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| author | Nicola Zaghen <nicola.zaghen@imgtec.com> | 2018-09-04 10:29:48 +0000 |
|---|---|---|
| committer | Nicola Zaghen <nicola.zaghen@imgtec.com> | 2018-09-04 10:29:48 +0000 |
| commit | 9588ad9611368d65a6f619ae5e79fff70854a1fc (patch) | |
| tree | f51068c83cdebf1b82bf5bdfd2512383917f2fb0 /llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp | |
| parent | ef16ea7f7ade8dbe3647e7c829a13d1dbeee0f0e (diff) | |
| download | bcm5719-llvm-9588ad9611368d65a6f619ae5e79fff70854a1fc.tar.gz bcm5719-llvm-9588ad9611368d65a6f619ae5e79fff70854a1fc.zip | |
[InstCombine] Fold icmp ugt/ult (add nuw X, C2), C --> icmp ugt/ult X, (C - C2)
Support for sgt/slt was added in rL294898, this adds the same cases also for unsigned compares.
This is the Alive proof: https://rise4fun.com/Alive/nyY
Differential Revision: https://reviews.llvm.org/D50972
llvm-svn: 341353
Diffstat (limited to 'llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp index 2926e268190..e0a1083b927 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -2338,12 +2338,15 @@ Instruction *InstCombiner::foldICmpAddConstant(ICmpInst &Cmp, CmpInst::Predicate Pred = Cmp.getPredicate(); // If the add does not wrap, we can always adjust the compare by subtracting - // the constants. Equality comparisons are handled elsewhere. SGE/SLE are - // canonicalized to SGT/SLT. - if (Add->hasNoSignedWrap() && - (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SLT)) { + // the constants. Equality comparisons are handled elsewhere. SGE/SLE/UGE/ULE + // are canonicalized to SGT/SLT/UGT/ULT. + if ((Add->hasNoSignedWrap() && + (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SLT)) || + (Add->hasNoUnsignedWrap() && + (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_ULT))) { bool Overflow; - APInt NewC = C.ssub_ov(*C2, Overflow); + APInt NewC = + Cmp.isSigned() ? C.ssub_ov(*C2, Overflow) : C.usub_ov(*C2, Overflow); // If there is overflow, the result must be true or false. // TODO: Can we assert there is no overflow because InstSimplify always // handles those cases? |
