The fundamental problem is that SROA didn't allow for overly wide loads
where the bits past the end of the alloca were masked away and the load
was sufficiently aligned to ensure there is no risk of page fault, or
other trapping behavior. With such widened loads, SROA would delete the
load entirely rather than clamping it to the size of the alloca in order
to allow mem2reg to fire. This was exposed by a test case that neatly
arranged for GVN to run first, widening certain loads, followed by an
inline step, and then SROA which miscompiles the code. However, I see no
reason why this hasn't been plaguing us in other contexts. It seems
deeply broken.
Diagnosing all of the above took all of 10 minutes of debugging. The
really annoying aspect is that fixing this completely breaks the pass.
;] There was an implicit reliance on the fact that no loads or stores
extended past the alloca once we decided to rewrite them in the final
stage of SROA. This was used to encode information about whether the
loads and stores had been split across multiple partitions of the
original alloca. That required threading explicit tracking of whether
a *use* of a partition is split across multiple partitions.
Once that was done, another problem arose: we allowed splitting of
integer loads and stores iff they were loads and stores to the entire
alloca. This is a really arbitrary limitation, and splitting at least
some integer loads and stores is crucial to maximize promotion
opportunities. My first attempt was to start removing the restriction
entirely, but currently that does Very Bad Things by causing *many*
common alloca patterns to be fully decomposed into i8 operations and
lots of or-ing together to produce larger integers on demand. The code
bloat is terrifying. That is still the right end-goal, but substantial
work must be done to either merge partitions or ensure that small i8
values are eagerly merged in some other pass. Sadly, figuring all this
out took essentially all the time and effort here.
So the end result is that we allow splitting only when the load or store
at least covers the alloca. That ensures widened loads and stores don't
hurt SROA, and that we don't rampantly decompose operations more than we
have previously.
All of this was already fairly well tested, and so I've just updated the
tests to cover the wide load behavior. I can add a test that crafts the
pass ordering magic which caused the original PR, but that seems really
brittle and to provide little benefit. The fundamental problem is that
widened loads should Just Work.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177055 91177308-0d34-0410-b5e6-96231b3b80d8
constructs default arguments. It can now take default arguments from
cl::opt'ions. Add a new -default-gcov-version=... option, and actually test it!
Sink the reverse-order of the version into GCOVProfiling, hiding it from our
users.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177002 91177308-0d34-0410-b5e6-96231b3b80d8
Clients of MemoryBuffer::getOpenFile expect it not to take ownership of the file
descriptor passed in. So don't.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176995 91177308-0d34-0410-b5e6-96231b3b80d8
emitProfileNotes(), similar to emitProfileArcs(). Also update its comment.
Also add a comment on Version[4] (there will be another comment in clang later),
and compress lines that exceeded 80 columns.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176994 91177308-0d34-0410-b5e6-96231b3b80d8
This doesn't reset all of the target options within the TargetOptions
object. This is because some of those are ABI-specific and must be determined if
it's okay to change those on the fly.
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codegen passes. This brings it in to line with clang and llc's codegen setup,
and tidies up the code.
If I understand correctly, adding ModulePasses to a FunctionPassManager is
bogus. It only seems to explode if an added ModulePass depends on a
FunctionPass though, which might be why this code has survived so long.
Fixes <rdar://problem/13386816>.
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In r176898 I updated the cost model to reflect the fact that sext/zext/cast on
v8i32 <-> v8i8 and v16i32 <-> v16i8 are expensive.
This test case is so that we make sure to update the cost model once we fix
CodeGen.
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This is the next step towards making the metadata for DIScopes have a common
prefix rather than having to delegate based on their tag type.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176913 91177308-0d34-0410-b5e6-96231b3b80d8
This could be 'null' or the empty string, DIDescriptor::getStringField
coalesces the two cases anyway so it's just a matter of legible/efficient
representation.
The change in behavior of the DICompileUnit::get* functions could be
subsumed by the full verification check - but ideally that should just be an
assertion if we could front-load the actual debug info metadata failure paths.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176907 91177308-0d34-0410-b5e6-96231b3b80d8
Increase the cost of v8/v16-i8 to v8/v16-i32 casts and truncates as the backend
currently lowers those using stack accesses.
This was responsible for a significant degradation on
MultiSource/Benchmarks/Trimaran/enc-pc1/enc-pc1
where we vectorize one loop to a vector factor of 16. After this patch we select
a vector factor of 4 which will generate reasonable code.
unsigned char cle[32];
void test(short c) {
unsigned short compte;
for (compte = 0; compte <= 31; compte++) {
cle[compte] = cle[compte] ^ c;
}
}
radar://13220512
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176898 91177308-0d34-0410-b5e6-96231b3b80d8
belongs to a different compile unit.
DW_FORM_ref_addr should be used for cross compile-unit reference.
When compiling a large application, we got a dwarfdump verification error where
abstract_origin points to nowhere.
This error can't be reproduced on any testing case in MultiSource.
We may have other cases where we use DW_FORM_ref4 unconditionally.
rdar://problem/13370501
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176882 91177308-0d34-0410-b5e6-96231b3b80d8
return 0 to indicate failure to create the disassembler. A library routine
should not assert and just let the caller handler the error. For example
darwin's otool(1) will simply print an error if it ends up using a library
that is not configured for a target it wants:
% otool -tv ViewController.o
ViewController.o:
(__TEXT,__text) section
can't create arm llvm disassembler
This is much better than an abort which appears as a crash to the user or
even the assert when using a Debug+Asserts built library:
Assertion failed: (MAI && "Unable to create target asm info!"), function LLVMCreateDisasmCPU, file /Volumes/SandBox/llvm/lib/MC/MCDisassembler/Disassembler.cpp, line 47.
radr://12539918
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This pass is meant to be immutable, however it holds mutable state to cache StructLayouts.
This method will allow the pass manager to clear the mutable state between runs.
Note that unfortunately it is still necessary to have the destructor, even though it does the
same thing as doFinalization. This is because most TargetMachines embed a DataLayout on which
doFinalization isn't run as its never added to the pass manager.
I also didn't think it was necessary to complication things with a deInit method for which
doFinalization and ~DataLayout both call as there's only one field of mutable state. If we had
more fields to finalize i'd have added this.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176877 91177308-0d34-0410-b5e6-96231b3b80d8
Now that only the register-scavenger version of the CR spilling code remains,
we no longer need the Darwin R2 hack. Darwin can use R0 as a spare register in
any case where the System V ABI uses it (R0 is special architecturally, and so
is reserved under all common ABIs).
A few test cases needed to be updated to reflect the register-allocation changes.
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