The option to control the emission of the new relocations
is -relax-relocations (blatantly copied from GNU as).
It can't be enabled by default because it breaks relatively
recent versions of ld.bfd/ld.gold (late 2015).
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Currently each Function points to a DISubprogram and DISubprogram has a
scope field. For member functions the scope is a DICompositeType. DIScopes
point to the DICompileUnit to facilitate type uniquing.
Distinct DISubprograms (with isDefinition: true) are not part of the type
hierarchy and cannot be uniqued. This change removes the subprograms
list from DICompileUnit and instead adds a pointer to the owning compile
unit to distinct DISubprograms. This would make it easy for ThinLTO to
strip unneeded DISubprograms and their transitively referenced debug info.
Motivation
----------
Materializing DISubprograms is currently the most expensive operation when
doing a ThinLTO build of clang.
We want the DISubprogram to be stored in a separate Bitcode block (or the
same block as the function body) so we can avoid having to expensively
deserialize all DISubprograms together with the global metadata. If a
function has been inlined into another subprogram we need to store a
reference the block containing the inlined subprogram.
Attached to https://llvm.org/bugs/show_bug.cgi?id=27284 is a python script
that updates LLVM IR testcases to the new format.
http://reviews.llvm.org/D19034
<rdar://problem/25256815>
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Since we can't emit diagnostics for missing "jmp 1f" labels until the end of
the file, we need to be able to restore the context used to calculate
file/line. This is basically the "# line file" directive that's being used at
the time the expression is seen.
rdar://25706972
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Before, ELF at least managed a diagnostic but it was a completely untraceable
"undefined symbol" error. MachO had a variety of even worse behaviours: crash,
emit corrupt file, or an equally bad message.
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This is a fix for PR26941.
When there is both a section and a global definition with the same
name, the global wins.
Section symbols are not added to the symbol table; section references
are left undefined and fixed up in the object writer unless they've
been satisfied by some other definition.
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When a symbol S shows up in an expression in assembly there are two
possible interpretations
* The expression is referring to the value of S in this file.
* The expression is referring to the value after symbol resolution.
In the first case the assembler can reason about the value and try to
produce a relocation.
In the second case, that is only possible if the symbol cannot be
preempted.
Assemblers are not very consistent about which interpretation gets used.
This changes MC to agree with GAS in the case of an expression of the
form "Sym - WeakSym".
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InitMCObjectFileInfo was trying to override the triple in awkward ways.
For example, a triple specifying COFF but not Windows was forced as ELF.
This makes it easy for internal invariants to get violated, such as
those which triggered PR25912.
This fixes PR25912.
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Prior to this patch, we would wrongly stick to the variant with imm8 encoding
even when the relocation could not fit that size.
rdar://problem/23785506
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Prior to this patch, we would wrongly stick to the variant with imm8 encoding
even when the relocation could not fit that size.
rdar://problem/23785506
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Summary: Lately, I have submitted a number of patches to fix bugs that
only occurred when using the same pass manager to compile multiple
modules (generally these bugs are failure to reset some persistent
state). Unfortunately I don't think there is currently a way to test
that from the command line. This adds a very simple flag to both llc
and opt, under which the tools will simply re-run their respective
pass pipelines using the same pass manager on (a clone of the same
module). Additionally, we verify that both outputs are bitwise the
same.
Reviewers: yaron.keren
Subscribers: loladiro, yaron.keren, kcc, llvm-commits
Differential Revision: http://reviews.llvm.org/D14965
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Currently, if the assembler encounters an error after parsing (such as an
out-of-range fixup), it reports this as a fatal error, and so stops after the
first error. However, for most of these there is an obvious way to recover
after emitting the error, such as emitting the fixup with a value of zero. This
means that we can report on all of the errors in a file, not just the first
one. MCContext::reportError records the fact that an error was encountered, so
we won't actually emit an object file with the incorrect contents.
Differential Revision: http://reviews.llvm.org/D14717
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Previously, subprograms contained a metadata reference to the function they
described. Because most clients need to get or set a subprogram for a given
function rather than the other way around, this created unneeded inefficiency.
For example, many passes needed to call the function llvm::makeSubprogramMap()
to build a mapping from functions to subprograms, and the IR linker needed to
fix up function references in a way that caused quadratic complexity in the IR
linking phase of LTO.
This change reverses the direction of the edge by storing the subprogram as
function-level metadata and removing DISubprogram's function field.
Since this is an IR change, a bitcode upgrade has been provided.
Fixes PR23367. An upgrade script for textual IR for out-of-tree clients is
attached to the PR.
Differential Revision: http://reviews.llvm.org/D14265
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We now create them as they are found and use higher level APIs.
This is a step in avoiding creating unnecessary sections.
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Remove code that was assuming that this would never work.
Thanks to Colin LeMahie for finding and diagnosing the bug.
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This extends the work done in r233995 so that now getFragment (in addition to
getSection) also works for variable symbols.
