[PATCH] D86395: InstCombine transform pattern "(~A & B) ^ A -> (A | B)" added

[Jaydeep Chauhan via Phabricator via llvm-commits]

Jac1494 created this revision.
Jac1494 added reviewers: silvas, dexonsmith, majnemer, nicholas, spatel, lebedev.ri.
Jac1494 added a project: LLVM.
Herald added a subscriber: hiraditya.
Jac1494 requested review of this revision.

This patch implements transform for pattern "(~A & B) ^ A -> (A | B)".

And this pattern is already implemented in gcc.


https://reviews.llvm.org/D86395

Files:
  llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
  llvm/test/Transforms/InstCombine/xor-or.ll


Index: llvm/test/Transforms/InstCombine/xor-or.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/InstCombine/xor-or.ll
@@ -0,0 +1,12 @@
+; RUN: opt -S -instcombine < %s | FileCheck %s
+
+; (~A & B) ^ A  -->   (A | B)
+define dso_local i32 @test1(i32 %0, i32 %1) local_unnamed_addr #0 {
+; CHECK-LABEL: @test1(
+; CHECK-NEXT: %3 = or i32 %0, %1
+; CHECK-NEXT: ret i32 %3
+  %3 = xor i32 %0, -1
+  %4 = and i32 %3, %1
+  %5 = xor i32 %4, %0
+  ret i32 %5
+}
Index: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -3353,6 +3353,11 @@
       match(Op1, m_Not(m_Specific(A))))
     return BinaryOperator::CreateNot(Builder.CreateAnd(A, B));
 
+  // (~A & B) ^ A  -->   (A | B)
+  if (match(Op0, m_c_And(m_Not(m_Value(A)), m_Value(B))) &&
+      match(Op1, m_Specific(A)))
+    return BinaryOperator::CreateOr(A, B);
+
   // (A | B) ^ (A | C) --> (B ^ C) & ~A -- There are 4 commuted variants.
   // TODO: Loosen one-use restriction if common operand is a constant.
   Value *D;


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