[llvm] r228954 - InstCombine: Allow folding of xor into icmp by changing the predicate for vectors

[Benjamin Kramer]

Author: d0k
Date: Thu Feb 12 14:26:46 2015
New Revision: 228954

URL: http://llvm.org/viewvc/llvm-project?rev=228954&view=rev
Log:
InstCombine: Allow folding of xor into icmp by changing the predicate for vectors

The loop vectorizer can create this pattern.

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
    llvm/trunk/test/Transforms/InstCombine/not.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=228954&r1=228953&r2=228954&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Thu Feb 12 14:26:46 2015
@@ -2604,15 +2604,16 @@ Instruction *InstCombiner::visitXor(Bina
     }
   }
 
-
-  if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
-    if (RHS->isOne() && Op0->hasOneUse())
+  if (Constant *RHS = dyn_cast<Constant>(Op1)) {
+    if (RHS->isAllOnesValue() && Op0->hasOneUse())
       // xor (cmp A, B), true = not (cmp A, B) = !cmp A, B
       if (CmpInst *CI = dyn_cast<CmpInst>(Op0))
         return CmpInst::Create(CI->getOpcode(),
                                CI->getInversePredicate(),
                                CI->getOperand(0), CI->getOperand(1));
+  }
 
+  if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
     // fold (xor(zext(cmp)), 1) and (xor(sext(cmp)), -1) to ext(!cmp).
     if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
       if (CmpInst *CI = dyn_cast<CmpInst>(Op0C->getOperand(0))) {

Modified: llvm/trunk/test/Transforms/InstCombine/not.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/not.ll?rev=228954&r1=228953&r2=228954&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/not.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/not.ll Thu Feb 12 14:26:46 2015
@@ -52,3 +52,9 @@ entry:
 	%retval67 = zext i1 %tmp3 to i8		; <i8> [#uses=1]
 	ret i8 %retval67
 }
+
+define <2 x i1> @test7(<2 x i32> %A, <2 x i32> %B) {
+        %cond = icmp sle <2 x i32> %A, %B
+        %Ret = xor <2 x i1> %cond, <i1 true, i1 true>
+        ret <2 x i1> %Ret
+}