[PATCH] D105013: [InstCombine] try to fold the expression "(A & ~B) + B" to "A | B"

[Yifeng Dong via Phabricator via llvm-commits]

dongAxis1944 updated this revision to Diff 354895.
dongAxis1944 added a comment.

add pattern in valuetrack


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D105013/new/

https://reviews.llvm.org/D105013

Files:
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/test/Transforms/InstCombine/and-to-xor.ll


Index: llvm/test/Transforms/InstCombine/and-to-xor.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/InstCombine/and-to-xor.ll
@@ -0,0 +1,28 @@
+; Try to fold (A & ~B) + B to A | B
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+; CHECK: define i32 @and_to_xor1(i32 %0, i32 %1) local_unnamed_addr
+; CHECK-NOT: %{{[0-9]+}} = xor i32 %{{[0-9]+}}, -1
+; CHECK-NOT:  %{{[0-9]+}} = and i32 %{{[0-9]+}}, %{{[0-9]+}}
+; CHECK: %{{[0-9]+}} = or i32 %{{[0-9]+}}, %{{[0-9]+}}
+define i32 @and_to_xor1(i32 %0, i32 %1) local_unnamed_addr #0 {
+  %3 = shl nsw i32 %0, 1
+  %4 = mul nsw i32 %1, %0
+  %5 = xor i32 %4, -1
+  %6 = and i32 %3, %5
+  %7 = add nsw i32 %6, %4
+  ret i32 %7
+}
+
+; CHECK: define i32 @and_to_xor2(i32 %0, i32 %1)
+; CHECK-NOT: %{{[0-9]+}} = xor i32 %{{[0-9]+}}, -1
+; CHECK-NOT:  %{{[0-9]+}} = and i32 %{{[0-9]+}}, %{{[0-9]+}}
+; CHECK: %{{[0-9]+}} = or i32 %{{[0-9]+}}, %{{[0-9]+}}
+define i32 @and_to_xor2(i32 %0, i32 %1) local_unnamed_addr #0 {
+  %3 = shl nsw i32 %0, 1
+  %4 = mul nsw i32 %1, %0
+  %5 = xor i32 %4, -1
+  %6 = and i32 %3, %5
+  %7 = add nsw i32 %4, %6
+  ret i32 %7
+}
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -270,6 +270,12 @@
   if (match(RHS, m_c_And(m_Not(m_Value(M)), m_Value())) &&
       match(LHS, m_c_And(m_Specific(M), m_Value())))
     return true;
+
+  // Look for a pattern:(A & ~B) op B
+  if (match(LHS, m_c_And(m_Not(m_Specific(RHS)), m_Value())) ||
+      match(RHS, m_c_And(m_Not(m_Specific(LHS)), m_Value())))
+    return true;
+
   IntegerType *IT = cast<IntegerType>(LHS->getType()->getScalarType());
   KnownBits LHSKnown(IT->getBitWidth());
   KnownBits RHSKnown(IT->getBitWidth());


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