This is the first in a series of patches that introduce C++20 importable
header units.
These differ from clang header modules in that:
(a) they are identifiable by an internal name
(b) they represent the top level source for a single header - although
that might include or import other headers.
We name importable header units with the path by which they are specified
(although that need not be the absolute path for the file).
So "foo/bar.h" would have a name "foo/bar.h". Header units are made a
separate module type so that we can deal with diagnosing places where they
are permitted but a named module is not.
Differential Revision: https://reviews.llvm.org/D121095
Allow goto, labelled statements as well as `static`, `thread_local`, and
non-literal variables in `constexpr` functions.
As specified. for all of the above (except labelled statements) constant
evaluation of the construct still fails.
For `constexpr` bodies, the proposal is implemented with diagnostics as
a language extension in older language modes. For determination of
whether a lambda body satisfies the requirements for a constexpr
function, the proposal is implemented only in C++2b mode to retain the
semantics of older modes for programs conforming to them.
Reviewed By: aaron.ballman, hubert.reinterpretcast, erichkeane
Differential Revision: https://reviews.llvm.org/D111400
Reimplements MisExpect diagnostics from D66324 to reconstruct its
original checking methodology only using MD_prof branch_weights
metadata.
New checks rely on 2 invariants:
1) For frontend instrumentation, MD_prof branch_weights will always be
populated before llvm.expect intrinsics are lowered.
2) for IR and sample profiling, llvm.expect intrinsics will always be
lowered before branch_weights are populated from the IR profiles.
These invariants allow the checking to assume how the existing branch
weights are populated depending on the profiling method used, and emit
the correct diagnostics. If these invariants are ever invalidated, the
MisExpect related checks would need to be updated, potentially by
re-introducing MD_misexpect metadata, and ensuring it always will be
transformed the same way as branch_weights in other optimization passes.
Frontend based profiling is now enabled without using LLVM Args, by
introducing a new CodeGen option, and checking if the -Wmisexpect flag
has been passed on the command line.
Differential Revision: https://reviews.llvm.org/D115907
Add facilities for extract-api:
- Structs/classes to hold collected API information: `APIRecord`, `API`
- Structs/classes for API information:
- `AvailabilityInfo`: aggregated availbility information
- `DeclarationFragments`: declaration fragments
- `DeclarationFragmentsBuilder`: helper class to build declaration
fragments for various types/declarations
- `FunctionSignature`: function signature
- Serialization: `Serializer`
- Add output file for `ExtractAPIAction`
- Refactor `clang::RawComment::getFormattedText` to provide an
additional `getFormattedLines` for a more detailed view of comment lines
used for the SymbolGraph format
Add support for global records (global variables and functions)
- Add `GlobalRecord` based on `APIRecord` to store global records'
information
- Implement `VisitVarDecl` and `VisitFunctionDecl` in `ExtractAPIVisitor` to
collect information
- Implement serialization for global records
- Add test case for global records
Differential Revision: https://reviews.llvm.org/D119479
clang has support for lazy headers in module maps - if size and/or
modtime and provided in the cppmap file, headers are only resolved when
an include directive for a file with that size/modtime is encoutered.
Before this change, the lazy resolution was all-or-nothing per module.
That means as soon as even one file in that module potentially matched
an include, all lazy files in that module were resolved. With this
change, only files with matching size/modtime will be resolved.
The goal is to avoid unnecessary stat() calls on non-included files,
which is especially valuable on networked file systems, with higher
latency.
Differential Revision: https://reviews.llvm.org/D120569
Exactly what it says on the tin! We had a nasty crash with the following incovation:
$ clang --analyze -Xclang -analyzer-constraints=z3 test.c
fatal error: error in backend: LLVM was not compiled with Z3 support, rebuild with -DLLVM_ENABLE_Z3_SOLVER=ON
... <stack trace> ...
Differential Revision: https://reviews.llvm.org/D120325
Introduce -fgpu-default-stream={legacy|per-thread} option to
support per-thread default stream for HIP runtime.
When -fgpu-default-stream=per-thread, HIP kernels are
launched through hipLaunchKernel_spt instead of
hipLaunchKernel. Also HIP_API_PER_THREAD_DEFAULT_STREAM=1
is defined by the preprocessor to enable other per-thread stream
API's.
