Commit Graph

176 Commits

Author SHA1 Message Date
Rafael Espindola e3a20f57d9 Fix pr24486.
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.

llvm-svn: 249303
2015-10-05 12:07:05 +00:00
Davide Italiano 983366ab12 [MC] Fix style bugs introduced in r247471. Reported by Rafael Espindola.
llvm-svn: 247483
2015-09-11 22:04:21 +00:00
Davide Italiano 63cee81c3c [MC] Don't crash on division by zero.
Differential Revision:	http://reviews.llvm.org/D12776

llvm-svn: 247471
2015-09-11 20:47:35 +00:00
Justin Bogner c16021514c MCExpr: Avoid UB by evaluating this shift as unsigned
We hit undefined behaviour in some MCExpr tests when the LHS of a left
shift is -1. Twos-complement semantics are completely reasonable here,
so we should just do the shift in unsigned.

llvm-svn: 240385
2015-06-23 07:32:55 +00:00
Matt Arsenault 8b643559d4 MC: Add target hook to control symbol quoting
llvm-svn: 239370
2015-06-09 00:31:39 +00:00
Jim Grosbach 36e60e9127 MC: Clean up naming in MCObjectWriter. NFC.
s/WriteObject/writeObject/
s/RecordRelocation/recordRelocation/
s/IsSymbolRefDifferenceFullyResolved/isSymbolRefDifferenceFullyResolved/
s/Write8/write8/
s/WriteLE16/writeLE16/
s/WriteLE32/writeLE32/
s/WriteLE64/writeLE64/
s/WriteBE16/writeBE16/
s/WriteBE32/writeBE32/
s/WriteBE64/writeBE64/
s/Write16/write16/
s/Write32/write32/
s/Write64/write64/
s/WriteZeroes/writeZeroes/
s/WriteBytes/writeBytes/

llvm-svn: 239108
2015-06-04 22:24:41 +00:00
Rafael Espindola 212fdde205 Remember if a weakref of a symbol has been used.
This avoids yet another last minute patching of the binding.

While at it, also simplify the weakref implementation a bit by not walking
past it in the expression evaluation.

llvm-svn: 238982
2015-06-03 21:52:06 +00:00
Jim Grosbach 13760bd152 MC: Clean up MCExpr naming. NFC.
llvm-svn: 238634
2015-05-30 01:25:56 +00:00
Rafael Espindola 4d37b2a259 Remove getData.
This completes the mechanical part of merging MCSymbol and MCSymbolData.

llvm-svn: 238617
2015-05-29 21:45:01 +00:00
Rafael Espindola beb6060a51 Remove the MCSymbolData typedef.
The getData member function is next.

llvm-svn: 238611
2015-05-29 20:41:47 +00:00
Rafael Espindola 14672508b1 Move common symbol related information from MCSectionData to MCSymbol.
llvm-svn: 238583
2015-05-29 17:48:04 +00:00
Pete Cooper c5a7177772 Fix crash in MCExpr::print.
Symbols are no longer required to be named, but this leads to a crash here if an
unnamed symbol checks that its first character is '$'.

Change the code to first check for a name, then check its first character.

No test case i'm afraid as this is debugging code, but any test case with temp labels
and 'llc --debug --filetype=obj' would have crashed.

llvm-svn: 238579
2015-05-29 17:19:11 +00:00
Rafael Espindola 3a5d3cce80 Remove a trivial forwarding function. NFC.
llvm-svn: 238506
2015-05-28 21:36:02 +00:00
Rafael Espindola f4a1365387 Use operator<< instead of print in a few more places.
llvm-svn: 238315
2015-05-27 13:05:42 +00:00
Rafael Espindola 079027ea90 Stop using MCSectionData in MCExpr.h.
llvm-svn: 238163
2015-05-26 00:52:18 +00:00
Rafael Espindola 7549f87672 Return a MCSection from MCFragment::getParent().
Another step in merging MCSectionData and MCSection.

llvm-svn: 238162
2015-05-26 00:36:57 +00:00
Rafael Espindola 0709a7bd1a Move alignment from MCSectionData to MCSection.
This starts merging MCSection and MCSectionData.

There are a few issues with the current split between MCSection and
MCSectionData.

* It optimizes the the not as important case. We want the production
of .o files to be really fast, but the split puts the information used
for .o emission in a separate data structure.

* The ELF/COFF/MachO hierarchy is not represented in MCSectionData,
leading to some ad-hoc ways to represent the various flags.

