Commit Graph

119841 Commits

Author SHA1 Message Date
Chandler Carruth
52ab0bc417 [PM/AA] Extract the ModRef enums from the AliasAnalysis class in
preparation for de-coupling the AA implementations.

In order to do this, they had to become fake-scoped using the
traditional LLVM pattern of a leading initialism. These can't be actual
scoped enumerations because they're bitfields and thus inherently we use
them as integers.

I've also renamed the behavior enums that are specific to reasoning
about the mod/ref behavior of functions when called. This makes it more
clear that they have a very narrow domain of applicability.

I think there is a significantly cleaner API for all of this, but
I don't want to try to do really substantive changes for now, I just
want to refactor the things away from analysis groups so I'm preserving
the exact original design and just cleaning up the names, style, and
lifting out of the class.

Differential Revision: http://reviews.llvm.org/D10564

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242963 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 23:15:57 +00:00
Chandler Carruth
90b20e96a1 [GMR] Continue my quest to remove linked datastructures from GMR, NFC.
This replaces the next-to-last std::map with a DenseMap. While DenseMap
doesn't yet make tons of sense (there are 32 bytes or so in the value
type), my next change will reduce the value type to a single pointer --
we only need a pointer and 3 bits, and that is exactly what we can have.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242956 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 22:32:34 +00:00
David Majnemer
1b072f2beb [ConstantFolding] Support folding loads from a GlobalAlias
The MSVC ABI requires that we generate an alias for the vtable which
means looking through a GlobalAlias which cannot be overridden improves
our ability to devirtualize.

Found while investigating PR20801.

Patch by Andrew Zhogin!

Differential Revision: http://reviews.llvm.org/D11306

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242955 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 22:29:30 +00:00
Anthony Pesch
186b8ca6dc Revert "Improve merging of stores from static constructors in GlobalOpt"
This reverts commit 0a9dee959a30b81b9e7df64c9a58ff9898c24024.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242954 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 22:26:54 +00:00
Anthony Pesch
63abd4b150 Revert "IPO: Avoid brace initialization of a map, some versions of libc++ don't like it"
This reverts commit fc2dad0c68f8d32273d3c2d790ed496961f829af.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242953 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 22:26:52 +00:00
Chandler Carruth
30b2dba663 [GMR] Make the collection of readers and writers of globals much more
efficient, NFC.

Previously, we built up vectors of function pointers to track readers
and writers. The primary problem here is that we would add the same
function to this vector every time we found an instruction that reads or
writes to the pointer. This could be a *lot* of redudant function
pointers. Instead of doing that, we can use a SmallPtrSet.

This does more than just reduce the size of the list of readers or
writers. We walk the entire lists of each and do a map lookup for each
one. By having sets, we will only do one map lookup per reader or writer
function.

But only one user of the pointer analyzer actually needs this
information, so we can also skip accumulating it (and doing a lot of
heap allocations) for all the other pointer analysis. This is
particularly useful because there are very many more pointers in some of
the other cases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242950 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 22:10:05 +00:00
Rafael Espindola
3b12bb79e8 Force the gnu archive format to fix the test on darwin.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242949 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 22:09:44 +00:00
Sanjay Patel
6b35fdb647 fix typo; NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242947 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 21:56:41 +00:00
Sanjay Patel
88836083ae fix indent; NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242946 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 21:47:13 +00:00
Justin Bogner
34e7058dc8 IPO: Avoid brace initialization of a map, some versions of libc++ don't like it
Should fix the build failure on these darwin bots:

http://lab.llvm.org:8080/green/job/clang-stage1-cmake-RA-incremental_build/12427/
http://lab.llvm.org:8080/green/job/clang-stage1-configure-RA_build/10389/

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242945 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 21:41:12 +00:00
Reid Kleckner
bc6cbbfa80 [lit] Fix launching executables relative to the cwd after 'cd'
This was affecting test/asan/TestCases/Windows/coverage-basic.cc in
compiler-rt. It does something like:

  cd %T/mydir
  %clang %s -o t.exe
  ./t.exe

Previously, we'd end up looking for t.exe relative to the cwd of the lit
process, not the cwd of the test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242941 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 21:35:27 +00:00
Bruno Cardoso Lopes
e7aafe5ecc [PeepholeOptimizer] Refactor optimizeUncoalescable logic
Reapply r242294.

