InstCombine: Stop using m_c_BinOp for non-commutative ops

[arsenm]

The previous flow tried both m_BinOp and m_c_BinOp for noncommutative
ops. Seems to have worked out OK though, since there are no test changes.

[arsenm]

• InstCombine: Stop using m_c_BinOp for non-commutative ops #172327 👈 (View in Graphite)
• main

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[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Matt Arsenault (arsenm)

Changes

The previous flow tried both m_BinOp and m_c_BinOp for noncommutative
ops. Seems to have worked out OK though, since there are no test changes.

---

Full diff: https://github.com/llvm/llvm-project/pull/172327.diff

1 Files Affected:

• (modified) llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp (+7-4)

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index c00551bc1f939..de7d9c8cde9ed 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -96,10 +96,13 @@ static Instruction *foldSelectBinOpIdentity(SelectInst &Sel,
 
   // Last, match the compare variable operand with a binop operand.
   Value *Y;
-  if (!BO->isCommutative() && !match(BO, m_BinOp(m_Value(Y), m_Specific(X))))
-    return nullptr;
-  if (!match(BO, m_c_BinOp(m_Value(Y), m_Specific(X))))
-    return nullptr;
+  if (BO->isCommutative()) {
+    if (!match(BO, m_c_BinOp(m_Value(Y), m_Specific(X))))
+      return nullptr;
+  } else {
+    if (!match(BO, m_BinOp(m_Value(Y), m_Specific(X))))
+      return nullptr;
+  }
 
   // +0.0 compares equal to -0.0, and so it does not behave as required for this
   // transform. Bail out if we can not exclude that possibility.

[dtcxzyw]

It is an NFC. m_c_BinOp always succeeds when m_BinOp succeeds.