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ab5a55e118
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Chandler Carruth ab5a55e118 Cleanup and relax a restriction on the matching of global offsets into 
x86 addressing modes. This allows PIE-based TLS offsets to fit directly
into an addressing mode immediate offset, which is the last remaining
code quality issue from PR12380. With this patch, that PR is completely
fixed.

To understand why this patch is correct to match these offsets into
addressing mode immediates, break it down by cases:
1) 32-bit is trivially correct, and unmodified here.
2) 64-bit non-small mode is unchanged and never matches.
3) 64-bit small PIC code which is RIP-relative is handled specially in
   the match to try to fit RIP into the base register. If it fails, it
   now early exits. This behavior is unchanged by the patch.
4) 64-bit small non-PIC code which is not RIP-relative continues to work
   as it did before. The reason these immediates are safe is because the
   ABI ensures they fit in small mode. This behavior is unchanged.
5) 64-bit small PIC code which is *not* using RIP-relative addressing.
   This is the only case changed by the patch, and the primary place you
   see it is in TLS, either the win64 section offset TLS or Linux
   local-exec TLS model in a PIC compilation. Here the ABI again ensures
   that the immediates fit because we are in small mode, and any other
   operations required due to the PIC relocation model have been handled
   externally to the Wrapper node (extra loads etc are made around the
   wrapper node in ISelLowering).

I've tested this as much as I can comparing it with GCC's output, and
everything appears safe. I discussed this with Anton and it made sense
to him at least at face value. That said, if there are issues with PIC
code after this patch, yell and we can revert it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154304 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-09 02:13:06 +00:00
autoconf Fix a problem in the target detection for Debian GNU/HURD 2012-04-05 19:34:15 +00:00
bindings [python] Add negative MemoryBuffer testcase 2012-03-22 11:23:52 +00:00
cmake Add InitializeNativeTargetDisassembler function. 2012-03-26 21:56:56 +00:00
docs Formatting changes. Don't put spaces in front of some code, which only makes it look 'off'. 2012-04-08 11:52:52 +00:00
examples Switch to a more idiomatic way of silencing unused variable warnings in 2012-02-20 00:02:49 +00:00
include Teach LLVM about a PIE option which, when enabled on top of PIC, makes 2012-04-08 17:51:45 +00:00
lib Cleanup and relax a restriction on the matching of global offsets into 2012-04-09 02:13:06 +00:00
projects Fix a problem in the target detection for Debian GNU/HURD 2012-04-05 19:34:15 +00:00
runtime Use the correct filename for the error message. 2012-03-28 02:39:06 +00:00
test Cleanup and relax a restriction on the matching of global offsets into 2012-04-09 02:13:06 +00:00
tools Teach LLVM about a PIE option which, when enabled on top of PIC, makes 2012-04-08 17:51:45 +00:00
unittests Add YAML parser to Support. 2012-04-03 23:09:22 +00:00
utils Do not include multiple -arch options in CPPFLAGS. 2012-04-05 00:35:55 +00:00
.gitignore git: Add tools/lldb to the ignore list. 2011-11-10 22:55:50 +00:00
CMakeLists.txt Add YAML parser to Support. 2012-04-03 23:09:22 +00:00
configure Fix a problem in the target detection for Debian GNU/HURD 2012-04-05 19:34:15 +00:00
CREDITS.TXT sort by alpha. 2012-03-12 21:12:59 +00:00
LICENSE.TXT Add YAML parser to Support. 2012-04-03 23:09:22 +00:00
llvm.spec.in Tidy up. s/Low Level Virtual Machine/LLVM/. 2012-01-25 22:00:23 +00:00
LLVMBuild.txt LLVMBuild: Introduce a common section which currently has a list of the 2011-12-12 22:45:54 +00:00
Makefile Makefile: add missing files to FilesToConfig 2012-01-17 02:56:49 +00:00
Makefile.common Removed trailing whitespace from Makefiles. 2009-01-09 16:44:42 +00:00
Makefile.config.in Add profiling support for Intel Parallel Amplifier XE (VTune) for JITted code in LLVM. 2012-03-13 08:33:15 +00:00
Makefile.rules Use a posix compliant regexp in export file construction. 2012-03-12 20:58:14 +00:00
README.txt test commit 2012-03-20 13:12:38 +00:00

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