Commit Graph

9 Commits

Author SHA1 Message Date
Rafael Espindola 4a04294882 Don't force symbols to be globals in .thumb_set.
We currently force symbols to be globals in .thumb_set. The intent
seems to be that given

.thumb_set foo, bar

we emit an undefined symbol to bar if it is never defined. The side
effect is that we mark bar as global, even if it is defined, which gas
does not.

Producing an undefined reference to bar is a general difference from MC and gas.
For example, given

a = b

gas will produce an undefined reference to b, MC will not. I would be surprised
if any code depends on this, but it it does, we should fix the general
difference, not special case .thumb_set.

llvm-svn: 207757
2014-05-01 12:45:43 +00:00
Rafael Espindola b60c829a2a 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).

llvm-svn: 207522
2014-04-29 12:46:50 +00:00
Rafael Espindola 466d66358d Add emitThumbSet to the arm target streamer.
This fixes the asm printer implementation and lets the parser be unaware of
what .thumb_set is.

llvm-svn: 207381
2014-04-27 20:23:58 +00:00
Saleem Abdulrasool 44419fc3cd ARM IAS: properly handle function entries in .thumb
When a label is parsed, check if there is type information available for the
label.  If so, check if the symbol is a function.  If the symbol is a function
and we are in thumb mode and no explicit thumb_func has been emitted, adjust the
symbol data to indicate that the function definition is a thumb function.

The application of this inferencing is improved value handling in the object
file (the required thumb bit is set on symbols which are thumb functions).  It
also helps improve compatibility with binutils.

The one complication that arises from this handling is the MCAsmStreamer.  The
default implementation of getOrCreateSymbolData in MCStreamer does not support
tracking the symbol data.  In order to support the semantics of thumb functions,
track symbol data in assembly streamer.  Although O(n) in number of labels in
the TU, this is already done in various other streamers and as such the memory
overhead is not a practical concern in this scenario.

llvm-svn: 204544
2014-03-22 19:26:18 +00:00
Saleem Abdulrasool 39f773f939 Reapply 'ARM IAS: support .thumb_set'
Re-apply the change after it was reverted to do conflicts due to another change
being reverted.

llvm-svn: 204306
2014-03-20 06:05:33 +00:00
Rafael Espindola 7bbd5c2636 Revert "Add back r203962, r204028 and r204059."
This reverts commit r204178.

llvm-svn: 204203
2014-03-19 00:13:43 +00:00
Rafael Espindola 574bfa12fa Add back r203962, r204028 and r204059.
This reverts commit r204137.

This includes a fix for handling aliases of aliases.

llvm-svn: 204178
2014-03-18 20:40:38 +00:00
Alexander Kornienko 64de613751 Revert r203962 and two revisions depending on it: r204028 and r204059.
The revision I'm reverting breaks handling of transitive aliases. This blocks us
and breaks sanitizer bootstrap:
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap/builds/2651
(and checked locally by Alexey).

This revision is the result of:

  svn merge -r204059:204058 -r204028:204027 -r203962:203961 .

+ the regression test added to test/MC/ELF/alias.s

Another way to reproduce the regression with clang:
  $ cat q.c
  void a1();
  void a2() __attribute__((alias("a1")));
  void a3() __attribute__((alias("a2")));
  void a1() {}

  $ ~/work/llvm-build/bin/clang-3.5-good -c q.c && mv q.o good.o && \
      ~/work/llvm-build/bin/clang-3.5-bad -c q.c && mv q.o bad.o && \
      objdump -t good.o bad.o

    good.o:     file format elf64-x86-64

    SYMBOL TABLE:
    0000000000000000 l    df *ABS*  0000000000000000 q.c
    0000000000000000 l    d  .text  0000000000000000 .text
    0000000000000000 l    d  .data  0000000000000000 .data
    0000000000000000 l    d  .bss   0000000000000000 .bss
    0000000000000000 l    d  .comment       0000000000000000 .comment
    0000000000000000 l    d  .note.GNU-stack        0000000000000000 .note.GNU-stack
    0000000000000000 l    d  .eh_frame      0000000000000000 .eh_frame
    0000000000000000 g     F .text  0000000000000006 a1
    0000000000000000 g     F .text  0000000000000006 a2
    0000000000000000 g     F .text  0000000000000006 a3



    bad.o:     file format elf64-x86-64

    SYMBOL TABLE:
    0000000000000000 l    df *ABS*  0000000000000000 q.c
    0000000000000000 l    d  .text  0000000000000000 .text
    0000000000000000 l    d  .data  0000000000000000 .data
    0000000000000000 l    d  .bss   0000000000000000 .bss
    0000000000000000 l    d  .comment       0000000000000000 .comment
    0000000000000000 l    d  .note.GNU-stack        0000000000000000 .note.GNU-stack
    0000000000000000 l    d  .eh_frame      0000000000000000 .eh_frame
    0000000000000000 g     F .text  0000000000000006 a1
    0000000000000000 g     F .text  0000000000000006 a2
    0000000000000000 g       .text  0000000000000000 a3

llvm-svn: 204137
2014-03-18 10:36:11 +00:00
Saleem Abdulrasool 11543a9953 ARM IAS: support .thumb_set
This performs the equivalent of a .set directive in that it creates a symbol
which is an alias for another symbol or value which may possibly be yet
undefined.  This directive also has the added property in that it marks the
aliased symbol as being a thumb function entry point, in the same way that the
.thumb_func directive does.

The current implementation fails one test due to an unrelated issue.  Functions
within .thumb sections are not marked as thumb_func.  The result is that
the aliasee function is not valued correctly.

llvm-svn: 204059
2014-03-17 17:13:54 +00:00