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Factor the GetGEPGlobalInitializer out of this pass and into Transforms/Utils 

as ConstantFoldLoadThroughGEPConstantExpr.

llvm-svn: 23445
This commit is contained in:
Chris Lattner 2005-09-26 05:28:06 +00:00
parent c13c7b9376
commit 0b011ec8e2
1 changed files with 2 additions and 44 deletions
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46
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
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@ -5149,49 +5149,6 @@ Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
}
/// GetGEPGlobalInitializer - Given a constant, and a getelementptr
/// constantexpr, return the constant value being addressed by the constant
/// expression, or null if something is funny.
///
static Constant *GetGEPGlobalInitializer(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())) {
const ArrayType *ATy = 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 {
return 0;
}
return C;
}
/// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
User *CI = cast<User>(LI.getOperand(0));
@ -5318,7 +5275,8 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
if (CE->getOpcode() == Instruction::GetElementPtr) {
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
if (GV->isConstant() && !GV->isExternal())
if (Constant *V = GetGEPGlobalInitializer(GV->getInitializer(), CE))
if (Constant *V =
ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
return ReplaceInstUsesWith(LI, V);
if (CE->getOperand(0)->isNullValue()) {
// Insert a new store to null instruction before the load to indicate