872 Commits

Author SHA1 Message Date
Nikita Popov
68e01339cc [CGBuilder] Remove type-less CreateAlignedLoad() APIs (NFC)
These are incompatible with opaque pointers. This is in preparation
of dropping this API on the IRBuilder side as well.

Instead explicitly pass the loaded type.
2021-03-11 10:41:23 +01:00
Michael Kruse
b119120673 [clang][OpenMP] Use OpenMPIRBuilder for workshare loops.
Initial support for using the OpenMPIRBuilder by clang to generate loops using the OpenMPIRBuilder. This initial support is intentionally limited to:
 * Only the worksharing-loop directive.
 * Recognizes only the nowait clause.
 * No loop nests with more than one loop.
 * Untested with templates, exceptions.
 * Semantic checking left to the existing infrastructure.

This patch introduces a new AST node, OMPCanonicalLoop, which becomes parent of any loop that has to adheres to the restrictions as specified by the OpenMP standard. These restrictions allow OMPCanonicalLoop to provide the following additional information that depends on base language semantics:
 * The distance function: How many loop iterations there will be before entering the loop nest.
 * The loop variable function: Conversion from a logical iteration number to the loop variable.

These allow the OpenMPIRBuilder to act solely using logical iteration numbers without needing to be concerned with iterator semantics between calling the distance function and determining what the value of the loop variable ought to be. Any OpenMP logical should be done by the OpenMPIRBuilder such that it can be reused MLIR OpenMP dialect and thus by flang.

The distance and loop variable function are implemented using lambdas (or more exactly: CapturedStmt because lambda implementation is more interviewed with the parser). It is up to the OpenMPIRBuilder how they are called which depends on what is done with the loop. By default, these are emitted as outlined functions but we might think about emitting them inline as the OpenMPRuntime does.

For compatibility with the current OpenMP implementation, even though not necessary for the OpenMPIRBuilder, OMPCanonicalLoop can still be nested within OMPLoopDirectives' CapturedStmt. Although OMPCanonicalLoop's are not currently generated when the OpenMPIRBuilder is not enabled, these can just be skipped when not using the OpenMPIRBuilder in case we don't want to make the AST dependent on the EnableOMPBuilder setting.

Loop nests with more than one loop require support by the OpenMPIRBuilder (D93268). A simple implementation of non-rectangular loop nests would add another lambda function that returns whether a loop iteration of the rectangular overapproximation is also within its non-rectangular subset.

Reviewed By: jdenny

Differential Revision: https://reviews.llvm.org/D94973
2021-03-04 22:52:59 -06:00
Reid Kleckner
1c2e7d200d [MS] Fix crash involving gnu stmt exprs and inalloca
Use a WeakTrackingVH to cope with the stmt emission logic that cleans up
unreachable blocks. This invalidates the reference to the deferred
replacement placeholder. Cope with it.

Fixes PR25102 (from 2015!)
2021-03-04 13:57:46 -08:00
Gui Andrade
10264a1b21 Introduce noundef attribute at call sites for stricter poison analysis
This change adds a new IR noundef attribute, which denotes when a function call argument or return val may never contain uninitialized bits.

In MemorySanitizer, this attribute enables optimizations which decrease instrumented code size by up to 17% (measured with an instrumented build of clang) . I'll introduce the change allowing msan to take advantage of this information in a separate patch.

Differential Revision: https://reviews.llvm.org/D81678
2021-03-04 12:15:12 -08:00
Dávid Bolvanský
053dc95839 Reduce the number of attributes attached to each function
Patch takes advantage of the implicit default behavior to reduce the number of attributes, which in turns reduces compilation time.

Reviewed By: serge-sans-paille

Differential Revision: https://reviews.llvm.org/D97116
2021-02-24 07:08:44 +01:00
Melanie Blower
e64fcdf8d5 [clang][patch] Inclusive language, modify filename SanitizerBlacklist.h to NoSanitizeList.h
This patch responds to a comment from @vitalybuka in D96203: suggestion to
do the change incrementally, and start by modifying this file name. I modified
the file name and made the other changes that follow from that rename.

