The limitation of the current pass that it skips initializer-less GV's
seems arbitrary, in all the reduced cases i (personally) looked at,
the globals weren't needed, yet they were kept.
So let's do two things:
1. allow reducing initializer-less globals
2. before reducing globals, reduce their initializers, much like we do function bodies
This patch adds a reduction of 'special' globals that lead to further
reductions (e.g. alias or regular globals reduction) being less efficient
because there are special constraints on values referenced in those
special globals. For example, values in @llvm.used and
@llvm.compiler.used need to be named, so replacing all uses of an
alias/global with undef or a different unnamed constant results in
invalid IR.
More details:
https://llvm.org/docs/LangRef.html#intrinsic-global-variables
Reviewed By: lebedev.ri
Differential Revision: https://reviews.llvm.org/D90302
This patch adds a new reduction pass that tries to remove aliases.
It runs early, as most of those likely can be removed up-front in
practice.
This substantially improves llvm-reduce for IR generated by the swift
compiler, which can generate a lot of aliases which lead to lots of
invalid reductions.
Reviewed By: lebedev.ri
Differential Revision: https://reviews.llvm.org/D90260
ReduceFunctions could do it, but it also replaces *all* calls with undef,
so if any of undef replacements makes reduction uninteresting,
it won't work.
ReduceBasicBlocks also could do it, but well, it may take many guesses
for all the blocks of a function to happen to be out-of-chunk,
which is not a very efficient way to go about it.
So let's just do this first.
Summary:
This handles all three places where attributes could currently be - `GlobalVariable`, `Function` and `CallBase`.
For last two, it correctly handles all three possible attribute locations (return value, arguments and function itself)
There was a previous attempt at it D73853,
which was committed in rGfc62b36a000681c01e993242b583c5ec4ab48a3c,
but then reverted all the way back in rGb12176d2aafa0ccb2585aa218fc3b454ba84f2a9
due to some (osx?) test failures.
Reviewers: nickdesaulniers, dblaikie, diegotf, george.burgess.iv, jdoerfert, Tyker, arsenm
Reviewed By: nickdesaulniers
Subscribers: wdng, MaskRay, arsenm, llvm-commits, mgorny
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D83351
Summary:
This would have been marginally useful to me during/for rG7ea46aee3670981827c04df89b2c3a1cbdc7561b.
With ongoing migration to representing assumes via operand bundles on the assume, this will be gradually more useful.
Reviewers: nickdesaulniers, diegotf, dblaikie, george.burgess.iv, jdoerfert, Tyker
Reviewed By: nickdesaulniers
Subscribers: hiraditya, mgorny, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D83177
Summary:
The output from llvm-reduce still has significantly more attributes than
bugpoint does. Teach llvm-reduce to remove attributes.
Reviewers: diegotf, dblaikie, george.burgess.iv
Subscribers: mgorny, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D73853
Fixing a couple of asan-identified bugs
* use of an invalid "Use" iterator after the element was removed
* use of StringRef to Function name after the Function was erased
This reapplies r371567, which was reverted in r371580.
llvm-svn: 371700
Summary:
This pass tries to remove Global Variables, as well as their derived uses. For example if a variable `@x` is used by `%call1` and `%call2`, both these uses and the definition of `@x` are deleted. Moreover if `%call1` or `%call2` are used elsewhere those uses are also deleted, and so on recursively.
I'm still uncertain if this pass should remove derived uses, I'm open to suggestions.
Subscribers: mgorny, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64176
> llvm-svn: 368918
llvm-svn: 369061
Summary:
This pass tries to remove Global Variables, as well as their derived uses. For example if a variable `@x` is used by `%call1` and `%call2`, both these uses and the definition of `@x` are deleted. Moreover if `%call1` or `%call2` are used elsewhere those uses are also deleted, and so on recursively.
I'm still uncertain if this pass should remove derived uses, I'm open to suggestions.
Subscribers: mgorny, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64176
llvm-svn: 368918
This reverts commits:
"Added Delta IR Reduction Tool"
"[Bugpoint redesign] Added Pass to Remove Global Variables"
"Added Tool as Dependency to tests & fixed warnings"
Reduce/remove-funcs.ll is failing on bots.
llvm-svn: 368122
Summary:
This pass tries to remove Global Variables, as well as their derived uses. For example if a variable `@x` is used by `%call1` and `%call2`, both these uses and the definition of `@x` are deleted. Moreover if `%call1` or `%call2` are used elsewhere those uses are also deleted, and so on recursively.
I'm still uncertain if this pass should remove derived uses, I'm open to suggestions.
Subscribers: mgorny, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64176
llvm-svn: 368115
Roman Lebedev