- Create a new CopyRewriter for Uncoalescable copy-like instructions
- Change the ValueTracker to return a ValueTrackerResult

This makes optimizeUncoalescable looks more like optimizeCoalescable and
use the CopyRewritter infrastructure.

This is also the preparation for looking up into PHI nodes in the
ValueTracker.

rdar://problem/20404526

Differential Revision: http://reviews.llvm.org/D11195

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242940 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 21:30:16 +00:00
JF Bastien
b18e7bdac8 WebAssembly: basic bitcode → assembly CodeGen test
Summary:
Add a basic CodeGen bitcode test which (for now) only prints out the function name and nothing else. The current code merely implements the basic needed for the test run to not crash / assert. Getting to that point required:

 - Basic InstPrinter.
 - Basic AsmPrinter.
 - DiagnosticInfoUnsupported (not strictly required, but nice to have, duplicated from AMDGPU/BPF's ISelLowering).
 - Some SP and register setup in WebAssemblyTargetLowering.
 - Basic LowerFormalArguments.
 - GenInstrInfo.
 - Placeholder LowerFormalArguments.
 - Placeholder CanLowerReturn and LowerReturn.
 - Basic DAGToDAGISel::Select, which requiresGenDAGISel.inc as well as GET_INSTRINFO_ENUM with GenInstrInfo.inc.
 - Remove WebAssemblyFrameLowering::determineCalleeSaves and rely on default.
 - Implement WebAssemblyFrameLowering::hasFP, same as AArch64's implementation.

Follow-up patches will implement a real AsmPrinter, which will require adding MI opcodes specific to WebAssembly.

Reviewers: sunfish

Subscribers: aemerson, jfb, llvm-commits

Differential Revision: http://reviews.llvm.org/D11369

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242939 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 21:28:15 +00:00
Alex Lorenz
6f3ab8dd7b MIR Serialization: Serialize the machine instruction's debug location.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242938 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 21:15:11 +00:00
Yaron Keren
27513fc040 Rename RunCallBacksToRun to llvm::sys::RunSignalHandlers
And expose it in Signals.h, allowing clients to call it directly,
possibly LLVMErrorHandler which currently calls RunInterruptHandlers
but not RunSignalHandlers, thus for example not printing the stack
backtrace on Unixish OSes. On Windows it does happen because
RunInterruptHandlers ends up calling the callbacks as well via 
Cleanup(). This difference in behaviour and code structures in
*/Signals.inc should be patched in the future.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242936 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 21:11:17 +00:00
Anthony Pesch
a5fd3fdc5b Improve merging of stores from static constructors in GlobalOpt
Summary:
While working on a project I wound up generating a fairly large lookup table (10k entries) of callbacks inside of a static constructor. Clang was taking upwards of ~10 minutes to compile the lookup table. I generated a smaller test case (http://www.inolen.com/static_initializer_test.ll) that, after running with -ftime-report, pointed fingers at GlobalOpt and MemCpyOptimizer.

Running globalopt took around ~9 minutes. The slowdown came from how GlobalOpt merged stores from static constructors individually into the global initializer in EvaluateStaticConstructor. For each store it discovered and wanted to commit, it would copy the existing global initializer and then merge in the individual store. I changed this so that stores are now grouped by global, and sorted from most significant to least significant by their GEP indexes (e.g. a store to GEP 0, 0 comes before GEP 0, 0, 1). With this representation, the existing initializer can be copied and all new stores merged into it in a single pass.

With this patch and http://reviews.llvm.org/D11198, the lookup table that was taking ~10 minutes to compile now compiles in around 5 seconds. I've ran 'make check' and the test-suite, which all passed.

I'm not really sure who to tag as a reviewer, Lang mentioned that Chandler may be appropriate.

Reviewers: chandlerc, nlewycky

Subscribers: nlewycky, llvm-commits

Differential Revision: http://reviews.llvm.org/D11200

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242935 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 21:10:45 +00:00
Alex Lorenz
d02a9a798c MIR Parser: Extract the MDNode parsing code into a separate method. NFC.
This change would allow the machine instruction parser to reuse this method when
parsing the metadata node for the machine instruction's debug location property.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242934 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 21:07:04 +00:00
Hans Wennborg
380de5479c Fix -Wextra-semi warnings.
Patch by Eugene Zelenko!