Reviewers: vitalybuka, echristo, MaskRay, jansvoboda11, aaron.ballman

Differential Revision: https://reviews.llvm.org/D96974
2021-02-22 15:11:37 -05:00
Dávid Bolvanský
ee51c42e00 Reduce the number of attributes attached to each function
This takes advantage of the implicit default behavior to reduce the number of
attributes.
2021-02-20 06:57:47 +01:00
Petr Hosek
bb9eb19829 Support for instrumenting only selected files or functions
This change implements support for applying profile instrumentation
only to selected files or functions. The implementation uses the
sanitizer special case list format to select which files and functions
to instrument, and relies on the new noprofile IR attribute to exclude
functions from instrumentation.

Differential Revision: https://reviews.llvm.org/D94820
2021-01-26 17:13:34 -08:00
Petr Hosek
1e634f3952 Revert "Support for instrumenting only selected files or functions"
This reverts commit 4edf35f11a9e20bd5df3cb47283715f0ff38b751 because
the test fails on Windows bots.
2021-01-26 12:25:28 -08:00
Petr Hosek
4edf35f11a Support for instrumenting only selected files or functions
This change implements support for applying profile instrumentation
only to selected files or functions. The implementation uses the
sanitizer special case list format to select which files and functions
to instrument, and relies on the new noprofile IR attribute to exclude
functions from instrumentation.

Differential Revision: https://reviews.llvm.org/D94820
2021-01-26 11:11:39 -08:00
Fangrui Song
b88c8f1aab CGDebugInfo: Delete unused parameters 2021-01-11 13:39:03 -08:00
Alan Phipps
9f2967bcfe [Coverage] Add support for Branch Coverage in LLVM Source-Based Code Coverage
This is an enhancement to LLVM Source-Based Code Coverage in clang to track how
many times individual branch-generating conditions are taken (evaluate to TRUE)
and not taken (evaluate to FALSE).  Individual conditions may comprise larger
boolean expressions using boolean logical operators.  This functionality is
very similar to what is supported by GCOV except that it is very closely
anchored to the ASTs.

Differential Revision: https://reviews.llvm.org/D84467
2021-01-05 09:51:51 -06:00
James Y Knight
4ddf140c00 Fix PR35902: incorrect alignment used for ubsan check.
UBSan was using the complete-object align rather than nv alignment
when checking the "this" pointer of a method.

Furthermore, CGF.CXXABIThisAlignment was also being set incorrectly,
due to an incorrectly negated test. The latter doesn't appear to have
had any impact, due to it not really being used anywhere.

Differential Revision: https://reviews.llvm.org/D93072
2020-12-28 18:11:17 -05:00
Kevin P. Neal
2069403cdf [FPEnv] Use strictfp metadata in casting nodes
The strictfp metadata was added to the casting AST nodes in D85960, but
we aren't using that metadata yet. This patch adds that support.

In order to avoid lots of ad-hoc passing around of the strictfp bits I
updated the IRBuilder when moving from a function that has the Expr* to a
function that lacks it. I believe we should switch to this pattern to keep
the strictfp support from being overly invasive.

For the purpose of testing that we're picking up the right metadata, I
also made my tests use a pragma to make the AST's strictfp metadata not
match the global strictfp metadata. This exposes issues that we need to
deal with in subsequent patches, and I believe this is the right method
for most all of our clang strictfp tests.

Differential Revision: https://reviews.llvm.org/D88913
2020-11-06 11:56:12 -05:00
Atmn Patel
ac73b73c16 [clang] Add mustprogress and llvm.loop.mustprogress attribute deduction
Since C++11, the C++ standard has a forward progress guarantee
[intro.progress], so all such functions must have the `mustprogress`
requirement. In addition, from C11 and onwards, loops without a non-zero
constant conditional or no conditional are also required to make
progress (C11 6.8.5p6). This patch implements these attribute deductions
so they can be used by the optimization passes.

