[InstSimplify] move minnum/maxnum with common op fold from instcombine

llvm-svn: 339144

1 files changed, 11 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 494ca656dba..02137a51844 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -4805,6 +4805,17 @@ static Value *simplifyBinaryIntrinsic(Function *F, Value *Op0, Value *Op1,
     if (match(Op0, m_CombineOr(m_NaN(), m_Undef()))) return Op1;
     if (match(Op1, m_CombineOr(m_NaN(), m_Undef()))) return Op0;
 
+    // Min/max of the same operation with common operand:
+    // m(m(X, Y)), X --> m(X, Y) (4 commuted variants)
+    if (auto *M0 = dyn_cast<IntrinsicInst>(Op0))
+      if (M0->getIntrinsicID() == IID &&
+          (M0->getOperand(0) == Op1 || M0->getOperand(1) == Op1))
+        return Op0;
+    if (auto *M1 = dyn_cast<IntrinsicInst>(Op1))
+      if (M1->getIntrinsicID() == IID &&
+          (M1->getOperand(0) == Op0 || M1->getOperand(1) == Op0))
+        return Op1;
+
     break;
   default:
     break;