Commit Graph

114118 Commits

Author SHA1 Message Date
Duncan P. N. Exon Smith
aaff953db4 llvm-dis: Stop crashing when dropping debug info
Since r199356, we've printed a warning when dropping debug info.
r225562 started crashing on that, since it registered a diagnostic
handler that only expected errors.  This fixes the handler to expect
other severities.  As a side effect, it now prints "error: " at the
start of error messages, similar to `llvm-as`.

There was a testcase for r199356, but it only really checked the
assembler.  Move `test/Bitcode/drop-debug-info.ll` to `test/Assembler`,
and introduce `test/Bitcode/drop-debug-info.3.5.ll` (and companion
`.bc`) to test the bitcode reader.

Note: tools/gold/gold-plugin.cpp has an equivalent bug, but I'm not sure
what the best fix is there.  I'll file a PR.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230416 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-25 01:10:03 +00:00
David Blaikie
6606ad944b [opaque pointer type] Bitcode support for explicit type parameter on GEP.
Like r230414, add bitcode support including backwards compatibility, for
an explicit type parameter to GEP.

At the suggestion of Duncan I tried coalescing the two older bitcodes into a
single new bitcode, though I did hit a wrinkle: I couldn't figure out how to
create an explicit abbreviation for a record with a variable number of
arguments (the indicies to the gep). This means the discriminator between
inbounds and non-inbounds gep is a full variable-length field I believe? Is my
understanding correct? Is there a way to create such an abbreviation? Should I
just use two bitcodes as before?

Reviewers: dexonsmith

Differential Revision: http://reviews.llvm.org/D7736

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230415 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-25 01:08:52 +00:00
David Blaikie
5e2e6f2855 [opaque pointer type] bitcode support for explicit type parameter to the load instruction
Summary:
I've taken my best guess at this, but I've cargo culted in places & so
explanations/corrections would be great.

This seems to pass all the tests (check-all, covering clang and llvm) so I
believe that pretty well exercises both the backwards compatibility and common
(same version) compatibility given the number of checked in bitcode files we
already have. Is that a reasonable approach to testing here? Would some more
explicit tests be desired?

1) is this the right way to do back-compat in this case (looking at the number
  of entries in the bitcode record to disambiguate between the old schema and
  the new?)

2) I don't quite understand the logarithm logic to choose the encoding type of
  the type parameter in the abbreviation description, but I found another
  instruction doing the same thing & it seems to work. Is that the right
  approach?

Reviewers: dexonsmith

Differential Revision: http://reviews.llvm.org/D7655

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230414 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-25 01:07:20 +00:00
Hal Finkel
f8d179ba76 [PowerPC] Add support for the QPX vector instruction set
This adds support for the QPX vector instruction set, which is used by the
enhanced A2 cores on the IBM BG/Q supercomputers. QPX vectors are 256 bytes
wide, holding 4 double-precision floating-point values. Boolean values, modeled
here as <4 x i1> are actually also represented as floating-point values
(essentially  { -1, 1 } for { false, true }). QPX shares many features with
Altivec and VSX, but is distinct from both of them. One major difference is
that, instead of adding completely-separate vector registers, QPX vector
registers are extensions of the scalar floating-point registers (lane 0 is the
corresponding scalar floating-point value). The operations supported on QPX
vectors mirrors that supported on the scalar floating-point values (with some
additional ones for permutations and logical/comparison operations).

I've been maintaining this support out-of-tree, as part of the bgclang project,
for several years. This is not the entire bgclang patch set, but is most of the
subset that can be cleanly integrated into LLVM proper at this time. Adding
this to the LLVM backend is part of my efforts to rebase bgclang to the current
LLVM trunk, but is independently useful (especially for codes that use LLVM as
a JIT in library form).

The assembler/disassembler test coverage is complete. The CodeGen test coverage
is not, but I've included some tests, and more will be added as follow-up work.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230413 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-25 01:06:45 +00:00
Rafael Espindola
76bdd01e0e Support SHF_MERGE sections in COMDATs.
This patch unifies the comdat and non-comdat code paths. By doing this
it add missing features to the comdat side and removes the fixed
section assumptions from the non-comdat side.

