Commit Graph

8 Commits

Author SHA1 Message Date
David Green 25312b2b6c [GlobalMerge] Set the alignment on merged global structs
If no alignment is set, the abi/preferred alignment of structs will be
used which may be higher than required. This can lead to extra padding
and in the end an increase in data size.

Differential Revision: https://reviews.llvm.org/D47633

llvm-svn: 334099
2018-06-06 14:48:32 +00:00
Peter Collingbourne 5ab4a4793e Reland r329956, "AArch64: Introduce a DAG combine for folding offsets into addresses.", with a fix for the bot failure.
This reland includes a check to prevent the DAG combiner from folding an
offset that is smaller than the existing one. This can cause oscillations
between two possible DAGs, which was the cause of the hang and later assertion
failure observed on the lnt-ctmark-aarch64-O3-flto bot.
http://green.lab.llvm.org/green/job/lnt-ctmark-aarch64-O3-flto/2024/

Original commit message:
> This is a code size win in code that takes offseted addresses
> frequently, such as C++ constructors that typically need to compute
> an offseted address of a vtable. This reduces the size of Chromium
> for Android's .text section by 108KB.

Differential Revision: https://reviews.llvm.org/D45199

llvm-svn: 330630
2018-04-23 19:09:34 +00:00
Peter Collingbourne ab40e44ba1 Revert r329956, "AArch64: Introduce a DAG combine for folding offsets into addresses."
Caused a hang and eventually an assertion failure in LTO builds
of 7zip-benchmark on aarch64 iOS targets.
http://green.lab.llvm.org/green/job/lnt-ctmark-aarch64-O3-flto/2024/

llvm-svn: 330063
2018-04-13 20:21:00 +00:00
Peter Collingbourne 00db326b0d AArch64: Introduce a DAG combine for folding offsets into addresses.
This is a code size win in code that takes offseted addresses
frequently, such as C++ constructors that typically need to compute
an offseted address of a vtable. This reduces the size of Chromium
for Android's .text section by 108KB.

Differential Revision: https://reviews.llvm.org/D45199

llvm-svn: 329956
2018-04-12 21:23:55 +00:00
Adrian Prantl 554fd99dd5 Revert "Use private linkage for MergedGlobals variables" on Darwin.
This is a partial revert of r244615 (http://reviews.llvm.org/D11942),
which caused a major regression in debug info quality.

Turning the artificial __MergedGlobal symbols into private symbols
(l__MergedGlobal) means that the linker will not include them in the
symbol table of the final executable. Without a symbol table entry
dsymutil is not be able to process the debug info for any of the
merged globals and thus drops the debug info for all of them.

This patch is enabling the old behavior for all MachO targets while
leaving all other targets unaffected.

rdar://problem/29160481
https://reviews.llvm.org/D26531

llvm-svn: 286607
2016-11-11 17:50:09 +00:00
Diana Picus 850043b25a [AArch64] Register passes so they can be run by llc
Initialize all AArch64-specific passes in the TargetMachine so they can be run
by llc. This can lead to conflicts in opt with some command line options that
share the same name as the pass, so I took this opportunity to do some cleanups:
* rename all relevant command line options from "aarch64-blah" to
  "aarch64-enable-blah" and update the tests accordingly
* run clang-format on their declarations
* move all these declarations to a common place (the TargetMachine) as opposed
  to having them scattered around (AArch64BranchRelaxation and
  AArch64AddressTypePromotion were the only offenders)

llvm-svn: 277322
2016-08-01 05:56:57 +00:00
John Brawn 863bfdbfb4 [GlobalMerge] Use private linkage for MergedGlobals variables
Other objects can never reference the MergedGlobals symbol so external linkage
is never needed. Using private instead of internal linkage means the object is
more similar to what it looks like when global merging is not enabled, with
the only difference being that the merged variables are addressed indirectly
relative to the start of the section they are in.

Also add aliases for merged variables with internal linkage, as this also makes
the object be more like what it is when they are not merged.

Differential Revision: http://reviews.llvm.org/D11942

llvm-svn: 244615
2015-08-11 15:48:04 +00:00
Ahmed Bougacha 279e3ee954 [GlobalMerge] Look at uses to create smaller global sets.
Instead of merging everything together, look at the users of
GlobalVariables, and try to group them by function, to create
sets of globals used "together".

Using that information, a less-aggressive alternative is to keep merging
everything together *except* globals that are only ever used alone, that
is, those for which it's clearly non-profitable to merge with others.

In my testing, grouping by Function is too aggressive, but grouping by
BasicBlock is too conservative.  Anything in-between isn't trivially
available, so stick with Function grouping for now.

cl::opts are added for testing; both enabled by default.

A few of the testcases aren't testing the merging proper, but just
various edge cases when merging does occur.  Update them to use the
previous grouping behavior. Also, one of the tests is unrelated to
GlobalMerge; change it accordingly.
While there, switch to r234666' flags rather than the brutal -O3.

Differential Revision: http://reviews.llvm.org/D8070

llvm-svn: 235249
2015-04-18 01:21:58 +00:00