[llvm] r188512 - InstCombine: Simplify if(x!=0 && x!=-1).
Jim Grosbach
grosbach at apple.com
Thu Aug 15 17:15:20 PDT 2013
Author: grosbach
Date: Thu Aug 15 19:15:20 2013
New Revision: 188512
URL: http://llvm.org/viewvc/llvm-project?rev=188512&view=rev
Log:
InstCombine: Simplify if(x!=0 && x!=-1).
When both constants are positive or both constants are negative,
InstCombine already simplifies comparisons like this, but when
it's exactly zero and -1, the operand sorting ends up reversed
and the pattern fails to match. Handle that special case.
Follow up for rdar://14689217
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
llvm/trunk/test/Transforms/InstCombine/and2.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=188512&r1=188511&r2=188512&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Thu Aug 15 19:15:20 2013
@@ -849,10 +849,15 @@ Value *InstCombiner::FoldAndOfICmps(ICmp
case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15
return RHS;
case ICmpInst::ICMP_NE:
+ // Special case to get the ordering right when the values wrap around
+ // zero.
+ if (LHSCst->getValue() == 0 && RHSCst->getValue() == -1)
+ std::swap(LHSCst, RHSCst);
if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1
Constant *AddCST = ConstantExpr::getNeg(LHSCst);
Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
- return Builder->CreateICmpUGT(Add, ConstantInt::get(Add->getType(), 1));
+ return Builder->CreateICmpUGT(Add, ConstantInt::get(Add->getType(), 1),
+ Val->getName()+".cmp");
}
break; // (X != 13 & X != 15) -> no change
}
Modified: llvm/trunk/test/Transforms/InstCombine/and2.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/and2.ll?rev=188512&r1=188511&r2=188512&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/and2.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/and2.ll Thu Aug 15 19:15:20 2013
@@ -42,3 +42,15 @@ define <4 x i32> @test5(<4 x i32> %A) {
%2 = and <4 x i32> <i32 1, i32 2, i32 3, i32 4>, %1
ret <4 x i32> %2
}
+
+; Check that we combine "if x!=0 && x!=-1" into "if x+1u>1"
+define i32 @test6(i64 %x) nounwind {
+; CHECK: @test6
+; CHECK-NEXT: add i64 %x, 1
+; CHECK-NEXT: icmp ugt i64 %x.off, 1
+ %cmp1 = icmp ne i64 %x, -1
+ %not.cmp = icmp ne i64 %x, 0
+ %.cmp1 = and i1 %cmp1, %not.cmp
+ %land.ext = zext i1 %.cmp1 to i32
+ ret i32 %land.ext
+}
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