* It makes it harder to remember where each item is.

The attached patch starts merging the two by moving the alignment from
MCSectionData to MCSection.

Most of the patch is actually just dropping 'const', since
MCSectionData is mutable, but MCSection was not.

llvm-svn: 237936
2015-05-21 19:20:38 +00:00
Duncan P. N. Exon Smith 5266ad9bec MC: Use MCSymbol in MCObjectWriter::isWeak(), NFC
Continue to prefer `MCSymbol` when we need both.

llvm-svn: 237798
2015-05-20 15:10:03 +00:00
Duncan P. N. Exon Smith 2a40483418 MC: Use MCSymbol in MCAsmLayout::getSymbolOffset(), NFC
Continue to canonicalize on MCSymbol instead of MCSymbolData when both
are needed.

llvm-svn: 237749
2015-05-19 23:53:20 +00:00
Jim Grosbach 6f482000e9 MC: Clean up method names in MCContext.
The naming was a mish-mash of old and new style. Update to be consistent
with the new. NFC.

llvm-svn: 237594
2015-05-18 18:43:14 +00:00
Colin LeMahieu b662565475 [Hexagon] Adding expression MC emission and removing XFAIL from test that hits this code path.
llvm-svn: 236348
2015-05-01 21:14:21 +00:00
Ahmed Bougacha 177c14852b [MC] Split MCBinaryExpr::Shr into LShr and AShr.
Defaulting to AShr without consulting the target MCAsmInfo isn't OK.
Add a flag to fix that.  Keep it off for now: target migrations will
follow in separate commits.

llvm-svn: 235951
2015-04-28 00:21:32 +00:00
Peter Collingbourne 10d362c51b MC: For variable symbols, maintain MCSymbol::Section as a cache.
Fixes PR19582.

Previously, when an asm assignment (.set or =) was created, we would look up
the section immediately in MCSymbol::setVariableValue. This caused symbols
to receive the wrong section if the RHS of the assignment had not been seen
yet. This had a knock-on effect in the object file emitters, causing them
to emit extra symbols, or to give symbols the wrong visibility or the wrong
section. For example, in the following asm:

.data
.Llocal:

.text
leaq .Llocal1(%rip), %rdi
.Llocal1 = .Llocal2
.Llocal2 = .Llocal

the first assignment would give .Llocal1 a null section, which would never get
fixed up by the second assignment. This would cause the ELF object file emitter
to consider .Llocal1 to be an undefined symbol and give it external linkage,
even though .Llocal1 should not have been emitted at all in the object file.

Or in the following asm:

alias_to_local = Ltmp0
Ltmp0:

the Mach-O object file emitter would give the alias_to_local symbol a n_type
of N_SECT and a n_sect of 0.  This is invalid under the Mach-O specification,
which requires N_SECT symbols to receive a non-zero section number if the
symbol is defined in a section in the object file.

https://developer.apple.com/library/mac/documentation/DeveloperTools/Conceptual/MachORuntime/#//apple_ref/c/tag/nlist

After this change we do not look up the section when the assignment is created,
but instead look it up on demand and store it in Section, which is treated
as a cache if the symbol is a variable symbol.

This change also fixes a bug in MCExpr::FindAssociatedSection. Previously,
if we saw a subtraction, we would return the first referenced section, even in
cases where we should have been returning the absolute pseudo-section. Now we
always return the absolute pseudo-section for expressions that subtract two
section-derived expressions. This isn't always correct (e.g. if one of the
sections ends up being laid out at an absolute address), but it's probably
the best we can do without more context.

This allows us to remove code in two places where we appear to have been
working around this bug, in MachObjectWriter::markAbsoluteVariableSymbols
and in X86AsmPrinter::EmitStartOfAsmFile.

Re-applies r233595 (aka D8586), which was reverted in r233898.

Differential Revision: http://reviews.llvm.org/D8798

llvm-svn: 233995
2015-04-03 01:46:11 +00:00
Peter Collingbourne 949eb3f6a7 Revert r233595, "MC: For variable symbols, maintain MCSymbol::Section as a cache."
llvm-svn: 233898
2015-04-02 07:02:51 +00:00
Peter Collingbourne 915a4b13ef MC: For variable symbols, maintain MCSymbol::Section as a cache.
This fixes the visibility of symbols in certain edge cases involving aliases
with multiple levels of indirection.

Fixes PR19582.

