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| author | Nikita Popov <nikita.ppv@gmail.com> | 2019-05-28 18:08:31 +0000 |
|---|---|---|
| committer | Nikita Popov <nikita.ppv@gmail.com> | 2019-05-28 18:08:31 +0000 |
| commit | 332c10056227d5da5557f50e8c64dc8814ca56f0 (patch) | |
| tree | 4ca1abc675a10809ee43eefec87544139d77c3ef /llvm/lib/IR/ConstantRange.cpp | |
| parent | 2fb0a820df9c9884b9f42efdd0919b309e2b1204 (diff) | |
| download | bcm5719-llvm-332c10056227d5da5557f50e8c64dc8814ca56f0.tar.gz bcm5719-llvm-332c10056227d5da5557f50e8c64dc8814ca56f0.zip | |
[ValueTracking][ConstantRange] Distinguish low/high always overflow
In order to fold an always overflowing signed saturating add/sub,
we need to know in which direction the always overflow occurs.
This patch splits up AlwaysOverflows into AlwaysOverflowsLow and
AlwaysOverflowsHigh to pass through this information (but it is
not used yet).
Differential Revision: https://reviews.llvm.org/D62463
llvm-svn: 361858
Diffstat (limited to 'llvm/lib/IR/ConstantRange.cpp')
| -rw-r--r-- | llvm/lib/IR/ConstantRange.cpp | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/llvm/lib/IR/ConstantRange.cpp b/llvm/lib/IR/ConstantRange.cpp index 0d44c3815b3..30b6a27078c 100644 --- a/llvm/lib/IR/ConstantRange.cpp +++ b/llvm/lib/IR/ConstantRange.cpp @@ -1208,9 +1208,9 @@ ConstantRange::OverflowResult ConstantRange::unsignedAddMayOverflow( APInt Min = getUnsignedMin(), Max = getUnsignedMax(); APInt OtherMin = Other.getUnsignedMin(), OtherMax = Other.getUnsignedMax(); - // a u+ b overflows iff a u> ~b. + // a u+ b overflows high iff a u> ~b. if (Min.ugt(~OtherMin)) - return OverflowResult::AlwaysOverflows; + return OverflowResult::AlwaysOverflowsHigh; if (Max.ugt(~OtherMax)) return OverflowResult::MayOverflow; return OverflowResult::NeverOverflows; @@ -1231,10 +1231,10 @@ ConstantRange::OverflowResult ConstantRange::signedAddMayOverflow( // a s+ b overflows low iff a s< 0 && b s< 0 && a s< smin - b. if (Min.isNonNegative() && OtherMin.isNonNegative() && Min.sgt(SignedMax - OtherMin)) - return OverflowResult::AlwaysOverflows; + return OverflowResult::AlwaysOverflowsHigh; if (Max.isNegative() && OtherMax.isNegative() && Max.slt(SignedMin - OtherMax)) - return OverflowResult::AlwaysOverflows; + return OverflowResult::AlwaysOverflowsLow; if (Max.isNonNegative() && OtherMax.isNonNegative() && Max.sgt(SignedMax - OtherMax)) @@ -1254,9 +1254,9 @@ ConstantRange::OverflowResult ConstantRange::unsignedSubMayOverflow( APInt Min = getUnsignedMin(), Max = getUnsignedMax(); APInt OtherMin = Other.getUnsignedMin(), OtherMax = Other.getUnsignedMax(); - // a u- b overflows iff a u< b. + // a u- b overflows low iff a u< b. if (Max.ult(OtherMin)) - return OverflowResult::AlwaysOverflows; + return OverflowResult::AlwaysOverflowsLow; if (Min.ult(OtherMax)) return OverflowResult::MayOverflow; return OverflowResult::NeverOverflows; @@ -1277,10 +1277,10 @@ ConstantRange::OverflowResult ConstantRange::signedSubMayOverflow( // a s- b overflows low iff a s< 0 && b s>= 0 && a s< smin + b. if (Min.isNonNegative() && OtherMax.isNegative() && Min.sgt(SignedMax + OtherMax)) - return OverflowResult::AlwaysOverflows; + return OverflowResult::AlwaysOverflowsHigh; if (Max.isNegative() && OtherMin.isNonNegative() && Max.slt(SignedMin + OtherMin)) - return OverflowResult::AlwaysOverflows; + return OverflowResult::AlwaysOverflowsLow; if (Max.isNonNegative() && OtherMin.isNegative() && Max.sgt(SignedMax + OtherMin)) @@ -1303,7 +1303,7 @@ ConstantRange::OverflowResult ConstantRange::unsignedMulMayOverflow( (void) Min.umul_ov(OtherMin, Overflow); if (Overflow) - return OverflowResult::AlwaysOverflows; + return OverflowResult::AlwaysOverflowsHigh; (void) Max.umul_ov(OtherMax, Overflow); if (Overflow) |
