[llvm] e10c3be - [InstCombine] add one-use check for min/max fold with not operands; NFC

[Sanjay Patel via llvm-commits]

Author: Sanjay Patel
Date: 2021-08-19T08:41:38-04:00
New Revision: e10c3beca5590fc7df099ab7c173a9a4a21de9d1

URL: https://github.com/llvm/llvm-project/commit/e10c3beca5590fc7df099ab7c173a9a4a21de9d1
DIFF: https://github.com/llvm/llvm-project/commit/e10c3beca5590fc7df099ab7c173a9a4a21de9d1.diff

LOG: [InstCombine] add one-use check for min/max fold with not operands; NFC

This makes the intrinsic logic match the cmp+select idiom folds
just below. It's not clearly a win either way unless we think
that a 'not' op costs more than min/max.

The cmp+select folds on these patterns are more extensive than
the intrinsics currently and may have some complicated interactions,
so I'm trying to make those line up and bring the optimizations
for intrinsics up to parity.

Added: 
    

Modified: 
    llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
    llvm/test/Transforms/InstCombine/minmax-intrinsics.ll

Removed: 
    


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diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 9be483651bd4..46d874885457 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -3576,13 +3576,13 @@ Instruction *InstCombinerImpl::visitXor(BinaryOperator &I) {
   // ~min(~X, ~Y) --> max(X, Y)
   // ~max(~X, Y) --> min(X, ~Y)
   auto *II = dyn_cast<IntrinsicInst>(Op0);
-  if (II && match(Op1, m_AllOnes())) {
+  if (II && II->hasOneUse() && match(Op1, m_AllOnes())) {
     if (match(Op0, m_MaxOrMin(m_Not(m_Value(X)), m_Not(m_Value(Y))))) {
       Intrinsic::ID InvID = getInverseMinMaxIntrinsic(II->getIntrinsicID());
       Value *InvMaxMin = Builder.CreateBinaryIntrinsic(InvID, X, Y);
       return replaceInstUsesWith(I, InvMaxMin);
     }
-    if (match(Op0, m_OneUse(m_c_MaxOrMin(m_Not(m_Value(X)), m_Value(Y))))) {
+    if (match(Op0, m_c_MaxOrMin(m_Not(m_Value(X)), m_Value(Y)))) {
       Intrinsic::ID InvID = getInverseMinMaxIntrinsic(II->getIntrinsicID());
       Value *NotY = Builder.CreateNot(Y);
       Value *InvMaxMin = Builder.CreateBinaryIntrinsic(InvID, X, NotY);

diff  --git a/llvm/test/Transforms/InstCombine/minmax-intrinsics.ll b/llvm/test/Transforms/InstCombine/minmax-intrinsics.ll
index df919cc8ffc4..90c4cc97753c 100644
--- a/llvm/test/Transforms/InstCombine/minmax-intrinsics.ll
+++ b/llvm/test/Transforms/InstCombine/minmax-intrinsics.ll
@@ -547,8 +547,8 @@ define i8 @not_smin_of_nots(i8 %x, i8 %y) {
 ; CHECK-NEXT:    call void @use(i8 [[NOTY]])
 ; CHECK-NEXT:    [[M:%.*]] = call i8 @llvm.smin.i8(i8 [[NOTX]], i8 [[NOTY]])
 ; CHECK-NEXT:    call void @use(i8 [[M]])
-; CHECK-NEXT:    [[TMP1:%.*]] = call i8 @llvm.smax.i8(i8 [[X]], i8 [[Y]])
-; CHECK-NEXT:    ret i8 [[TMP1]]
+; CHECK-NEXT:    [[NOTM:%.*]] = xor i8 [[M]], -1
+; CHECK-NEXT:    ret i8 [[NOTM]]
 ;
   %notx = xor i8 %x, -1
   call void @use(i8 %notx)