[PATCH] D86363: InstCombine transform pattern "(A ^ B) | ~(A | B) -> ~(A & B)" added

[Jaydeep Chauhan via Phabricator via llvm-commits]

Jac1494 created this revision.
Jac1494 added reviewers: silvas, dexonsmith, majnemer, nicholas.
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 | B) -> ~(A & B)".

And this pattern is already implemented in gcc.


https://reviews.llvm.org/D86363

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


Index: llvm/test/Transforms/InstCombine/or-and.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/InstCombine/or-and.ll
@@ -0,0 +1,14 @@
+; RUN: opt -S -instcombine < %s | FileCheck %s
+
+; (A ^ B) | ~(A | B) -> ~(A & B)
+define i32 @test1(i32 %0, i32 %1) {
+; CHECK-LABEL: @test1(
+; CHECK-NEXT: %3 = and i32 %0, %1
+; CHECK-NEXT: %4 = xor i32 %3, -1
+; CHECK-NEXT: ret i32 %4
+  %3 = xor i32 %0, %1
+  %4 = or i32 %0, %1
+  %5 = xor i32 %4, -1
+  %6 = or i32 %3, %5
+  ret i32 %6
+}
Index: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -2694,6 +2694,11 @@
     }
   }
 
+  // (A ^ B) | ~(A | B) -> ~(A & B)
+  if (match(Op0, m_Xor(m_Value(A), m_Value(B))))
+    if (match(Op1, m_Not(m_Or(m_Value(A), m_Value(B)))))
+      return BinaryOperator::CreateNot(Builder.CreateAnd(A, B));
+
   // (A ^ B) | ((B ^ C) ^ A) -> (A ^ B) | C
   if (match(Op0, m_Xor(m_Value(A), m_Value(B))))
     if (match(Op1, m_Xor(m_Xor(m_Specific(B), m_Value(C)), m_Specific(A))))


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