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LLVM backend for 6502
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acfb3584c5
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Michael Gottesman acfb3584c5 [objc-arc-opts] In the presense of an alloca unconditionally remove RR pairs if and only if we are both KnownSafeBU/KnownSafeTD rather than just either or. 
In the presense of a block being initialized, the frontend will emit the
objc_retain on the original pointer and the release on the pointer loaded from
the alloca. The optimizer will through the provenance analysis realize that the
two are related (albiet different), but since we only require KnownSafe in one
direction, will match the inner retain on the original pointer with the guard
release on the original pointer. This is fixed by ensuring that in the presense
of allocas we only unconditionally remove pointers if both our retain and our
release are KnownSafe (i.e. we are KnownSafe in both directions) since we must
deal with the possibility that the frontend will emit what (to the optimizer)
appears to be unbalanced retain/releases.

An example of the miscompile is:

  %A = alloca
  retain(%x)
  retain(%x) <--- Inner Retain
  store %x, %A
  %y = load %A
  ... DO STUFF ...
  release(%y)
  call void @use(%x)
  release(%x) <--- Guarding Release

getting optimized to:

  %A = alloca
  retain(%x)
  store %x, %A
  %y = load %A
  ... DO STUFF ...
  release(%y)
  call void @use(%x)

rdar://13750319

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181743 91177308-0d34-0410-b5e6-96231b3b80d8
2013-05-13 23:49:42 +00:00
autoconf We're in 3.4 land now. 2013-05-07 20:31:28 +00:00
bindings We're in 3.4 land now. 2013-05-07 20:31:28 +00:00
cmake [SystemZ] Add configure bits 2013-05-06 16:22:34 +00:00
docs Better output for long help strings for command-line options. 2013-05-10 17:15:51 +00:00
examples Remove exception handling support from the old JIT. 2013-05-07 20:53:59 +00:00
include Remove the MachineMove class. 2013-05-13 01:16:13 +00:00
lib [objc-arc-opts] In the presense of an alloca unconditionally remove RR pairs if and only if we are both KnownSafeBU/KnownSafeTD rather than just either or. 2013-05-13 23:49:42 +00:00
projects [SystemZ] Add to --enable-targets=all 2013-05-06 16:23:07 +00:00
runtime Remove GCDAProfiling.c. This copy is old, the copy in compiler-rt is newer and 2013-03-07 02:03:08 +00:00
test [objc-arc-opts] In the presense of an alloca unconditionally remove RR pairs if and only if we are both KnownSafeBU/KnownSafeTD rather than just either or. 2013-05-13 23:49:42 +00:00
tools Remove the MachineMove class. 2013-05-13 01:16:13 +00:00
unittests Fix a bug that APFloat::fusedMultiplyAdd() mistakenly evaluate "14.5f * -14.5f + 225.0f" to 225.0f. 2013-05-13 18:03:12 +00:00
utils Add libcxx and clang-tools-extra to the testing thing. 2013-05-08 09:31:10 +00:00
.arcconfig
.gitignore
CMakeLists.txt Change version to 3.4 in the cmake build too. 2013-05-07 20:44:22 +00:00
CODE_OWNERS.TXT Add myself as SystemZ code owner 2013-05-08 14:41:29 +00:00
configure We're in 3.4 land now. 2013-05-07 20:31:28 +00:00
CREDITS.TXT Test commit. 2013-05-09 12:32:36 +00:00
LICENSE.TXT Add LICENSE.TXT covering contributions made by ARM. 2013-01-07 10:04:49 +00:00
llvm.spec.in
LLVMBuild.txt
Makefile Improved svn repo searching for 'make update' 2013-01-28 03:19:57 +00:00
Makefile.common
Makefile.config.in Add basic zlib support to LLVM. This would allow to use compression/uncompression in selected LLVM tools. 2013-04-23 08:28:39 +00:00
Makefile.rules Remove this hack. We can support this better with function attributes. 2013-05-03 21:53:50 +00:00
README.txt test 2013-04-17 05:34:03 +00:00

README.txt 

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