[llvm] c50f7e9 - [InstCombine] Remove mul of SPF abs fold (#88675)

[via llvm-commits]

Author: Nikita Popov
Date: 2024-04-16T09:17:52+09:00
New Revision: c50f7e9a425bfa4ab8655c79a715c88ed3b1e830

URL: https://github.com/llvm/llvm-project/commit/c50f7e9a425bfa4ab8655c79a715c88ed3b1e830
DIFF: https://github.com/llvm/llvm-project/commit/c50f7e9a425bfa4ab8655c79a715c88ed3b1e830.diff

LOG: [InstCombine] Remove mul of SPF abs fold (#88675)

Remove the fold working on abs in SPF representation now that we
canonicalize SPF to intrinsics.

This is not strictly NFC because the SPF fold might fire for
non-canonical IR due to multi-use, but given the lack of test coverage,
I assume this is not important.

Added: 
    

Modified: 
    llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 4dc1319f1c437f..48372381a0d1cd 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -319,19 +319,12 @@ Instruction *InstCombinerImpl::visitMul(BinaryOperator &I) {
   }
 
   // abs(X) * abs(X) -> X * X
-  // nabs(X) * nabs(X) -> X * X
-  if (Op0 == Op1) {
-    Value *X, *Y;
-    SelectPatternFlavor SPF = matchSelectPattern(Op0, X, Y).Flavor;
-    if (SPF == SPF_ABS || SPF == SPF_NABS)
-      return BinaryOperator::CreateMul(X, X);
-
-    if (match(Op0, m_Intrinsic<Intrinsic::abs>(m_Value(X))))
-      return BinaryOperator::CreateMul(X, X);
-  }
+  Value *X;
+  if (Op0 == Op1 && match(Op0, m_Intrinsic<Intrinsic::abs>(m_Value(X))))
+    return BinaryOperator::CreateMul(X, X);
 
   {
-    Value *X, *Y;
+    Value *Y;
     // abs(X) * abs(Y) -> abs(X * Y)
     if (I.hasNoSignedWrap() &&
         match(Op0,
@@ -344,7 +337,7 @@ Instruction *InstCombinerImpl::visitMul(BinaryOperator &I) {
   }
 
   // -X * C --> X * -C
-  Value *X, *Y;
+  Value *Y;
   Constant *Op1C;
   if (match(Op0, m_Neg(m_Value(X))) && match(Op1, m_Constant(Op1C)))
     return BinaryOperator::CreateMul(X, ConstantExpr::getNeg(Op1C));