Commit Graph

304 Commits

Author SHA1 Message Date
Duncan P. N. Exon Smith
9e6378de57 MC: Use MCSymbol in MCObject::IsSymbolRefDifferenceFullyResolvedImpl()
Transition one API from `MCSymbolData` to `MCSymbol`.  The function
needs both, and the backpointer from `MCSymbolData` to `MCSymbol` is
going away.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237498 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-16 01:01:55 +00:00
Duncan P. N. Exon Smith
5f7c1f8415 MC: Change MCFragment::Atom to an MCSymbol, NFC
Change `MCFragment::Atom` from an `MCSymbolData` to an `MCSymbol`,
moving in the direction of removing the back-pointer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237497 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-16 00:48:58 +00:00
Duncan P. N. Exon Smith
c5f2ba0401 MC: Merge MCSymbol and MCSymbolData
Turn `MCSymbolData` into a field inside of `MCSymbol`.  Keep all the old
API alive for now, so that consumers can be updated in a later commit.
This means we still temporarily need the back pointer from
`MCSymbolData` to `MCSymbol`, but I'll remove it in a follow-up.

This optimizes for object emission over assembly emission.  By removing
the `DenseMap` in `MCAssembler`, llc memory usage drops from around 1040
MB to 1001 MB (3.8%).

(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`;
see r236629 for details.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237490 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-16 00:03:06 +00:00
Duncan P. N. Exon Smith
eaf14f30c8 MC: Reduce MCAssembler::Symbols API exposure, NFC
Stop exposing the storage for `MCAssembler::Symbols`, and have
`MCAssembler` add symbols directly to its list instead of using a hook
in `MCSymbolData`.  This opens up room for a follow-up commit to switch
from a linked list to a vector.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237486 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-15 22:33:34 +00:00
Jim Grosbach
251a66ec37 MC: Update MCCodeEmitter naming. NFC.
s/EncodeInstruction/encodeInstruction/

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237469 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-15 19:13:16 +00:00
Rafael Espindola
fb118bd226 Compute A-B when A or B is weak.
Similar to r235222, but for the weak symbol case.

In an "ideal" assembler/object format an expression would always refer to the
final value and A-B would only be computed from a section in the same
comdat as A and B with A and B strong.

Unfortunately that is not the case with debug info on ELF, so we need an
heuristic.  Since we need an heuristic, we may as well use the same one as
gas:

* call weak_sym : produces a relocation, even if in the same section.
* A - weak_sym and weak_sym -A: don't produce a relocation if we can
  compute it.

This fixes pr23272 and changes the fix of pr22815 to match what gas does.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235227 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-17 21:15:17 +00:00
Petr Hosek
054db7df5b [MC] Write padding into fragments when -mc-relax-all flag is used
Summary:
When instruction bundling is enabled and the -mc-relax-all flag is
set, we can write bundle padding directly into fragments and avoid
creating large number of fragments significantly reducing LLVM MC
memory usage.

Test Plan: Regression test attached

Reviewers: eliben

Subscribers: jfb, mseaborn

Differential Revision: http://reviews.llvm.org/D8072

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234714 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-12 23:42:25 +00:00
Rafael Espindola
e17e7a2400 Remove unnecessary uses of AliasedSymbol.
As pr19627 points out, every use of AliasedSymbol is likely a bug.

The main use was to avoid the oddity of a variable showing up as undefined. That
was fixed in r233995, which made these calls nops.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234169 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-06 16:10:05 +00:00
Rafael Espindola
9428f184be Be consistent when deciding if a relocation is needed.
Before when deciding if we needed a relocation in A-B, we wore only checking
if A was weak.

This fixes the asymmetry.

The "InSet" argument should probably be renamed to "ForValue", since InSet is
very MachO specific, but doing so in this patch would make it hard to read.

