[InstCombine] remove unneeded one-use checks for icmp fold
This fold and several others were added in:
rL125734 <https://reviews.llvm.org/rL125734>
...with no explanation for the one-use checks other than the code
comments about register pressure.
Given that this is IR canonicalization, we shouldn't be worried
about register pressure though; the backend should be able to
adjust for that as needed.
This is part of solving PR43310 the theoretically right way:
https://bugs.llvm.org/show_bug.cgi?id=43310
...ie, if we don't cripple basic transforms, then we won't
need to add special-case code to detect larger patterns.
rL371940 is a related patch in this series.
llvm-svn: 371981
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index a7732c4..5c443fa 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3849,10 +3849,7 @@
return new ICmpInst(Pred, A, C);
// icmp (A-B), (A-D) -> icmp D, B for equalities or if there is no overflow.
- // TODO: The one-use checks should not be necessary.
- if (A && C && A == C && NoOp0WrapProblem && NoOp1WrapProblem &&
- // Try not to increase register pressure.
- BO0->hasOneUse() && BO1->hasOneUse())
+ if (A && C && A == C && NoOp0WrapProblem && NoOp1WrapProblem)
return new ICmpInst(Pred, D, B);
// icmp (0-X) < cst --> x > -cst