| Commit message (Collapse) | Author | Age | Files | Lines |
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Recognize -mrecord-mcount from the command line and add a function attribute
"mrecord-mcount" when passed.
Only valid on SystemZ (when used with -mfentry).
Review: Ulrich Weigand
https://reviews.llvm.org/D71627
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Summary:
The vector pattern `(a + b + 1) / 2` was previously selected to an
avgr_u instruction regardless of nuw flags, but this is incorrect in
the case where either addition may have an unsigned wrap. This CL
changes the existing pattern to require both adds to have nuw flags
and adds builtin functions and intrinsics for the avgr_u instructions
because the corrected pattern is not representable in C.
Reviewers: aheejin
Subscribers: dschuff, sbc100, jgravelle-google, hiraditya, sunfish, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D71648
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Let the "mnop-mcount" function attribute simply be present or non-present.
Update SystemZ backend as well to use hasFnAttribute() instead.
Review: Ulrich Weigand
https://reviews.llvm.org/D71669
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Summary:
This adds parsing of the qualifiers __ptr32, __ptr64, __sptr, and __uptr and
lowers them to the corresponding address space pointer for 32-bit and 64-bit pointers.
(32/64-bit pointers added in https://reviews.llvm.org/D69639)
A large part of this patch is making these pointers ignore the address space
when doing things like overloading and casting.
https://bugs.llvm.org/show_bug.cgi?id=42359
Reviewers: rnk, rsmith
Subscribers: jholewinski, jvesely, nhaehnle, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D71039
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The following intrinsics currently carry a rounding mode metadata argument:
llvm.experimental.constrained.minnum
llvm.experimental.constrained.maxnum
llvm.experimental.constrained.ceil
llvm.experimental.constrained.floor
llvm.experimental.constrained.round
llvm.experimental.constrained.trunc
This is not useful since the semantics of those intrinsics do not in any way
depend on the rounding mode. In similar cases, other constrained intrinsics
do not have the rounding mode argument. Remove it here as well.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D71218
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Recognize -mpacked-stack from the command line and add a function attribute
"mpacked-stack" when passed. This is needed for building the Linux kernel.
If this option is passed for any other target than SystemZ, an error is
generated.
Review: Ulrich Weigand
https://reviews.llvm.org/D71441
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The FP-classification builtins (__builtin_isfinite, etc) use variadic
packs in the definition file to mean an overload set. Because of that,
floats were converted to doubles, which is incorrect. There WAS a patch
to remove the cast after the fact.
THis patch switches these builtins to just be custom type checking,
calls the implicit conversions for the integer members, and makes sure
the correct L->R casts are put into place, then does type checking like
normal.
A future direction (that wouldn't be NFC) would consider making
conversions for the floating point parameter legal.
Note: The initial patch for this missed that certain systems need to
still convert half to float, since they dont' support that type.
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This change updates the clang front end to add symbols to llvm.used
when they have explicit export_name attribute.
Differential Revision: https://reviews.llvm.org/D71493
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Summary:
The instructions were originally implemented via builtins and
intrinsics so users would have to explicitly opt-in to using
them. This was useful while were validating whether these instructions
should have been merged into the spec proposal. Now that they have
been, we can use normal codegen patterns, so the intrinsics and
builtins are no longer useful.
Reviewers: aheejin
Subscribers: dschuff, sbc100, jgravelle-google, hiraditya, sunfish, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D71500
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As brought up in D71467, a group of floating point builtins
automatically promoted floats to doubles because they used the variadic
builtin tag to support an overload set. The result is that the
parameters were treated as a variadic pack, which always promots
float->double.
This resulted in the wrong answer being given in cases with certain
values of NaN.
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numbers.
Fix broken tests. I can't yet explain how they worked locally pre-commit.
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Summary:
This patch adds intrinsics for the following MVE instructions:
* VABAV
* VMLADAV, VMLSDAV
* VMLALDAV, VMLSLDAV
* VRMLALDAVH, VRMLSLDAVH
Each of the above 4 groups has a corresponding new LLVM IR intrinsic,
since the instructions cannot be easily represented using
general-purpose IR operations.
