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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66867 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling
2009-03-13 04:39:26 +00:00
parent c7a09ab311
commit 0582ae99ba
14 changed files with 233 additions and 254 deletions
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120
lib/Analysis/ValueTracking.cpp
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@ -17,10 +17,9 @@
#include "llvm/Instructions.h"
#include "llvm/GlobalVariable.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Target/TargetData.h"
#include <cstring>
using namespace llvm;
@ -929,7 +928,6 @@ Value *llvm::FindInsertedValue(Value *V, const unsigned *idx_begin,
return FindInsertedValue(I->getAggregateOperand(), Idxs.begin(), Idxs.end(),
InsertBefore);
}
// Otherwise, we don't know (such as, extracting from a function return value
// or load instruction)
return 0;
@ -938,86 +936,55 @@ Value *llvm::FindInsertedValue(Value *V, const unsigned *idx_begin,
/// GetConstantStringInfo - This function computes the length of a
/// null-terminated C string pointed to by V. If successful, it returns true
/// and returns the string in Str. If unsuccessful, it returns false.
const char *llvm::GetConstantStringInfo(Value *V, uint64_t Offset,
bool StopAtNul) {
static DenseMap<Value*, std::string> StringInfoMap;
static DenseMap<Value*, bool> NulMap;
// If we've already determined that the Value is NUL, then return 0.
if (NulMap[V])
return 0;
// Check to see if we've already calculated the string info.
if (StringInfoMap.find(V) != StringInfoMap.end())
return StringInfoMap.lookup(V).c_str();
// If V is NULL then return nul.
if (V == 0) {
NulMap[V] = true;
return 0;
}
std::string *Str = &StringInfoMap.FindAndConstruct(V).second;
Str->clear();
bool llvm::GetConstantStringInfo(Value *V, std::string &Str, uint64_t Offset,
bool StopAtNul) {
// If V is NULL then return false;
if (V == NULL) return false;
// Look through bitcast instructions.
if (BitCastInst *BCI = dyn_cast<BitCastInst>(V))
return GetConstantStringInfo(BCI->getOperand(0), Offset, StopAtNul);
return GetConstantStringInfo(BCI->getOperand(0), Str, Offset, StopAtNul);
// If the value is not a GEP instruction nor a constant expression with a
// GEP instruction, then return false because ConstantArray can't occur
// any other way
User *GEP = 0;
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
GEP = GEPI;
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
if (CE->getOpcode() == Instruction::BitCast)
return GetConstantStringInfo(CE->getOperand(0), Offset, StopAtNul);
if (CE->getOpcode() != Instruction::GetElementPtr) {
NulMap[V] = true;
return 0;
}
return GetConstantStringInfo(CE->getOperand(0), Str, Offset, StopAtNul);
if (CE->getOpcode() != Instruction::GetElementPtr)
return false;
GEP = CE;
}
if (GEP) {
// Make sure the GEP has exactly three arguments.
if (GEP->getNumOperands() != 3) {
NulMap[V] = true;
return 0;
}
if (GEP->getNumOperands() != 3)
return false;
// Make sure the index-ee is a pointer to array of i8.
const PointerType *PT = cast<PointerType>(GEP->getOperand(0)->getType());
const ArrayType *AT = dyn_cast<ArrayType>(PT->getElementType());
if (AT == 0 || AT->getElementType() != Type::Int8Ty) {
NulMap[V] = true;
return 0;
}
if (AT == 0 || AT->getElementType() != Type::Int8Ty)
return false;
// Check to make sure that the first operand of the GEP is an integer and
// has value 0 so that we are sure we're indexing into the initializer.
ConstantInt *FirstIdx = dyn_cast<ConstantInt>(GEP->getOperand(1));
if (FirstIdx == 0 || !FirstIdx->isZero()) {
NulMap[V] = true;
return 0;
}
if (FirstIdx == 0 || !FirstIdx->isZero())
return false;
// If the second index isn't a ConstantInt, then this is a variable index
// into the array. If this occurs, we can't say anything meaningful about
// the string.
uint64_t StartIdx = 0;
if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2))) {
if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
StartIdx = CI->getZExtValue();
} else {
NulMap[V] = true;
return 0;
}
return GetConstantStringInfo(GEP->getOperand(0), StartIdx + Offset,
else
return false;
return GetConstantStringInfo(GEP->getOperand(0), Str, StartIdx+Offset,
StopAtNul);
}
@ -1025,53 +992,42 @@ const char *llvm::GetConstantStringInfo(Value *V, uint64_t Offset,
// variable that is a constant and is initialized. The referenced constant
// initializer is the array that we'll use for optimization.
GlobalVariable* GV = dyn_cast<GlobalVariable>(V);
if (!GV || !GV->isConstant() || !GV->hasInitializer()) {
NulMap[V] = true;
return 0;
}
if (!GV || !GV->isConstant() || !GV->hasInitializer())
return false;
Constant *GlobalInit = GV->getInitializer();
// Handle the ConstantAggregateZero case
if (isa<ConstantAggregateZero>(GlobalInit))
if (isa<ConstantAggregateZero>(GlobalInit)) {
// This is a degenerate case. The initializer is constant zero so the
// length of the string must be zero.
return "";
Str.clear();
return true;
}
// Must be a Constant Array
ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
if (Array == 0 || Array->getType()->getElementType() != Type::Int8Ty) {
NulMap[V] = true;
return 0;
}
if (Array == 0 || Array->getType()->getElementType() != Type::Int8Ty)
return false;
// Get the number of elements in the array
uint64_t NumElts = Array->getType()->getNumElements();
if (Offset > NumElts) {
NulMap[V] = true;
return 0;
}
if (Offset > NumElts)
return false;
// Traverse the constant array from 'Offset' which is the place the GEP refers
// to in the array.
Str->reserve(NumElts - Offset);
Str.reserve(NumElts-Offset);
for (unsigned i = Offset; i != NumElts; ++i) {
Constant *Elt = Array->getOperand(i);
ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
if (!CI) { // This array isn't suitable, non-int initializer.
StringInfoMap.erase(V);
NulMap[V] = true;
return 0;
}
if (!CI) // This array isn't suitable, non-int initializer.
return false;
if (StopAtNul && CI->isZero())
return Str->c_str(); // we found end of string, success!
Str->operator+=((char)CI->getZExtValue());
return true; // we found end of string, success!
Str += (char)CI->getZExtValue();
}
// The array isn't null terminated, but maybe this is a memcpy, not a strcpy.
return Str->c_str();
return true;
}