Differential Revision: https://reviews.llvm.org/D86841
2020-11-04 22:03:14 -05:00
Mark de Wever
b46fddf75f [CodeGen] Implement [[likely]] and [[unlikely]] for while and for loop.
The attribute has no effect on a do statement since the path of execution
will always include its substatement.

It adds a diagnostic when the attribute is used on an infinite while loop
since the codegen omits the branch here. Since the likelihood attributes
have no effect on a do statement no diagnostic will be issued for
do [[unlikely]] {...} while(0);

Differential Revision: https://reviews.llvm.org/D89899
2020-10-31 17:51:29 +01:00
Liu, Chen3
00090a2b82 Support complex target features combinations
This patch is mainly doing two things:

1. Adding support for parentheses, making the combination of target features
   more diverse;
2. Making the priority of ’,‘ is higher than that of '|' by default. So I need
   to make some change with PTX Builtin function.

Differential Revision: https://reviews.llvm.org/D89184
2020-10-30 10:32:53 +08:00
Tyker
d3205bbca3 [Annotation] Allows annotation to carry some additional constant arguments.
This allows using annotation in a much more contexts than it currently has.
especially when annotation with template or constexpr.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D88645
2020-10-26 10:50:05 +01:00
Melanie Blower
2e204e2391 [clang] Enable support for #pragma STDC FENV_ACCESS
Reviewers: rjmccall, rsmith, sepavloff

Differential Revision: https://reviews.llvm.org/D87528
2020-10-25 06:46:25 -07:00
Mark de Wever
2bcda6bb28 [Sema, CodeGen] Implement [[likely]] and [[unlikely]] in SwitchStmt
This implements the likelihood attribute for the switch statement. Based on the
discussion in D85091 and D86559 it only handles the attribute when placed on
the case labels or the default labels.

It also marks the likelihood attribute as feature complete. There are more QoI
patches in the pipeline.

Differential Revision: https://reviews.llvm.org/D89210
2020-10-18 13:48:42 +02:00
Mark de Wever
1113fbf44c [CodeGen] Improve likelihood branch weights
Bruno De Fraine discovered some issues with D85091. The branch weights
generated for `logical not` and `ternary conditional` were wrong. The
`logical and` and `logical or` differed from the code generated of
`__builtin_predict`.

Adjusted the generated code for the likelihood to match
`__builtin_predict`. The patch is based on Bruno's suggestions.

Differential Revision: https://reviews.llvm.org/D88363
2020-10-04 14:24:27 +02:00
Ian Levesque
6f7fbdd285 [xray] Function coverage groups
Add the ability to selectively instrument a subset of functions by dividing the functions into N logical groups and then selecting a group to cover. By selecting different groups over time you could cover the entire application incrementally with lower overhead than instrumenting the entire application at once.

Differential Revision: https://reviews.llvm.org/D87953
2020-09-24 22:09:53 -04:00
Tyker
78de7297ab Reland [AssumeBundles] Use operand bundles to encode alignment assumptions
NOTE: There is a mailing list discussion on this: http://lists.llvm.org/pipermail/llvm-dev/2019-December/137632.html

Complemantary to the assumption outliner prototype in D71692, this patch
shows how we could simplify the code emitted for an alignemnt
assumption. The generated code is smaller, less fragile, and it makes it
easier to recognize the additional use as a "assumption use".

As mentioned in D71692 and on the mailing list, we could adopt this
scheme, and similar schemes for other patterns, without adopting the
assumption outlining.
2020-09-12 15:36:06 +02:00
Mark de Wever
08196e0b2e Implements [[likely]] and [[unlikely]] in IfStmt.
This is the initial part of the implementation of the C++20 likelihood
attributes. It handles the attributes in an if statement.

Differential Revision: https://reviews.llvm.org/D85091
2020-09-09 20:48:37 +02:00
Richard Smith
740a164dec PR46377: Fix dependence calculation for function types and typedef
types.