Reviewers: simon_tatham, ostannard, dmgreen, MarkMurrayARM
Reviewed By: MarkMurrayARM
Subscribers: merge_guards_bot, kristof.beyls, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D71062
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Summary:
This fills in the remaining shift operations that take a single vector
input and an immediate shift count: the `vqshl`, `vqshlu`, `vrshr` and
`vshll[bt]` families.
`vshll[bt]` (which shifts each input lane left into a double-width
output lane) is the most interesting one. There are separate MC
instruction ids for shifting by exactly the input lane width and
shifting by less than that, because the instruction encoding is so
completely different for the lane-width special case. So I had to
write two sets of patterns to match based on the immediate shift
count, which involved adding a ComplexPattern matcher to avoid the
general-case pattern accidentally matching the special case too. For
that family I've made sure to add an llc codegen test for both
versions of each instruction.
I'm experimenting with a new strategy for parametrising the isel
patterns for all these instructions: adding extra fields to the
relevant `Instruction` subclass itself, which are ignored by the
Tablegen backends that generate the MC data, but can be retrieved from
each instance of that instruction subclass when it's passed as a
template parameter to the multiclass that generates its isel patterns.
A nice effect of that is that I can fill in those informational fields
using `let` blocks, rather than having to type them out once per
instruction at `defm` time.
(As a result, quite a lot of existing instruction `def`s are
reindented by this patch, so it's clearer to read with whitespace
changes ignored.)
Reviewers: dmgreen, MarkMurrayARM, miyuki, ostannard
Reviewed By: MarkMurrayARM
Subscribers: kristof.beyls, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D71458
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Summary:
Better use of multiclass is used, and this helped find some existing
bugs in the predicated VMULL* intrinsics, which are now fixed.
The refactored VMULL[TB]Q_(INT|POLY)_M() intrinsics were discovered
to have an argument ("inactive") with incorrect type, and this required
a fix that is included in this whole patch. The argument "inactive"
should have been the same width (per vector element) as the return
type of the intrinsic, but was not in the case where the return type
was double the element width of the input types.
To assist in testing the multiclassing , and to thwart further gremlins,
the unit tests are improved in scope.
The *.ll tests are all generated by a small bit of throw-away scripting
from the corresponding *.c tests, and as such the diffs are large and
nasty. Look at the file rather than the diff.
Reviewers: dmgreen, miyuki, ostannard, simon_tatham
Subscribers: kristof.beyls, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D71421
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Summary:
This is a follow up on https://reviews.llvm.org/D61634#1742154 to turn the clang driver -fno-builtin flag into an IR attribute.
I also investigated pushing the attribute earlier on (in Sema) but it looks like this patch is simple and will cover all function calls.
Reviewers: aaron.ballman, courbet
Subscribers: cfe-commits, tejohnson
Tags: #clang
Differential Revision: https://reviews.llvm.org/D71193
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This is patch C2 as mentioned in RFC
http://lists.llvm.org/pipermail/cfe-dev/2019-March/061834.html
This adds CMSE builtin functions, and introduces arm_cmse.h header which has
useful macros, functions, and data types for end-users of CMSE.
Patch by Javed Absar.
Diferential Revision: https://reviews.llvm.org/D70817
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export names
This is equivalent to the existing `import_name` and `import_module`
attributes which control the import names in the final wasm binary
produced by lld.
This maps the existing
This attribute currently requires a string rather than using the
symbol name for a couple of reasons:
1. Avoid confusion with static and dynamic linking which is
based on symbol name. Exporting a function from a wasm module using
this directive is orthogonal to both static and dynamic linking.
2. Avoids name mangling.
Differential Revision: https://reviews.llvm.org/D70520
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Summary:
Attribute annotations are recorded in a special global composite variable
that points to annotation strings and the annotated objects.
As a restriction of the LLVM IR type system, those pointers are all
pointers to address space 0, so let's insert an addrspacecast when the
annotated global is in a non-0 address space.