In ELF there is no one true section for "4 byte mergeable" constants.
We are better off computing the required properties of the section
and asking the context for it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230411 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-25 00:52:15 +00:00
David Blaikie
6bc72f8262 BitcodeWriter: Refactor common computation of bits required for a type index.
Suggested by Duncan. Happy to bikeshed the name, cache the result, etc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230410 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-25 00:51:52 +00:00
Philip Reames
b4ecacfe06 Fix consistently wrong sphinx markup
I'd been using '' where I should have been using ``.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230407 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-25 00:22:07 +00:00
Philip Reames
b0991ba014 Update the GC docs to explicitly mention both gcroot and gc.statepoint
Also, fix confusing bit of the gcroot documentation that bit me personally.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230405 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-25 00:18:04 +00:00
Eric Christopher
7c5314a076 Make this test even more OS and register allocation neutral.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230404 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-25 00:12:11 +00:00
Philip Reames
a230eee39a [GC] Sync documentation with code naming
Fixing an issue pointed out by Sean Silva.  Thanks!



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230403 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 23:57:26 +00:00
Philip Reames
1e91e94aac More GC documentation cleanup
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230402 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 23:51:37 +00:00
Eric Christopher
8269a59b1c Make this test not dependent upon the triple. All that was needed
was some flexibility in the check line for the comment basic block.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230400 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 23:43:26 +00:00
Philip Reames
aa94c06fa5 More GC doc cleanup
Mostly minor wording changes for readability.  Nothing major to see here.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230397 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 23:34:24 +00:00
Zachary Turner
af2092060c [CMake] Set policy CMP0051 to OLD globally.
When you use generator expressions in a library sources list,
and then later access the SOURCES property, the OLD behavior
(CMake 3.0 and earlier) would not include these expressions in
the SOURCES property.  The NEW behavior (starting in CMake 3.1)
is that they do include the generator expressions in the SOURCES
property.

Differential Revision: http://reviews.llvm.org/D7870
Reviewed By: Chris Bieneman

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230396 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 23:32:47 +00:00
Peter Collingbourne
0bf03cb473 LowerBitSets: Introduce global layout builder.
The builder is based on a layout algorithm that tries to keep members of
small bit sets together. The new layout compresses Chromium's bit sets to
around 15% of their original size.

Differential Revision: http://reviews.llvm.org/D7796

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230394 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 23:17:02 +00:00
Philip Reames
7a1721e7c3 Improve the getting started instructions in the GC docs
This is still gcroot vs gc.statepoint agnostic.  I'm just trying to clarify the general documentation at this point.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230393 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 23:12:27 +00:00
David Majnemer
af91a06d0f PrologEpilogInserter: Clean up math in calculateFrameObjectOffsets
There is no need to open-code the alignment calculation, we have a
handy RoundUpToAlignment function which "Does The Right Thing (TM)".

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230392 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 23:08:13 +00:00
Sanjay Patel
7b59672e39 remove function names from comments; NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230391 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 22:43:06 +00:00
Simon Pilgrim
41cda40157 Reapplied D7816 & rL230177 & rL230278 - with an additional fix toensure that the smallest build vector input scalar type is always used. Additional (crash) test cases already committed.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230388 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 22:08:56 +00:00
Simon Pilgrim
0115755020 Added test case for PR22678 (check CONCAT_VECTORS DAG combiner pass doesn't introduce illegal types)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230386 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 21:46:23 +00:00
Justin Bogner
564b4a8e3e InstrProf: Test for appropriate linkage of the profiling structures
This test checks that the symbols instrprof creates have appropriate
linkage. The tests already exist in clang in a slightly different form
from before we sunk profile generation into an LLVM pass, but that's
an awkward place for them now. I'll remove/simplify the clang versions
shortly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230383 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 21:42:42 +00:00
Andrew Kaylor
8f475e9d77 Fixing eol-style
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230378 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 20:49:35 +00:00
Hans Wennborg
2f7ccecf4e ReleaseNotes: add notes about VS2014 Update 4 requirement
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230363 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 20:36:40 +00:00
Arch D. Robison
16310941b4 Fix typo: qual -> equal
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230361 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 20:11:49 +00:00
Philip Reames
989ffa936e Starting to cleanup the garbage collection documentation
In this change:
- Put the getting started section first
- Create a dedicated section to document the built in collector strategies
- Move discuss of ShadowStack into new section
- Add placeholders for erlang, ocaml, and statepoint-example collectors

There will be many more changes following.  I plan on full integrating the documentation for gc.statepoint and gc.root.  I want to make it much clearer on how to get started and what users should expect in terms of effort.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230359 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 19:44:46 +00:00
Eric Christopher
7c611d59cc Revert:
Author: Simon Pilgrim <llvm-dev@redking.me.uk>
Date:   Mon Feb 23 23:04:28 2015 +0000

    Fix based on post-commit comment on D7816 & rL230177 - BUILD_VECTOR operand truncation was using the the BV's output scalar type instead of the input type.

and

Author: Simon Pilgrim <llvm-dev@redking.me.uk>
Date:   Sun Feb 22 18:17:28 2015 +0000

    [DagCombiner] Generalized BuildVector Vector Concatenation

    The CONCAT_VECTORS combiner pass can transform the concat of two BUILD_VECTOR nodes into a single BUILD_VECTOR node.

