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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315718 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index 92452d7df73aaea0bcdad559e67d75082e138b59..3921ab4374e3be515cdceda59f9675147ff3b5c6 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -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);

diff --git a/test/Transforms/InstCombine/add.ll b/test/Transforms/InstCombine/add.ll
index 728262a208a37bd7bf6c0bb227bd7f90844054e7..e1fcbe0b1af1c97cd5011967da1909a2200fb1f7 100644 (file)
--- a/test/Transforms/InstCombine/add.ll
+++ b/test/Transforms/InstCombine/add.ll
@@ -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>