Since this addrspacecast is only reachable from the global annotations
object, this should allow us to represent annotations on all globals
regardless of which addrspacecasts are usually legal for the target.
Reviewers: rjmccall
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D71208
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This adds the family of `vshlq_n` and `vshrq_n` ACLE intrinsics, which
shift every lane of a vector left or right by a compile-time
immediate. They mostly work by expanding to the IR `shl`, `lshr` and
`ashr` operations, with their second operand being a vector splat of
the immediate.
There's a fiddly special case, though. ACLE specifies that the
immediate in `vshrq_n` can take values up to //and including// the bit
size of the vector lane. But LLVM IR thinks that shifting right by the
full size of the lane is UB, and feels free to replace the `lshr` with
an `undef` half way through the optimization pipeline. Hence, to keep
this legal in source code, I have to detect it at codegen time.
Logical (unsigned) right shifts by the element size are handled by
simply emitting the zero vector; arithmetic ones are converted into a
shift of one bit less, which will always give the same output.
In order to do that check, I also had to enhance the tablegen
MveEmitter so that it can cope with converting a builtin function's
operand into a bare integer to pass to a code-generating subfunction.
Previously the only bare integers it knew how to handle were flags
generated from within `arm_mve.td`.
Reviewers: dmgreen, miyuki, MarkMurrayARM, ostannard
Reviewed By: dmgreen, MarkMurrayARM
Subscribers: echristo, hokein, rdhindsa, kristof.beyls, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D71065
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Reviewers: dblaikie, aprantl, probinson
Tags: #debug-info #llvm
Differential Revision: https://reviews.llvm.org/D71185
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This reverts commit 6ef01588f4d75ef43da4ed2a37ba7a8b8daab259.
Missing Differetial revision.
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https://github.com/llvm/llvm-project/commit/5b330e8d6122c336d81dfd11c864e6c6240a381e caused
a regression on s390:
https://bugs.llvm.org/show_bug.cgi?id=44190
we need to copy if if either the argument is non-byval or the argument is underaligned.
Differential Revision: https://reviews.llvm.org/D71282
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Change the IRBuilder and clang so that constrained FP intrinsics will be
emitted for builtins when appropriate. Only non-target-specific builtins
are affected in this patch.
Differential Revision: https://reviews.llvm.org/D70256
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Summary:
This patch refactors instruction selection of the complex vector
addition, multiplication and multiply-add intrinsics, so that it is
now based on TableGen patterns rather than C++ code.
It also changes the first parameter (halving vs non-halving) of the
arm_mve_vcaddq IR intrinsic to match the corresponding instruction
encoding, hence it requires some changes in the tests.
The patch addresses David's comment in https://reviews.llvm.org/D71190
Reviewers: dmgreen, ostannard, simon_tatham, MarkMurrayARM
Reviewed By: dmgreen
Subscribers: merge_guards_bot, kristof.beyls, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D71245
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Extern variable usage in BPF is different from traditional
pure user space application. Recent discussion in linux bpf
mailing list has two use cases where debug info types are
required to use extern variables:
- extern types are required to have a suitable interface
in libbpf (bpf loader) to provide kernel config parameters
to bpf programs.
https://lore.kernel.org/bpf/CAEf4BzYCNo5GeVGMhp3fhysQ=_axAf=23PtwaZs-yAyafmXC9g@mail.gmail.com/T/#t
- extern types are required so kernel bpf verifier can
verify program which uses external functions more precisely.
This will make later link with actual external function no
need to reverify.
https://lore.kernel.org/bpf/87eez4odqp.fsf@toke.dk/T/#m8d5c3e87ffe7f2764e02d722cb0d8cbc136880ed
This patch added clang support to emit debuginfo for extern variables
with a TargetInfo hook to enable it. The debuginfo for the
extern variable is emitted only if that extern variable is
referenced in the current compilation unit.
