these DAG combines.
The DAG auto-CSE thing is truly terrible. Due to it, when RAUW-ing
a node with its operand, you can cause its uses to CSE to itself, which
then causes their uses to become your uses which causes them to be
picked up by the RAUW. For nodes that are determined to be "no-ops",
this is "fine". But if the RAUW is one of several steps to enact
a transformation, this causes the DAG to really silently eat an discard
nodes that you would never expect. It took days for me to actually
pinpoint a test case triggering this and a really frustrating amount of
time to even comprehend the bug because I never even thought about the
ability of RAUW to iteratively consume nodes due to CSE-ing them into
itself.
To fix this, we have to build up a brand-new chain of operations any
time we are combining across (potentially) intervening nodes. But once
the logic is added to do this, another issue surfaces: CombineTo eagerly
deletes the one node combined, *but no others*. This is... really
frustrating. If deleting it makes its operands become dead, those
operand nodes often won't go onto the worklist in the
order you would want -- they're already on it and not near the top. That
means things higher on the worklist will get combined prior to these
dead nodes being GCed out of the worklist, and if the chain is long, the
immediate users won't be enough to re-detect where the root of the chain
is that became single-use again after deleting the dead nodes. The
better way to do this is to never immediately delete nodes, and instead
to just enqueue them so we can recursively delete them. The
combined-from node is typically not on the worklist anyways by virtue of
having been popped off.... But that in turn breaks other tests that
*require* CombineTo to delete unused nodes. :: sigh ::
Fortunately, there is a better way. This whole routine should have been
returning the replacement rather than using CombineTo which is quite
hacky. Switch to that, and all the pieces fall together.
I suspect the same kind of miscompile is possible in the half-shuffle
folding code, and potentially the recursive folding code. I'll be
switching those over to a pattern more like this one for safety's sake
even though I don't immediately have any test cases for them. Note that
the only way I got a test case for this instance was with *heavily* DAG
combined 256-bit shuffle sequences generated by my fuzzer. ;]
llvm-svn: 216319
Summary:
In order to gather more information about testsuite results these flags should be added to LIT's default args.
These new switches were recently added to LIT. It been more than two weeks since both switches were added.
I think its time we add these to our LIT flags.
Reviewers: mclow.lists, danalbert
Reviewed By: danalbert
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D5037
llvm-svn: 216315
declared, rather than putting them into the template parameter scope. We
previously had *no record* in the scope for class template declarations, once
those declarations completed and their template parameter scopes were popped.
This in turn caused us to be unable to merge class template declarations that
were declared in the global scope (where we use scope lookup rather than
DeclContext lookup for merging), when loading a module.
llvm-svn: 216311
There are two parts to this. First, the plugin needs to tell gold the comdat by
setting comdat_key.
What gets things a bit more complicated is that gold only seems
symbols. In particular, if A is an alias to B, it only sees the symbols
A and B. It can then ask us to keep symbol A but drop symbol B. What
we have to do instead is to create an internal version of B and make A
an alias to that.
At some point some of this logic should be moved to lib/Linker so that
we don't map a Constant to an internal version just to have lib/Linker
map that again to the destination module.
The reason for implementing this in tools/gold for now is simplicity.
With it in place it should be possible to update clang to use comdats
for constructors and destructors on ELF without breaking the LTO
bootstrap. Once that is done I intend to come back and improve the
interface lib/Linker exposes.
llvm-svn: 216302
This commit expands llvm-cov's functionality by adding support for a new code coverage
tool that uses LLVM's coverage mapping format and clang's instrumentation based profiling.
The gcov compatible tool can be invoked by supplying the 'gcov' command as the first argument,
or by modifying the tool's name to end with 'gcov'.
Differential Revision: http://reviews.llvm.org/D4445
llvm-svn: 216300
Summary:
Fixes PR20425.
During slice building, if all of the incoming values of a PHI node are the same, replace the PHI node with the common value. This simplification makes alloca's used by PHI nodes easier to promote.