Reviewed by: Artem Belevich
Differential Revision: https://reviews.llvm.org/D120298
This patch enables inferring framework modules in explicit builds in all contexts. Until now, inferring framework modules only worked with `-fimplicit-module-maps` due to this block of code:
```
// HeaderSearch::loadFrameworkModule
case LMM_InvalidModuleMap:
// Try to infer a module map from the framework directory.
if (HSOpts->ImplicitModuleMaps)
ModMap.inferFrameworkModule(Dir, IsSystem, /*Parent=*/nullptr);
break;
```
Reviewed By: Bigcheese
Differential Revision: https://reviews.llvm.org/D113880
It is useful to be able to visualise the C++20 modules content of a PCM file
both for inspection and for testing. In particular, when adding more module
types to support C++20 Partitions and Header Units, we would like to be able
to confirm that the output PCM has the intended structure.
The existing scheme for dumping data is restricted to the content of the AST
file control block, which does not include structural data beyond imports.
The change here makes use of the AST unit that is set up by BeginSourceFile
to query for the information on the primary and sub-modules. We can then
inspect each of these in turn, accounting for Global, Private, Imported and
Exported modules/fragments and then showing the sub-stucture of the main
module(s).
The disadvantage of this mechanism is that it has no easy method to control
the granularity of the output. Perhaps more detailed inspection would be
better handled by a stand-alone module inspection tool.
Differential Revision: https://reviews.llvm.org/D119823
MSVC currently doesn't support 80 bits long double. But ICC does support
it on Windows. Besides, there're also some users asked for this feature.
We can find the discussions from stackoverflow, msdn etc.
Given Clang has already support `-mlong-double-80`, extending it to
support for Windows seems worthwhile.
Reviewed By: rnk, erichkeane
Differential Revision: https://reviews.llvm.org/D115441
Implement P2128R6 in C++23 mode.
Unlike GCC's implementation, this doesn't try to recover when a user
meant to use a comma expression.
Because the syntax changes meaning in C++23, the patch is *NOT*
implemented as an extension. Instead, declaring an array with not
exactly 1 parameter is an error in older languages modes. There is an
off-by-default extension warning in C++23 mode.
Unlike the standard, we supports default arguments;
Ie, we assume, based on conversations in WG21, that the proposed
resolution to CWG2507 will be accepted.
We allow arrays OpenMP sections and C++23 multidimensional array to
coexist:
[a , b] multi dimensional array
[a : b] open mp section
[a, b: c] // error
The rest of the patch is relatively straight forward: we take care to
support an arbitrary number of arguments everywhere.
This patch completely removes the old OpenMP device runtime. Previously,
the old runtime had the prefix `libomptarget-new-` and the old runtime
was simply called `libomptarget-`. This patch makes the formerly new
runtime the only runtime available. The entire project has been deleted,
and all references to the `libomptarget-new` runtime has been replaced
with `libomptarget-`.
Reviewed By: JonChesterfield
Differential Revision: https://reviews.llvm.org/D118934
The lexer can attempt to lex a _Pragma and crash with an out of bounds string access when it's
lexing a _Pragma whose string token is an invalid buffer, e.g. when a module header file from which the macro
expansion for that token was deleted from the file system.
Differential Revision: https://reviews.llvm.org/D116052
This patch extends clang frontend to add metadata that can be used to emit macho files with two build version load commands.
It utilizes "darwin.target_variant.triple" and "darwin.target_variant.SDK Version" metadata names for that.
MachO uses two build version load commands to represent an object file / binary that is targeting both the macOS target,
and the Mac Catalyst target. At runtime, a dynamic library that supports both targets can be loaded from either a native
macOS or a Mac Catalyst app on a macOS system. We want to add support to this to upstream to LLVM to be able to build
compiler-rt for both targets, to finish the complete support for the Mac Catalyst platform, which is right now targetable
by upstream clang, but the compiler-rt bits aren't supported because of the lack of this multiple build version support.
Differential Revision: https://reviews.llvm.org/D115415
Part of the _BitInt feature in C2x
(http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2763.pdf) is a new
macro in limits.h named BITINT_MAXWIDTH that can be used to determine
the maximum width of a bit-precise integer type. This macro must expand
to a value that is at least as large as ULLONG_WIDTH.
This adds an implementation-defined macro named __BITINT_MAXWIDTH__ to
specify that value, which is used by limits.h for the standard macro.
