Commit Graph

124 Commits

Author SHA1 Message Date
Jim Grosbach
586c0042da MC: Clean up MCExpr naming. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238634 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-30 01:25:56 +00:00
Jim Grosbach
19696daa21 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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237594 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-18 18:43:14 +00:00
Ahmed Bougacha
e1f835ab59 [MC] Use LShr for constant evaluation of ">>" on ELF/arm64--darwin.
This matches other assemblers and is less unexpected (e.g. PR23227).
On ELF, I tried binutils gas v2.24 and nasm 2.10.09, and they both
agree on LShr.  On COFF, I couldn't get my hands on an assembler yet,
so don't change the behavior.  For now, don't change it on non-AArch64
Darwin either, as the other assembler is gas v1.38, which does an AShr.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235963 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-28 01:37:11 +00:00
Ahmed Bougacha
dac39b1fef [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.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235951 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-28 00:21:32 +00:00
Matt Arsenault
b638e142b4 Revert accidentally committed "MC: Allow targets to stop symbol name quoting"
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235672 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-23 23:34:51 +00:00
Matt Arsenault
6ec2992aca MC: Allow targets to stop symbol name quoting
Currently symbol names are printed in quotes if it contains something
outside of the arbitrary set of characters that isAcceptableChar tests
for. On somem targets, it is never OK to print a symbol name in quotes
so allow targets to opt out of this behavior.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235670 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-23 23:34:05 +00:00
Jingyue Wu
3ea0adcdd5 [NVPTXAsmPrinter] do not print .align on function headers
Summary:
PTX does not allow .align directives on function headers.

Fixes PR21551.

Test Plan: test/Codegen/NVPTX/function-align.ll

Reviewers: eliben, jholewinski

Reviewed By: eliben, jholewinski

Subscribers: llvm-commits, eliben, jpienaar, jholewinski

Differential Revision: http://reviews.llvm.org/D8274

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232004 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-12 01:50:30 +00:00
Rafael Espindola
2e2dbc35da Use the generic Lfunc_begin label on ppc.
This removes yet another custom label to mark the start of a function.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231390 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-05 18:55:50 +00:00
Lang Hames
4c553e0367 Recommit r224935 with a fix for the ObjC++/AArch64 bug that that revision
introduced.

A test case for the bug was already committed in r225385.

Patch by Rafael Espindola.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225534 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-09 18:55:42 +00:00
Lang Hames
84acf09f32 Revert r224935 "Refactor duplicated code. No intended functionality change."
This is affecting the behavior of some ObjC++ / AArch64 test cases on Darwin.
Reverting to get the bots green while I track down the source of the changed
behavior.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225311 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-06 23:04:36 +00:00
Rafael Espindola
2a1c1c9dea Refactor duplicated code.
No intended functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224935 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-29 15:18:31 +00:00
Matt Arsenault
459e595697 Allow target to specify prefix for labels
Use the MCAsmInfo instead of the DataLayout, and allow
specifying a custom prefix for labels specifically. HSAIL
requires that labels begin with @, but global symbols with &.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223323 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-04 00:06:57 +00:00
Jingyue Wu
b043278834 [NVPTX] Do not emit .weak symbols for NVPTX
Summary:
".weak" symbols cannot be consumed by ptxas (PR21685). This patch makes the
weak directive in MCAsmPrinter customizable, and disables emitting ".weak"
symbols for NVPTX.

Test Plan: weak-linkage.ll

Reviewers: jholewinski

Reviewed By: jholewinski

Subscribers: majnemer, jholewinski, llvm-commits

Differential Revision: http://reviews.llvm.org/D6455

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223077 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-01 21:16:17 +00:00
Rafael Espindola
4af7ead7bd Drop support for an old version of ld64 (from darwin 9).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220310 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-21 18:31:09 +00:00
Rafael Espindola
45968c54e9 Fix a bit of confusion about .set and produce more readable assembly.
Every target we support has support for assembly that looks like

a = b - c
.long a

What is special about MachO is that the above combination suppresses the
production of a relocation.

