Implement (A&((~A)|B)) -> A&B transformation in the instruction combiner. This

takes care of all permutations of this pattern.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60290 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 55 insertions, 10 deletions

diff --git a/lib/Target/README.txt b/lib/Target/README.txt
index b0d93f0..bf7c0b1 100644
--- a/lib/Target/README.txt
+++ b/lib/Target/README.txt
@@ -1086,16 +1086,6 @@ produces better code on X86.
 
 //===---------------------------------------------------------------------===//
 
-From GCC Bug 33512:
-int f(int y, int x)
-{
- return x & ((~x) | y);
-}
-Should combine to x & y.  Currently not optimized with "clang
--emit-llvm-bc | opt -std-compile-opts".
-
-//===---------------------------------------------------------------------===//
-
 From GCC Bug 15784:
 #define abs(x) x>0?x:-x
 int f(int x, int y)
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 8716e9a..ace3ff8 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -3993,6 +3993,7 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
         std::swap(Op0, Op1);
       }
     }
+
     if (Op1->hasOneUse() &&
         match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
       if (B == Op0) {                                // B&(A^B) -> B&(B^A)
@@ -4005,6 +4006,24 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
         return BinaryOperator::CreateAnd(A, NotB);
       }
     }
+
+    // (A&((~A)|B)) -> A&B
+    if (match(Op0, m_Or(m_Not(m_Value(A)), m_Value(B)))) {
+      if (A == Op1)
+        return BinaryOperator::CreateAnd(A, B);
+    }
+    if (match(Op0, m_Or(m_Value(A), m_Not(m_Value(B))))) {
+      if (B == Op1)
+        return BinaryOperator::CreateAnd(A, B);
+    }
+    if (match(Op1, m_Or(m_Not(m_Value(A)), m_Value(B)))) {
+      if (A == Op0)
+        return BinaryOperator::CreateAnd(A, B);
+    }
+    if (match(Op1, m_Or(m_Value(A), m_Not(m_Value(B))))) {
+      if (B == Op0)
+        return BinaryOperator::CreateAnd(A, B);
+    }
   }
   
   if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1)) {
diff --git a/test/Transforms/InstCombine/and-not-or.ll b/test/Transforms/InstCombine/and-not-or.ll
new file mode 100644
index 0000000..b183b21
--- /dev/null
+++ b/test/Transforms/InstCombine/and-not-or.ll
@@ -0,0 +1,36 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {and i32 %y, %x} | count 2
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {and i32 %x, %y} | count 2
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep {xor}
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep {or}
+
+define i32 @func1(i32 %x, i32 %y) nounwind {
+entry:
+	%n = xor i32 %y, -1
+	%o = or i32 %n, %x
+	%a = and i32 %o, %y
+	ret i32 %a
+}
+
+define i32 @func2(i32 %x, i32 %y) nounwind {
+entry:
+	%n = xor i32 %y, -1
+	%o = or i32 %x, %n
+	%a = and i32 %o, %y
+	ret i32 %a
+}
+
+define i32 @func3(i32 %x, i32 %y) nounwind {
+entry:
+	%n = xor i32 %y, -1
+	%o = or i32 %n, %x
+	%a = and i32 %y, %o
+	ret i32 %a
+}
+
+define i32 @func4(i32 %x, i32 %y) nounwind {
+entry:
+	%n = xor i32 %y, -1
+	%o = or i32 %x, %n
+	%a = and i32 %y, %o
+	ret i32 %a
+}