Implement ((A|B)&1)|(B&-2) -> (A&1) | B transformation. This also takes care of

permutations of this pattern.

llvm-svn: 60312

2 files changed, 67 insertions, 6 deletions

diff --git a/llvm/lib/Target/README.txt b/llvm/lib/Target/README.txt
index 17b830d5d4a..fb6b0cd53d5 100644
--- a/llvm/lib/Target/README.txt
+++ b/llvm/lib/Target/README.txt
@@ -1147,12 +1147,6 @@ There's an unnecessary zext in the generated code with "clang
 
 //===---------------------------------------------------------------------===//
 
-int a(int a, int b) {return ((a|b)&1) | (b&-2);}
-Should be combined to "(a&1)|b".  Currently not optimized with "clang
--emit-llvm-bc | opt -std-compile-opts".
-
-//===---------------------------------------------------------------------===//
-
 int a(unsigned b) {return ((b << 31) | (b << 30)) >> 31;}
 Should be combined to  "((b >> 1) | b) & 1".  Currently not optimized
 with "clang -emit-llvm-bc | opt -std-compile-opts".
diff --git a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
index 9cb1875b958..4e2e8a409bc 100644
--- a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -4649,6 +4649,73 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
       }
   }
 
+  // ((A|B)&1)|(B&-2) -> (A&1) | B
+  if (match(Op0, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
+      match(Op0, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
+    if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) {
+      if (CI->getValue() == 1) {
+        Value *V1 = 0, *C2 = 0;
+        if (match(Op1, m_And(m_Value(V1), m_Value(C2)))) {
+          ConstantInt *CI2 = dyn_cast<ConstantInt>(C2);
+
+          if (!CI2) {
+            std::swap(V1, C2);
+            CI2 = dyn_cast<ConstantInt>(C2);
+          }
+
+          if (CI2) {
+            APInt NegTwo = -APInt(CI2->getValue().getBitWidth(), 2, true);
+            if (CI2->getValue().eq(NegTwo)) {
+              if (V1 == B) {
+                Instruction *NewOp =
+                  InsertNewInstBefore(BinaryOperator::CreateAnd(A, CI), I);
+                return BinaryOperator::CreateOr(NewOp, B);
+              }
+              if (V1 == A) {
+                Instruction *NewOp =
+                  InsertNewInstBefore(BinaryOperator::CreateAnd(B, CI), I);
+                return BinaryOperator::CreateOr(NewOp, A);
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+  // (B&-2)|((A|B)&1) -> (A&1) | B
+  if (match(Op1, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
+      match(Op1, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
+    if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) {
+      if (CI->getValue() == 1) {
+        Value *V1 = 0, *C2 = 0;
+        if (match(Op0, m_And(m_Value(V1), m_Value(C2)))) {
+          ConstantInt *CI2 = dyn_cast<ConstantInt>(C2);
+
+          if (!CI2) {
+            std::swap(V1, C2);
+            CI2 = dyn_cast<ConstantInt>(C2);
+          }
+
+          if (CI2) {
+            APInt NegTwo = -APInt(CI2->getValue().getBitWidth(), 2, true);
+            if (CI2->getValue().eq(NegTwo)) {
+              if (V1 == B) {
+                Instruction *NewOp =
+                  InsertNewInstBefore(BinaryOperator::CreateAnd(A, CI), I);
+                return BinaryOperator::CreateOr(NewOp, B);
+              }
+              if (V1 == A) {
+                Instruction *NewOp =
+                  InsertNewInstBefore(BinaryOperator::CreateAnd(B, CI), I);
+                return BinaryOperator::CreateOr(NewOp, A);
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+
   if (match(Op0, m_Not(m_Value(A)))) {   // ~A | Op1
     if (A == Op1)   // ~A | A == -1
       return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));