Differential Revision: http://reviews.llvm.org/D11400

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242930 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 20:46:11 +00:00
Rafael Espindola
9db135a5f1 Fix fetching the symbol table of a thin archive.
We were trying to read it as an external file.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242926 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 19:34:26 +00:00
Yaron Keren
1d5c214e84 De-duplicate Unix & Windows CallBacksToRun
Move CallBacksToRun into the common Signals.cpp, create RunCallBacksToRun()
and use these in both Unix/Signals.inc and Windows/Signals.inc.

Lots of potential code to be merged here.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242925 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 19:01:14 +00:00
Anthony Pesch
dc719f5fdf Test commit, added blank line
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242923 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 18:50:10 +00:00
Chad Rosier
3e455d8ae0 Simplify switch as all cases other than default return true. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242922 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 18:41:57 +00:00
Rafael Espindola
bd58d4eb97 Identify thin archives as archives.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242921 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 18:29:39 +00:00
Yaron Keren
1a737f5714 Remove C++98 workaround in llvm::sys::DontRemoveFileOnSignal()
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242920 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 18:23:51 +00:00
Renato Golin
c6f36fe9f7 [Release] Allow release testers to disable certain components
Not all components build correctly on all targets and the release
script had no way to disable them other than editing the script locally.

This change provides a way to disable the test-suite, compiler-rt and
the libraries, as well as allowing you to re-run on the same directory
without checking out all sources again.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242919 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 18:21:39 +00:00
Alex Lorenz
03c5b6047e MIR Serialization: Serialize the metadata machine operands.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242916 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 17:58:46 +00:00
Quentin Colombet
c59ca90970 [ARM] Make the frame lowering code ready for shrink-wrapping.
Shrink-wrapping can now be tested on ARM with -enable-shrink-wrap.

Related to <rdar://problem/20821730>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242908 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 16:34:37 +00:00
Rafael Espindola
55b052ae66 Delete ELFEntityIterator. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242901 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 14:09:20 +00:00
Asaf Badouh
717d8ad6cf [X86][AVX512] add reduce/range/scalef/rndScale
include encoding and intrinsics

Differential Revision: http://reviews.llvm.org/D11222

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242896 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 12:00:43 +00:00
Chandler Carruth
c63b4b9f3a [GMR] Add a flag to enable GlobalsModRef in the normal compilation
pipeline.

Even before I started improving its runtime, it was already crazy fast
once the call graph exists, and if we can get it to be conservatively
correct, will still likely catch a lot of interesting and useful cases.
So it may well be useful to enable by default.

But more importantly for me, this should make it easier for me to test
that changes aren't breaking it in fundamental ways by enabling it for
normal builds.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242895 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 11:57:28 +00:00
Benjamin Kramer
55556435fd [dsymutil] Remove extra semicolon. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242894 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 11:54:19 +00:00
Chandler Carruth
6accb77bd2 [GMR] Switch from std::set to SmallPtrSet. NFC.
This almost certainly doesn't matter in some deep sense, but std::set is
essentially always going to be slower here. Now the alias query should
be essentially constant time instead of having to chase the set tree
each time.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242893 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 11:47:54 +00:00
Chandler Carruth
5b6ebf5b5c [GMR] Only look in the associated allocs map for an underlying value if
it wasn't one of the indirect globals (which clearly cannot be an
allocation function call). Also only do a single lookup into this map
instead of two. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242892 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 11:43:24 +00:00
Chandler Carruth
f28cb39e4c [GMR] Switch to a DenseMap and clean up the iteration loop. NFC.
Since we have to iterate this map not that infrequently, we should use
a map that is efficient for iteration. It is also almost certainly much
faster for lookups as well. There is more to do in terms of reducing the
wasted overhead of GMR's runtime though. Not sure how much is worthwhile
though.

