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Implement test/Regression/Assembler/2004-03-07-FunctionAddressAlignment.llx

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llvm-svn: 12218
This commit is contained in:
Chris Lattner 2004-03-08 06:17:35 +00:00
parent cf72011426
commit 38c2e1d1df
1 changed files with 20 additions and 0 deletions
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20
lib/VMCore/ConstantFolding.cpp
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@ -22,6 +22,7 @@
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include <cmath>
using namespace llvm;
@ -523,6 +524,15 @@ Constant *llvm::ConstantFoldCastInstruction(const Constant *V,
const Type *DestTy) {
if (V->getType() == DestTy) return (Constant*)V;
// Cast of a global address to boolean is always true.
if (const ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(V))
if (DestTy == Type::BoolTy)
// FIXME: When we support 'external weak' references, we have to prevent
// this transformation from happening. In the meantime we avoid folding
// any cast of an external symbol.
if (!CPR->getValue()->isExternal())
return ConstantBool::True;
if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
if (CE->getOpcode() == Instruction::Cast) {
Constant *Op = const_cast<Constant*>(CE->getOperand(0));
@ -873,6 +883,16 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
if (cast<ConstantIntegral>(V2)->isAllOnesValue())
return const_cast<Constant*>(V1); // X & -1 == X
if (V2->isNullValue()) return const_cast<Constant*>(V2); // X & 0 == 0
if (CE1->getOpcode() == Instruction::Cast &&
isa<ConstantPointerRef>(CE1->getOperand(0))) {
ConstantPointerRef *CPR =cast<ConstantPointerRef>(CE1->getOperand(0));
// Functions are at least 4-byte aligned. If and'ing the address of a
// function with a constant < 4, fold it to zero.
if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
if (CI->getRawValue() < 4 && isa<Function>(CPR->getValue()))
return Constant::getNullValue(CI->getType());
}
break;
case Instruction::Or:
if (V2->isNullValue()) return const_cast<Constant*>(V1); // X | 0 == X