Test Plan: Added three more tests in phi-and-select.ll
Reviewers: nlewycky, eliben, meheff, chandlerc
Reviewed By: chandlerc
Subscribers: zinovy.nis, hfinkel, baldrick, llvm-commits
Differential Revision: http://reviews.llvm.org/D4659
llvm-svn: 216299
This already works, but somewhat by accident (due to the order of
emission in clang, the location is set to the loop header (during the
emission of the iteratior increment) before the loop backedge is
emitted), so let's just add a test for symmetry and future-proofing.
llvm-svn: 216298
Similar to r215768 (which fixed the same case for while loops). To quote
r215768's commit message:
"A little test case simplification - this could be simplified further,
though there are certainly interesting connections to the if/else
construct so I'm hesitant to remove that entirely though it does appear
somewhat unrelated.
(similar fix to r215766, related to PR19864)"
llvm-svn: 216297
There's no need to do this if the user doesn't call va_start. In the
future, we're going to have thunks that forward these register
parameters with musttail calls, and they won't need these spills for
handling va_start.
Most of the test suite changes are adding va_start calls to existing
tests to keep things working.
llvm-svn: 216294
for loops introduce two scopes - one for the outer loop variable and its
initialization, and another for the body of the loop, including any
variable declared inside the loop condition.
llvm-svn: 216288
The situation it is warning about (see PR20725) is not very likely
to be a real problem, and it is unclear what action the user should take
if the warning does fire.
llvm-svn: 216283
This patch aims at fixing PR17239.
This bug happens because the /link (clang-cl.exe argument) is marked as
"consume all remaining arguments". However, when inside a response file,
/link should only consume all remaining arguments inside the response
file where it is located, not the entire command line after expansion.
The LLVM side of the patch will change the semantics of the
RemainingArgsClass kind to always consume only until the end of the
response file when the option originally came from a response file.
There are only two options in this class: dash dash (--) and /link.
This is the Clang side of the patch in http://reviews.llvm.org/D4899
Reviewered By: rafael, rnk
Differential Revision: http://reviews.llvm.org/D4900
Patch by Rafael Auler!
llvm-svn: 216281
This patch contains the LLVM side of the fix of PR17239.
This bug that happens because the /link (clang-cl.exe argument) is
marked as "consume all remaining arguments". However, when inside a
response file, /link should only consume all remaining arguments inside
the response file where it is located, not the entire command line after
expansion.
My patch will change the semantics of the RemainingArgsClass kind to
always consume only until the end of the response file when the option
originally came from a response file. There are only two options in this
class: dash dash (--) and /link.
Reviewed By: rnk
Differential Revision: http://reviews.llvm.org/D4899
Patch by Rafael Auler!
llvm-svn: 216280
These pointers are really just offsets and they will always be
less than 16-bits. Using AssertZExt allows us to use computeKnownBits
to prove that these values are positive. We will use this information
in a later commit.
llvm-svn: 216277
Moreover, rework some patterns to actually check the emitted instructions
instead of matching unrelated string!
E.g.,
some of the "// CHECK: vmov" were matching stuff like ".globl
funcname_with_vmov" instead of actual instructions.
llvm-svn: 216275
instruction from ARMInstrInfo to ARMBaseInstrInfo.
That way, thumb mode can also benefit from the advanced copy optimization.
<rdar://problem/12702965>
llvm-svn: 216274
Consider:
%add = add nuw i32 %a, -16777216
%and = and i32 %add, 255
Regardless of whether or not we demand the sign bit of %add, we cannot
replace -16777216 with 2130706432 without also removing 'nuw' from the
instruction.
llvm-svn: 216273
The ObjCDealloc checker is currently disabled because it was too aggressive, but this
is a good first step in getting it back to a useful state.
Patch by David Kilzer!
llvm-svn: 216272
Fixes build for SPEC 2000 CPU. MSVC disables these aliases under /Za,
which enables stricter standards compliance. We don't currently have any
way to disable them.
Patch by Kevin Smith!
llvm-svn: 216270
Chandler Carruth