The loop improvements should hopefully address the code review that
Duncan gave when he saw this code as I moved it around.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242891 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 11:36:09 +00:00
Chandler Carruth
e284e481f2 Fix a -Winconsistent-missing-override failure in the .intel_syntax
patch.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242890 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 11:22:29 +00:00
Michael Kuperstein
989e1eb99f Fix test from r242886 to use the right triple.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242889 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 11:19:22 +00:00
Chandler Carruth
048e3fa68e [PM/AA] Try to fix libc++ build bots which require the type used in
std::list to be complete by hoisting the entire definition into the
class. Ugly, but hopefully works.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242888 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 11:10:41 +00:00
Michael Kuperstein
93d5626c13 [X86] Add .intel_syntax noprefix directive to intel-syntax x86 asm output
Patch by: michael.zuckerman@intel.com
Differential Revision: http://reviews.llvm.org/D11223

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242886 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 10:49:44 +00:00
Michael Kuperstein
6418278e7d Fix mem2reg to correctly handle allocas only used in a single block
Currently, a load from an alloca that is used in as single block and is not preceded
by a store is replaced by undef. This is not always correct if the single block is
inside a loop.
Fix the logic so that:
1) If there are no stores in the block, replace the load with an undef, as before.
2) If there is a store (regardless of where it is in the block w.r.t the load), bail
out, and let the rest of mem2reg handle this alloca.

Patch by: gil.rapaport@intel.com
Differential Revision: http://reviews.llvm.org/D11355

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242884 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 10:29:29 +00:00
Kuba Brecka
a5812d5bbf [asan] Improve moving of non-instrumented allocas
In r242510, non-instrumented allocas are now moved into the first basic block.  This patch limits that to only move allocas that are present *after* the first instrumented one (i.e. only move allocas up).  A testcase was updated to show behavior in these two cases.  Without the patch, an alloca could be moved down, and could cause an invalid IR.

Differential Revision: http://reviews.llvm.org/D11339



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242883 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 10:25:38 +00:00
Chandler Carruth
f020cb2f75 [PM/AA] Remove all of the dead AliasAnalysis pointers being threaded
through APIs that are no longer necessary now that the update API has
been removed.

This will make changes to the AA interfaces significantly less
disruptive (I hope). Either way, it seems like a really nice cleanup.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242882 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 09:52:54 +00:00
Chandler Carruth
ac17c4d9b5 [PM/AA] Remove the last of the legacy update API from AliasAnalysis as
part of simplifying its interface and usage in preparation for porting
to work with the new pass manager.

Note that this will likely expose that we have dead arguments, members,
and maybe even pass requirements for AA. I'll be cleaning those up in
seperate patches. This just zaps the actual update API.

Differential Revision: http://reviews.llvm.org/D11325

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242881 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 09:49:59 +00:00
Chandler Carruth
bf35115273 [PM/AA] Switch to an early-exit. NFC. This was split out of another
change because the diff is *useless*. I assure you, I just switched to
early-return in this function.

Cleanup in preparation for my next commit, as requested in code review!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242880 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 09:44:54 +00:00
Chandler Carruth
3f1d2f9e78 [PM/AA] Put the 'final' keyword in the correct place. And actually
succeed at compiling my change before committing it too!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242879 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 09:34:18 +00:00
Chandler Carruth
0ea4760295 [PM/AA] Replace the only use of the AliasAnalysis::deleteValue API (in
GlobalsModRef) with CallbackVHs that trigger the same behavior.

This is technically more expensive, but in benchmarking some LTO runs,
it seems unlikely to even be above the noise floor. The only way I was
able to measure the performance of GMR at all was to run nothing else
but this one analysis on a linked clang bitcode file. The call graph
analysis still took 5x more time than GMR, and this change at most made
GMR 2% slower (this is well within the noise, so its hard for me to be
sure that this is an actual change). However, in a real LTO run over the
same bitcode, the GMR run takes so little time that the pass timers
don't measure it.

With this, I can remove the last update API from the AliasAnalysis
interface, but I'll actually remove the interface hook point in
a follow-up commit.

Differential Revision: http://reviews.llvm.org/D11324

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242878 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 09:27:58 +00:00
Elena Demikhovsky
78d824a9ff AVX-512: Added intrinsics for VCVT* instructions.
All SKX forms. All VCVT instructions for float/double/int/long types.

