[llvm] 222e1c7 - [InstSimplify] don't commute constant expression operand in min/max calls

[Sanjay Patel via llvm-commits]

Author: Sanjay Patel
Date: 2022-09-26T16:01:09-04:00
New Revision: 222e1c73f319560765f1e82ece9be4315e6109c0

URL: https://github.com/llvm/llvm-project/commit/222e1c73f319560765f1e82ece9be4315e6109c0
DIFF: https://github.com/llvm/llvm-project/commit/222e1c73f319560765f1e82ece9be4315e6109c0.diff

LOG: [InstSimplify] don't commute constant expression operand in min/max calls

The test shows that we would fail to consistently fold the
instruction based on the max value operand. This is also
the root cause for issue #57986, but I'll add an instcombine
test + assert for that exact problem in another commit.

Added: 
    

Modified: 
    llvm/lib/Analysis/InstructionSimplify.cpp
    llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 40943d7c4530..e57d9800b04e 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -5843,8 +5843,8 @@ static Value *simplifyBinaryIntrinsic(Function *F, Value *Op0, Value *Op1,
     if (Op0 == Op1)
       return Op0;
 
-    // Canonicalize constant operand as Op1.
-    if (isa<Constant>(Op0))
+    // Canonicalize immediate constant operand as Op1.
+    if (match(Op0, m_ImmConstant()))
       std::swap(Op0, Op1);
 
     // Assume undef is the limit value.

diff  --git a/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll b/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
index d6326baf4b11..e7123b208084 100644
--- a/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
+++ b/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
@@ -27,8 +27,7 @@ define i8 @constexpr_maxvalue() {
 
 define i8 @constexpr_maxvalue_commute() {
 ; CHECK-LABEL: @constexpr_maxvalue_commute(
-; CHECK-NEXT:    [[UMIN:%.*]] = call i8 @llvm.umin.i8(i8 ptrtoint (ptr @g to i8), i8 -1)
-; CHECK-NEXT:    ret i8 [[UMIN]]
+; CHECK-NEXT:    ret i8 ptrtoint (ptr @g to i8)
 ;
   %umin = call i8 @llvm.umin.i8(i8 ptrtoint (ptr @g to i8), i8 255)
   ret i8 %umin