6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-01-12 17:32:19 +00:00
Code Issues Projects Releases Wiki Activity

remove two trunc xforms that are subsumed by EvaluateInDifferentType.

Browse Source 
The only difference is that EvaluateInDifferentType checks to ensure
they are profitable before doing them :)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92788 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2010-01-05 22:01:41 +00:00
parent c04d3d37e4
commit c0f79af143
2 changed files with 2 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
lib/Transforms/InstCombine/InstCombineCasts.cpp
View File

@ -628,7 +628,6 @@ Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
return 0;
}
Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
if (Instruction *Result = commonIntCastTransforms(CI))
return Result;
@ -646,41 +645,6 @@ Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
return new ICmpInst(ICmpInst::ICMP_NE, Src, Zero);
}
// Optimize trunc(lshr(x, c)) to pull the shift through the truncate.
ConstantInt *ShAmtV = 0;
Value *ShiftOp = 0;
if (Src->hasOneUse() &&
match(Src, m_LShr(m_Value(ShiftOp), m_ConstantInt(ShAmtV)))) {
uint32_t ShAmt = ShAmtV->getLimitedValue(SrcBitWidth);
// Get a mask for the bits shifting in.
APInt Mask(APInt::getLowBitsSet(SrcBitWidth, ShAmt).shl(DestBitWidth));
if (MaskedValueIsZero(ShiftOp, Mask)) {
if (ShAmt >= DestBitWidth) // All zeros.
return ReplaceInstUsesWith(CI, Constant::getNullValue(DestTy));
// Okay, we can shrink this. Truncate the input, then return a new
// shift.
Value *V1 = Builder->CreateTrunc(ShiftOp, DestTy, ShiftOp->getName());
Value *V2 = ConstantExpr::getTrunc(ShAmtV, DestTy);
return BinaryOperator::CreateLShr(V1, V2);
}
}
// Transform trunc(shl(X, C)) -> shl(trunc(X), C)
if (Src->hasOneUse() &&
match(Src, m_Shl(m_Value(ShiftOp), m_ConstantInt(ShAmtV)))) {
uint32_t ShAmt = ShAmtV->getLimitedValue(SrcBitWidth);
if (ShAmt >= DestBitWidth) // All zeros.
return ReplaceInstUsesWith(CI, Constant::getNullValue(DestTy));
// Okay, we can shrink this. Truncate the input, then return a new
// shift.
Value *V1 = Builder->CreateTrunc(ShiftOp, DestTy, ShiftOp->getName());
Value *V2 = ConstantExpr::getTrunc(ShAmtV, DestTy);
return BinaryOperator::CreateShl(V1, V2);
}
return 0;
}

2
test/Transforms/InstCombine/bswap.ll
View File

@ -1,3 +1,5 @@
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32"
; RUN: opt < %s -instcombine -S | \
; RUN: grep {call.*llvm.bswap} | count 6