We previously did not treat a function type as dependent if it had a
parameter pack with a non-dependent type -- such a function type depends
on the arity of the pack so is dependent even though none of the
parameter types is dependent. In order to properly handle this, we now
treat pack expansion types as always being dependent types (depending on
at least the pack arity), and always canonically being pack expansion
types, even in the unusual case when the pattern is not a dependent
type. This does mean that we can have canonical types that are pack
expansions that contain no unexpanded packs, which is unfortunate but
not inaccurate.

We also previously did not treat a typedef type as
instantiation-dependent if its canonical type was not
instantiation-dependent. That's wrong because instantiation-dependence
is a property of the type sugar, not of the type; an
instantiation-dependent type can have a non-instantiation-dependent
canonical type.
2020-07-28 13:23:13 -07:00
Eric Christopher
7bfaa40086 Temporarily Revert "[AssumeBundles] Use operand bundles to encode alignment assumptions"
due to the performance bugs filed in https://bugs.llvm.org/show_bug.cgi?id=46753.

An SROA change soon may obviate some of these problems.

This reverts commit 8d09f20798ac180b1749276bff364682ce0196ab.
2020-07-16 11:54:04 -07:00
Tyker
8d09f20798 [AssumeBundles] Use operand bundles to encode alignment assumptions
Summary:
NOTE: There is a mailing list discussion on this: http://lists.llvm.org/pipermail/llvm-dev/2019-December/137632.html

Complemantary to the assumption outliner prototype in D71692, this patch
shows how we could simplify the code emitted for an alignemnt
assumption. The generated code is smaller, less fragile, and it makes it
easier to recognize the additional use as a "assumption use".

As mentioned in D71692 and on the mailing list, we could adopt this
scheme, and similar schemes for other patterns, without adopting the
assumption outlining.

Reviewers: hfinkel, xbolva00, lebedev.ri, nikic, rjmccall, spatel, jdoerfert, sstefan1

Reviewed By: jdoerfert

Subscribers: thopre, yamauchi, kuter, fhahn, merge_guards_bot, hiraditya, bollu, rkruppe, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D71739
2020-07-14 01:05:58 +02:00
sstefan1
6aab27ba85 [OpenMPIRBuilder][Fix] Move llvm::omp::types to OpenMPIRBuilder.
Summary:
D82193 exposed a problem with global type definitions in
`OMPConstants.h`. This causes a race when running in thinLTO mode.
Types now live inside of OpenMPIRBuilder to prevent this from happening.

Reviewers: jdoerfert

Subscribers: yaxunl, hiraditya, guansong, dexonsmith, aaron.ballman, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D83176
2020-07-08 17:23:55 +02:00
Roman Lebedev
7ea46aee36
Revert "[AssumeBundles] Use operand bundles to encode alignment assumptions"
Assume bundle can have more than one entry with the same name,
but at least AlignmentFromAssumptionsPass::extractAlignmentInfo() uses
getOperandBundle("align"), which internally assumes that it isn't the
case, and happily crashes otherwise.

Minimal reduced reproducer: run `opt -alignment-from-assumptions` on

target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

%0 = type { i64, %1*, i8*, i64, %2, i32, %3*, i8* }
%1 = type opaque
%2 = type { i8, i8, i16 }
%3 = type { i32, i32, i32, i32 }

; Function Attrs: nounwind
define i32 @f(%0* noalias nocapture readonly %arg, %0* noalias %arg1) local_unnamed_addr #0 {
bb:
  call void @llvm.assume(i1 true) [ "align"(%0* %arg, i64 8), "align"(%0* %arg1, i64 8) ]
  ret i32 0
}

; Function Attrs: nounwind willreturn
declare void @llvm.assume(i1) #1

attributes #0 = { nounwind "reciprocal-estimates"="none" }
attributes #1 = { nounwind willreturn }


This is what we'd have with -mllvm -enable-knowledge-retention

This reverts commit c95ffadb2474a4d8c4f598d94d35a9f31d9606cb.
2020-07-04 23:49:23 +03:00
Melanie Blower
f4aaed3bf1 Reland D81869 "Modify FPFeatures to use delta not absolute settings"
This reverts commit defd43a5b393bb63a902042adf578081b03b171d.
with correction to solve msan report

To solve https://bugs.llvm.org/show_bug.cgi?id=46166 where the
floating point settings in PCH files aren't compatible, rewrite
FPFeatures to use a delta in the settings rather than absolute settings.
With this patch, these floating point options can be benign.

