//===----------------------------------------------------------------------===//
#include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/Pass.h"
-#include "llvm/Argument.h"
-#include "llvm/iOther.h"
-#include "llvm/iMemory.h"
#include "llvm/Constants.h"
-#include "llvm/GlobalVariable.h"
#include "llvm/DerivedTypes.h"
+#include "llvm/Function.h"
+#include "llvm/GlobalVariable.h"
+#include "llvm/iOther.h"
+#include "llvm/iMemory.h"
+#include "llvm/Pass.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
using namespace llvm;
void llvm::BasicAAStub() {}
namespace {
- struct BasicAliasAnalysis : public ImmutablePass, public AliasAnalysis {
-
+ /// NoAA - This class implements the -no-aa pass, which always returns "I
+ /// don't know" for alias queries. NoAA is unlike other alias analysis
+ /// implementations, in that it does not chain to a previous analysis. As
+ /// such it doesn't follow many of the rules that other alias analyses must.
+ ///
+ struct NoAA : public ImmutablePass, public AliasAnalysis {
+ virtual AliasResult alias(const Value *V1, unsigned V1Size,
+ const Value *V2, unsigned V2Size) {
+ return MayAlias;
+ }
+
+ virtual void getMustAliases(Value *P, std::vector<Value*> &RetVals) { }
+ virtual bool pointsToConstantMemory(const Value *P) { return false; }
+ virtual bool doesNotAccessMemory(Function *F) { return false; }
+ virtual bool onlyReadsMemory(Function *F) { return false; }
+ virtual ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size) {
+ return ModRef;
+ }
+ virtual ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
+ return ModRef;
+ }
+ virtual bool hasNoModRefInfoForCalls() const { return true; }
+
+ virtual void deleteValue(Value *V) {}
+ virtual void copyValue(Value *From, Value *To) {}
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {}
+ };
+
+ // Register this pass...
+ RegisterOpt<NoAA>
+ U("no-aa", "No Alias Analysis (always returns 'may' alias)");
+
+ // Declare that we implement the AliasAnalysis interface
+ RegisterAnalysisGroup<AliasAnalysis, NoAA> V;
+} // End of anonymous namespace
+
+
+namespace {
+ /// BasicAliasAnalysis - This is the default alias analysis implementation.
+ /// Because it doesn't chain to a previous alias analysis (like -no-aa), it
+ /// derives from the NoAA class.
+ struct BasicAliasAnalysis : public NoAA {
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AliasAnalysis::getAnalysisUsage(AU);
+ AU.addRequired<TargetData>();
}
- virtual void initializePass();
+ virtual void initializePass() {
+ TD = &getAnalysis<TargetData>();
+ }
AliasResult alias(const Value *V1, unsigned V1Size,
const Value *V2, unsigned V2Size);
ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
+ /// hasNoModRefInfoForCalls - We have no way to test one call against
+ /// another, unless they are pure or const.
+ virtual bool hasNoModRefInfoForCalls() const { return true; }
+
/// pointsToConstantMemory - Chase pointers until we find a (constant
/// global) or not.
bool pointsToConstantMemory(const Value *P);
+ virtual bool doesNotAccessMemory(Function *F);
+ virtual bool onlyReadsMemory(Function *F);
+
private:
// CheckGEPInstructions - Check two GEP instructions with known
// must-aliasing base pointers. This checks to see if the index expressions
RegisterAnalysisGroup<AliasAnalysis, BasicAliasAnalysis, true> Y;
} // End of anonymous namespace
-void BasicAliasAnalysis::initializePass() {
- InitializeAliasAnalysis(this);
-}
-
// hasUniqueAddress - Return true if the specified value points to something
// with a unique, discernable, address.
static inline bool hasUniqueAddress(const Value *V) {
return NoModRef;
}
- // If P points to a constant memory location, the call definitely could not
- // modify the memory location.
- return pointsToConstantMemory(P) ? Ref : ModRef;
+ // The AliasAnalysis base class has some smarts, lets use them.
+ return AliasAnalysis::getModRefInfo(CS, P, Size);
}
// alias - Provide a bunch of ad-hoc rules to disambiguate in common cases, such
return MayAlias;
}
+static bool ValuesEqual(Value *V1, Value *V2) {
+ if (V1->getType() == V2->getType())
+ return V1 == V2;
+ if (Constant *C1 = dyn_cast<Constant>(V1))
+ if (Constant *C2 = dyn_cast<Constant>(V2)) {
+ // Sign extend the constants to long types.