With this change we avoid producing the intermediary labels when they don't
add any value.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220256 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-21 01:17:30 +00:00
Saleem Abdulrasool
0c1740ce1a MC: remove unnecessary enumeration prefix
This is an enum class, and will be appropriately prefixed, making the encoding
type prefix redundant.  No change to any uses as the use of this was not yet
introduced.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216893 91177308-0d34-0410-b5e6-96231b3b80d8
2014-09-01 23:48:29 +00:00
Rafael Espindola
a348fc7fda Remove HasLEB128.
We already require CFI, so it should be safe to require .leb128 and .uleb128.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215712 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-15 14:01:07 +00:00
Rafael Espindola
4186005edc Print a=b as an assignment.
In assembly the expression a=b is parsed as an assignment, so it should be
printed as one.

This remove a truly horrible hack for producing a label with "a=.". It would
be used by codegen but would never be reached by the asm parser. Sorry I
missed this when it was first committed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211639 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-24 22:45:16 +00:00
Saleem Abdulrasool
9c7ddf7373 MC: add enumeration of WinEH data encoding
Most Windows platforms use auxiliary data for unwinding.  This information is
stored in the .pdata section.  The encoding format for the data differs between
architectures and Windows variants.  Windows MIPS and Alpha use identical
formats; Alpha64 is the same with different widths.  Windows x86_64 and Itanium
share the representation.  All Windows CE entries are identical irrespective of
the architecture.  ARMv7 (Windows [NT] on ARM) has its own format.

This enumeration will become the differentiator once the windows EH emission
infrastructure is generalised, allowing us to emit the necessary unwinding
information for Windows on ARM.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210634 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-11 04:19:25 +00:00
Craig Topper
4266ae8067 [C++11] More 'nullptr' conversion or in some cases just using a boolean check instead of comparing to nullptr.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206129 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-13 04:57:38 +00:00
Tim Northover
c5d592d5d2 MachO: allow each section to have a linker-private symbol
The upcoming ARM64 backend doesn't have section-relative relocations,
so we give each section its own symbol to provide this functionality.
Of course, it doesn't need to appear in the final executable, so
linker-private is the best kind for this purpose.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205081 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-29 07:05:06 +00:00
David Blaikie
0a0c4cc56f DebugInfo: Support for compressed debug info sections
1) When creating a .debug_* section and instead create a .zdebug_
   section.
2) When creating a fragment in a .zdebug_* section, make it a compressed
   fragment.
3) When computing the size of a compressed section, compress the data
   and use the size of the compressed data.
4) Emit the compressed bytes.

Also, check that only if a section has a compressed fragment, then that
is the only fragment in the section.

Assert-fail if the fragment's data is modified after it is compressed.

Initial review on llvm-commits by Eric Christopher and Rafael Espindola.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204958 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-27 20:45:58 +00:00
Logan Chien
80668d18e8 Move get[S|U]LEB128Size() to LEB128.h.
This commit moves getSLEB128Size() and getULEB128Size() from
MCAsmInfo to LEB128.h and removes some copy-and-paste code.

Besides, this commit also adds some unit tests for the LEB128
functions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201937 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-22 14:00:39 +00:00
Daniel Sanders
38c6b58eec Re-commit: Demote EmitRawText call in AsmPrinter::EmitInlineAsm() and remove hasRawTextSupport() call
Summary:
AsmPrinter::EmitInlineAsm() will no longer use the EmitRawText() call for
targets with mature MC support. Such targets will always parse the inline
assembly (even when emitting assembly). Targets without mature MC support
continue to use EmitRawText() for assembly output.

The hasRawTextSupport() check in AsmPrinter::EmitInlineAsm() has been replaced
with MCAsmInfo::UseIntegratedAs which when true, causes the integrated assembler
to parse inline assembly (even when emitting assembly output). UseIntegratedAs
is set to true for targets that consider any failure to parse valid assembly
to be a bug. Target specific subclasses generally enable the integrated
assembler in their constructor. The default value can be overridden with
-no-integrated-as.

All tests that rely on inline assembly supporting invalid assembly (for example,
those that use mnemonics such as 'foo' or 'hello world') have been updated to
disable the integrated assembler.