Differential Revision: http://reviews.llvm.org/D11343



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242877 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 08:56:00 +00:00
Chen Li
5015f9766b [LoopUnswitch] Code refactoring to separate trivial loop unswitch and non-trivial loop unswitch in processCurrentLoop()
Summary: The current code in LoopUnswtich::processCurrentLoop() mixes trivial loop unswitch and non-trivial loop unswitch together. It goes over all basic blocks in the loop and checks if a condition is trivial or non-trivial unswitch condition. However, trivial unswitch condition can only occur in the loop header basic block (where it controls whether or not the loop does something at all). This refactoring separate trivial loop unswitch and non-trivial loop unswitch. Before going over all basic blocks in the loop, it checks if the loop header contains a trivial unswitch condition. If so, unswitch it. Otherwise, go over all blocks like before but don't check trivial condition any more since they are not possible to be in the other blocks. This code has no functionality change.

Reviewers: meheff, reames, broune

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D11276

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242873 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 05:26:29 +00:00
Jingyue Wu
9764983070 [BranchFolding] do not iterate the aliases of virtual registers
Summary:
MCRegAliasIterator only works for physical registers. So, do not run it
on virtual registers.

With this issue fixed, we can resurrect the BranchFolding pass in NVPTX
backend.

Reviewers: jholewinski, bkramer

Subscribers: henryhu, meheff, llvm-commits, jholewinski

Differential Revision: http://reviews.llvm.org/D11174

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242871 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 04:16:52 +00:00
Chandler Carruth
2cf40d1ae5 [SROA] Fix a nasty pile of bugs to do with big-endian, different alloca
types and loads, loads or stores widened past the size of an alloca,
etc.

This started off with a bug report about big-endian behavior with
bitfields and loads and stores to a { i32, i24 } struct. An initial
attempt to fix this was sent for review in D10357, but that didn't
really get to the root of the problem.

The core issue was that canConvertValue and convertValue in SROA were
handling different bitwidth integers by doing a zext of the integer. It
wouldn't do a trunc though, only a zext! This would in turn lead SROA to
form an i24 load from an i24 alloca, zext it to i32, and then use it.
This would at least produce the wrong value for big-endian systems.

One of my many false starts here was to correct the computation for
big-endian systems by shifting. But this doesn't actually work because
the original code has a 64-bit store to the entire 8 bytes, and a 32-bit
load of the last 4 bytes, and because the alloc size is 8 bytes, we
can't lose that last (least significant if bigendian) byte! The real
problem here is that we're forming an i24 load in SROA which is actually
not sufficiently wide to load all of the necessary bits here. The source
has an i32 load, and SROA needs to form that as well.

The straightforward way to do this is to disable the zext logic in
canConvertValue and convertValue, forcing us to actually load all
32-bits. This seems like a really good change, but it in turn breaks
several other parts of SROA.

First in the chain of knock-on failures, we had places where we were
doing integer-widening promotion even though some of the integer loads
or stores extended *past the end* of the alloca's memory! There was even
a comment about preventing this, but it only prevented the case where
the type had a different bit size from its store size. So I added checks
to handle the cases where we actually have a widened load or store and
to avoid trying to special integer widening promotion in those cases.

Second, we actually rely on the ability to promote in the face of loads
past the end of an alloca! This is important so that we can (for
example) speculate loads around PHI nodes to do more promotion. The bits
loaded are garbage, but as long as they aren't used and the alignment is
suitable high (which it wasn't in the test case!) this is "fine". And we
can't stop promoting here, lots of things stop working well if we do. So
we need to add specific logic to handle the extension (and truncation)
case, but *only* where that extension or truncation are over bytes that
*are outside the alloca's allocated storage* and thus totally bogus to
load or store.

And of course, once we add back this correct handling of extension or
truncation, we need to correctly handle bigendian systems to avoid
re-introducing the exact bug that started us off on this chain of misery
in the first place, but this time even more subtle as it only happens
along speculated loads atop a PHI node.

I've ported an existing test for PHI speculation to the big-endian test
file and checked that we get that part correct, and I've added several
more interesting big-endian test cases that should help check that we're
getting this correct.

Fun times.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242869 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 03:32:42 +00:00
Richard Smith
54b8d4eaf8 SetVector: add reverse_iterator support.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242865 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-22 01:30:58 +00:00