Currently, only BPF target enables to generate debug info for
extern variables. The emission of such debuginfo is disabled for C++
at this moment since BPF only supports a subset of C language.
Emission with C++ can be enabled later if an appropriate use case
is identified.
-fstandalone-debug permits us to see more debuginfo with the cost
of bloated binary size. This patch did not add emission of extern
variable debug info with -fstandalone-debug. This can be
re-evaluated if there is a real need.
Differential Revision: https://reviews.llvm.org/D70696
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types for fp classification builtins
Summary:
It shouldn't promote half to double or any larger precision types for fp classification builtins.
Because fp classification builtins would get incorrect result with promoted argument.
For example, __builtin_isnormal with a subnormal half value should return false, but it is not.
That the subnormal half value is promoted to a normal double value.
Reviewers: aaron.ballman
Reviewed By: aaron.ballman
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D71049
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and two follow-on commits: one warning fix and one functionality.
As it's breaking at least the lto bot:
http://lab.llvm.org:8011/builders/clang-with-lto-ubuntu/builds/15132/steps/test-stage1-compiler/logs/stdio
This reverts commits:
8d70f3c933a5b81a87a5ab1af0e3e98ee2cd7c67
ff4dceef9201c5ae3924e92f6955977f243ac71d
d97b3e3e65cd77a81b39732af84a1a4229e95091
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VQDMULHQ, VQRDMULHQ intrinsics.
Summary: Add VQADDQ, VHADDQ, VRHADDQ, VQSUBQ, VHSUBQ, VQDMULHQ, VQRDMULHQ intrinsics and unit tests.
Reviewers: simon_tatham, ostannard, dmgreen, miyuki
Subscribers: kristof.beyls, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D71198
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Summary: Add VMULL[BT]Q_(INT|POLY) intrinsics and unit tests.
Reviewers: simon_tatham, ostannard, dmgreen
Subscribers: kristof.beyls, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D71066
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Summary:
This adds the family of `vshlq_n` and `vshrq_n` ACLE intrinsics, which
shift every lane of a vector left or right by a compile-time
immediate. They mostly work by expanding to the IR `shl`, `lshr` and
`ashr` operations, with their second operand being a vector splat of
the immediate.
There's a fiddly special case, though. ACLE specifies that the
immediate in `vshrq_n` can take values up to //and including// the bit
size of the vector lane. But LLVM IR thinks that shifting right by the
full size of the lane is UB, and feels free to replace the `lshr` with
an `undef` half way through the optimization pipeline. Hence, to keep
this legal in source code, I have to detect it at codegen time.
Logical (unsigned) right shifts by the element size are handled by
simply emitting the zero vector; arithmetic ones are converted into a
shift of one bit less, which will always give the same output.
In order to do that check, I also had to enhance the tablegen
MveEmitter so that it can cope with converting a builtin function's
operand into a bare integer to pass to a code-generating subfunction.
Previously the only bare integers it knew how to handle were flags
generated from within `arm_mve.td`.
Reviewers: dmgreen, miyuki, MarkMurrayARM, ostannard
Reviewed By: MarkMurrayARM
Subscribers: kristof.beyls, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D71065
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https://reviews.llvm.org/D70691
Fixed the LIT test case. Added the REQUIRES instruction.
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Summary:
This patch adds intrinsics for the following MVE instructions:
* VCADD, VHCADD
* VCMUL
* VCMLA
Each of the above 3 groups has a corresponding new LLVM IR intrinsic.
Reviewers: simon_tatham, MarkMurrayARM, ostannard, dmgreen
Reviewed By: MarkMurrayARM
Subscribers: merge_guards_bot, kristof.beyls, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D71190
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https://reviews.llvm.org/D70691
Upated LIT test.
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validateOutputSize and validateInputSize."
This reverts commit e1578fd2b79fe5af5f80c0c166a8abd0f816c022.
It introduces a dependency on Attr.h which I am removing from
ASTContext.h.
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and validateInputSize.
The validateOutputSize and validateInputSize need to check whether
AVX or AVX512 are enabled. But this can be affected by the
target attribute so we need to factor that in.
