[llvm] r274891 - [InstCombine] check for one-use before turning simple logic op into a select

[Sanjay Patel via llvm-commits]

Author: spatel
Date: Fri Jul  8 12:26:47 2016
New Revision: 274891

URL: http://llvm.org/viewvc/llvm-project?rev=274891&view=rev
Log:
[InstCombine] check for one-use before turning simple logic op into a select

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

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=274891&r1=274890&r2=274891&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Fri Jul  8 12:26:47 2016
@@ -2394,10 +2394,10 @@ Instruction *InstCombiner::visitOr(Binar
     return CastedOr;
 
   // or(sext(A), B) / or(B, sext(A)) --> A ? -1 : B, where A is i1 or <N x i1>.
-  if (match(Op0, m_SExt(m_Value(A))) &&
+  if (match(Op0, m_OneUse(m_SExt(m_Value(A)))) &&
       A->getType()->getScalarType()->isIntegerTy(1))
     return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op1);
-  if (match(Op1, m_SExt(m_Value(A))) &&
+  if (match(Op1, m_OneUse(m_SExt(m_Value(A)))) &&
       A->getType()->getScalarType()->isIntegerTy(1))
     return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op0);
 

Modified: llvm/trunk/test/Transforms/InstCombine/or.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/or.ll?rev=274891&r1=274890&r2=274891&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/or.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/or.ll Fri Jul  8 12:26:47 2016
@@ -445,12 +445,10 @@ define i32 @orsext_to_sel_swap(i32 %x, i
   ret i32 %or
 }
 
-; FIXME: Don't replace an 'or' with a select unless it allows further simplification.
-
 define i32 @orsext_to_sel_multi_use(i32 %x, i1 %y) {
 ; CHECK-LABEL: @orsext_to_sel_multi_use(
 ; CHECK-NEXT:    [[SEXT:%.*]] = sext i1 %y to i32
-; CHECK-NEXT:    [[OR:%.*]] = select i1 %y, i32 -1, i32 %x
+; CHECK-NEXT:    [[OR:%.*]] = or i32 [[SEXT]], %x
 ; CHECK-NEXT:    [[ADD:%.*]] = add i32 [[SEXT]], [[OR]]
 ; CHECK-NEXT:    ret i32 [[ADD]]
 ;