Reviewers: rjmccall

Differential Revision: https://reviews.llvm.org/D81869
2020-06-27 01:34:57 -07:00
Melanie Blower
defd43a5b3 Revert "Revert "Revert "Modify FPFeatures to use delta not absolute settings"""
This reverts commit 9518763d710bfbbf9315fa88972c55898be44a0e.
Memory sanitizer fails in CGFPOptionsRAII::CGFPOptionsRAII dtor
2020-06-26 08:47:04 -07:00
Melanie Blower
9518763d71 Revert "Revert "Modify FPFeatures to use delta not absolute settings""
This reverts commit b55d723ed61052b77e720dcffecac43abe873186.
Reapply Modify FPFeatures to use delta not absolute settings

To solve https://bugs.llvm.org/show_bug.cgi?id=46166 where the
floating point settings in PCH files aren't compatible, rewrite
FPFeatures to use a delta in the settings rather than absolute settings.
With this patch, these floating point options can be benign.

Reviewers: rjmccall

Differential Revision: https://reviews.llvm.org/D81869
2020-06-26 08:00:08 -07:00
Melanie Blower
b55d723ed6 Revert "Modify FPFeatures to use delta not absolute settings"
This reverts commit 3a748cbf86cea3844fada04eeff4cc64b01f67e0.
I'm reverting this commit because I forgot to format the commit message
propertly. Sorry for the thrash.
2020-06-26 07:52:57 -07:00
Melanie Blower
3a748cbf86 Modify FPFeatures to use delta not absolute settings 2020-06-26 07:41:09 -07:00
Tyker
c95ffadb24 [AssumeBundles] Use operand bundles to encode alignment assumptions
Summary:
NOTE: There is a mailing list discussion on this: http://lists.llvm.org/pipermail/llvm-dev/2019-December/137632.html

Complemantary to the assumption outliner prototype in D71692, this patch
shows how we could simplify the code emitted for an alignemnt
assumption. The generated code is smaller, less fragile, and it makes it
easier to recognize the additional use as a "assumption use".

As mentioned in D71692 and on the mailing list, we could adopt this
scheme, and similar schemes for other patterns, without adopting the
assumption outlining.

Reviewers: hfinkel, xbolva00, lebedev.ri, nikic, rjmccall, spatel, jdoerfert, sstefan1

Reviewed By: jdoerfert

Subscribers: yamauchi, kuter, fhahn, merge_guards_bot, hiraditya, bollu, rkruppe, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D71739
2020-06-25 12:59:44 +02:00
Akira Hatanaka
c9a52de002 [CodeGen] Simplify the way lifetime of block captures is extended
Rather than pushing inactive cleanups for the block captures at the
entry of a full expression and activating them during the creation of
the block literal, just call pushLifetimeExtendedDestroy to ensure the
cleanups are popped at the end of the scope enclosing the block
expression.

rdar://problem/63996471

Differential Revision: https://reviews.llvm.org/D81624
2020-06-11 16:06:22 -07:00
John McCall
7fac1acc61 Set the LLVM FP optimization flags conservatively.
Functions can have local pragmas that override the global settings.
We set the flags eagerly based on global settings, but if we emit
an expression under the influence of a pragma, we clear the
appropriate flags from the function.

In order to avoid doing a ton of redundant work whenever we emit
an FP expression, configure the IRBuilder to default to global
settings, and only reconfigure it when we see an FP expression
that's not using the global settings.

