstruction(II)) {
+bool llvm::doConstantPropagation(BasicBlock::iterator &II,
+ const TargetData *TD) {
+ if (Constant *C = ConstantFoldInstruction(II, TD)) {
// Replaces all of the uses of a variable with uses of the constant.
II->replaceAllUsesWith(C);
return false;
}
-/// ConstantFoldInstruction - Attempt to constant fold the specified
-/// instruction. If successful, the constant result is returned, if not, null
-/// is returned. Note that this function can only fail when attempting to fold
-/// instructions like loads and stores, which have no constant expression form.
-///
-Constant *llvm::ConstantFoldInstruction(Instruction *I) {
- if (PHINode *PN = dyn_cast<PHINode>(I)) {
- if (PN->getNumIncomingValues() == 0)
- return Constant::getNullValue(PN->getType());
-
- Constant *Result = dyn_cast<Constant>(PN->getIncomingValue(0));
- if (Result == 0) return 0;
-
- // Handle PHI nodes specially here...
- for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i)
- if (PN->getIncomingValue(i) != Result && PN->getIncomingValue(i) != PN)
- return 0; // Not all the same incoming constants...
-
- // If we reach here, all incoming values are the same constant.
- return Result;
- } else if (CallInst *CI = dyn_cast<CallInst>(I)) {
- if (Function *F = CI->getCalledFunction())
- if (canConstantFoldCallTo(F)) {
- std::vector<Constant*> Args;
- for (unsigned i = 1, e = CI->getNumOperands(); i != e; ++i)
- if (Constant *Op = dyn_cast<Constant>(CI->getOperand(i)))
- Args.push_back(Op);
- else
- return 0;
- return ConstantFoldCall(F, Args);
- }
- return 0;
- }
-
- Constant *Op0 = 0, *Op1 = 0;
- switch (I->getNumOperands()) {
- default:
- case 2:
- Op1 = dyn_cast<Constant>(I->getOperand(1));
- if (Op1 == 0) return 0; // Not a constant?, can't fold
- case 1:
- Op0 = dyn_cast<Constant>(I->getOperand(0));
- if (Op0 == 0) return 0; // Not a constant?, can't fold
- break;
- case 0: return 0;
- }
-
- if (isa<BinaryOperator>(I) || isa<ShiftInst>(I))
- return ConstantExpr::get(I->getOpcode(), Op0, Op1);
-
- switch (I->getOpcode()) {
- default: return 0;
- case Instruction::Cast:
- return ConstantExpr::getCast(Op0, I->getType());
- case Instruction::Select:
- if (Constant *Op2 = dyn_cast<Constant>(I->getOperand(2)))
- return ConstantExpr::getSelect(Op0, Op1, Op2);
- return 0;
- case Instruction::ExtractElement:
- return ConstantExpr::getExtractElement(Op0, Op1);
- case Instruction::InsertElement:
- if (Constant *Op2 = dyn_cast<Constant>(I->getOperand(2)))
- return ConstantExpr::getInsertElement(Op0, Op1, Op2);
- return 0;
- case Instruction::ShuffleVector:
- if (Constant *Op2 = dyn_cast<Constant>(I->getOperand(2)))
- return ConstantExpr::getShuffleVector(Op0, Op1, Op2);
- return 0;
- case Instruction::GetElementPtr:
- std::vector<Constant*> IdxList;
- IdxList.reserve(I->getNumOperands()-1);
- if (Op1) IdxList.push_back(Op1);
- for (unsigned i = 2, e = I->getNumOperands(); i != e; ++i)
- if (Constant *C = dyn_cast<Constant>(I->getOperand(i)))
- IdxList.push_back(C);
- else
- return 0; // Non-constant operand
- return ConstantExpr::getGetElementPtr(Op0, IdxList);
- }
-}
-
// ConstantFoldTerminator - If a terminator instruction is predicated on a
// constant value, convert it into an unconditional branch to the constant
// destination.
BasicBlock *Dest1 = cast<BasicBlock>(BI->getOperand(0));
BasicBlock *Dest2 = cast<BasicBlock>(BI->getOperand(1));
- if (ConstantBool *Cond = dyn_cast<ConstantBool>(BI->getCondition())) {
+ if (ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition())) {
// Are we branching on constant?
// YES. Change to unconditional branch...