This fixes PR22815.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234165 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-06 15:27:57 +00:00
Rafael Espindola
9d2f0da138 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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233318 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-26 21:11:00 +00:00
Rafael Espindola
d033c4b576 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).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233187 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-25 13:16:53 +00:00
Rafael Espindola
41509f4261 Fix warning on non-assert build.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233158 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-25 00:45:41 +00:00
Rafael Espindola
49dba99a89 Produce an error instead of asserting on invalid .sleb128/.uleb128.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233155 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-25 00:25:37 +00:00
Yaron Keren
703b185464 Remove many superfluous SmallString::str() calls.
Now that SmallString is a first-class citizen, most SmallString::str()
calls are not required. This patch removes a whole bunch of them, yet
there are lots more.

There are two use cases where str() is really needed:
1) To use one of StringRef member functions which is not available in
SmallString.
2) To convert to std::string, as StringRef implicitly converts while 
SmallString do not. We may wish to change this, but it may introduce
ambiguity.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232622 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-18 10:17:07 +00:00
David Blaikie
7610ba7d24 Fix uses of reserved identifiers starting with an underscore followed by an uppercase letter
This covers essentially all of llvm's headers and libs. One or two weird
cases I wasn't sure were worth/appropriate to fix.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232394 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-16 18:06:57 +00:00
Rafael Espindola
a23cc6a1ea Add r224985 back with fixes.
The fixes are to note that AArch64 has additional restrictions on when local
relocations can be used. In particular, ld64 requires that relocations to
cstring/cfstrings use linker visible symbols.

Original message:

In an assembly expression like

bar:
  .long L0 + 1

the intended semantics is that bar will contain a pointer one byte past L0.

In sections that are merged by content (strings, 4 byte constants, etc), a
single position in the section doesn't give the linker enough information.
For example, it would not be able to tell a relocation must point to the
end of a string, since that would look just like the start of the next.

The solution used in ELF to use relocation with symbols if there is a non-zero
addend.

In MachO before this patch we would just keep all symbols in some sections.

This would miss some cases (only cstrings on x86_64 were implemented) and was
inefficient since most relocations have an addend of 0 and can be represented
without the symbol.

This patch implements the non-zero addend logic for MachO too.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226503 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 21:11:14 +00:00
Rafael Espindola
a7e4c407ad Produce errors when an assignment expression would use a common symbol.
An assignment will produce a symbol with a given section and offset. There is
no way to represent something like "1 byte after a common symbol".

This matches the behavior of GNU as.

Part of PR22217.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226470 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 17:30:24 +00:00
Rafael Espindola
8327f0bca1 Revert "Add r224985 back with two fixes."
This reverts commit r225644 while I debug a regression.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226022 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-14 19:07:23 +00:00
Chandler Carruth
1b279144ec [cleanup] Re-sort all the #include lines in LLVM using
utils/sort_includes.py.

I clearly haven't done this in a while, so more changed than usual. This
even uncovered a missing include from the InstrProf library that I've
added. No functionality changed here, just mechanical cleanup of the
include order.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225974 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-14 11:23:27 +00:00
Rafael Espindola
5512415ade Add r224985 back with two fixes.
One is that AArch64 has additional restrictions on when local relocations can
be used. We have to take those into consideration when deciding to put a L
symbol in the symbol table or not.

The other is that ld64 requires the relocations to cstring to use linker
visible symbols on AArch64.

Thanks to Michael Zolotukhin for testing this!

Remove doesSectionRequireSymbols.

In an assembly expression like

bar:
.long L0 + 1

the intended semantics is that bar will contain a pointer one byte past L0.

In sections that are merged by content (strings, 4 byte constants, etc), a
single position in the section doesn't give the linker enough information.
For example, it would not be able to tell a relocation must point to the
end of a string, since that would look just like the start of the next.

The solution used in ELF to use relocation with symbols if there is a non-zero
addend.

In MachO before this patch we would just keep all symbols in some sections.

This would miss some cases (only cstrings on x86_64 were implemented) and was
inefficient since most relocations have an addend of 0 and can be represented
without the symbol.

