In various places in LLD's hot loops, we have expressions of the form
"E == R_FOO || E == R_BAR || ..." (E is a RelExpr).
Some of these expressions are quite long, and even though they usually go just
a very small number of ways and so should be well predicted, they can still
occupy branch predictor resources harming other parts of the code, or they
won't be predicted well if they overflow branch predictor resources or if the
branches are too dense and the branch predictor can't track them all (the
compiler can in theory avoid this, at a cost in text size). And some of these
expressions are so large and executed so frequently that even when
well-predicted they probably still have a nontrivial cost.
This speedup should be pretty portable. The cost of these simple bit tests is
independent of:
- the target we are linking for
- the distribution of RelExpr's for a given link (which can depend on how the
input files were compiled)
- what compiler was used to compile LLD (it is just a simple bit test;
hopefully the compiler gets it right!)
- adding new target-dependent relocations (e.g. needsPlt doesn't pay any extra
cost checking R_PPC_PLT_OPD on x86-64 builds)
I did some rough measurements on clang-fsds and this patch gives over about 4%
speedup for a regular -O1 link, about 2.5% for -O3 --gc-sections and over 5%
for -O0. Sorry, I don't have my current machine set up for doing really
accurate measurements right now.
This also is just a bit cleaner. Thanks for Joerg for suggesting for
this approach.
Differential Revision: https://reviews.llvm.org/D27156
llvm-svn: 288314
- Rename currentBuffer -> getCurrentMB to start it with verb.
- Simplify containsString.
- Add llvm_unreachable at end of getCurrentMB.
llvm-svn: 288310
If LoopInfo is available during GVN, BasicAA will use it. However
MergeBlockIntoPredecessor does not update LI as it merges blocks.
This didn't use to cause problems because LI was freed before
GVN/BasicAA. Now with OptimizationRemarkEmitter, the lifetime of LI is
extended so LI needs to be kept up-to-date during GVN.
Differential Revision: https://reviews.llvm.org/D27288
llvm-svn: 288307
Summary:
it's often the case when the rules in the SpecialCaseList
are of the form hel.o*bar. That gives us a chance to build
trigram index to quickly discard 99% of inputs without
running a full regex. A similar idea was used in Google Code Search
as described in the blog post:
https://swtch.com/~rsc/regexp/regexp4.html
The check is defeated, if there's at least one regex
more complicated than that. In this case, all inputs
will go through the regex. That said, the real-world
rules are often simple or can be simplied. That considerably
speeds up compiling Chromium with CFI and UBSan.
As measured on Chromium's content_message_generator.cc:
before, CFI: 44 s
after, CFI: 23 s
after, CFI, no blacklist: 23 s (~1% slower, but 3 runs were unable to show the difference)
after, regular compilation to bitcode: 23 s
Reviewers: pcc
Subscribers: mgorny, llvm-commits
Differential Revision: https://reviews.llvm.org/D27188
llvm-svn: 288303
arguments from a declaration; despite what the standard says, this form of
deduction should not be considering exception specifications.
llvm-svn: 288301
Primarily: try to use DenseSet<StringRef> instead of
std::set<std::string>, and use pretty range algos where we can.
Small sizes were arbitrarily chosen.
llvm-svn: 288297
Support a new assembler directive, .import_global, to declare imported
global variables (i.e. those with external linkage and no
initializer). The linker turns these into wasm imports.
Patch by Jacob Gravelle
Differential Revision: https://reviews.llvm.org/D26875
llvm-svn: 288296
This patch is to implement sema and parsing for 'teams distribute parallel for simd' pragma.
Differential Revision: https://reviews.llvm.org/D27084
llvm-svn: 288294
Most of the exception handling members in MachineModuleInfo is actually
per function data (talks about the "current function") so it is better
to keep it at the function instead of the module.
This is a necessary step to have machine module passes work properly.
Also:
- Rename TidyLandingPads() to tidyLandingPads()
- Use doxygen member groups instead of "//===- EH ---"... so it is clear
where a group ends.
- I had to add an ugly const_cast at two places in the AsmPrinter
because the available MachineFunction pointers are const, but the code
wants to call tidyLandingPads() in between
(markFunctionEnd()/endFunction()).
Differential Revision: https://reviews.llvm.org/D27227
llvm-svn: 288293
VariableDbgInfo is per function data, so it makes sense to have it with
the function instead of the module.
This is a necessary step to have machine module passes work properly.
Differential Revision: https://reviews.llvm.org/D27186
llvm-svn: 288292
This is per function data so it is better kept at the function instead
of the module.
This is a necessary step to have machine module passes work properly.