With that the existing logic to decide if a-b can be computed works even if
a or b are variables. Given that, the expression evaluation can avoid expanding
variables as aggressively and that in turn lets the relocation code see the
original variable.
In order for this to work with the asm streamer, there is now a dummy fragment
per section. It is used to assign a section to a symbol when no other fragment
exists.
This patch is a joint work by Maxim Ostapenko andy myself.
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When building LLVM as a (potentially dynamic) library that can be linked against
by multiple compilers, the default triple is not really meaningful.
We allow to explicitely set it to an empty string when configuring LLVM.
In this case, said "target independent" tests in the test suite that are using
the default triple are disabled by matching the newly available feature
"default_triple".
Reviewers: probinson, echristo
Differential Revision: http://reviews.llvm.org/D12660
From: Mehdi Amini <mehdi.amini@apple.com>
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.align directive refuses alignment 0 -- a comment in the code hints this is
done for GNU as compatibility, but it seems GNU as accepts .align 0
(and silently rounds up alignment to 1).
Differential Revision: http://reviews.llvm.org/D12682
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As a follow-up to r246098, require `DISubprogram` definitions
(`isDefinition: true`) to be 'distinct'. Specifically, add an assembler
check, a verifier check, and bitcode upgrading logic to combat testcase
bitrot after the `DIBuilder` change.
While working on the testcases, I realized that
test/Linker/subprogram-linkonce-weak-odr.ll isn't relevant anymore. Its
purpose was to check for a corner case in PR22792 where two subprogram
definitions match exactly and share the same metadata node. The new
verifier check, requiring that subprogram definitions are 'distinct',
precludes that possibility.
I updated almost all the IR with the following script:
git grep -l -E -e '= !DISubprogram\(.* isDefinition: true' |
grep -v test/Bitcode |
xargs sed -i '' -e 's/= \(!DISubprogram(.*, isDefinition: true\)/= distinct \1/'
Likely some variant of would work for out-of-tree testcases.
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Since r241097, `DIBuilder` has only created distinct `DICompileUnit`s.
The backend is liable to start relying on that (if it hasn't already),
so make uniquable `DICompileUnit`s illegal and automatically upgrade old
bitcode. This is a nice cleanup, since we can remove an unnecessary
`DenseSet` (and the associated uniquing info) from `LLVMContextImpl`.
Almost all the testcases were updated with this script:
git grep -e '= !DICompileUnit' -l -- test |
grep -v test/Bitcode |
xargs sed -i '' -e 's,= !DICompileUnit,= distinct !DICompileUnit,'
I imagine something similar should work for out-of-tree testcases.
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Only consider an instruction a candidate for relaxation if the last operand of the
instruction is an expression. We previously checked whether any operand is an expression,
which is useless, since for all instructions concerned, the only operand that may be
affected by relaxation is the last one.
In addition, this removes the check for having RIP as an argument, since it was
plain wrong - even when one of the arguments is RIP, relaxation may still be needed.
This fixes PR9807.
Patch by: david.l.kreitzer@intel.com
Differential Revision: http://reviews.llvm.org/D10766
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The AArch32 assembler parses the '@' as a comment symbol, so the error message shouldn't suggest
that '@<type>' is a valid replacement when assembling for AArch32 target.
Differential Revision: http://reviews.llvm.org/D10651
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It is perfectly possible for SHNDX to contain indexes that have the same value
as reserved st_shndx values.
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This causes errors like:
ld: error: blah.o: requires dynamic R_X86_64_PC32 reloc against '' which
may overflow at runtime; recompile with -fPIC
blah.cc:function f(): error: undefined reference to ''
blah.o:g(): error: undefined reference to ''
I have not yet come up with an appropriate reproduction.
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r226830 moved the declaration of Buf to a nested scope, resulting
in a dangling reference (in StringRef Name), and a use-after-free.
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Now that pr23900 is fixed, we can bring it back with no changes.
Original message:
Make all temporary symbols unnamed.
What this does is make all symbols that would otherwise start with a .L
(or L on MachO) unnamed.
Some of these symbols still show up in the symbol table, but we can just
make them unnamed.
In order to make sure we produce identical results when going thought assembly,
all .L (not just the compiler produced ones), are now unnamed.
Running llc on llvm-as.opt.bc, the peak memory usage goes from 208.24MB to
205.57MB.
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What this does is make all symbols that would otherwise start with a .L
(or L on MachO) unnamed.
Some of these symbols still show up in the symbol table, but we can just
make them unnamed.
In order to make sure we produce identical results when going thought assembly,
all .L (not just the compiler produced ones), are now unnamed.
Running llc on llvm-as.opt.bc, the peak memory usage goes from 208.24MB to
205.57MB.
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Section symbols exist as an optimization: instead of having multiple relocations
point to different symbols, many of them can point to a single section symbol.
When that optimization is unused, a section symbol is also unused and adds no
extra information to the object file.
This saves a bit of space on the object files and makes the output of
llvm-objdump -t easier to read and consequently some tests get quite a bit
simpler.
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