Changes since review (and last commit attempt):
- Fixed test failures that were missed due to configuration of local build.
  (fixes crash.ll and a couple others).
- Fixed tests that happened to pass because the local build was on X86
  (should fix 2007-12-17-InvokeAsm.ll)
- mature-mc-support.ll's should no longer require all targets to be compiled.
  (should fix ARM and PPC buildbots)
- Object output (-filetype=obj and similar) now forces the integrated assembler
  to be enabled regardless of default setting or -no-integrated-as.
  (should fix SystemZ buildbots)

Reviewers: rafael

Reviewed By: rafael

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D2686



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201333 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-13 14:44:26 +00:00
Daniel Sanders
7580df334e Revert r201237+r201238: Demote EmitRawText call in AsmPrinter::EmitInlineAsm() and remove hasRawTextSupport() call
It introduced multiple test failures in the buildbots.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201241 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-12 15:39:20 +00:00
Daniel Sanders
57edb9588b Demote EmitRawText call in AsmPrinter::EmitInlineAsm() and remove hasRawTextSupport() call
Summary:
AsmPrinter::EmitInlineAsm() will no longer use the EmitRawText() call for targets with mature MC support. Such targets will always parse the inline assembly (even when emitting assembly). Targets without mature MC support continue to use EmitRawText() for assembly output.

The hasRawTextSupport() check in AsmPrinter::EmitInlineAsm() has been replaced with MCAsmInfo::UseIntegratedAs which when true, causes the integrated assembler to parse inline assembly (even when emitting assembly output). UseIntegratedAs is set to true for targets that consider any failure to parse valid assembly to be a bug. Target specific subclasses generally enable the integrated assembler in their constructor. The default value can be overridden with -no-integrated-as.

All tests that rely on inline assembly supporting invalid assembly (for example, those that use mnemonics such as 'foo' or 'hello world') have been updated to disable the integrated assembler.

Reviewers: rafael

Reviewed By: rafael

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D2686

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201237 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-12 14:44:54 +00:00
Rafael Espindola
5e47632b8f Every target uses .align. Simplify.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200782 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-04 18:39:51 +00:00
Rafael Espindola
9dcfdf61a8 CommentColumn is always 40. Simplify.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199357 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-16 07:04:11 +00:00
Iain Sandoe
9c0a05c7af [patch] Adjust behavior of FDE cross-section relocs for targets that don't support abs-differences.
Modern versions of OSX/Darwin's ld (ld64 > 97.17) have an optimisation present that allows the back end to omit relocations (and replace them with an absolute difference) for FDE some text section refs.

This patch allows a backend to opt-in to this behaviour by setting "DwarfFDESymbolsUseAbsDiff".  At present, this is only enabled for modern x86 OSX ports.

test changes by David Fang.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198744 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-08 10:22:54 +00:00
Rafael Espindola
8e0f67dcec Make the llvm mangler depend only on DataLayout.
Before this patch any program that wanted to know the final symbol name of a
GlobalValue had to link with Target.

This patch implements a compromise solution where the mangler uses DataLayout.
This way, any tool that already links with Target (llc, clang) gets the exact
behavior as before and new IR files can be mangled without linking with Target.

With this patch the mangler is constructed with just a DataLayout and DataLayout
is extended to include the information the Mangler needs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198438 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-03 19:21:54 +00:00
David Fang
b59d46efa5 on darwin<10, fallback to .weak_definition (PPC,X86)
.weak_def_can_be_hidden was not yet supported by the system assembler

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196970 91177308-0d34-0410-b5e6-96231b3b80d8
2013-12-10 21:37:41 +00:00
David Peixotto
0fc8c68b11 Add support for parsing ARM symbol variants on ELF targets
ARM symbol variants are written with parens instead of @ like this:

  .word __GLOBAL_I_a(target1)

This commit adds support for parsing these symbol variants in
expressions. We introduce a new flag to MCAsmInfo that indicates the
parser should use parens to parse the symbol variant. The expression
parser is modified to look for symbol variants using parens instead
of @ when the corresponding MCAsmInfo flag is true.

The MCAsmInfo parens flag is enabled only for ARM on ELF.

By adding this flag to MCAsmInfo, we are able to get rid of
redundant ARM-specific symbol variants and use the generic variants
instead (e.g. VK_GOT instead of VK_ARM_GOT). We use the new
UseParensForSymbolVariant attribute in MCAsmInfo to correctly print
the symbol variants for arm.

