[llvm] 5419b67 - [SimplifyCFG] Update FoldTwoEntryPHINode to handle and/or of select and binop equally

[Juneyoung Lee via llvm-commits]

Author: Juneyoung Lee
Date: 2021-03-01T13:34:51+09:00
New Revision: 5419b671375c46299ff1da6c929859040e7beaf5

URL: https://github.com/llvm/llvm-project/commit/5419b671375c46299ff1da6c929859040e7beaf5
DIFF: https://github.com/llvm/llvm-project/commit/5419b671375c46299ff1da6c929859040e7beaf5.diff

LOG: [SimplifyCFG] Update FoldTwoEntryPHINode to handle and/or of select and binop equally

This is a minor change that fixes FoldTwoEntryPHINode to handle
phis with and/ors of select form and binop form equally.

Added: 
    

Modified: 
    llvm/include/llvm/IR/PatternMatch.h
    llvm/lib/Transforms/Utils/SimplifyCFG.cpp

Removed: 
    


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diff  --git a/llvm/include/llvm/IR/PatternMatch.h b/llvm/include/llvm/IR/PatternMatch.h
index 6edbf32de199..575eff4650e1 100644
--- a/llvm/include/llvm/IR/PatternMatch.h
+++ b/llvm/include/llvm/IR/PatternMatch.h
@@ -2446,6 +2446,9 @@ m_LogicalAnd(const LHS &L, const RHS &R) {
   return LogicalOp_match<LHS, RHS, Instruction::And>(L, R);
 }
 
+/// Matches L && R where L and R are arbitrary values.
+inline auto m_LogicalAnd() { return m_LogicalAnd(m_Value(), m_Value()); }
+
 /// Matches L || R either in the form of L | R or L ? true : R.
 /// Note that the latter form is poison-blocking.
 template <typename LHS, typename RHS>

diff  --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index e8dd03367113..8ca324291886 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2598,13 +2598,17 @@ static bool FoldTwoEntryPHINode(PHINode *PN, const TargetTransformInfo &TTI,
     return match(V0, m_Not(m_Value())) && match(V1, Invertible);
   };
 
-  // Don't fold i1 branches on PHIs which contain binary operators, unless one
-  // of the incoming values is an 'not' and another one is freely invertible.
+  // Don't fold i1 branches on PHIs which contain binary operators or
+  // select form of or/ands, unless one of the incoming values is an 'not' and
+  // another one is freely invertible.
   // These can often be turned into switches and other things.
+  auto IsBinOpOrAnd = [](Value *V) {
+    return match(
+        V, m_CombineOr(m_BinOp(), m_CombineOr(m_LogicalAnd(), m_LogicalOr())));
+  };
   if (PN->getType()->isIntegerTy(1) &&
-      (isa<BinaryOperator>(PN->getIncomingValue(0)) ||
-       isa<BinaryOperator>(PN->getIncomingValue(1)) ||
-       isa<BinaryOperator>(IfCond)) &&
+      (IsBinOpOrAnd(PN->getIncomingValue(0)) ||
+       IsBinOpOrAnd(PN->getIncomingValue(1)) || IsBinOpOrAnd(IfCond)) &&
       !CanHoistNotFromBothValues(PN->getIncomingValue(0),
                                  PN->getIncomingValue(1)))
     return Changed;