    This patch generalises this to support any number of BUILD_VECTOR nodes, and also permits UNDEF nodes to be included as well.

    This was noticed as AVX vec128 -> vec256 canonicalization sometimes creates a CONCAT_VECTOR with a real vec128 lower and an vec128 UNDEF upper.

    Differential Revision: http://reviews.llvm.org/D7816

as the root cause of PR22678 which is causing an assertion inside the DAG combiner.

I'll follow up to the main thread as well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230358 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 19:11:00 +00:00
Eric Christopher
f8c57a105e Rename UpdateRegAllocHint to match style guidelines.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230357 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 19:10:57 +00:00
Matthias Braun
dd1a6e074d AArch64: Relax assert about large shift sizes.
The reason why these large shift sizes happen is because OpaqueConstants
currently inhibit alot of DAG combining, but that has to be addressed in
another commit (like the proposal in D6946).

Differential Revision: http://reviews.llvm.org/D6940

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230355 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 18:52:04 +00:00
Matthias Braun
8b1add3c13 DAGCombiner: Move variable definitions closer to use; NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230354 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 18:52:01 +00:00
Matthias Braun
5f146de042 DAGCombiner: Move variable declaration closer to definiion; NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230353 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 18:51:59 +00:00
Tom Stellard
ba150ed636 R600/SI: Remove isel mubuf legalization
We legalize mubuf instructions post-instruction selection, so this
code is no longer needed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230352 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 17:59:19 +00:00
Tim Northover
5530ac99e6 ARM: treat [N x i32] and [N x i64] as AAPCS composite types
The logic is almost there already, with our special homogeneous aggregate
handling. Tweaking it like this allows front-ends to emit AAPCS compliant code
without ever having to count registers or add discarded padding arguments.

Only arrays of i32 and i64 are needed to model AAPCS rules, but I decided to
apply the logic to all integer arrays for more consistency.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230348 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 17:22:34 +00:00
Tobias Grosser
bc8f84c030 Revert "Raising minimum required CMake version to 2.8.12.2."
This reverts commit r230062.

Debian stable (wheezy) ships still with cmake 2.8.9.

The commit broke my LLVM/Polly buildbot, to my knowledge our only Linux+cmake
buildbot.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230343 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 16:39:46 +00:00
Sanjay Patel
a90eb87f7e simplify control flow; NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230342 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 16:26:02 +00:00
Hans Wennborg
b499b73e30 Revert r230280: "Bugfix: SCEVExpander incorrectly marks increment operations as no-wrap"
This caused PR22674, failing this assert:

Instructions.h:2281: llvm::Value* llvm::PHINode::getOperand(unsigned int) const: Assertion `i_nocapture < OperandTraits<PHINode>::operands(this) && "getOperand() out of range!"' failed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230341 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 16:19:29 +00:00
Michael Kuperstein
09d756a7e0 [x32] Mark RBX as reserved when EBX is the base pointer.
This should have gone into r230334.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230339 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 16:13:16 +00:00
Sanjay Patel
269510242b fix typo in comment; NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230338 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 16:11:05 +00:00
Michael Kuperstein
2379e8a2ee [x32] x32 should use ebx as the base pointer.
This fixes the original issue in PR22655, but not the secondary one.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230334 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 15:27:13 +00:00
Hal Finkel
cccfe54933 [SDAG] Handle LowerOperation returning its input consistently
For almost all node types, if the target requested custom lowering, and
LowerOperation returned its input, we'd treat the original node as legal. This
did not work, however, for many loads and stores, because they follow
slightly different code paths, and we did not account for the possibility of
LowerOperation returning its input at those call sites.

I think that we now handle this consistently everywhere. At the call sites in
LegalizeDAG, we used to assert in this case, so there's no functional change
for any existing code there. For the call sites in LegalizeVectorOps, this
really only affects whether or not we set Changed = true, but I think makes the
semantics clearer.

No test case here, but it will be covered by an upcoming PowerPC commit adding
QPX support.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230332 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 12:59:47 +00:00
Toma Tabacu
41ecf2b99e [mips] Reformat some TableGen definitions. NFC.
Summary: Separated some instruction and pseudo-instruction definitions from InstAlias definitions, added banner for pseudo-instructions and removed a redundant whitespace from a pseudo-instruction definition. No functional change.