Differential Revision: http://reviews.llvm.org/D8586

llvm-svn: 233595
2015-03-30 20:41:21 +00:00
Rafael Espindola aeed3cbce0 Fix PR23025.
There is something in link.exe that requires a relocation to use a
global symbol. Not doing so breaks the chrome build on windows.

This patch sets isWeak for that to work. To compensate,
we then need to look past those symbols when not creating relocations.

This patch includes an ELF test that matches GNU as behaviour.

I am still reducing the chrome build issue and will add a test
once that is done.

llvm-svn: 233318
2015-03-26 21:11:00 +00:00
Rafael Espindola 59f90b215d clang-format bits of code to make another patch readable.
llvm-svn: 233203
2015-03-25 19:24:39 +00:00
Rafael Espindola f275ad8af1 Fix fixup evaluation when deciding what to relocate with.
The previous logic was to first try without relocations at all
and failing that stop on the first defined symbol.

That was inefficient and incorrect in the case part of the
expression could be simplified and another part could not
(see included test).

We now stop the evaluation when we get to a variable whose value
can change (i.e. is weak).

llvm-svn: 233187
2015-03-25 13:16:53 +00:00
Rafael Espindola dbb4021b64 Produce an error instead of asserting on invalid .sleb128/.uleb128.
llvm-svn: 233155
2015-03-25 00:25:37 +00:00
Rafael Espindola 266b8c8043 Expand variables when evaluating absolute expressions.
This allows for variables to be used in .size.
This matches gnu AS functionality.

llvm-svn: 231295
2015-03-04 22:03:21 +00:00
Davide Italiano fcae934c03 [MC][Target] Implement support for R_X86_64_SIZE{32,64}.
Differential Revision:	D7990
Reviewed by:	rafael, majnemer

llvm-svn: 231216
2015-03-04 06:49:39 +00:00
Saleem Abdulrasool fe781977b9 ARM: add support for segment base relocations (SBREL)
This adds support for parsing and emitting the SBREL relocation variant for the
ARM target.  Handling this relocation variant is necessary for supporting the
full ARM ELF specification.  Addresses PR22128.

llvm-svn: 225595
2015-01-11 04:39:18 +00:00
Roman Divacky a93d002321 Instead of explicitely comparing both lowercase and uppercase variants.
.lower() the Name and compare only the lowecase. Removing 81 compares/lines of
code. This changes the accepted string to be mixed lower/upper case but it
should be ok.

Discussed with Jim Grosbach.

llvm-svn: 224547
2014-12-18 23:12:34 +00:00
Justin Hibbits 88030b94c6 Add a corresponding '@LOCAL' parse to match r224415.
Pointed out by Jim Grosbach.

llvm-svn: 224494
2014-12-18 03:06:37 +00:00
Justin Hibbits 0c0d5deff1 Add parsing of 'foo@local".
Summary:
Currently, it supports generating, but not parsing, this expression.
Test added as well.

Test Plan: New test added, no regressions due to this.

Reviewers: hfinkel

Reviewed By: hfinkel

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D6672

llvm-svn: 224415
2014-12-17 06:23:35 +00:00
Justin Hibbits a88b605721 Add support for small-model PIC for PowerPC.
Summary:
Large-model was added first.  With the addition of support for multiple PIC
models in LLVM, now add small-model PIC for 32-bit PowerPC, SysV4 ABI.  This
generates more optimal code, for shared libraries with less than about 16380
data objects.

Test Plan: Test cases added or updated

Reviewers: joerg, hfinkel

Reviewed By: hfinkel

Subscribers: jholewinski, mcrosier, emaste, llvm-commits

Differential Revision: http://reviews.llvm.org/D5399

llvm-svn: 221791
2014-11-12 15:16:30 +00:00
Benjamin Kramer dd13643b97 MC: Shrink MCSymbolRefExpr by only storing the bits we need.
32 -> 16 bytes on x86_64. NFC.

llvm-svn: 219574
2014-10-11 17:57:27 +00:00
Reid Kleckner 81782f0cb8 MC: Use @IMGREL instead of @IMGREL32, which we can't parse
Nico Rieck added support for this 32-bit COFF relocation some time ago
for Win64 stuff. It appears that as an oversight, the assembly output
used "foo"@IMGREL32 instead of "foo"@IMGREL, which is what we can parse.

