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1edc33b924
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David Peixotto 1edc33b924 ARM integrated assembler generates incorrect nop opcode 
This patch fixes a bug in the assembler that was causing bad code to
be emitted.  When switching modes in an assembly file (e.g. arm to
thumb mode) we would always emit the opcode from the original mode.

Consider this small example:

$ cat align.s
.code 16
foo:
  add r0, r0
.align 3
  add r0, r0

$ llvm-mc -triple armv7-none-linux align.s -filetype=obj -o t.o
$ llvm-objdump -triple thumbv7 -d t.o
Disassembly of section .text:
foo:
       0:       00 44         add     r0, r0
       2:       00 f0 20 e3   blx #4195904
       6:       00 00         movs    r0, r0
       8:       00 44         add     r0, r0

This shows that we have actually emitted an arm nop (e320f000)
instead of a thumb nop. Unfortunately, this encodes to a thumb
branch which causes bad things to happen when compiling assembly
code with align directives.

The fix is to notify the ARMAsmBackend when we switch mode. The
MCMachOStreamer was already doing this correctly. This patch makes
the same change for the MCElfStreamer.

There is still a bug in the way nops are emitted for alignment
because the MCAlignment fragment does not store the correct mode.
The ARMAsmBackend will emit nops for the last mode it knew about. In
the example above, we still generate an arm nop if we add a `.code
32` to the end of the file.

PR18019


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195677 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-25 19:11:13 +00:00
autoconf Update to reflect the next release. 2013-11-20 10:10:50 +00:00
bindings [OCaml] Unbreak make install by providing ocamldoc target 2013-11-21 10:10:16 +00:00
cmake Revert my CMake patches concerning building with /MT (r194589, r194596) 2013-11-13 20:29:10 +00:00
docs Remove dangling documentation. llvm-prof was deleted a while ago. 2013-11-21 19:32:37 +00:00
examples [weak vtables] Place class definitions into anonymous namespaces to prevent weak vtables. 2013-11-19 03:08:35 +00:00
include Put an unused result attribute on SmallSet::empty() 2013-11-23 23:06:20 +00:00
lib ARM integrated assembler generates incorrect nop opcode 2013-11-25 19:11:13 +00:00
projects Revert "Revert "Windows: Add support for unicode command lines"" 2013-10-07 01:00:07 +00:00
test ARM integrated assembler generates incorrect nop opcode 2013-11-25 19:11:13 +00:00
tools VS integration: use the correct registry key after r195379 2013-11-22 18:25:43 +00:00
unittests [PM] Complete the cross-layer interfaces with a Module-to-Function 2013-11-23 01:25:07 +00:00
utils Default to a better compression algorithm. 2013-11-24 05:29:35 +00:00
.arcconfig Add .arcconfig to the repository. Useful if someone wants to use phabricator's command line tool. 2012-12-01 12:07:58 +00:00
.clang-format Add a clang-format file so that the tool can automatically detect the 2013-09-02 07:19:04 +00:00
.gitignore Add extra vim swap file pattern 2012-10-09 23:48:34 +00:00
CMakeLists.txt CMake: Some changes to package version names: 2013-11-21 22:47:21 +00:00
CODE_OWNERS.TXT Add loop rerolling code owner 2013-11-20 20:54:33 +00:00
configure Update to reflect the next release. 2013-11-20 10:10:50 +00:00
CREDITS.TXT Update CREDITS 2013-11-17 11:44:36 +00:00
LICENSE.TXT Be more specific and capitalize filenames. 2013-05-21 21:22:34 +00:00
llvm.spec.in
LLVMBuild.txt Remove the very substantial, largely unmaintained legacy PGO 2013-10-02 15:42:23 +00:00
Makefile Remove the very substantial, largely unmaintained legacy PGO 2013-10-02 15:42:23 +00:00
Makefile.common Makefile.common: Update a description, s/Source/SOURCES/ , according to MakefileGuide.html#control-variables . 2012-12-07 01:43:23 +00:00
Makefile.config.in Add an autoconf option for turning on -gsplit-dwarf by default 2013-06-25 01:12:25 +00:00
Makefile.rules Teach the Makefile build system how to handle SOURCES which include 2013-11-14 23:51:29 +00:00
README.txt Revert "Test commit to check e-mail address. Please discard this." 2013-10-04 10:59:13 +00:00

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