[llvm] cb7cb83 - [InstCombine] Add check to avoid dependent optimization order, NFC

[via llvm-commits]

Author: zhongyunde 00443407
Date: 2024-04-21T12:07:56+08:00
New Revision: cb7cb83010bbcd8e5325d81b6d80653c7b513516

URL: https://github.com/llvm/llvm-project/commit/cb7cb83010bbcd8e5325d81b6d80653c7b513516
DIFF: https://github.com/llvm/llvm-project/commit/cb7cb83010bbcd8e5325d81b6d80653c7b513516.diff

LOG: [InstCombine] Add check to avoid dependent optimization order, NFC

Since PR86428, foldPowiReassoc is called by both FMul and FDiv,
as the optimization of FDiv is placed after the FMul, so now
it is correct we don't add the checking of FDiv for powi(X, Y) / X.
But, we may add more matching scenarios later, so add the checking opcode
explicitly is easier to understand.

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 a0333b7db8f7a9..000d33a091970a 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -582,6 +582,9 @@ Instruction *InstCombinerImpl::foldPowiReassoc(BinaryOperator &I) {
   };
 
   Value *X, *Y, *Z;
+  unsigned Opcode = I.getOpcode();
+  assert((Opcode == Instruction::FMul || Opcode == Instruction::FDiv) &&
+         "Unexpected opcode");
 
   // powi(X, Y) * X --> powi(X, Y+1)
   // X * powi(X, Y) --> powi(X, Y+1)
@@ -596,7 +599,7 @@ Instruction *InstCombinerImpl::foldPowiReassoc(BinaryOperator &I) {
   // powi(x, y) * powi(x, z) -> powi(x, y + z)
   Value *Op0 = I.getOperand(0);
   Value *Op1 = I.getOperand(1);
-  if (I.isOnlyUserOfAnyOperand() &&
+  if (Opcode == Instruction::FMul && I.isOnlyUserOfAnyOperand() &&
       match(Op0, m_AllowReassoc(
                      m_Intrinsic<Intrinsic::powi>(m_Value(X), m_Value(Y)))) &&
       match(Op1, m_AllowReassoc(m_Intrinsic<Intrinsic::powi>(m_Specific(X),
@@ -608,7 +611,7 @@ Instruction *InstCombinerImpl::foldPowiReassoc(BinaryOperator &I) {
   // This is legal when (Y - 1) can't wraparound, in which case reassoc and nnan
   // are required.
   // TODO: Multi-use may be also better off creating Powi(x,y-1)
-  if (I.hasAllowReassoc() && I.hasNoNaNs() &&
+  if (Opcode == Instruction::FDiv && I.hasAllowReassoc() && I.hasNoNaNs() &&
       match(Op0, m_OneUse(m_AllowReassoc(m_Intrinsic<Intrinsic::powi>(
                      m_Specific(Op1), m_Value(Y))))) &&
       willNotOverflowSignedSub(Y, ConstantInt::get(Y->getType(), 1), I)) {