[InstCombine] add min/max intrinsics as freely invertible candidates

In the optimized test, we are able to peak through the min/max that has 2 min/max operands and invert them all: https://alive2.llvm.org/ce/z/7gYMN5
llvm · Aug 19, 2021 · eee0ded · eee0ded
1 parent 610d3d5
commit eee0ded
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Showing 3 changed files with 17 additions and 8 deletions.
diff --git a/llvm/include/llvm/Transforms/InstCombine/InstCombiner.h b/llvm/include/llvm/Transforms/InstCombine/InstCombiner.h
@@ -259,6 +259,12 @@ class LLVM_LIBRARY_VISIBILITY InstCombiner {
                        m_Not(PatternMatch::m_Value()))))
       return WillInvertAllUses;
 
+    // Min/max may be in the form of intrinsics, so handle those identically
+    // to select patterns.
+    if (match(V, m_MaxOrMin(m_Not(PatternMatch::m_Value()),
+                            m_Not(PatternMatch::m_Value()))))
+      return WillInvertAllUses;
+
     return false;
   }
 

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -3577,9 +3577,13 @@ Instruction *InstCombinerImpl::visitXor(BinaryOperator &I) {
   // ~max(~X, Y) --> min(X, ~Y)
   auto *II = dyn_cast<IntrinsicInst>(Op0);
   if (II && II->hasOneUse() && match(Op1, m_AllOnes())) {
-    if (match(Op0, m_MaxOrMin(m_Not(m_Value(X)), m_Not(m_Value(Y))))) {
+    if (match(Op0, m_MaxOrMin(m_Value(X), m_Value(Y))) &&
+        isFreeToInvert(X, X->hasOneUse()) &&
+        isFreeToInvert(Y, Y->hasOneUse())) {
       Intrinsic::ID InvID = getInverseMinMaxIntrinsic(II->getIntrinsicID());
-      Value *InvMaxMin = Builder.CreateBinaryIntrinsic(InvID, X, Y);
+      Value *NotX = Builder.CreateNot(X);
+      Value *NotY = Builder.CreateNot(Y);
+      Value *InvMaxMin = Builder.CreateBinaryIntrinsic(InvID, NotX, NotY);
       return replaceInstUsesWith(I, InvMaxMin);
     }
     if (match(Op0, m_c_MaxOrMin(m_Not(m_Value(X)), m_Value(Y)))) {

diff --git a/llvm/test/Transforms/InstCombine/minmax-intrinsics.ll b/llvm/test/Transforms/InstCombine/minmax-intrinsics.ll
@@ -1158,7 +1158,7 @@ define i8 @freeToInvert(i8 %x, i8 %y, i8 %z) {
 ; CHECK-NEXT:    call void @use(i8 [[NY]])
 ; CHECK-NEXT:    call void @use(i8 [[NZ]])
 ; CHECK-NEXT:    [[TMP1:%.*]] = call i8 @llvm.umin.i8(i8 [[X]], i8 [[Y]])
-; CHECK-NEXT:    [[TMP2:%.*]] = call i8 @llvm.smax.i8(i8 [[Z]], i8 [[TMP1]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call i8 @llvm.smax.i8(i8 [[TMP1]], i8 [[Z]])
 ; CHECK-NEXT:    ret i8 [[TMP2]]
 ;
   %nx = xor i8 %x, -1
@@ -1266,11 +1266,10 @@ define i8 @freeToInvert_two_minmax_ops(i8 %x, i8 %y, i8 %z, i8 %w) {
 ; CHECK-NEXT:    call void @use(i8 [[NY]])
 ; CHECK-NEXT:    call void @use(i8 [[NZ]])
 ; CHECK-NEXT:    call void @use(i8 [[NW]])
-; CHECK-NEXT:    [[M1:%.*]] = call i8 @llvm.umax.i8(i8 [[NX]], i8 [[NY]])
-; CHECK-NEXT:    [[M2:%.*]] = call i8 @llvm.smax.i8(i8 [[NW]], i8 [[NZ]])
-; CHECK-NEXT:    [[M3:%.*]] = call i8 @llvm.smin.i8(i8 [[M1]], i8 [[M2]])
-; CHECK-NEXT:    [[NOT:%.*]] = xor i8 [[M3]], -1
-; CHECK-NEXT:    ret i8 [[NOT]]
+; CHECK-NEXT:    [[TMP1:%.*]] = call i8 @llvm.umin.i8(i8 [[X]], i8 [[Y]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call i8 @llvm.smin.i8(i8 [[W]], i8 [[Z]])
+; CHECK-NEXT:    [[TMP3:%.*]] = call i8 @llvm.smax.i8(i8 [[TMP1]], i8 [[TMP2]])
+; CHECK-NEXT:    ret i8 [[TMP3]]
 ;
   %nx = xor i8 %x, -1
   %ny = xor i8 %y, -1