This patch implements the non-zero addend logic for MachO too.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225644 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 18:13:07 +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
Lang Hames
bce877c84c Revert r225048: It broke ObjC on AArch64.
I've filed http://llvm.org/PR22100 to track this issue.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225228 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-06 00:54:32 +00:00
Rafael Espindola
8093abb745 Add r224985 back with a fix.
The issues was that AArch64 has additional restrictions on when local
relocations can be used. We have to take those into consideration when
deciding to put a L symbol in the symbol table or not.

Original message:

Remove doesSectionRequireSymbols.

In an assembly expression like

bar:
.long L0 + 1

the intended semantics is that bar will contain a pointer one byte past L0.

In sections that are merged by content (strings, 4 byte constants, etc), a
single position in the section doesn't give the linker enough information.
For example, it would not be able to tell a relocation must point to the
end of a string, since that would look just like the start of the next.

The solution used in ELF to use relocation with symbols if there is a non-zero
addend.

In MachO before this patch we would just keep all symbols in some sections.

This would miss some cases (only cstrings on x86_64 were implemented) and was
inefficient since most relocations have an addend of 0 and can be represented
without the symbol.

This patch implements the non-zero addend logic for MachO too.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225048 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-31 17:19:34 +00:00
Rafael Espindola
937e781f49 Revert "Remove doesSectionRequireSymbols."
This reverts commit r224985.

I am investigating why it made an Apple bot unhappy.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225044 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-31 16:06:48 +00:00
Rafael Espindola
65300b95e6 Remove doesSectionRequireSymbols.
In an assembly expression like

bar:
.long L0 + 1

the intended semantics is that bar will contain a pointer one byte past L0.

In sections that are merged by content (strings, 4 byte constants, etc), a
single position in the section doesn't give the linker enough information.
For example, it would not be able to tell a relocation must point to the
end of a string, since that would look just like the start of the next.

The solution used in ELF to use relocation with symbols if there is a non-zero
addend.

In MachO before this patch we would just keep all symbols in some sections.

This would miss some cases (only cstrings on x86_64 were implemented) and was
inefficient since most relocations have an addend of 0 and can be represented
without the symbol.

This patch implements the non-zero addend logic for MachO too.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224985 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-30 13:13:27 +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
Derek Schuff
279b5504a3 [MC] Make bundle alignment mode setting idempotent and support nested bundles
Summary:
Currently an error is thrown if bundle alignment mode is set more than once
per module (either via the API or the .bundle_align_mode directive). This
change allows setting it multiple times as long as the alignment doesn't
change.

Also nested bundle_lock groups are currently not allowed. This change allows
them, with the effect that the group stays open until all nests are exited,
and if any of the bundle_lock directives has the align_to_end flag, the
group becomes align_to_end.

These changes make the bundle aligment simpler to use in the compiler, and
also better match the corresponding support in GNU as.

Reviewers: jvoung, eliben

Differential Revision: http://reviews.llvm.org/D5801

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219811 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-15 17:10:04 +00:00
Rafael Espindola
90ce9f70e2 Simplify handling of --noexecstack by using getNonexecutableStackSection.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219799 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-15 16:12:52 +00:00
Benjamin Kramer
fedd0e2a21 MC: Bit pack MCSymbolData.
On x86_64 this brings it from 80 bytes to 64 bytes. Also make any member
variables private and clean up uses to go through the existing accessors.

NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219573 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-11 15:07:21 +00:00
Yaron Keren
c63035aa56 Add and update reset() and doInitialization() methods to MC* and passes.
This enables reusing a PassManager instead of re-constructing it every time.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217948 91177308-0d34-0410-b5e6-96231b3b80d8
2014-09-17 09:25:36 +00:00
Rafael Espindola
216fdfe9ac Add a helper to MCExpr for when an expression is know to be absolute.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215713 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-15 14:20:32 +00:00
Joerg Sonnenberger
b2b363408b 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.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215310 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-10 11:35:12 +00:00
David Majnemer
8be730695d MC: make MCSymbolData::dump work on const objects
This just lets us dump a const MCSymbolData object, no functionality
changed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212365 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-05 00:39:52 +00:00
Rafael Espindola
4551671908 Avoid revocations when possible.
This is a small targeted fix for pr20119. The code needs quiet a bit of
refactoring and I added some FIXMEs about it, but I want to get the testcase
passing first.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212101 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-01 14:34:30 +00:00
Weiming Zhao
09f104fc32 Report error for non-zero data in .bss
User may initialize a var with non-zero value and specify .bss section.
E.g. : int a __attribute__((section(".bss"))) = 2;

This patch converts an assertion to error report for better user
experience.

