so that we can reduce away incidental parts of the CFG in cases where
the full simplifyCFG pass makes the test case uninteresting
Differential Revision: https://reviews.llvm.org/D131920
Try to insert an implicit_def to replace the instruction's value,
replacing the original instruction's def with a dead register. If all
defs are delete the instruction entirely.
This is pretty similar to the instruction reduction, but leaves the
new defs in the same place as the original instruction. This could
possibly replace it. I'm not sure if we should directly delete the
instructions here, or leave dead ones behind.
This could also further work to replace physical register defs.
I have a register allocator failure that only reproduces with IPRA
enabled, and requires the specific regmask if I want to only run the
one relevant pass. The printed custom regmask is enormous and I would
like to reduce it.
This reduces each individual bit in the mask, but it would probably be
better to start at register units and clear all aliasing fields at a
time. This would require stricter verification that all aliasing bits
are set in regmasks (although I would prefer to switch regmasks to use
register units in the first place).
Adds support for reading and writing LTO bitcode files.
- Emit a summary if the original bitcode file had a summary
- Use split LTO units if the original bitcode file used them.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D127168
I'm a bit confused by what's actually stored for the allocation
hints. The MIR parser only handles the "simple" case where there's a
single hint. I don't really understand the assertion in
clearSimpleHint, or under what circumstances there are multiple hint
registers.
This patch adds parallel processing of chunks. When reducing very large
inputs, e.g. functions with 500k basic blocks, processing chunks in
parallel can significantly speed up the reduction.
To allow modifying clones of the original module in parallel, each clone
needs their own LLVMContext object. To achieve this, each job parses the
input module with their own LLVMContext. In case a job successfully
reduced the input, it serializes the result module as bitcode into a
result array.
To ensure parallel reduction produces the same results as serial
reduction, only the first successfully reduced result is used, and
results of other successful jobs are dropped. Processing resumes after
the chunk that was successfully reduced.
The number of threads to use can be configured using the -j option.
It defaults to 1, which means serial processing.
Reviewed By: Meinersbur
Differential Revision: https://reviews.llvm.org/D113857
Add a new "operands-skip" pass whose goal is to remove instructions in the middle of dependency chains. For instance:
```
%baseptr = alloca i32
%arrayidx = getelementptr i32, i32* %baseptr, i32 %idxprom
store i32 42, i32* %arrayidx
```
might be reducible to
```
%baseptr = alloca i32
%arrayidx = getelementptr ... ; now dead, together with the computation of %idxprom
store i32 42, i32* %baseptr
```
Other passes would either replace `%baseptr` with undef (operands, instructions) or move it to become a function argument (operands-to-args), both of which might fail the interestingness check.
In principle the implementation allows operand replacement with any value or instruction in the function that passes the filter constraints (same type, dominance, "more reduced"), but is limited in this patch to values that are directly or indirectly used to compute the current operand value, motivated by the example above. Additionally, function arguments are added to the candidate set which helps reducing the number of relevant arguments mitigating a concern of too many arguments mentioned in https://reviews.llvm.org/D110274#3025013.
Possible future extensions:
* Instead of requiring the same type, bitcast/trunc/zext could be automatically inserted for some more flexibility.
* If undef is added to the candidate set, "operands-skip"is able to produce any reduction that "operands" can do. Additional candidates might be zero and one, where the "reductive power" classification can prefer one over the other. If undefined behaviour should not be introduced, undef can be removed from the candidate set.
Recommit after resolving conflict with D112651 and reusing
shouldReduceOperand from D113532.
Reviewed By: aeubanks
Differential Revision: https://reviews.llvm.org/D111818
This reverts commit fa4210a9a0729eba04593b7df7b701e2b243de39.
It causes compile failures, presumably because conflicting with another
patch landed after I checked locally.
Add a new "operands-skip" pass whose goal is to remove instructions in the middle of dependency chains. For instance:
```
%baseptr = alloca i32
%arrayidx = getelementptr i32, i32* %baseptr, i32 %idxprom
store i32 42, i32* %arrayidx
```
might be reducible to
```
%baseptr = alloca i32
%arrayidx = getelementptr ... ; now dead, together with the computation of %idxprom
store i32 42, i32* %baseptr
```
Other passes would either replace `%baseptr` with undef (operands, instructions) or move it to become a function argument (operands-to-args), both of which might fail the interestingness check.
In principle the implementation allows operand replacement with any value or instruction in the function that passes the filter constraints (same type, dominance, "more reduced"), but is limited in this patch to values that are directly or indirectly used to compute the current operand value, motivated by the example above. Additionally, function arguments are added to the candidate set which helps reducing the number of relevant arguments mitigating a concern of too many arguments mentioned in https://reviews.llvm.org/D110274#3025013.
Possible future extensions:
* Instead of requiring the same type, bitcast/trunc/zext could be automatically inserted for some more flexibility.
* If undef is added to the candidate set, "operands-skip"is able to produce any reduction that "operands" can do. Additional candidates might be zero and one, where the "reductive power" classification can prefer one over the other. If undefined behaviour should not be introduced, undef can be removed from the candidate set.
Reviewed By: aeubanks
Differential Revision: https://reviews.llvm.org/D111818
(Second try. Need to link against CodeGen and MC libs.)
The llvm-reduce tool has been extended to operate on MIR (import, clone and
export). Current limitation is that only a single machine function is
supported. A single reducer pass that operates on machine instructions (while
on SSA-form) has been added. Additional MIR specific reducer passes can be
added later as needed.
Differential Revision: https://reviews.llvm.org/D110527
The llvm-reduce tool has been extended to operate on MIR (import, clone and
export). Current limitation is that only a single machine function is
supported. A single reducer pass that operates on machine instructions (while
on SSA-form) has been added. Additional MIR specific reducer passes can be
added later as needed.
Differential Revision: https://reviews.llvm.org/D110527
Instead of setting operands to undef as the "operands" pass does,
convert the operands to a function argument. This avoids having to
introduce undef values into the IR which have some unpredictability
during optimizations.
For instance,
define void @func() {
entry:
%val = add i32 32, 21
store i32 %val, i32* null
ret void
}
is reduced to
define void @func(i32 %val) {
entry:
%val1 = add i32 32, 21
store i32 %val, i32* null
ret void
}
(note that the instruction %val is renamed to %val1 when printing
the IR to avoid ambiguity; ideally %val1 would be removed by dce or the
instruction reduction pass)
Any call to @func is replaced with a call to the function with the
new signature and filled with undef. This is not ideal for IPA passes,
but those out-of-scope for now.
Reviewed By: aeubanks
Differential Revision: https://reviews.llvm.org/D111503
This removes the data layout, target triple, source filename, and module
identifier when possible.
Reviewed By: swamulism
Differential Revision: https://reviews.llvm.org/D108568
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
