[llvm] r301316 - [InstCombine] Add missing commute handling to (A | B) & (B ^ (~A)) -> (A & B)

[Craig Topper via llvm-commits]

Author: ctopper
Date: Tue Apr 25 10:19:04 2017
New Revision: 301316

URL: http://llvm.org/viewvc/llvm-project?rev=301316&view=rev
Log:
[InstCombine] Add missing commute handling to (A | B) & (B ^ (~A)) -> (A & B)

The matching here wasn't able to handle all the possible commutes. It always assumed the not would be on the left of the xor, but that's not guaranteed.

Differential Revision: https://reviews.llvm.org/D32474

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
    llvm/trunk/test/Transforms/InstCombine/and.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=301316&r1=301315&r2=301316&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Tue Apr 25 10:19:04 2017
@@ -1425,13 +1425,18 @@ Instruction *InstCombiner::visitAnd(Bina
           return BinaryOperator::CreateAnd(Op1, Builder->CreateNot(C));
 
     // (A | B) & ((~A) ^ B) -> (A & B)
-    if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
-        match(Op1, m_Xor(m_Not(m_Specific(A)), m_Specific(B))))
+    // (A | B) & (B ^ (~A)) -> (A & B)
+    // (B | A) & ((~A) ^ B) -> (A & B)
+    // (B | A) & (B ^ (~A)) -> (A & B)
+    if (match(Op1, m_c_Xor(m_Not(m_Value(A)), m_Value(B))) &&
+        match(Op0, m_c_Or(m_Specific(A), m_Specific(B))))
       return BinaryOperator::CreateAnd(A, B);
 
     // ((~A) ^ B) & (A | B) -> (A & B)
     // ((~A) ^ B) & (B | A) -> (A & B)
-    if (match(Op0, m_Xor(m_Not(m_Value(A)), m_Value(B))) &&
+    // (B ^ (~A)) & (A | B) -> (A & B)
+    // (B ^ (~A)) & (B | A) -> (A & B)
+    if (match(Op0, m_c_Xor(m_Not(m_Value(A)), m_Value(B))) &&
         match(Op1, m_c_Or(m_Specific(A), m_Specific(B))))
       return BinaryOperator::CreateAnd(A, B);
   }

Modified: llvm/trunk/test/Transforms/InstCombine/and.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/and.ll?rev=301316&r1=301315&r2=301316&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/and.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/and.ll Tue Apr 25 10:19:04 2017
@@ -617,10 +617,7 @@ final:
 define i32 @test42(i32 %a, i32 %c, i32 %d) {
 ; CHECK-LABEL: @test42(
 ; CHECK-NEXT:    [[FORCE:%.*]] = mul i32 [[C:%.*]], [[D:%.*]]
-; CHECK-NEXT:    [[OR:%.*]] = or i32 [[FORCE]], [[A:%.*]]
-; CHECK-NEXT:    [[NOTA:%.*]] = xor i32 [[A]], -1
-; CHECK-NEXT:    [[XOR:%.*]] = xor i32 [[FORCE]], [[NOTA]]
-; CHECK-NEXT:    [[AND:%.*]] = and i32 [[XOR]], [[OR]]
+; CHECK-NEXT:    [[AND:%.*]] = and i32 [[FORCE]], [[A:%.*]]
 ; CHECK-NEXT:    ret i32 [[AND]]
 ;
   %force = mul i32 %c, %d ; forces the complexity sorting
@@ -634,10 +631,7 @@ define i32 @test42(i32 %a, i32 %c, i32 %
 define i32 @test43(i32 %a, i32 %c, i32 %d) {
 ; CHECK-LABEL: @test43(
 ; CHECK-NEXT:    [[FORCE:%.*]] = mul i32 [[C:%.*]], [[D:%.*]]
-; CHECK-NEXT:    [[OR:%.*]] = or i32 [[FORCE]], [[A:%.*]]
-; CHECK-NEXT:    [[NOTA:%.*]] = xor i32 [[A]], -1
-; CHECK-NEXT:    [[XOR:%.*]] = xor i32 [[FORCE]], [[NOTA]]
-; CHECK-NEXT:    [[AND:%.*]] = and i32 [[OR]], [[XOR]]
+; CHECK-NEXT:    [[AND:%.*]] = and i32 [[FORCE]], [[A:%.*]]
 ; CHECK-NEXT:    ret i32 [[AND]]
 ;
   %force = mul i32 %c, %d ; forces the complexity sorting