This also limits the maximum bit width to 128 bits because backends do
not currently support all mathematical operations (such as division) on
wider types yet. This maximum is expected to be increased in the future.
This matches GCC: https://godbolt.org/z/sM5q95PGY
I realize this is an API break for clang+clang - so I'm totally open to
discussing how we should deal with that. If Apple wants to keep the
Clang layout indefinitely, if we want to put a flag on this so non-Apple
folks can opt out of this fix/new behavior.
Differential Revision: https://reviews.llvm.org/D117616
This reverts commit ef82063207.
- It conflicts with the existing llvm::size in STLExtras, which will now
never be called.
- Calling it without llvm:: breaks C++17 compat
The Clang frontend sometimes fails on the following assertion when launched with `-serialize-diagnostic-file <x>`:
```
Assertion failed: (BlockScope.empty() && CurAbbrevs.empty() && "Block imbalance"), function ~BitstreamWriter, file BitstreamWriter.h, line 125.
```
This was first noticed when passing an unknown command-line argument to `-cc1`.
It turns out the `DiagnosticConsumer::finish()` function should be called as soon as processing of all source files ends, but there are some code paths where that doesn't happen:
1. when command line parsing fails in `cc1_main()`,
2. when `!Act.PrepareToExecute(*this)` or `!createTarget()` evaluate to `true` in `CompilerInstance::ExecuteAction` and the function returns early.
This patch ensures `finish()` is called in all those code paths.
Reviewed By: Bigcheese
Differential Revision: https://reviews.llvm.org/D118150
Patch originally by oktal3000: https://github.com/mikael-s-persson/templight/pull/40
When a template parameter is unnamed, the name of -templight-dump might return
an empty string. This is fine, they are unnamed after all, but it might be more
user friendly to at least describe what entity is unnamed.
Differential Revision: https://reviews.llvm.org/D115521
This change moves EOL detection out of the clang::InclusionRewriter into
llvm::StringRef so that it can be easily reused elsewhere. It also adds
additional explicit test cases to verify the correct and expected return
results.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D117626
Intel's CET/IBT requires every indirect branch target to be an ENDBR instruction. Because of that, the compiler needs to correctly emit these instruction on function's prologues. Because this is a security feature, it is desirable that only actual indirect-branch-targeted functions are emitted with ENDBRs. While it is possible to identify address-taken functions through LTO, minimizing these ENDBR instructions remains a hard task for user-space binaries because exported functions may end being reachable through PLT entries, that will use an indirect branch for such. Because this cannot be determined during compilation-time, the compiler currently emits ENDBRs to every non-local-linkage function.
Despite the challenge presented for user-space, the kernel landscape is different as no PLTs are used. With the intent of providing the most fit ENDBR emission for the kernel, kernel developers proposed an optimization named "ibt-seal" which replaces the ENDBRs for NOPs directly in the binary. The discussion of this feature can be seen in [1].
This diff brings the enablement of the flag -mibt-seal, which in combination with LTO enforces a different policy for ENDBR placement in when the code-model is set to "kernel". In this scenario, the compiler will only emit ENDBRs to address taken functions, ignoring non-address taken functions that are don't have local linkage.
A comparison between an LTO-compiled kernel binaries without and with the -mibt-seal feature enabled shows that when -mibt-seal was used, the number of ENDBRs in the vmlinux.o binary patched by objtool decreased from 44383 to 33192, and that the number of superfluous ENDBR instructions nopped-out decreased from 11730 to 540.
The 540 missed superfluous ENDBRs need to be investigated further, but hypotheses are: assembly code not being taken care of by the compiler, kernel exported symbols mechanisms creating bogus address taken situations or even these being removed due to other binary optimizations like kernel's static_calls. For now, I assume that the large drop in the number of ENDBR instructions already justifies the feature being merged.
[1] - https://lkml.org/lkml/2021/11/22/591
Reviewed By: xiangzhangllvm
Differential Revision: https://reviews.llvm.org/D116070
The `{HeaderSearch,Preprocessor}::LookupFile()` functions take an out-parameter `const DirectoryLookup *&`. Most callers end up creating a `const DirectoryLookup *` variable that's otherwise unused.
This patch changes the out-parameter from reference to a pointer, making it possible to simply pass `nullptr` to the function without the ceremony.