Differential Revision: https://reviews.llvm.org/D27185
llvm-svn: 288291
Choosing a "cfi" name makes the intend a bit clearer in an assembly dump
and more importantly the assembly dumps are slightly more stable as the
numbers don't move around anymore when unrelated code calls
createTempSymbol() more or less often.
As they are temp labels the name doesn't influence the generated object
code.
Differential Revision: https://reviews.llvm.org/D27244
llvm-svn: 288290
Maintain the command line resolutions as a map to a list of resolutions
rather than a single resolution, and apply the resolutions in the order
observed. This is not only simpler but allows us to test the scenario where
the two symbols have different resolutions.
Differential Revision: https://reviews.llvm.org/D27285
llvm-svn: 288288
performed at the CodeGenModule level.
Would be NFC except we now also use a different uniquing structure so
that we don't get spurious conflicts if you ask for both an NSString
and a CFString for the same content (which is possible with builtins).
llvm-svn: 288287
The LLDB tests are now ready for this patch.
DWARF specifies that "line 0" really means "no appropriate source
location" in the line table. Use this for branch targets and some
other cases that have no specified source location, to prevent
inheriting unfortunate line numbers from physically preceding
instructions (which might be from completely unrelated source).
Differential Revision: http://reviews.llvm.org/D24180
llvm-svn: 288283
Summary:
When using thin archives, and processing the same archive multiple times, we were mangling existing entries. The root cause is that we were calling computeRelativePath() more than once. Here, we only call it when adding new members to an archive.
Note that D27218 changes the way thin archives are printed, and will break the new unit test included here. Depending on which one lands first, the other will need to be slightly modified.
Reviewers: rafael, davide
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D27217
llvm-svn: 288280
Summary:
This is preparation for ThunderX processors that have Large
System Extension (LSE) atomic instructions, but not the
other instructions introduced by V8.1a.
This will mimic changes to GCC as described here:
https://gcc.gnu.org/ml/gcc-patches/2015-06/msg00388.html
LSE instructions are: LD/ST<op>, CAS*, SWP
Reviewers: t.p.northover, echristo, jmolloy, rengolin
Subscribers: aemerson, mehdi_amini
Differential Revision: https://reviews.llvm.org/D26621
llvm-svn: 288279
Summary:
Fix a case when first register in a search has maximum
RegUses.getUsedByIndices(Reg).count()
Reviewers: qcolombet
Differential Revision: http://reviews.llvm.org/D26877
From: Evgeny Stupachenko <evstupac@gmail.com>
llvm-svn: 288278
No test case necessary as the problematic condition is checked with the
newly introduced assertAllSuperRegsMarked() function.
Differential Revision: https://reviews.llvm.org/D26648
llvm-svn: 288277
This patch moves some posix specific file i/o code into a new
file, FuzzerIOPosix.cpp, and provides implementations for these
functions on Windows in FuzzerIOWindows.cpp. This is another
incremental step towards getting libfuzzer working on Windows,
although it still should not be expected to be fully working.
Patch by Marcos Pividori
Differential Revision: https://reviews.llvm.org/D27233
llvm-svn: 288275
This implements PGO-driven loop peeling.
The basic idea is that when the average dynamic trip-count of a loop is known,
based on PGO, to be low, we can expect a performance win by peeling off the
first several iterations of that loop.
Unlike unrolling based on a known trip count, or a trip count multiple, this
doesn't save us the conditional check and branch on each iteration. However,
it does allow us to simplify the straight-line code we get (constant-folding,
etc.). This is important given that we know that we will usually only hit this
code, and not the actual loop.
This is currently disabled by default.
Differential Revision: https://reviews.llvm.org/D25963
llvm-svn: 288274
Summary:
The current code was sometimes attempting to release huge chunks of
memory due to undesired RoundUp/RoundDown interaction when the requested
range is fully contained within one memory page.
Reviewers: eugenis
Subscribers: kubabrecka, llvm-commits
Patch by Aleksey Shlyapnikov.
Differential Revision: https://reviews.llvm.org/D27228
llvm-svn: 288271
declared variables.
Teach Sema to check the aligned attribute attached to variable
declarations so that it doesn't issue spurious warnings.
rdar://problem/26517471
Differential revision: https://reviews.llvm.org/D21099
llvm-svn: 288267
When svn does not know the password and it has to prompt, it needs to query.
However it won't when invoked from the Python script and instead fails with:
svn: E215004: Authentication failed and interactive prompting is disabled; see the --force-interactive option
Differential Revision: https://reviews.llvm.org/D27274
llvm-svn: 288266
Sean Silva