Patch by Michele Scandale!

https://reviews.llvm.org/D80462
2020-06-11 18:16:41 -04:00
Wei Mi
7a6c89427c [SampleFDO] Add use-sample-profile function attribute.
When sampleFDO is enabled, people may expect they can use
-fno-profile-sample-use to opt-out using sample profile for a certain file.
That could be either for debugging purpose or for performance tuning purpose.
However, when thinlto is enabled, if a function in file A compiled with
-fno-profile-sample-use is imported to another file B compiled with
-fprofile-sample-use, the inlined copy of the function in file B may still
get its profile annotated.

The inconsistency may even introduce profile unused warning because if the
target is not compiled with explicit debug information flag, the function
in file A won't have its debug information enabled (debug information will
be enabled implicitly only when -fprofile-sample-use is used). After it is
imported into file B which is compiled with -fprofile-sample-use, profile
annotation for the outline copy of the function will fail because the
function has no debug information, and that will trigger  profile unused
warning.

We add a new attribute use-sample-profile to control whether a function
will use its sample profile no matter for its outline or inline copies.
That will make the behavior of -fno-profile-sample-use consistent.

Differential Revision: https://reviews.llvm.org/D79959
2020-06-02 17:23:17 -07:00
John McCall
8a8d703be0 Fix how cc1 command line options are mapped into FP options.
Canonicalize on storing FP options in LangOptions instead of
redundantly in CodeGenOptions.  Incorporate -ffast-math directly
into the values of those LangOptions rather than considering it
separately when building FPOptions.  Build IR attributes from
those options rather than a mix of sources.

We should really simplify the driver/cc1 interaction here and have
the driver pass down options that cc1 directly honors.  That can
happen in a follow-up, though.

Patch by Michele Scandale!
https://reviews.llvm.org/D80315
2020-06-01 22:00:30 -04:00
Eli Friedman
62f3ef2b53 [CGCall] Annotate references with "align" attribute.
If we're going to assume references are dereferenceable, we should also
assume they're aligned: otherwise, we can't actually dereference them.

See also D80072.

Differential Revision: https://reviews.llvm.org/D80166
2020-05-19 20:21:30 -07:00
Florian Hahn
1065869195 [Matrix] Add matrix type to Clang.
This patch adds a matrix type to Clang as described in the draft
specification in clang/docs/MatrixSupport.rst. It introduces a new option
-fenable-matrix, which can be used to enable the matrix support.

The patch adds new MatrixType and DependentSizedMatrixType types along
with the plumbing required. Loads of and stores to pointers to matrix
values are lowered to memory operations on 1-D IR arrays. After loading,
the loaded values are cast to a vector. This ensures matrix values use
the alignment of the element type, instead of LLVM's large vector
alignment.

The operators and builtins described in the draft spec will will be added in
follow-up patches.

Reviewers: martong, rsmith, Bigcheese, anemet, dexonsmith, rjmccall, aaron.ballman

Reviewed By: rjmccall

Differential Revision: https://reviews.llvm.org/D72281
2020-05-11 18:55:45 +01:00
Melanie Blower
f5360d4bb3 Reapply "Add support for #pragma float_control" with buildbot fixes
Add support for #pragma float_control

Reviewers: rjmccall, erichkeane, sepavloff

Differential Revision: https://reviews.llvm.org/D72841

This reverts commit fce82c0ed310174fe48e2402ac731b6340098389.
2020-05-04 05:51:25 -07:00
Melanie Blower
fce82c0ed3 Revert "Reapply "Add support for #pragma float_control" with improvements to"
This reverts commit 69aacaf699922ffe0450f567e21208c10c84731f.
2020-05-01 10:31:09 -07:00
Melanie Blower
69aacaf699 Reapply "Add support for #pragma float_control" with improvements to
test cases
Add support for #pragma float_control