Sadly, there were actually tests that took in IMGREL and put out
IMGREL32, and we didn't notice the inconsistency. Oh well. Now LLVM can
assemble it's own output with slightly more fidelity.

llvm-svn: 218437
2014-09-25 02:09:18 +00:00
Rafael Espindola adbe02435d Add a helper to MCExpr for when an expression is know to be absolute.
llvm-svn: 215713
2014-08-15 14:20:32 +00:00
Joerg Sonnenberger b696d46045 Fix tabs.
llvm-svn: 215311
2014-08-10 11:37:07 +00:00
Joerg Sonnenberger 752b91bd82 If available, pass down the Fixup object to EvaluateAsRelocatable.
At least on PowerPC, the interpretation of certain modifiers depends on
the context they appear in.

llvm-svn: 215310
2014-08-10 11:35:12 +00:00
Zoran Jovanovic b355e8f604 [mips][mips64r6] Add Relocations R_MIPS_PCHI16, R_MIPS_PCLO16
Differential Revision: http://reviews.llvm.org/D3860

llvm-svn: 209659
2014-05-27 14:58:51 +00:00
Rafael Espindola 3d082fa507 Fix pr19645.
The fix itself is fairly simple: move getAccessVariant to MCValue so that we
replace the old weak expression evaluation with the far more general
EvaluateAsRelocatable.

This then requires that EvaluateAsRelocatable stop when it finds a non
trivial reference kind. And that in turn requires the ELF writer to look
harder for weak references.

Last but not least, this found a case where we were being bug by bug
compatible with gas and accepting an invalid input. I reported pr19647
to track it.

llvm-svn: 207920
2014-05-03 19:57:04 +00:00
Joerg Sonnenberger dd18d5b0f6 Parse and create GOT_PREL relocations.
llvm-svn: 207526
2014-04-29 13:42:02 +00:00
Rafael Espindola bc91d7e25a Add an option for evaluating past symbols.
When evaluating an assembly expression for a relocation, we want to
stop at MCSymbols that are in the symbol table, even if they are variables.
This is needed since the semantics may require that the relocation use them.

That is not the case when computing the value of a symbol in the symbol table.
There are no relocations in this case and we have to keep going until we hit
a section or find out that the expression doesn't have an assembly time
value.

llvm-svn: 207445
2014-04-28 20:53:11 +00:00
David Blaikie 908f4d4bf5 Spread some const around for non-mutating uses of MCSymbolData.
I discovered this const-hole while attempting to coalesnce the Symbol
and SymbolMap data structures. There's some pending issues with that,
but I figured this change was easy to flush early.

llvm-svn: 207124
2014-04-24 16:59:40 +00:00
Chandler Carruth f58e376d23 [Modules] Fix potential ODR violations by sinking the DEBUG_TYPE
definition below all the header #include lines. This updates most of the
miscellaneous other lib/... directories. A few left though.

llvm-svn: 206845
2014-04-22 03:04:17 +00:00
Craig Topper bb694de649 [C++11] More 'nullptr' conversion or in some cases just using a boolean check instead of comparing to nullptr.
llvm-svn: 206129
2014-04-13 04:57:38 +00:00
Tim Northover 00ed9964c6 ARM64: initial backend import
This adds a second implementation of the AArch64 architecture to LLVM,
accessible in parallel via the "arm64" triple. The plan over the
coming weeks & months is to merge the two into a single backend,
during which time thorough code review should naturally occur.

Everything will be easier with the target in-tree though, hence this
commit.

llvm-svn: 205090
2014-03-29 10:18:08 +00:00
Rafael Espindola 7fadc0ea7d Look through variables when computing relocations.
Given

bar = foo + 4
	.long bar

MC would eat the 4. GNU as includes it in the relocation. The rule seems to be
that a variable that defines a symbol is used in the relocation and one that
does not define a symbol is evaluated and the result included in the relocation.

Fixing this unfortunately required some other changes:

* Since the variable is now evaluated, it would prevent the ELF writer from
  noticing the weakref marker the elf streamer uses. This patch then replaces
  that with a VariantKind in MCSymbolRefExpr.

* Using VariantKind then requires us to look past other VariantKind to see

	.weakref	bar,foo
	call	bar@PLT

  doing this also fixes

	zed = foo +2
	call zed@PLT

  so that is a good thing.

* Looking past VariantKind means that the relocation selection has to use
  the fixup instead of the target.

This is a reboot of the previous fixes for MC. I will watch the sanitizer
buildbot and wait for a build before adding back the previous fixes.

llvm-svn: 204294
2014-03-20 02:12:01 +00:00