[llvm] r245678 - Revert r245635, "[InstCombine] Transform A & (L - 1) u< L --> L != 0"

[NAKAMURA Takumi via llvm-commits]

Author: chapuni
Date: Fri Aug 21 02:46:07 2015
New Revision: 245678

URL: http://llvm.org/viewvc/llvm-project?rev=245678&view=rev
Log:
Revert r245635, "[InstCombine] Transform A & (L - 1) u< L --> L != 0"

It caused miscompilation in clang.

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

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=245678&r1=245677&r2=245678&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp Fri Aug 21 02:46:07 2015
@@ -3490,19 +3490,6 @@ Instruction *InstCombiner::visitICmpInst
       }
       }
     }
-
-    if (BO0) {
-      // Transform  A & (L - 1) `ult` L --> L != 0
-      Value *L;
-      auto LSubOne = m_Add(m_Value(L), m_AllOnes());
-      auto BitwiseAnd =
-          m_CombineOr(m_And(m_Value(), LSubOne), m_And(LSubOne, m_Value()));
-
-      if (match(BO0, BitwiseAnd) && I.getPredicate() == ICmpInst::ICMP_ULT) {
-        auto *Zero = Constant::getNullValue(BO0->getType());
-        return new ICmpInst(ICmpInst::ICMP_NE, L, Zero);
-      }
-    }
   }
 
   { Value *A, *B;

Modified: llvm/trunk/test/Transforms/InstCombine/icmp.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/icmp.ll?rev=245678&r1=245677&r2=245678&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/icmp.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/icmp.ll Fri Aug 21 02:46:07 2015
@@ -1603,23 +1603,3 @@ define i32 @f7(i32 %a, i32 %b) {
   %s = select i1 %cmp, i32 10000, i32 0
   ret i32 %s
 }
-
-; CHECK: @f8(
-; CHECK-NEXT: [[RESULT:%[a-z0-9]+]] = icmp ne i32 %lim, 0
-; CHECK-NEXT: ret i1 [[RESULT]]
-define i1 @f8(i32 %val, i32 %lim) {
-  %lim.sub = add i32 %lim, -1
-  %val.and = and i32 %val, %lim.sub
-  %r = icmp ult i32 %val.and, %lim
-  ret i1 %r
-}
-
-; CHECK: @f9(
-; CHECK-NEXT: [[RESULT:%[a-z0-9]+]] = icmp ne i32 %lim, 0
-; CHECK-NEXT: ret i1 [[RESULT]]
-define i1 @f9(i32 %val, i32 %lim) {
-  %lim.sub = sub i32 %lim, 1
-  %val.and = and i32 %val, %lim.sub
-  %r = icmp ult i32 %val.and, %lim
-  ret i1 %r
-}