Reviewers: dsanders

Reviewed By: dsanders

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D7552

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230327 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 11:52:19 +00:00
Kuba Brecka
81dce4c02c Fix alloca_instruments_all_paddings.cc test to work under higher -O levels (llvm part)
When AddressSanitizer only a single dynamic alloca and no static allocas, due to an early exit from FunctionStackPoisoner::poisonStack we forget to unpoison the dynamic alloca.  This patch fixes that.

Reviewed at http://reviews.llvm.org/D7810



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230316 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 09:47:05 +00:00
Craig Topper
c3b9d471f6 [X86] Remove the AbsMem32 type from the assembly parser. Only really need the 16-bit version which will automatically get prioritized over AbsMem.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230313 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 08:02:13 +00:00
Reed Kotler
aecbb87ee8 Beginning of alloca implementation for Mips fast-isel
Summary: Begin to add various address modes; including alloca.

Test Plan: Make sure there are no regressions in test-suite at O0/02 in mips32r1/r2

Reviewers: dsanders

Reviewed By: dsanders

Subscribers: echristo, rfuhler, llvm-commits

Differential Revision: http://reviews.llvm.org/D6426

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230300 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 02:36:45 +00:00
Bob Wilson
b664a60ecf Fix handling of negative offsets for AddrModeT2_i8s4 in rewriteT2FrameIndex.
This is a follow up to r230233 to fix something that I noticed by
inspection. The AddrModeT2_i8s4 addressing mode does not support
negative offsets. I spent a good chunk of the day trying to come up with
a testcase for this but was not successful. This addressing mode is used
to spill and restore GPRPair registers in Thumb2 code and that does not
happen often. We also make very limited used of negative offsets when
lowering frame indexes. I am going ahead with the change anyway, because
I am pretty confident that it is correct. I also added a missing assertion
to check that the low bits of the scaled offset are zero.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230297 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 01:37:31 +00:00
Sanjoy Das
edf1700d33 Fix bug 22641
The bug was a result of getPreStartForExtend interpreting nsw/nuw
flags on an add recurrence more strongly than is legal.  {S,+,X}<nsw>
implies S+X is nsw only if the backedge of the loop is taken at least
once.

NOTE: I had accidentally committed an unrelated change with the commit
message of this change in r230275 (r230275 was reverted in r230279).
This is the correct change for this commit message.

Differential Revision: http://reviews.llvm.org/D7808



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230291 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 01:02:42 +00:00
Manman Ren
bd26e6a006 [LTO API] add lto_codegen_set_module to set the destination module.
When debugging LTO issues with ld64, we use -save-temps to save the merged
optimized bitcode file, then invoke ld64 again on the single bitcode file to
speed up debugging code generation passes and ld64 stuff after code generation.

llvm linking a single bitcode file via lto_codegen_add_module will generate a
different bitcode file from the single input. With the newly-added
lto_codegen_set_module, we can make sure the destination module is the same as
the input.

lto_codegen_set_module will transfer the ownship of the module to code
generator.

rdar://19024554


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230290 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 00:45:56 +00:00
Adam Nemet
989a0200c2 [LoopAccesses] LAA::getInfo to use const reference for stride parameter
And other required const-correctness fixes to make this work.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230289 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 00:41:59 +00:00
David Majnemer
fbdee9f0c0 X86: Only use 'lea' in Win64 epilogues if a frame pointer exists
We can only use 'add' in epilogues, 'lea' is not permitted unless we've
established a frame pointer in the prologue.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230286 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 00:11:32 +00:00
Sanjoy Das
f922d9cfe4 New instcombine rule: max(~a,~b) -> ~min(a, b)
This case is interesting because ScalarEvolutionExpander lowers min(a,
b) as ~max(~a,~b).  I think the profitability heuristics can be made
more clever/aggressive, but this is a start.

Differential Revision: http://reviews.llvm.org/D7821



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230285 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-24 00:08:41 +00:00
Sanjoy Das
8d16a81c33 Bugfix: SCEVExpander incorrectly marks increment operations as no-wrap
When emitting the increment operation, SCEVExpander marks the
operation as nuw or nsw based on the flags on the preincrement SCEV.
This is incorrect because, for instance, it is possible that {-6,+,1}
is <nuw> while {-6,+,1}+1 = {-5,+,1} is not.

This change teaches SCEV to mark the increment as nuw/nsw only if it
can explicitly prove that the increment operation won't overflow.

Apart from the attached test case, another (more realistic) manifestation
of the bug can be seen in Transforms/IndVarSimplify/pr20680.ll.

NOTE: this change was landed with an incorrect commit message in
rL230275 and was reverted for that reason in rL230279.  This commit
message is the correct one.

Differential Revision: http://reviews.llvm.org/D7778



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230280 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-23 23:22:58 +00:00