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Instcombile optimization: extractelement(cast) -> cast(extractelement) 

llvm-svn: 128683
This commit is contained in:
Nadav Rotem 2011-03-31 22:57:29 +00:00
parent ff51d4e559
commit d74b72b8a9
2 changed files with 36 additions and 1 deletions
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10
llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
View File

@ -230,8 +230,16 @@ Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
ConstantInt::get(Int32Ty,
SrcIdx, false));
}
} else if (CastInst *CI = dyn_cast<CastInst>(I)) {
// Canonicalize extractelement(cast) -> cast(extractelement)
// bitcasts can change the number of vector elements and they cost nothing
if (CI->hasOneUse() && EI.hasOneUse() &&
(CI->getOpcode() != Instruction::BitCast)) {
Value *EE = Builder->CreateExtractElement(CI->getOperand(0),
EI.getIndexOperand());
return CastInst::Create(CI->getOpcode(), EE, EI.getType());
}
}
// FIXME: Canonicalize extractelement(bitcast) -> bitcast(extractelement)
}
return 0;
}

27
llvm/test/Transforms/InstCombine/ExtractCast.ll Normal file
View File

@ -0,0 +1,27 @@
; RUN: opt < %s -instcombine -S -o - | FileCheck %s
; CHECK: @a
define i32 @a(<4 x i64> %I) {
entry:
; CHECK-NOT: trunc <4 x i64>
%J = trunc <4 x i64> %I to <4 x i32>
%K = extractelement <4 x i32> %J, i32 3
; CHECK: extractelement <4 x i64>
; CHECK: trunc i64
; CHECK: ret
ret i32 %K
}
; CHECK: @b
define i32 @b(<4 x float> %I) {
entry:
; CHECK-NOT: fptosi <4 x float>
%J = fptosi <4 x float> %I to <4 x i32>
%K = extractelement <4 x i32> %J, i32 3
; CHECK: extractelement <4 x float>
; CHECK: fptosi float
; CHECK: ret
ret i32 %K
}