Summary:
We don't want to decay hot callsites to import chains of hot
callsites. The same mechanism is used in LIPO.
Reviewers: tejohnson, eraman, mehdi_amini
Subscribers: llvm-commits, mehdi_amini
Differential Revision: https://reviews.llvm.org/D24976
llvm-svn: 282833
Summary:
This patch improves thinlto importer
by importing 3x larger functions that are called from hot block.
I compared performance with the trunk on spec, and there
were about 2% on povray and 3.33% on milc. These results seems
to be consistant and match the results Teresa got with her simple
heuristic. Some benchmarks got slower but I think they are just
noisy (mcf, xalancbmki, omnetpp)- running the benchmarks again with
more iterations to confirm. Geomean of all benchmarks including the noisy ones
were about +0.02%.
I see much better improvement on google branch with Easwaran patch
for pgo callsite inlining (the inliner actually inline those big functions)
Over all I see +0.5% improvement, and I get +8.65% on povray.
So I guess we will see much bigger change when Easwaran patch will land
(it depends on new pass manager), but it is still worth putting this to trunk
before it.
Implementation details changes:
- Removed CallsiteCount.
- ProfileCount got replaced by Hotness
- hot-import-multiplier is set to 3.0 for now,
didn't have time to tune it up, but I see that we get most of the interesting
functions with 3, so there is no much performance difference with higher, and
binary size doesn't grow as much as with 10.0.
Reviewers: eraman, mehdi_amini, tejohnson
Subscribers: mehdi_amini, llvm-commits
Differential Revision: https://reviews.llvm.org/D24638
llvm-svn: 282437
Summary:
This patch adds IsVariadicFunction bit to summary in order
to not import variadic functions. Inliner doesn't inline
variadic functions because it is hard to reason about it.
This one small fix improves Importer by about 16%
(going from 86% to 100% of imported functions that are
inlined anywhere)
on some spec benchmarks like 'int' and others.
Reviewers: eraman, mehdi_amini, tejohnson
Subscribers: mehdi_amini, llvm-commits
Differential Revision: https://reviews.llvm.org/D23339
llvm-svn: 278432
There is not point in importing a "weak" or a "linkonce" function
since we won't be able to inline it anyway.
We already had a targeted check for WeakAny, this is using the
same check on GlobalValue as the inline, i.e.
isMayBeOverriddenLinkage()
From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 268341
There is not point in importing a "weak" or a "linkonce" function
since we won't be able to inline it anyway.
We already had a targeted check for WeakAny, this is using the
same check on GlobalValue as the inline, i.e.
isMayBeOverriddenLinkage()
From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 268315
Summary:
The function importer already decided what symbols need to be pulled
in. Also these magically added ones will not be in the export list
for the source module, which can confuse the internalizer for
instance.
Reviewers: tejohnson, rafael
Subscribers: joker.eph, llvm-commits
Differential Revision: http://reviews.llvm.org/D19096
From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266948
Summary:
This patch prevents importing from (and therefore exporting from) any
module with a "llvm.used" local value. Local values need to be promoted
and renamed when importing, and their presense on the llvm.used variable
indicates that there are opaque uses that won't see the rename. One such
example is a use in inline assembly.
See also the discussion at:
http://lists.llvm.org/pipermail/llvm-dev/2016-April/098047.html
As part of this, move collectUsedGlobalVariables out of Transforms/Utils
and into IR/Module so that it can be used more widely. There are several
other places in LLVM that used copies of this code that can be cleaned
up as a follow on NFC patch.
Reviewers: joker.eph
Subscribers: pcc, llvm-commits, joker.eph
Differential Revision: http://reviews.llvm.org/D18986
llvm-svn: 266877
Currently each Function points to a DISubprogram and DISubprogram has a
scope field. For member functions the scope is a DICompositeType. DIScopes
point to the DICompileUnit to facilitate type uniquing.
Distinct DISubprograms (with isDefinition: true) are not part of the type
hierarchy and cannot be uniqued. This change removes the subprograms
list from DICompileUnit and instead adds a pointer to the owning compile
unit to distinct DISubprograms. This would make it easy for ThinLTO to
strip unneeded DISubprograms and their transitively referenced debug info.
Motivation
----------
Materializing DISubprograms is currently the most expensive operation when
doing a ThinLTO build of clang.
We want the DISubprogram to be stored in a separate Bitcode block (or the
same block as the function body) so we can avoid having to expensively
deserialize all DISubprograms together with the global metadata. If a
function has been inlined into another subprogram we need to store a
reference the block containing the inlined subprogram.
Attached to https://llvm.org/bugs/show_bug.cgi?id=27284 is a python script
that updates LLVM IR testcases to the new format.
http://reviews.llvm.org/D19034
<rdar://problem/25256815>
llvm-svn: 266446
The current function importer will walk the callgraph, importing
transitively any callee that is below the threshold. This can
lead to import very deep which is costly in compile time and not
necessarily beneficial as most of the inline would happen in
imported function and not necessarilly in user code.
The actual factor has been carefully chosen by flipping a coin ;)
Some tuning need to be done (just at the existing limiting threshold).
Reviewers: tejohnson
Differential Revision: http://reviews.llvm.org/D17082
From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 260466
The findExternalCalls routine ignores calls to functions already
defined in the dest module. This was not handling the case where
the definition in the current module is actually an alias to a
function call.
llvm-svn: 257493
Function::copyAttributesFrom will copy the personality function, prefix
data and prolog data from the source function to the new function, and
is invoked when the IRMover copies the function prototype. This puts a
reference to a constant in the source module on a function in the dest
module, which causes an error when deleting the source module after
importing, since the personality function in the source module still has
uses (this would presumably also be an issue for the prologue and prefix
data). Remove the copies added to the dest copy when creating the new
prototype, as they are mapped properly when/if we link the function body.
llvm-svn: 257420
Summary:
Second patch split out from http://reviews.llvm.org/D14752.
Maps metadata as a post-pass from each module when importing complete,
suturing up final metadata to the temporary metadata left on the
imported instructions.
This entails saving the mapping from bitcode value id to temporary
metadata in the importing pass, and from bitcode value id to final
metadata during the metadata linking postpass.
Depends on D14825.
Reviewers: dexonsmith, joker.eph
Subscribers: davidxl, llvm-commits, joker.eph
Differential Revision: http://reviews.llvm.org/D14838
llvm-svn: 255909
Skip imports for weak_any aliases as well. Fix the test to check
non-import of weak aliases and functions, and import of normal alias.
llvm-svn: 253991
Summary:
This is a helper to perform cross-module import for ThinLTO. Right now
it is importing naively every possible called functions.
Reviewers: tejohnson
Subscribers: dexonsmith, llvm-commits
Differential Revision: http://reviews.llvm.org/D14914
From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 253954
Piotr Padlewski