+ C1 = ConstantExpr::getSignExtend(C1, Type::LongTy);
+ C2 = ConstantExpr::getSignExtend(C2, Type::LongTy);
+ return C1 == C2;
+ }
+ return false;
+}
+
/// CheckGEPInstructions - Check two GEP instructions with known must-aliasing
/// base pointers. This checks to see if the index expressions preclude the
/// pointers from aliasing...
unsigned MaxOperands = std::max(NumGEP1Operands, NumGEP2Operands);
unsigned UnequalOper = 0;
while (UnequalOper != MinOperands &&
- GEP1Ops[UnequalOper] == GEP2Ops[UnequalOper]) {
+ ValuesEqual(GEP1Ops[UnequalOper], GEP2Ops[UnequalOper])) {
// Advance through the type as we go...
++UnequalOper;
if (const CompositeType *CT = dyn_cast<CompositeType>(BasePtr1Ty))
if (SizeMax == ~0U) return MayAlias; // Avoid frivolous work...
// Scan for the first operand that is constant and unequal in the
- // two getelemenptrs...
+ // two getelementptrs...
unsigned FirstConstantOper = UnequalOper;
for (; FirstConstantOper != MinOperands; ++FirstConstantOper) {
const Value *G1Oper = GEP1Ops[FirstConstantOper];
if (G1Oper != G2Oper) // Found non-equal constant indexes...
if (Constant *G1OC = dyn_cast<Constant>(const_cast<Value*>(G1Oper)))
if (Constant *G2OC = dyn_cast<Constant>(const_cast<Value*>(G2Oper))) {
- // Make sure they are comparable (ie, not constant expressions)...
- // and make sure the GEP with the smaller leading constant is GEP1.
- Constant *Compare = ConstantExpr::get(Instruction::SetGT, G1OC, G2OC);
- if (ConstantBool *CV = dyn_cast<ConstantBool>(Compare)) {
- if (CV->getValue()) // If they are comparable and G2 > G1
- std::swap(GEP1Ops, GEP2Ops); // Make GEP1 < GEP2
- break;
+ if (G1OC->getType() != G2OC->getType()) {
+ // Sign extend both operands to long.
+ G1OC = ConstantExpr::getSignExtend(G1OC, Type::LongTy);
+ G2OC = ConstantExpr::getSignExtend(G2OC, Type::LongTy);
+ GEP1Ops[FirstConstantOper] = G1OC;
+ GEP2Ops[FirstConstantOper] = G2OC;
+ }
+
+ if (G1OC != G2OC) {
+ // Make sure they are comparable (ie, not constant expressions)...
+ // and make sure the GEP with the smaller leading constant is GEP1.
+ Constant *Compare = ConstantExpr::getSetGT(G1OC, G2OC);
+ if (ConstantBool *CV = dyn_cast<ConstantBool>(Compare)) {
+ if (CV->getValue()) // If they are comparable and G2 > G1
+ std::swap(GEP1Ops, GEP2Ops); // Make GEP1 < GEP2
+ break;
+ }
}
}
BasePtr1Ty = cast<CompositeType>(BasePtr1Ty)->getTypeAtIndex(G1Oper);
// point, the GEP instructions have run through all of their operands, and we
// haven't found evidence that there are any deltas between the GEP's.
// However, one GEP may have more operands than the other. If this is the
- // case, there may still be hope. This this now.
+ // case, there may still be hope. Check this now.
if (FirstConstantOper == MinOperands) {
// Make GEP1Ops be the longer one if there is a longer one.
if (GEP1Ops.size() < GEP2Ops.size())
// initial equal sequence of variables into constant zeros to start with.
for (unsigned i = 0; i != FirstConstantOper; ++i) {
if (!isa<Constant>(GEP1Ops[i]) || isa<ConstantExpr>(GEP1Ops[i]) ||
- !isa<Constant>(GEP2Ops[i]) || isa<ConstantExpr>(GEP2Ops[i])) {
- GEP1Ops[i] = Constant::getNullValue(GEP1Ops[i]->getType());
- GEP2Ops[i] = Constant::getNullValue(GEP2Ops[i]->getType());
- }
+ !isa<Constant>(GEP2Ops[i]) || isa<ConstantExpr>(GEP2Ops[i]))
+ GEP1Ops[i] = GEP2Ops[i] = Constant::getNullValue(Type::UIntTy);
}
// We know that GEP1Ops[FirstConstantOper] & GEP2Ops[FirstConstantOper] are ok
return MayAlias;
}
+namespace {
+ struct StringCompare {
+ bool operator()(const char *LHS, const char *RHS) {
+ return strcmp(LHS, RHS) < 0;
+ }
+ };
+}
+
+// Note that this list cannot contain libm functions (such as acos and sqrt)
+// that set errno on a domain or other error.
