6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-09-24 23:28:41 +00:00
Code Issues Projects Releases Wiki Activity

implement a simple instcombine xform that has been in the

Browse Source 
readme forever.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94318 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2010-01-23 18:49:30 +00:00
parent a9cf5b3cc9
commit 818ff34bc0
3 changed files with 44 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
lib/Transforms/InstCombine/InstCombineShifts.cpp
View File

@@ -12,6 +12,7 @@
//===----------------------------------------------------------------------===//
#include "InstCombine.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/Support/PatternMatch.h"
using namespace llvm;
using namespace PatternMatch;
@@ -69,10 +70,9 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
if (Op1->uge(TypeBits)) {
if (I.getOpcode() != Instruction::AShr)
return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
else {
I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1));
return &I;
}
// ashr i32 X, 32 --> ashr i32 X, 31
I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1));
return &I;
}
// ((X*C1) << C2) == (X * (C1 << C2))
@@ -387,7 +387,29 @@ Instruction *InstCombiner::visitShl(BinaryOperator &I) {
}
Instruction *InstCombiner::visitLShr(BinaryOperator &I) {
return commonShiftTransforms(I);
if (Instruction *R = commonShiftTransforms(I))
return R;
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1))
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Op0)) {
// ctlz.i32(x)>>5 --> zext(x == 0)
// cttz.i32(x)>>5 --> zext(x == 0)
// ctpop.i32(x)>>5 --> zext(x == -1)
if ((II->getIntrinsicID() == Intrinsic::ctlz ||
II->getIntrinsicID() == Intrinsic::cttz ||
II->getIntrinsicID() == Intrinsic::ctpop) &&
(1ULL << Op1C->getZExtValue()) ==
Op0->getType()->getScalarSizeInBits()) {
bool isCtPop = II->getIntrinsicID() == Intrinsic::ctpop;
Constant *RHS = ConstantInt::getSigned(Op0->getType(), isCtPop ? -1 : 0);
Value *Cmp = Builder->CreateICmpEQ(II->getOperand(1), RHS);
return new ZExtInst(Cmp, II->getType());
}
}
return 0;
}
Instruction *InstCombiner::visitAShr(BinaryOperator &I) {