[llvm-commits] [llvm] r171270 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineAndOrXor.cpp test/Transforms/InstCombine/icmp.ll

[Jakub Staszak]

Author: kuba
Date: Sun Dec 30 18:34:55 2012
New Revision: 171270

URL: http://llvm.org/viewvc/llvm-project?rev=171270&view=rev
Log:
Transform (A == C1 || A == C2) into (A & ~(C1 ^ C2)) == C1
if C1 and C2 differ only with one bit.
Fixes PR14708.

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

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=171270&r1=171269&r2=171270&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Sun Dec 30 18:34:55 2012
@@ -1524,6 +1524,18 @@
         AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
         return Builder->CreateICmpULT(Add, AddCST);
       }
+
+      if (LHS->getOperand(0) == RHS->getOperand(0)) {
+        // if LHSCst and RHSCst differ with only one bit:
+        // (A == C1 || A == C2) -> (A & ~(C1 ^ C2)) == C1
+        APInt Xor = LHSCst->getValue() ^ RHSCst->getValue();
+        if (Xor.isPowerOf2()) {
+          Value *NegCst = Builder->getInt(~Xor);
+          Value *And = Builder->CreateAnd(LHS->getOperand(0), NegCst);
+          return Builder->CreateICmp(ICmpInst::ICMP_EQ, And, LHSCst);
+        }
+      }
+
       break;                         // (X == 13 | X == 15) -> no change
     case ICmpInst::ICMP_UGT:         // (X == 13 | X u> 14) -> no change
     case ICmpInst::ICMP_SGT:         // (X == 13 | X s> 14) -> no change

Modified: llvm/trunk/test/Transforms/InstCombine/icmp.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/icmp.ll?rev=171270&r1=171269&r2=171270&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/icmp.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/icmp.ll Sun Dec 30 18:34:55 2012
@@ -694,3 +694,14 @@
   %cmp = icmp sgt i32 %and, 30
   ret i1 %cmp
 }
+
+; PR14708
+; CHECK: @test69
+; CHECK: %1 = and i32 %c, -33
+; CHECK: %2 = icmp eq i32 %1, 65
+define i1 @test69(i32 %c) nounwind uwtable {
+  %1 = icmp eq i32 %c, 97
+  %2 = icmp eq i32 %c, 65
+  %3 = or i1 %1, %2
+  ret i1 %3
+}