To achive this we need to keep a handle to the MCAsmInfo in the
MCSymbolRefExpr class that we can check when printing the symbol
variant.

Updated Tests:
  Changed case of symbol variant to match the generic kind.
  test/CodeGen/ARM/tls-models.ll
  test/CodeGen/ARM/tls1.ll
  test/CodeGen/ARM/tls2.ll
  test/CodeGen/Thumb2/tls1.ll
  test/CodeGen/Thumb2/tls2.ll

PR18080


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196424 91177308-0d34-0410-b5e6-96231b3b80d8
2013-12-04 22:43:20 +00:00
Rafael Espindola
9472fd7403 Refactor the setting of PrivateGlobalPrefix.
No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196170 91177308-0d34-0410-b5e6-96231b3b80d8
2013-12-02 23:39:26 +00:00
Rafael Espindola
29a0d2abfe Convert two char* that are only ever used as booleans to bool.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196168 91177308-0d34-0410-b5e6-96231b3b80d8
2013-12-02 23:04:51 +00:00
Rafael Espindola
4ca0ef70cd The global prefix is always one char. Don't use a string for it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195926 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-28 17:00:49 +00:00
Rafael Espindola
de9a1a2055 Remove AllowQuotesInName and friends from MCAsmInfo.
Accepting quotes is a property of an assembler, not of an object file. For
example, ELF can support any names for sections and symbols, but the gnu
assembler only accepts quotes in some contexts and llvm-mc in a few more.

LLVM should not produce different symbols based on a guess about which assembler
will be reading the code it is printing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194575 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-13 14:01:59 +00:00
Rafael Espindola
328066513d Remove always true flag.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194530 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-12 23:27:08 +00:00
Rafael Espindola
b46bc1c91b Remove unused flag.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193752 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-31 15:49:39 +00:00
Hans Wennborg
22f9dd4591 MC asm parser: allow ?'s in symbol names, and handle @'s in names in MS asm
This is another (final?) stab at making us able to parse our own asm output
on Windows.

Symbols on Windows often contain @'s and ?'s in their names. Our asm parser
didn't like this. ?'s were not allowed, and @'s were intepreted as trying to
reference PLT/GOT/etc.

We can't just add quotes around the bad names, since e.g. for MinGW, we use gas
to assemble, and it doesn't like quotes in some places (notably in .def
directives).

This commit makes us allow ?'s in symbol names, and @'s in symbol names for MS
assembly.

Differential Revision: http://llvm-reviews.chandlerc.com/D1978

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193000 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-18 20:46:28 +00:00
Rafael Espindola
c7ce3e4f42 Move .ident handling to MCStreamer.
No functionality change, but exposes the API so that codegen can use it too.

Patch by Katya Romanova.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192757 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-16 01:05:45 +00:00
David Majnemer
3f22cc1df6 MC: Add support for treating $ as a reference to the PC
The binutils assembler supports a mode called DOLLAR_DOT which treats
the dollar sign token as a reference to the current program counter if
the dollar sign doesn't precede a constant or identifier.

This commit adds a new MCAsmInfo flag stating whether or not a given
target supports this interpretation of the dollar sign token; by
default, this flag is not enabled.

Further, enable this flag for PPC. The system assembler for AIX and
binutils both support using the dollar sign in this manner.

This fixes PR17353.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191368 91177308-0d34-0410-b5e6-96231b3b80d8
2013-09-25 10:47:21 +00:00
David Majnemer
8ba3f9c900 MC: Remove vestigial PCSymbol field from AsmInfo
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191362 91177308-0d34-0410-b5e6-96231b3b80d8
2013-09-25 09:36:11 +00:00
Eric Christopher
6b6345f016 Remove support for the .debug_inlined section. No known software
in use supports it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189439 91177308-0d34-0410-b5e6-96231b3b80d8
2013-08-28 04:04:28 +00:00
David Blaikie
fe2e66a6da DebugInfo: PR14404: Avoid truncating 64 bit values into 32 bits for ULEB128/SLEB128 generation
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184669 91177308-0d34-0410-b5e6-96231b3b80d8
2013-06-23 18:31:11 +00:00
Ulrich Weigand
c1f4a4b264 [MC/DWARF] Support .debug_frame / .debug_line code alignment factors
I've been comparing the object file output of LLVM's integrated
assembler against the external assembler on PowerPC, and one
area where differences still remain are in DWARF sections.

