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[InstCombine] add hasOneUse check to add-zext-add fold to prevent increasing instructions 

llvm-svn: 315718
This commit is contained in:
Sanjay Patel 2017-10-13 17:47:25 +00:00
parent 399fcbea37
commit c419c9f640
2 changed files with 4 additions and 7 deletions
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6
llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
View File

@ -988,10 +988,8 @@ Instruction *InstCombiner::foldAddWithConstant(BinaryOperator &Add) {
return CastInst::Create(Instruction::SExt, X, Ty);
// (add (zext (add nuw X, C2)), C) --> (zext (add nuw X, C2 + C))
// FIXME: This should check hasOneUse to not increase the instruction count?
if (C->isNegative() &&
match(Op0, m_ZExt(m_NUWAdd(m_Value(X), m_APInt(C2)))) &&
C->sge(-C2->sext(C->getBitWidth()))) {
if (match(Op0, m_OneUse(m_ZExt(m_NUWAdd(m_Value(X), m_APInt(C2))))) &&
C->isNegative() && C->sge(-C2->sext(C->getBitWidth()))) {
Constant *NewC =
ConstantInt::get(X->getType(), *C2 + C->trunc(C2->getBitWidth()));
return new ZExtInst(Builder.CreateNUWAdd(X, NewC), Ty);

5
llvm/test/Transforms/InstCombine/add.ll
View File

@ -633,9 +633,8 @@ define <2 x i64> @test41vec_and_multiuse(<2 x i32> %a) {
; CHECK-LABEL: @test41vec_and_multiuse(
; CHECK-NEXT: [[ADD:%.*]] = add nuw <2 x i32> %a, <i32 16, i32 16>
; CHECK-NEXT: [[ZEXT:%.*]] = zext <2 x i32> [[ADD]] to <2 x i64>
; CHECK-NEXT: [[TMP1:%.*]] = add nuw <2 x i32> %a, <i32 15, i32 15>
; CHECK-NEXT: [[SUB:%.*]] = zext <2 x i32> [[TMP1]] to <2 x i64>
; CHECK-NEXT: [[EXTRAUSE:%.*]] = add nuw nsw <2 x i64> [[ZEXT]], [[SUB]]
; CHECK-NEXT: [[SUB:%.*]] = add nsw <2 x i64> [[ZEXT]], <i64 -1, i64 -1>
; CHECK-NEXT: [[EXTRAUSE:%.*]] = add nsw <2 x i64> [[SUB]], [[ZEXT]]
; CHECK-NEXT: ret <2 x i64> [[EXTRAUSE]]
;
%add = add nuw <2 x i32> %a, <i32 16, i32 16>