This patch copies some of the code from CodeGen to create an
appropriate feature map that we can pass to the function. Probably
need some refactoring here to share more code with Codegen. Is
there a good place to do that? Also need to support the cpu_specific
attribute as well.
Differential Revision: https://reviews.llvm.org/D68627
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Review is here: https://reviews.llvm.org/D70691
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ftrapping-math, -ffp-model=, and -ffp-exception-behavior="
Patch was reverted because https://bugs.llvm.org/show_bug.cgi?id=44048
The original patch is modified to set the strictfp IR attribute
explicitly in CodeGen instead of as a side effect of IRBuilder.
In the 2nd attempt to reapply there was a windows lit test fail, the
tests were fixed to use wildcard matching.
Differential Revision: https://reviews.llvm.org/D62731
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-frounding-math, ftrapping-math, -ffp-model=, and -ffp-exception-behavior=""
This reverts commit cdbed2dd856c14687efd741c2d8321686102acb8.
Build break on Windows (lit fail)
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ftrapping-math, -ffp-model=, and -ffp-exception-behavior="
Patch was reverted because https://bugs.llvm.org/show_bug.cgi?id=44048
The original patch is modified to set the strictfp IR attribute
explicitly in CodeGen instead of as a side effect of IRBuilder
Differential Revision: https://reviews.llvm.org/D62731
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Summary: Add MVE VMULH/VRMULH intrinsics and unit tests.
Reviewers: simon_tatham, ostannard, dmgreen
Subscribers: kristof.beyls, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D70948
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Minor improvement to a test added in 1ac700cdef787383ad49a
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The test is complaining on some of the builders. This attempts to
adjust the run line to be more line the others in the same folder, using
clang_cc1 as opposed to the driver.
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Summary:
This commit adds the `vpselq` intrinsics which take an MVE predicate
word and select lanes from two vectors; the `vctp` intrinsics which
create a tail predicate word suitable for processing the first m
elements of a vector (e.g. in the last iteration of a loop); and
`vpnot`, which simply complements a predicate word and is just
syntactic sugar for the `~` operator.
The `vctp` ACLE intrinsics are lowered to the IR intrinsics we've
already added (and which D70592 just reorganized). I've filled in the
missing isel rule for VCTP64, and added another set of rules to
generate the predicated forms.
I needed one small tweak in MveEmitter to allow the `unpromoted` type
modifier to apply to predicates as well as integers, so that `vpnot`
doesn't pointlessly convert its input integer to an `<n x i1>` before
complementing it.
Reviewers: ostannard, MarkMurrayARM, dmgreen
Reviewed By: dmgreen
Subscribers: kristof.beyls, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D70485
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Summary:
Add support for vcadd_* family of intrinsics. This set of intrinsics is
available in Armv8.3-A.
The fp16 versions require the FP16 extension, which has been available
(opt-in) since Armv8.2-A.
Reviewers: t.p.northover
Reviewed By: t.p.northover
Subscribers: t.p.northover, kristof.beyls, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D70862
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Summary: Add VMINQ/VMAXQ/VMINNMQ/VMAXNMQ intrinsics and their predicated versions. Add unit tests.
Subscribers: kristof.beyls, hiraditya, dmgreen, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D70829
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Now Clang does not check that features required by built-in functions
are enabled. That causes errors in the backend reported in PR44018.
This patch fixes this bug by checking that required features
are enabled.
This should fix PR44018.
Differential Revision: https://reviews.llvm.org/D70808
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Summary: Fix PR43700
The ConstantEmitter in AggExprEmitter::EmitArrayInit was initialized
with the CodeGenFunction set to null, which caused the crash.
Also simplify another call, and make the CGF member a const pointer
since it is public but only assigned in the constructor.
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D70302
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(PR44054)(take 2)
Summary:
Implicit Conversion Sanitizer is *almost* feature complete.
There aren't *that* much unsanitized things left,
two major ones are increment/decrement (this patch) and bit fields.