In particular, the GNU assembler generates .debug_frame and
.debug_line sections using a code alignment factor of 4, since
all PowerPC instructions have size 4 and must be aligned to a
multiple of 4.  However, current MC code hard-codes a code
alignment factor of 1.

This patch changes this by adding a "minimum instruction alignment"
data element to MCAsmInfo and using this as code alignment factor.

This requires passing a MCContext into MCDwarfLineAddr::Encode
and MCDwarfLineAddr::EncodeAdvanceLoc.  Note that one caller,
MCDwarfLineAddr::Write, didn't actually have that information
available.  However, it turns out that this routine is in fact
never used in the whole code base, so the patch simply removes
it.  If it turns out to be needed again at a later time, it
could be re-added with an updated interface.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183834 91177308-0d34-0410-b5e6-96231b3b80d8
2013-06-12 14:46:54 +00:00
Matt Arsenault
9a0e12a6ed Remove unused DwarfSectionOffsetDirective string
The value isn't actually used, and setting it emits a COFF specific
directive.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180064 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-22 22:49:11 +00:00
Eli Bendersky
e752feee52 Clean up assignment of CalleeSaveStackSlotSize: get rid of the default and explicitly set this in every target that needs to change it from the default.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173270 91177308-0d34-0410-b5e6-96231b3b80d8
2013-01-23 16:22:04 +00:00
Eli Bendersky
9dd2a3b1f2 Initial patch for x32 ABI support.
Add the x32 environment kind to the triple, and separate the concept of
pointer size and callee save stack slot size, since they're not equal
on x32.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173175 91177308-0d34-0410-b5e6-96231b3b80d8
2013-01-22 18:02:49 +00:00
Reed Kotler
2c3a4641a7 This patch is needed to make c++ exceptions work for mips16.
Mips16 is really a processor decoding mode (ala thumb 1) and in the same
program, mips16 and mips32 functions can exist and can call each other.

If a jal type instruction encounters an address with the lower bit set, then
the processor switches to mips16 mode (if it is not already in it). If the
lower bit is not set, then it switches to mips32 mode.

The linker knows which functions are mips16 and which are mips32.
When relocation is performed on code labels, this lower order bit is
set if the code label is a mips16 code label.

In general this works just fine, however when creating exception handling
tables and dwarf, there are cases where you don't want this lower order
bit added in.

This has been traditionally distinguished in gas assembly source by using a
different syntax for the label.

lab1:      ; this will cause the lower order bit to be added
lab2=.     ; this will not cause the lower order bit to be added

In some cases, it does not matter because in dwarf and debug tables
the difference of two labels is used and in that case the lower order
bits subtract each other out.

To fix this, I have added to mcstreamer the notion of a debuglabel.
The default is for label and debug label to be the same. So calling
EmitLabel and EmitDebugLabel produce the same result.

For various reasons, there is only one set of labels that needs to be
modified for the mips exceptions to work. These are the "$eh_func_beginXXX" 
labels.

Mips overrides the debug label suffix from ":" to "=." .

This initial patch fixes exceptions. More changes most likely
will be needed to DwarfCFException to make all of this work
for actual debugging. These changes will be to emit debug labels in some
places where a simple label is emitted now.

Some historical discussion on this from gcc can be found at:
http://gcc.gnu.org/ml/gcc-patches/2008-08/msg00623.html
http://gcc.gnu.org/ml/gcc-patches/2008-11/msg01273.html 



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170279 91177308-0d34-0410-b5e6-96231b3b80d8
2012-12-16 04:00:45 +00:00
Benjamin Kramer
a9e37c5eaf Fix alignment of .comm and .lcomm on mingw32.
For some reason .lcomm uses byte alignment and .comm log2 alignment so we can't
use the same setting for both. Fix this by reintroducing the LCOMM enum.
I verified this against mingw's gcc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163420 91177308-0d34-0410-b5e6-96231b3b80d8
2012-09-07 21:08:01 +00:00