r271020 added an early out to skip the signed multiply portion of ConstantRange::multiply. The comment says we don't need to do signed multiply if the range is only positive numbers, but the implemented check only ensures that the start of the range is positive. It doesn't look at the end of the range.
This patch checks the end of the range instead. Because Upper is one more than the end we have to see if its positive or if its one past the last positive number.
llvm-svn: 302717
This change teaches getEquivalentICmp to be smarter about generating
ICMP_NE and ICMP_EQ predicates.
An earlier version of this change was landed as rL283057 which had a
use-after-free bug. This new version has a fix for that bug, and a (C++
unittests/) test case that would have triggered it rL283057.
llvm-svn: 283078
They've broken the sanitizer-bootstrap bots. Reverting while I investigate.
Original commit messages:
r283057: "[ConstantRange] Make getEquivalentICmp smarter"
r283058: "[SCEV] Rely on ConstantRange instead of custom logic; NFCI"
llvm-svn: 283062
Rename makeNoWrapRegion to a more obvious makeGuaranteedNoWrapRegion,
and add a comment about the counter-intuitive aspects of the function.
This is to help prevent cases like PR26628.
llvm-svn: 261532
Summary: This will be used in a future change to ScalarEvolution.
Reviewers: hfinkel, reames, nlewycky
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D13612
llvm-svn: 250975
Summary:
This change splits `makeICmpRegion` into `makeAllowedICmpRegion` and
`makeSatisfyingICmpRegion` with slightly different contracts. The first
one is useful for determining what values some expression //may// take,
given that a certain `icmp` evaluates to true. The second one is useful
for determining what values are guaranteed to //satisfy// a given
`icmp`.
Reviewers: nlewycky
Reviewed By: nlewycky
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D8345
llvm-svn: 232575
Multiplication is not dependent on signedness, so just treating
all input ranges as unsigned is not incorrect. However it will cause
overly pessimistic ranges (such as full-set) when used with signed
negative values.
Teach multiply to try to interpret its inputs as both signed and
unsigned, and then to take the most specific (smallest population)
as its result.
llvm-svn: 231483
a bit surprising, as the class is almost entirely abstracted away from
any particular IR, however it encodes the comparsion predicates which
mutate ranges as ICmp predicate codes. This is reasonable as they're
used for both instructions and constants. Thus, it belongs in the IR
library with instructions and constants.
llvm-svn: 202838
Craig Topper