Differential Revision: http://reviews.llvm.org/D4199


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211455 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-22 00:33:44 +00:00
Rafael Espindola
f2b88ce2fd Move getBaseSymbol somewhere the COFF writer can use.
I will use it there in a second.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207761 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-01 13:24:25 +00:00
Rafael Espindola
593cb79eb5 Provide a version of getSymbolOffset that returns false on error.
This simplifies ELFObjectWriter::SymbolValue a bit more. This new version
will also be used in the COFF writer to fix pr19147.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207711 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-30 21:51:13 +00:00
Rafael Espindola
ff56f416a5 Grammar fix.
Thanks to Saleem Abdulrasool for noticing it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207643 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-30 12:42:22 +00:00
Rafael Espindola
c8556d725f Simplify getSymbolOffset.
We can now use EvaluateAsValue to make it non recursive and remove some code
duplication.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207604 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-30 03:06:06 +00:00
Benjamin Kramer
d17f593e72 Another missing include for MSVC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207596 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-29 23:46:48 +00:00
Rafael Espindola
1c5f439f41 Centralize the handling of the thumb bit.
This patch centralizes the handling of the thumb bit around
MCStreamer::isThumbFunc and makes isThumbFunc handle aliases.

This fixes a corner case, but the main advantage is having just one
way to check if a MCSymbol is thumb or not. This should still be
refactored to be ARM only, but at least now it is just one predicate
that has to be refactored instead of 3 (isThumbFunc,
ELF_Other_ThumbFunc, and SF_ThumbFunc).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207522 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-29 12:46:50 +00:00
Chandler Carruth
0d338a59bd [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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206845 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-22 03:04:17 +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
David Blaikie
22f3236dd6 Revert debug info compression support.
To support compression for debug_line and debug_frame a different
approach is required. To simplify review, revert the old implementation
and XFAIL the test case. New implementation to follow shortly.

Reverts r205059 and r204958.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205989 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-10 21:53:47 +00:00
David Blaikie
b4074c010b Simplify compression API by compressing into a SmallVector rather than a MemoryBuffer
This is the other half of r205676.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205677 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-05 21:53:04 +00:00
Tim Northover
1330ee3189 MachO: Add linker-optimisation hint framework to MC.
Another part of the ARM64 backend (so tests will be following soon).
This is currently used by the linker to relax adrp/ldr pairs into nops
where possible, though could well be more broadly applicable.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205084 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-29 07:34:53 +00:00
Rafael Espindola
224dbf4aec Completely rewrite ELFObjectWriter::RecordRelocation.
I started trying to fix a small issue, but this code has seen a small fix too
many.

The old code was fairly convoluted. Some of the issues it had:

* It failed to check if a symbol difference was in the some section when
  converting a relocation to pcrel.
* It failed to check if the relocation was already pcrel.
* The pcrel value computation was wrong in some cases (relocation-pc.s)
* It was missing quiet a few cases where it should not convert symbol
  relocations to section relocations, leaving the backends to patch it up.
* It would not propagate the fact that it had changed a relocation to pcrel,
  requiring a quiet nasty work around in ARM.
* It was missing comments.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205076 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-29 06:26:49 +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
Jim Grosbach
d55fc3f151 Darwin: Add assembler directives to create version-min load commands.
Allow object files to be tagged with a version-min load command for iOS
or MacOSX.

Teach macho-dump to understand the version-min load commands for
testcases.

rdar://11337778

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204190 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-18 22:09:05 +00:00