- BasicBlock *Destination = Cond->getValue() ? Dest1 : Dest2;
- BasicBlock *OldDest = Cond->getValue() ? Dest2 : Dest1;
+ BasicBlock *Destination = Cond->getZExtValue() ? Dest1 : Dest2;
+ BasicBlock *OldDest = Cond->getZExtValue() ? Dest2 : Dest1;
//cerr << "Function: " << T->getParent()->getParent()
// << "\nRemoving branch from " << T->getParent()
} else if (SI->getNumSuccessors() == 2) {
// Otherwise, we can fold this switch into a conditional branch
// instruction if it has only one non-default destination.
- Value *Cond = new SetCondInst(Instruction::SetEQ, SI->getCondition(),
- SI->getSuccessorValue(1), "cond", SI);
+ Value *Cond = new ICmpInst(ICmpInst::ICMP_EQ, SI->getCondition(),
+ SI->getSuccessorValue(1), "cond", SI);
// Insert the new branch...
new BranchInst(SI->getSuccessor(1), SI->getSuccessor(0), Cond, SI);
return false;
}
-/// ConstantFoldLoadThroughGEPConstantExpr - Given a constant and a
-/// getelementptr constantexpr, return the constant value being addressed by the
-/// constant expression, or null if something is funny and we can't decide.
-Constant *llvm::ConstantFoldLoadThroughGEPConstantExpr(Constant *C,
- ConstantExpr *CE) {
- if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
- return 0; // Do not allow stepping over the value!
-
- // Loop over all of the operands, tracking down which value we are
- // addressing...
- gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
- for (++I; I != E; ++I)
- if (const StructType *STy = dyn_cast<StructType>(*I)) {
- ConstantUInt *CU = cast<ConstantUInt>(I.getOperand());
- assert(CU->getValue() < STy->getNumElements() &&
- "Struct index out of range!");
- unsigned El = (unsigned)CU->getValue();
- if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
- C = CS->getOperand(El);
- } else if (isa<ConstantAggregateZero>(C)) {
- C = Constant::getNullValue(STy->getElementType(El));
- } else if (isa<UndefValue>(C)) {
- C = UndefValue::get(STy->getElementType(El));
- } else {
- return 0;
- }
- } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
- if (const ArrayType *ATy = dyn_cast<ArrayType>(*I)) {
- if ((uint64_t)CI->getRawValue() >= ATy->getNumElements()) return 0;
- if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
- C = CA->getOperand((unsigned)CI->getRawValue());
- else if (isa<ConstantAggregateZero>(C))
- C = Constant::getNullValue(ATy->getElementType());
- else if (isa<UndefValue>(C))
- C = UndefValue::get(ATy->getElementType());
- else
- return 0;
- } else if (const PackedType *PTy = dyn_cast<PackedType>(*I)) {
- if ((uint64_t)CI->getRawValue() >= PTy->getNumElements()) return 0;
- if (ConstantPacked *CP = dyn_cast<ConstantPacked>(C))
- C = CP->getOperand((unsigned)CI->getRawValue());
- else if (isa<ConstantAggregateZero>(C))
- C = Constant::getNullValue(PTy->getElementType());
- else if (isa<UndefValue>(C))
- C = UndefValue::get(PTy->getElementType());
- else
- return 0;
- } else {
- return 0;
- }
- } else {
- return 0;
- }
- return C;
-}
-
//===----------------------------------------------------------------------===//
// Local dead code elimination...
bool llvm::isInstructionTriviallyDead(Instruction *I) {
if (!I->use_empty() || isa<TerminatorInst>(I)) return false;
- if (!I->mayWriteToMemory()) return true;
+ if (!I->mayWriteToMemory())
+ return true;
- if (CallInst *CI = dyn_cast<CallInst>(I))
- if (Function *F = CI->getCalledFunction()) {
- unsigned IntrinsicID = F->getIntrinsicID();
-#define GET_SIDE_EFFECT_INFO
-#include "llvm/Intrinsics.gen"
-#undef GET_SIDE_EFFECT_INFO
- }
+ // Special case intrinsics that "may write to memory" but can be deleted when
+ // dead.
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
+ // Safe to delete llvm.stacksave if dead.
+ if (II->getIntrinsicID() == Intrinsic::stacksave)
+ return true;
+
return false;
}
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