+static const char *DoesntAccessMemoryTable[] = {
+ // LLVM intrinsics:
+ "llvm.frameaddress", "llvm.returnaddress", "llvm.readport", "llvm.isnan",
+
+ "abs", "labs", "llabs", "imaxabs", "fabs", "fabsf", "fabsl",
+ "trunc", "truncf", "truncl", "ldexp",
+
+ "atan", "atanf", "atanl", "atan2", "atan2f", "atan2l",
+ "cbrt",
+ "cos", "cosf", "cosl", "cosh", "coshf", "coshl",
+ "exp", "expf", "expl",
+ "hypot",
+ "sin", "sinf", "sinl", "sinh", "sinhf", "sinhl",
+ "tan", "tanf", "tanl", "tanh", "tanhf", "tanhl",
+
+ // ctype.h
+ "isalnum", "isalpha", "iscntrl", "isdigit", "isgraph", "islower", "isprint"
+ "ispunct", "isspace", "isupper", "isxdigit", "tolower", "toupper",
+
+ // wctype.h"
+ "iswalnum", "iswalpha", "iswcntrl", "iswdigit", "iswgraph", "iswlower",
+ "iswprint", "iswpunct", "iswspace", "iswupper", "iswxdigit",
+
+ "iswctype", "towctrans", "towlower", "towupper",
+
+ "btowc", "wctob",
+
+ "isinf", "isnan", "finite",
+
+ // C99 math functions
+ "copysign", "copysignf", "copysignd",
+ "nexttoward", "nexttowardf", "nexttowardd",
+ "nextafter", "nextafterf", "nextafterd",
+
+ // glibc functions:
+ "__fpclassify", "__fpclassifyf", "__fpclassifyl",
+ "__signbit", "__signbitf", "__signbitl",
+};
+
+static const unsigned DAMTableSize =
+ sizeof(DoesntAccessMemoryTable)/sizeof(DoesntAccessMemoryTable[0]);
+
+/// doesNotAccessMemory - Return true if we know that the function does not
+/// access memory at all. Since basicaa does no analysis, we can only do simple
+/// things here. In particular, if we have an external function with the name
+/// of a standard C library function, we are allowed to assume it will be
+/// resolved by libc, so we can hardcode some entries in here.
+bool BasicAliasAnalysis::doesNotAccessMemory(Function *F) {
+ if (!F->isExternal()) return false;
+
+ static bool Initialized = false;
+ if (!Initialized) {
+ // Sort the table the first time through.
+ std::sort(DoesntAccessMemoryTable, DoesntAccessMemoryTable+DAMTableSize,
+ StringCompare());
+ Initialized = true;
+ }
+
+ const char **Ptr = std::lower_bound(DoesntAccessMemoryTable,
+ DoesntAccessMemoryTable+DAMTableSize,
+ F->getName().c_str(), StringCompare());
+ return Ptr != DoesntAccessMemoryTable+DAMTableSize && *Ptr == F->getName();
+}
+
+
+static const char *OnlyReadsMemoryTable[] = {
+ "atoi", "atol", "atof", "atoll", "atoq", "a64l",
+ "bcmp", "memcmp", "memchr", "memrchr", "wmemcmp", "wmemchr",
+
+ // Strings
+ "strcmp", "strcasecmp", "strcoll", "strncmp", "strncasecmp",
+ "strchr", "strcspn", "strlen", "strpbrk", "strrchr", "strspn", "strstr",
+ "index", "rindex",
+
+ // Wide char strings
+ "wcschr", "wcscmp", "wcscoll", "wcscspn", "wcslen", "wcsncmp", "wcspbrk",
+ "wcsrchr", "wcsspn", "wcsstr",
+
+ // glibc
+ "alphasort", "alphasort64", "versionsort", "versionsort64",
+
+ // C99
+ "nan", "nanf", "nand",
+
+ // File I/O
+ "feof", "ferror", "fileno",
+ "feof_unlocked", "ferror_unlocked", "fileno_unlocked"
+};
+
+static const unsigned ORMTableSize =
+ sizeof(OnlyReadsMemoryTable)/sizeof(OnlyReadsMemoryTable[0]);
+
+bool BasicAliasAnalysis::onlyReadsMemory(Function *F) {
+ if (doesNotAccessMemory(F)) return true;
+ if (!F->isExternal()) return false;
+
+ static bool Initialized = false;
+ if (!Initialized) {
+ // Sort the table the first time through.
+ std::sort(OnlyReadsMemoryTable, OnlyReadsMemoryTable+ORMTableSize,
+ StringCompare());
+ Initialized = true;
+ }
+
+ const char **Ptr = std::lower_bound(OnlyReadsMemoryTable,
+ OnlyReadsMemoryTable+ORMTableSize,
+ F->getName().c_str(), StringCompare());
+ return Ptr != OnlyReadsMemoryTable+ORMTableSize && *Ptr == F->getName();
+}
+
+
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