Reviewed By: ahoppen
Differential Revision: https://reviews.llvm.org/D117312
This patch removes bitrotten/dead uses of `DirectoryLookup` in `InclusionRewriter.cpp`.
Reviewed By: ahoppen
Differential Revision: https://reviews.llvm.org/D117309
This completes the implementation of
WG14 N2412 (http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2412.pdf),
which standardizes C on a twos complement representation for integer
types. The only work that remained there was to define the correct
macros in the standard headers, which this patch does.
In D116750, the `clangFrontend` library was added as a dependency of `LexTests` in order to make `clang::ApplyHeaderSearchOptions()` available. This increased the number of TUs the test depends on.
This patch moves the function into `clangLex` and removes dependency of `LexTests` on `clangFrontend`.
Reviewed By: thakis
Differential Revision: https://reviews.llvm.org/D117024
This causes modern glibc to unset math_errhandling MATH_ERRNO. gcc 12
also sets some other macros, but most of them are associated with
flags ignored by clang, so without library examples, it is difficult to
determine whether they should be set. I think setting this one macro is
OK for now.
Implementation is based on the "expected type" as used for
designated-initializers in braced init lists. This means it can deduce the type
in some cases where it's not written:
void foo(Widget);
foo({ /*help here*/ });
Only basic constructor calls are in scope of this patch, excluded are:
- aggregate initialization (no help is offered for aggregates)
- initializer_list initialization (no help is offered for these constructors)
Fixes https://github.com/clangd/clangd/issues/306
Differential Revision: https://reviews.llvm.org/D116317
This avoids an unnecessary copy required by 'return OS.str()', allowing
instead for NRVO or implicit move. The .str() call (which flushes the
stream) is no longer required since 65b13610a5,
which made raw_string_ostream unbuffered by default.
Differential Revision: https://reviews.llvm.org/D115374
The default for min is changed to 1. The behaviour of -mvscale-{min,max}
in Clang is also changed such that 16 is the max vscale when targeting
SVE and no max is specified.
Reviewed By: sdesmalen, paulwalker-arm
Differential Revision: https://reviews.llvm.org/D113294
Currently, BeforeExecute is called before BeginSourceFile which does not allow
using PP in the callbacks. Change the ordering to ensure it is possible.
This is a prerequisite for D114370.
Originated from a discussion with @kadircet.
Reviewed By: sammccall
Differential Revision: https://reviews.llvm.org/D114525
Add an AtomicScopeModel for HIP and support for OpenCL builtins
that are missing in HIP.
Patch by: Michael Liao
Revised by: Anshil Ghandi
Reviewed by: Yaxun Liu
Differential Revision: https://reviews.llvm.org/D113925
This removes the ability to disable roundtripping in assert builds.
(Roundtripping happens by default in assert builds both before and after
this patch.)
The CLANG_ROUND_TRIP_CC1_ARGS was added as an escape hatch 9 months ago
in https://reviews.llvm.org/D97462, with a FIXME to remove it eventually.
It's probably time to remove it.
Differential Revision: https://reviews.llvm.org/D114120
With this,
void f() { __asm__("mov eax, ebx"); }
now compiles with clang with -masm=intel.
This matches gcc.
The flag is not accepted in clang-cl mode. It has no effect on
MSVC-style `__asm {}` blocks, which are unconditionally in intel
mode both before and after this change.
One difference to gcc is that in clang, inline asm strings are
"local" while they're "global" in gcc. Building the following with
-masm=intel works with clang, but not with gcc where the ".att_syntax"
from the 2nd __asm__() is in effect until file end (or until a
".intel_syntax" somewhere later in the file):
__asm__("mov eax, ebx");
__asm__(".att_syntax\nmovl %ebx, %eax");
__asm__("mov eax, ebx");
This also updates clang's intrinsic headers to work both in
-masm=att (the default) and -masm=intel modes.
The official solution for this according to "Multiple assembler dialects in asm
templates" in gcc docs->Extensions->Inline Assembly->Extended Asm
is to write every inline asm snippet twice:
bt{l %[Offset],%[Base] | %[Base],%[Offset]}
This works in LLVM after D113932 and D113894, so use that.
