Reapply r153423; the original commit was fine. The failing test, distray, had

undefined behavior, which Rafael was kind enough to fix.

Original commit message for r153423:
Use the new range metadata in computeMaskedBits and add a new optimization to
instruction simplify that lets us remove an and when loding a boolean value.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153521 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 15 insertions, 0 deletions

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 16e7a72659..28400b08b1 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -1370,6 +1370,21 @@ static Value *SimplifyAndInst(Value *Op0, Value *Op1, const Query &Q,
       return Op1;
   }
 
+  unsigned Bitwidth = Op1->getType()->getScalarSizeInBits();
+  APInt DemandedMask = APInt::getAllOnesValue(Bitwidth);
+  APInt KnownZero0 = APInt::getNullValue(Bitwidth);
+  APInt KnownOne0 = APInt::getNullValue(Bitwidth);
+  ComputeMaskedBits(Op0, DemandedMask, KnownZero0, KnownOne0);
+  APInt KnownZero1 = APInt::getNullValue(Bitwidth);
+  APInt KnownOne1 = APInt::getNullValue(Bitwidth);
+  ComputeMaskedBits(Op1, DemandedMask, KnownZero1, KnownOne1);
+
+  if ((KnownZero0 | KnownOne1).isAllOnesValue())
+    return Op0;
+
+  if ((KnownZero1 | KnownOne0).isAllOnesValue())
+    return Op1;
+
   // Try some generic simplifications for associative operations.
   if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
                                           MaxRecurse))