[InstCombine] allow icmp-xor folds for vectors (PR33138)

This fixes the first part of:
https://bugs.llvm.org/show_bug.cgi?id=33138

More work is needed for the bitcasted variant.

llvm-svn: 303660

1 files changed, 9 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 6492eaedae9..fed67780e0f 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3030,18 +3030,21 @@ Instruction *InstCombiner::foldICmpBinOp(ICmpInst &I) {
       break;
     case Instruction::Add:
     case Instruction::Sub:
-    case Instruction::Xor:
+    case Instruction::Xor: {
       if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b
         return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
-      // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
-      if (ConstantInt *CI = dyn_cast<ConstantInt>(BO0->getOperand(1))) {
-        if (CI->getValue().isSignMask()) {
+
+      const APInt *C;
+      if (match(BO0->getOperand(1), m_APInt(C))) {
+        // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
+        if (C->isSignMask()) {
           ICmpInst::Predicate NewPred =
               I.isSigned() ? I.getUnsignedPredicate() : I.getSignedPredicate();
           return new ICmpInst(NewPred, BO0->getOperand(0), BO1->getOperand(0));
         }
 
-        if (BO0->getOpcode() == Instruction::Xor && CI->isMaxValue(true)) {
+        // icmp u/s (a ^ maxsignval), (b ^ maxsignval) --> icmp s/u' a, b
+        if (BO0->getOpcode() == Instruction::Xor && C->isMaxSignedValue()) {
           ICmpInst::Predicate NewPred =
               I.isSigned() ? I.getUnsignedPredicate() : I.getSignedPredicate();
           NewPred = I.getSwappedPredicate(NewPred);
@@ -3049,6 +3052,7 @@ Instruction *InstCombiner::foldICmpBinOp(ICmpInst &I) {
         }
       }
       break;
+    }
     case Instruction::Mul:
       if (!I.isEquality())
         break;