Summary:
CVP, unlike InstCombine, does not run till exaustion.
It only does a single pass.
When dealing with those special binops, if we prove that they can
safely be demoted into their usual binop form,
we do set the no-wrap we deduced. But when dealing with usual binops,
we try to deduce both no-wraps.
So if we convert e.g. @llvm.uadd.with.overflow() to `add nuw`,
we won't attempt to check whether it can be `add nuw nsw`.
This patch proposes to call `processBinOp()` on newly-created binop,
which is identical to what we do for div/rem already.
Reviewers: nikic, spatel, reames
Reviewed By: nikic
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D69183
llvm-svn: 375273
This is really a known bits style transformation, but known bits isn't context sensitive. The particular case which comes up happens to involve a range which allows range based reasoning to eliminate the mask pattern, so handle that case specifically in CVP.
InstCombine likes to generate the mask-by-low-bits pattern when widening an arithmetic expression which includes a zext in the middle.
Differential Revision: https://reviews.llvm.org/D68811
llvm-svn: 374506
This addresses the issue mentioned on D19867. When we simplify
with.overflow instructions in CVP, we leave behind extractvalue
of insertvalue sequences that LVI no longer understands. This
means that we can not simplify any instructions based on the
with.overflow anymore (until some over pass like InstCombine
cleans them up).
This patch extends LVI extractvalue handling by calling
SimplifyExtractValueInst (which doesn't do anything more than
constant folding + looking through insertvalue) and using the block
value of the simplification.
A possible alternative would be to do something similar to
SimplifyIndVars, where we instead directly try to replace
extractvalue users of the with.overflow. This would need some
additional structural changes to CVP, as it's currently not legal
to remove anything but the current instruction -- we'd have to
introduce a worklist with instructions scheduled for deletion or similar.
Differential Revision: https://reviews.llvm.org/D67035
llvm-svn: 371306
Use a { iN undef, i1 false } struct as the base, and only insert
the first operand, instead of using { iN undef, i1 undef } as the
base and inserting both. This is the same as what we do in InstCombine.
Differential Revision: https://reviews.llvm.org/D67034
llvm-svn: 370573
If we can determine that a saturating add/sub will not overflow based
on range analysis, convert it into a simple binary operation. This is
a sibling transform to the existing with.overflow handling.
Reapplying this with an additional check that the saturating intrinsic
has integer type, as LVI currently does not support vector types.
Differential Revision: https://reviews.llvm.org/D62703
llvm-svn: 362263
Noticed on D62703. LVI only handles plain integers, not vectors of
integers. This was previously not an issue, because vector support
for with.overflow is only a relatively recent addition.
llvm-svn: 362261
If we can determine that a saturating add/sub will not overflow
based on range analysis, convert it into a simple binary operation.
This is a sibling transform to the existing with.overflow handling.
Differential Revision: https://reviews.llvm.org/D62703
llvm-svn: 362242
As it's causing some bot failures (and per request from kbarton).
This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.
llvm-svn: 358546
If a umul.with.overflow or smul.with.overflow operation cannot
overflow, simplify it to a simple mul nuw / mul nsw. After the
refactoring in D60668 this is just a matter of removing an
explicit check against multiplications.
Differential Revision: https://reviews.llvm.org/D60791
llvm-svn: 358521
When CVP determines that a with.overflow intrinsic cannot overflow,
it currently inserts a simple add/sub. As we already determined that
there can be no overflow, we should add the appropriate NUW/NSW flag.
Differential Revision: https://reviews.llvm.org/D60585
llvm-svn: 358298
Fix all of the missing debug location errors in CVP found by debugify.
This includes the missing-location-after-udiv-truncation case described
in llvm.org/PR38178.
llvm-svn: 347147
This uses ConstantRange::makeGuaranteedNoWrapRegion's newly-added handling for subtraction to allow CVP to remove some subtraction overflow checks.
Differential Revision: https://reviews.llvm.org/D40039
llvm-svn: 319807
Summary:
This adds logic to CVP to remove some overflow checks. It uses LVI to remove
operations with at least one constant. Specifically, this can remove many
overflow intrinsics immediately following an overflow check in the source code,
such as:
if (x < INT_MAX)
... x + 1 ...
Patch by Joel Galenson!
Reviewers: sanjoy, regehr
Reviewed By: sanjoy
Subscribers: fhahn, pirama, srhines, llvm-commits
Differential Revision: https://reviews.llvm.org/D39483
llvm-svn: 317911
Roman Lebedev