(Just putting `.att_syntax` at the start of the snippet works in some but not
all cases: When LLVM interpolates in parameters like `%0`, it uses at&t or
intel syntax according to the inline asm snippet's flavor, so the `.att_syntax`
within the snippet happens to late: The interpolated-in parameter is already
in intel style, and then won't parse in the switched `.att_syntax`.)
It might be nice to invent a `#pragma clang asm_dialect push "att"` /
`#pragma clang asm_dialect pop` to be able to force asm style per snippet,
so that the inline asm string doesn't contain the same code in two variants,
but let's leave that for a follow-up.
Fixes PR21401 and PR20241.
Differential Revision: https://reviews.llvm.org/D113707
Change the error message to use ignorelist, and changed some variable and function
names in related code and test.
Reviewed By: thakis
Differential Revision: https://reviews.llvm.org/D113189
Add new triple and target info for ‘spirv32’ and ‘spirv64’ and,
thus, enabling clang (LLVM IR) code emission to SPIR-V target.
The target for SPIR-V is mostly reused from SPIR by derivation
from a common base class since IR output for SPIR-V is mostly
the same as SPIR. Some refactoring are made accordingly.
Added and updated tests for parts that are different between
SPIR and SPIR-V.
Patch by linjamaki (Henry Linjamäki)!
Differential Revision: https://reviews.llvm.org/D109144
The PragmaAssumeNonNullHandler (and maybe others) passes an invalid
SourceLocation to its callback, hence PrintPreprocessedOutput does not
know how many lines to insert between the previous token and the
pragma and does nothing.
With this patch we instead assume that the unknown token is on the same
line as the previous such that we can call the procedure that also emits
semantically significant whitespace.
Fixes bug reported here: https://reviews.llvm.org/D104601#3105044
This is reported by msvc as
warning C6287: redundant code: the left and right subexpressions are identical
EmittedDirectiveOnThisLine implies EmittedTokensOnThisLine
making this an NFC change. To be on the safe side and because both of
them are checked at other places as well, we continue to check both.
Compiler warning reported here:
https://reviews.llvm.org/D104601#2957333
Now in libcxx and clang, all the coroutine components are defined in
std::experimental namespace.
And now the coroutine TS is merged into C++20. So in the working draft
like N4892, we could find the coroutine components is defined in std
namespace instead of std::experimental namespace.
And the coroutine support in clang seems to be relatively stable. So I
think it may be suitable to move the coroutine component into the
experiment namespace now.
This patch would make clang lookup coroutine_traits in std namespace
first. For the compatibility consideration, clang would lookup in
std::experimental namespace if it can't find definitions in std
namespace. So the existing codes wouldn't be break after update
compiler.
And in case the compiler found std::coroutine_traits and
std::experimental::coroutine_traits at the same time, it would emit an
error for it.
The support for looking up std::experimental::coroutine_traits would be
removed in Clang16.
Reviewed By: lxfind, Quuxplusone
Differential Revision: https://reviews.llvm.org/D108696
Downstream users may have Clang plugins. By default these plugins run
after the main action if they are specified on the command line.
Since these plugins are ASTConsumers, presumably they inspect the AST.
So we shouldn't clear it if any plugins run after the main action.
Reviewed By: dblaikie, hans
Differential Revision: https://reviews.llvm.org/D112190
Currently we have a way to run a plugin if specified on the command line
after the main action, and ways to unconditionally run the plugin before
or after the main action, but no way to run a plugin if specified on the
command line before the main action.
This introduces the missing option.
This is helpful because -clear-ast-before-backend clears the AST before
codegen, while some plugins may want access to the AST.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D112096
When using explicit Clang modules, some declarations might unexpectedly become invisible.
This is caused by the mechanism that loads PCM files passed via `-fmodule-file=<path>` and creates an `IdentifierInfo` for the module name. The `IdentifierInfo` creation takes place when the `ASTReader` is in a weird state, with modules that are loaded but not yet set up properly. This patch delays the creation of `IdentifierInfo` until the `ASTReader` is done with reading the PCM.
Note that the `-fmodule-file=<name>=<path>` form of the argument doesn't suffer from this issue, since it doesn't create `IdentifierInfo` for the module name.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D111543
Previously, we reported the same value as for C17, now we report 202000L, which
is the same value currently used by GCC.
Once C23 ships, this value will be bumped to the correct date.