As it was discussed in
[[ https://bugs.llvm.org/show_bug.cgi?id=39519 | PR39519 ]],
unlike `CompoundAssignOperator` (which is promoted internally),
or `BinaryOperator` (for which we always have promotion/demotion in AST)
or parts of `UnaryOperator` (we have promotion/demotion but only for
certain operations), for inc/dec, clang omits promotion/demotion
altogether, under as-if rule.
This is technically correct: https://rise4fun.com/Alive/zPgD
As it can be seen in `InstCombineCasts.cpp` `canEvaluateTruncated()`,
`add`/`sub`/`mul`/`and`/`or`/`xor` operators can all arbitrarily
be extended or truncated:
https://github.com/llvm/llvm-project/blob/901cd3b3f62d0c700e5d2c3f97eff97d634bec5e/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp#L1320-L1334
But that has serious implications:
1. Since we no longer model implicit casts, do we pessimise
their AST representation and everything that uses it?
2. There is no demotion, so lossy demotion sanitizer does not trigger :]
Now, i'm not going to argue about the first problem here,
but the second one **needs** to be addressed. As it was stated
in the report, this is done intentionally, so changing
this in all modes would be considered a penalization/regression.
Which means, the sanitization-less codegen must not be altered.
It was also suggested to not change the sanitized codegen
to the one with demotion, but i quite strongly believe
that will not be the wise choice here:
1. One will need to re-engineer the check that the inc/dec was lossy
in terms of `@llvm.{u,s}{add,sub}.with.overflow` builtins
2. We will still need to compute the result we would lossily demote.
(i.e. the result of wide `add`ition/`sub`traction)
3. I suspect it would need to be done right here, in sanitization.
Which kinda defeats the point of
using `@llvm.{u,s}{add,sub}.with.overflow` builtins:
we'd have two `add`s with basically the same arguments,
one of which is used for check+error-less codepath and other one
for the error reporting. That seems worse than a single wide op+check.
4. OR, we would need to do that in the compiler-rt handler.
Which means we'll need a whole new handler.
But then what about the `CompoundAssignOperator`,
it would also be applicable for it.
So this also doesn't really seem like the right path to me.
5. At least X86 (but likely others) pessimizes all sub-`i32` operations
(due to partial register stalls), so even if we avoid promotion+demotion,
the computations will //likely// be performed in `i32` anyways.
So i'm not really seeing much benefit of
not doing the straight-forward thing.
While looking into this, i have noticed a few more LLVM middle-end
missed canonicalizations, and filed
[[ https://bugs.llvm.org/show_bug.cgi?id=44100 | PR44100 ]],
[[ https://bugs.llvm.org/show_bug.cgi?id=44102 | PR44102 ]].
Those are not specific to inc/dec, we also have them for
`CompoundAssignOperator`, and it can happen for normal arithmetics, too.
But if we take some other path in the patch, it will not be applicable
here, and we will have most likely played ourselves.
TLDR: front-end should emit canonical, easy-to-optimize yet
un-optimized code. It is middle-end's job to make it optimal.
I'm really hoping reviewers agree with my personal assessment
of the path this patch should take..
This originally landed in 9872ea4ed1de4c49300430e4f1f4dfc110a79ab9
but got immediately reverted in cbfa237892e55b7129a1178c9b03f26683d643af
because the assertion was faulty. That fault ended up being caused
by the enum - while there will be promotion, both types are unsigned,
with same width. So we still don't need to sanitize non-signed cases.
So far. Maybe the assert will tell us this isn't so.
Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=44054 | PR44054 ]].
Refs. https://github.com/google/sanitizers/issues/940
Reviewers: rjmccall, erichkeane, rsmith, vsk
Reviewed By: erichkeane
Subscribers: mehdi_amini, dexonsmith, cfe-commits, #sanitizers, llvm-commits, aaron.ballman, t.p.northover, efriedma, regehr
Tags: #llvm, #clang, #sanitizers
Differential Revision: https://reviews.llvm.org/D70539
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