Utilize the generalized MCAsmBackend::evaluateFixup hook. This reduces
overhead for other targets (e.g., x86).
Now MCAsmBackend::getFixupKindInfo is only used by MCAsmStreamer
-show-encoding in the generic code.
Generalize evaluateTargetFixup to be called by all targets,
making FKF_IsTarget unneeded.
Next: Update targets that use FKF_IsAlignedDownTo32Bits to define
`evaluateFixup` and remove FKF_IsAlignedDownTo32Bits from the generic
code.
The generic FK_Data_ fixup kinds handle both absolute and PC-relative
fixups. ELFObjectWriter sets IsPCRel to true for `.long foo-.`, so the
backend has to handle PC-relative FK_Data_.
However, the existence of FK_PCRel_ encouraged backends to implement it
as a separate fixup type, leading to redundant and error-prone code.
Removing FK_PCRel_ simplifies the overall fixup mechanism.
We will unify the generic fixup kinds FK_Data_ and FK_PCRel_. A
FK_PCRel_ kind is essentially the corresponding FK_Data_ fixup with the
PCRel flag set.
PC-relative fixups compute their values as
`sym_a - current_location + offset` (S - P + A).
Now that targets have set PCRel at fixup creation time, we can remove
some overhead from MCAssembler::evaluateFixup.
Remove the redundant MCFixup::Loc member and instead use MCExpr::Loc to
determine the location for fixups. Previously, many target MCCodeEmitter would
use the beginning of an instruction for fixup locations, which often
resulted in inaccurate column information.
```
// RISCVMCCodeEmitter::getImmOpValue
Fixups.push_back(MCFixup::create(0, Expr, FixupKind, MI.getLoc()));
// X86MCCodeEmitter::emitImmediate
Fixups.push_back(MCFixup::create(static_cast<uint32_t>(CB.size() - StartByte), Expr, FixupKind, Loc));
```
While MCExpr::Loc generally provides more meaningful location data,
tests should avoid over-relying on it. For instance, MCBinaryExpr's
location refers to its operator, and for operands with sigils (like
`$foo`), the location often omits the sigils.
https://llvm-compile-time-tracker.com/compare.php?from=8740ff822d462844506134bb7c425e1778518b95&to=831a11f75d22d64982b13dba132d656ac8567612&stat=instructions%3Au
I've also considered removing MCExpr::Loc (revert
https://reviews.llvm.org/D28861), but we'd lose too much information.
It's also difficult to carry location information to improve location
tracking in target MCCodeEmitter.
This change utilizes previous MCExpr::Loc improvement like
7e3e2e1b8c6ff21e68782a56164139cca334fcf3
7b517cf743f112f980cf6a4d6e6190c2a5b3e451
Follow-up to #141333. Relocation generation called both addReloc and
applyFixup, with the default addReloc invoking shouldForceRelocation,
resulting in three virtual calls. This approach was also inflexible, as
targets needing additional data required extending
`shouldForceRelocation` (see #73721, resolved by #141311).
This change integrates relocation handling into applyFixup, eliminating
two virtual calls. The prior default addReloc is renamed to
maybeAddReloc. Targets overriding addReloc now call their customized
addReloc implementation.
This reverts commit 1108cf64196a056aa350baba98e3fab6d7529a59.
Caused a regression for a weird but interesting case (STT_SECTION symbol
as group signature). We no longer define `sec`
```
.section sec,"ax"
.section .foo,"axG",@progbits,sec
nop
```
Fix#146581
... due to their close relationship. MCSection's inline functions (e.g.
iterator) access MCFragment, and we want MCFragment's inline functions
to access MCSection similarly (#146307).
Pull Request: https://github.com/llvm/llvm-project/pull/146315
* Make pre-layout to -debug-only=mc-dump-pre. This output is not useful
for most debugging needs.
* Print fragment-associated symbols. Make it easier to locate relevant
fragments.
* Print the LinkerRelaxable flag.
The "Symbol" stanza includes symbol names with all zero indexes. which
are not useful.
The "assembler backend - post-relaxation" part is not useful. Only
Hexagon (and X86 when x86-pad-for-align is set) might change the layout
between "post-relaxation" and "final-layout". From my experience
debugging the two passes requires more dumping code not served by the
output.
Remove unneeded details like "<" and ">". Reduce indentation.
Omit `this` address to simplify output comparison.
Add a -debug-only=mc-dump test.
While here, add fixup printing for MCRelaxableFragment.
GNU Assembler supports `a = %eax` for x86. We use X86MCExpr to support a
register expression. https://reviews.llvm.org/D47545 added reassignment
support but this code is not necessary.
Printing an expression is error-prone without a MCAsmInfo argument.
Remove the operator<< overload and replace callers with
MCAsmInfo::printExpr. Some callers are changed to MCExpr::print, with
the goal of eventually making it private.
so that subclasses can provide the appropriate MCAsmInfo to print
MCExpr objects.
At present, llvm/utils/TableGen/AsmMatcherEmitter.cpp constucts a
generic MCAsmInfo.
Implements static samplers parsing from root signature metadata
representation. This is required to support Root Signatures in HLSL.
Closes: #[126641](https://github.com/llvm/llvm-project/issues/126641)
---------
Co-authored-by: joaosaffran <joao.saffran@microsoft.com>
We introduced VariantKinds after MCSymbolRefExpr::VariantKind and then
deprecated the VariantKind naming in favor of AtSpecifier (#133214).
Rename the function and type to use the recommended convention.
Sections which are not allowed to carry data are marked as virtual. Only
complication when writing out the text is that it must be written in
chunks of 32k-1 bytes, which is done by having a wrapper stream writing
those records.
Data of BSS sections is not written, since the contents is known to be
zero. Instead, the fill byte value is used.
Unlike other formats, the GOFF object file format uses a 2 dimensional structure
to define the location of data. For example, the equivalent of the ELF .text
section is made up of a Section Definition (SD) and a class (Element Definition;
ED). The name of the SD symbol depends on the application, while the class has
the predefined name C_CODE/C_CODE64 in AMODE31 and AMODE64 respectively.
Data can be placed into this structure in 2 ways. First, the data (in a text
record) can be associated with an ED symbol. To refer to data, a Label
Definition (LD) is used to give an offset into the data a name. When binding,
the whole data is pulled into the resulting executable, and the addresses
given by the LD symbols are resolved.
The alternative is to use a Part Definition (PR). In this case, the data (in
a text record) is associated with the part. When binding, only the data of
referenced PRs is pulled into the resulting binary.
Both approaches are used. SD, ED, and PR elements are modeled by nested
MCSectionGOFF instances, while LD elements are associated with MCSymbolGOFF
instances.
At the binary level, a record called "External Symbol Definition" (ESD) is used. The
ESD has a type (SD, ED, PR, LD), and depending on the type a different subset of
the fields is used.
The GOFFWriter has 2 purposes:
- Simplify resource management
- Enable writing of split DWARF files
It follows the design of the other writer classes. No added
functionality at this point.
This changes also makes the GOFFObjectWriter a public class.