During explicit modular build, PCM files are typically specified via the `-fmodule-file=<path>` command-line option. Early during the compilation, Clang uses the `ASTReader` to read their contents and caches the result so that the module isn't loaded implicitly later on. A listener is attached to the `ASTReader` to collect names of the modules read from the PCM files. However, if the PCM has already been loaded previously via PCH:
1. the `ASTReader` doesn't do anything for the second time,
2. the listener is not invoked at all,
3. the module load result is not cached,
4. the compilation fails when attempting to load the module implicitly later on.
This patch solves this problem by attaching the listener to the `ASTReader` for PCH reading as well.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D111560
For dependency scanning, it would be useful to collect header search paths (provided on command-line via `-I` and friends) that were actually used during preprocessing. This patch adds that feature to `HeaderSearch` along with a new remark that reports such paths as they get used.
Previous version of this patch tried to use the existing `LookupFileCache` to report used paths via `HitIdx`. That doesn't work for `ComputeUserEntryUsage` (which is intended to be called *after* preprocessing), because it indexes used search paths by the file name. This means the values get overwritten when the code contains `#include_next`.
Note that `HeaderSearch` doesn't use `HeaderSearchOptions::UserEntries` directly. Instead, `InitHeaderSearch` pre-processes them (adds platform-specific paths, removes duplicates, removes paths that don't exist) and creates `DirectoryLookup` instances. This means we need a mechanism for translating between those two. It's not possible to go from `DirectoryLookup` back to the original `HeaderSearch`, so `InitHeaderSearch` now tracks the relationships explicitly.
Depends on D111557.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D102923
This patch propagates the import `SourceLocation` into `HeaderSearch::lookupModule`. This enables remarks on search path usage (implemented in D102923) to point to the source code that initiated header search.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D111557
Without this, the combination of `-ast-dump=json` and `-ast-dump-filter FILTER` produces invalid JSON: the first line is a string that says `Dumping $SOME_DECL_NAME: `.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D108441
This patch adds two flags to be supported for the new runtime. The flags
are `-fopenmp-assume-threads-oversubscription` and
-fopenmp-assume-teams-oversubscription`. These add global values that
can be checked by the work sharing runtime functions to make better
judgements about how to distribute work between the threads.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D111348
Modify the IfStmt node to suppoort constant evaluated expressions.
Add a new ExpressionEvaluationContext::ImmediateFunctionContext to
keep track of immediate function contexts.
This proved easier/better/probably more efficient than walking the AST
backward as it allows diagnosing nested if consteval statements.
A followup to D110201.
For example, we'd set OptimizationRemarkMissed's Regex to '.*' when
encountering -Rpass. Normally this doesn't actually affect remarks we
emit because in clang::ProcessWarningOptions() we'll separately look at
all -R arguments and turn on/off corresponding diagnostic groups.
However, this is reproducible with -round-trip-args.
Reviewed By: JamesNagurne
Differential Revision: https://reviews.llvm.org/D110673
Based on feedback from Paul Robinson on 38c09ea that the 'mangled' mode
is only useful as an LLVM-developer-internal tool in combination with
llvm-dwarfdump --verify, so demote that to a frontend-only (not driver)
option. The driver support is simply -g{no-,}simple-template-names to
switch on simple template names, without the option to use the mangled
template name scheme there.
This is to build the foundation of a new debug info feature to use only
the base name of template as its debug info name (eg: "t1" instead of
the full "t1<int>"). The intent being that a consumer can still retrieve
all that information from the DW_TAG_template_*_parameters.
So gno-simple-template-names is business as usual/previously ("t1<int>")
=simple is the simplified name ("t1")
=mangled is a special mode to communicate the full information, but
also indicate that the name should be able to be simplified. The data
is encoded as "_STNt1|<int>" which will be matched with an
llvm-dwarfdump --verify feature to deconstruct this name, rebuild the
original name, and then try to rebuild the simple name via the DWARF
tags - then compare the latter and the former to ensure that all the
data necessary to fully rebuild the name is present.
Previously with -Rpass (and friends) we'd have remarks "enabled", but
without an actual regex.
As seen in the test change to line numbers, this can give us better
diagnostics by properly enabling NeedLocTracking with -Rpass.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D110201
Rename methods to clearly signal when they only deal with ASCII,
simplify the parsing of identifier, and use start/continue instead of
head/body for consistency with Unicode terminology.
Fangrui Song