Reviewers: rjmccall, erichkeane, sepavloff

Differential Revision: https://reviews.llvm.org/D72841

This reverts commit 85dc033caccaa6ab919d57f9759290be41240146, and makes
corrections to the test cases that failed on buildbots.
2020-05-01 10:03:30 -07:00
Melanie Blower
85dc033cac Revert "Add support for #pragma float_control"
This reverts commit 4f1e9a17e9d28bdfd035313c96b3a5d4c91a7733.
due to fail on buildbot, sorry for the noise
2020-05-01 06:36:58 -07:00
Melanie Blower
4f1e9a17e9 Add support for #pragma float_control
Reviewers: rjmccall, erichkeane, sepavloff

Differential Revision: https://reviews.llvm.org/D72841
2020-05-01 06:14:24 -07:00
Craig Topper
a58b62b4a2 [IR] Replace all uses of CallBase::getCalledValue() with getCalledOperand().
This method has been commented as deprecated for a while. Remove
it and replace all uses with the equivalent getCalledOperand().

I also made a few cleanups in here. For example, to removes use
of getElementType on a pointer when we could just use getFunctionType
from the call.

Differential Revision: https://reviews.llvm.org/D78882
2020-04-27 22:17:03 -07:00
Erich Keane
5f0903e9be Reland Implement _ExtInt as an extended int type specifier.
I fixed the LLDB issue, so re-applying the patch.

This reverts commit a4b88c044980337bb14390be654fe76864aa60ec.
2020-04-17 10:45:48 -07:00
Sterling Augustine
a4b88c0449 Revert "Implement _ExtInt as an extended int type specifier."
This reverts commit 61ba1481e200b5b35baa81ffcff81acb678e8508.

I'm reverting this because it breaks the lldb build with
incomplete switch coverage warnings. I would fix it forward,
but am not familiar enough with lldb to determine the correct
fix.

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp:3958:11: error: enumeration values 'DependentExtInt' and 'ExtInt' not handled in switch [-Werror,-Wswitch]
  switch (qual_type->getTypeClass()) {
          ^
lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp:4633:11: error: enumeration values 'DependentExtInt' and 'ExtInt' not handled in switch [-Werror,-Wswitch]
  switch (qual_type->getTypeClass()) {
          ^
lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp:4889:11: error: enumeration values 'DependentExtInt' and 'ExtInt' not handled in switch [-Werror,-Wswitch]
  switch (qual_type->getTypeClass()) {
2020-04-17 10:29:40 -07:00
Erich Keane
61ba1481e2 Implement _ExtInt as an extended int type specifier.
Introduction/Motivation:
LLVM-IR supports integers of non-power-of-2 bitwidth, in the iN syntax.
Integers of non-power-of-two aren't particularly interesting or useful
on most hardware, so much so that no language in Clang has been
motivated to expose it before.

However, in the case of FPGA hardware normal integer types where the
full bitwidth isn't used, is extremely wasteful and has severe
performance/space concerns.  Because of this, Intel has introduced this
functionality in the High Level Synthesis compiler[0]
under the name "Arbitrary Precision Integer" (ap_int for short). This
has been extremely useful and effective for our users, permitting them
to optimize their storage and operation space on an architecture where
both can be extremely expensive.

We are proposing upstreaming a more palatable version of this to the
community, in the form of this proposal and accompanying patch.  We are
proposing the syntax _ExtInt(N).  We intend to propose this to the WG14
committee[1], and the underscore-capital seems like the active direction
for a WG14 paper's acceptance.  An alternative that Richard Smith
suggested on the initial review was __int(N), however we believe that
is much less acceptable by WG14.  We considered _Int, however _Int is
used as an identifier in libstdc++ and there is no good way to fall
back to an identifier (since _Int(5) is indistinguishable from an
unnamed initializer of a template type named _Int).

[0]https://www.intel.com/content/www/us/en/software/programmable/quartus-prime/hls-compiler.html)
[1]http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2472.pdf

Differential Revision: https://reviews.llvm.org/D73967
2020-04-17 07:10:57 -07:00