forked from OSchip/llvm-project
5 Commits
| Author | SHA1 | Message | Date |
|---|---|---|---|
Wei Mi
|
90707394e3 |
[LSR] Narrow search space by filtering non-optimal formulae with the same ScaledReg and Scale.
When the formulae search space is huge, LSR uses a series of heuristic to keep pruning the search space until the number of possible solutions are within certain limit. The big hammer of the series of heuristics is NarrowSearchSpaceByPickingWinnerRegs, which picks the register which is used by the most LSRUses and deletes the other formulae which don't use the register. This is a effective way to prune the search space, but quite often not a good way to keep the best solution. We saw cases before that the heuristic pruned the best formula candidate out of search space. To relieve the problem, we introduce a new heuristic called NarrowSearchSpaceByFilterFormulaWithSameScaledReg. The basic idea is in order to reduce the search space while keeping the best formula, we want to keep as many formulae with different Scale and ScaledReg as possible. That is because the central idea of LSR is to choose a group of loop induction variables and use those induction variables to represent LSRUses. An induction variable candidate is often represented by the Scale and ScaledReg in a formula. If we have more formulae with different ScaledReg and Scale to choose, we have better opportunity to find the best solution. That is why we believe pruning search space by only keeping the best formula with the same Scale and ScaledReg should be more effective than PickingWinnerReg. And we use two criteria to choose the best formula with the same Scale and ScaledReg. The first criteria is to select the formula using less non shared registers, and the second criteria is to select the formula with less cost got from RateFormula. The patch implements the heuristic before NarrowSearchSpaceByPickingWinnerRegs, which is the last resort. Testing shows we get 1.8% and 2% on two internal benchmarks on x86. llvm nightly testsuite performance is neutral. We also tried lsr-exp-narrow and it didn't help on the two improved internal cases we saw. Differential Revision: https://reviews.llvm.org/D34583 llvm-svn: 307269 |
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Dan Gohman
|
61d15ae4f5 |
[MC] Use .p2align instead of .align
For historic reasons, the behavior of .align differs between targets. Fortunately, there are alternatives, .p2align and .balign, which make the interpretation of the parameter explicit, and which behave consistently across targets. This patch teaches MC to use .p2align instead of .align, so that people reading code for multiple architectures don't have to remember which way each platform does its .align directive. Differential Revision: http://reviews.llvm.org/D16549 llvm-svn: 258750 |
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|
David Blaikie
|
a79ac14fa6 |
[opaque pointer type] Add textual IR support for explicit type parameter to load instruction
Essentially the same as the GEP change in r230786.
A similar migration script can be used to update test cases, though a few more
test case improvements/changes were required this time around: (r229269-r229278)
import fileinput
import sys
import re
pat = re.compile(r"((?:=|:|^)\s*load (?:atomic )?(?:volatile )?(.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$)")
for line in sys.stdin:
sys.stdout.write(re.sub(pat, r"\1, \2\3*\4", line))
Reviewers: rafael, dexonsmith, grosser
Differential Revision: http://reviews.llvm.org/D7649
llvm-svn: 230794
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David Blaikie
|
79e6c74981 |
[opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction
One of several parallel first steps to remove the target type of pointers,
replacing them with a single opaque pointer type.
This adds an explicit type parameter to the gep instruction so that when the
first parameter becomes an opaque pointer type, the type to gep through is
still available to the instructions.
* This doesn't modify gep operators, only instructions (operators will be
handled separately)
* Textual IR changes only. Bitcode (including upgrade) and changing the
in-memory representation will be in separate changes.
* geps of vectors are transformed as:
getelementptr <4 x float*> %x, ...
->getelementptr float, <4 x float*> %x, ...
Then, once the opaque pointer type is introduced, this will ultimately look
like:
getelementptr float, <4 x ptr> %x
with the unambiguous interpretation that it is a vector of pointers to float.
* address spaces remain on the pointer, not the type:
getelementptr float addrspace(1)* %x
->getelementptr float, float addrspace(1)* %x
Then, eventually:
getelementptr float, ptr addrspace(1) %x
Importantly, the massive amount of test case churn has been automated by
same crappy python code. I had to manually update a few test cases that
wouldn't fit the script's model (r228970,r229196,r229197,r229198). The
python script just massages stdin and writes the result to stdout, I
then wrapped that in a shell script to handle replacing files, then
using the usual find+xargs to migrate all the files.
update.py:
import fileinput
import sys
import re
ibrep = re.compile(r"(^.*?[^%\w]getelementptr inbounds )(((?:<\d* x )?)(.*?)(| addrspace\(\d\)) *\*(|>)(?:$| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$))")
normrep = re.compile( r"(^.*?[^%\w]getelementptr )(((?:<\d* x )?)(.*?)(| addrspace\(\d\)) *\*(|>)(?:$| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$))")
def conv(match, line):
if not match:
return line
line = match.groups()[0]
if len(match.groups()[5]) == 0:
line += match.groups()[2]
line += match.groups()[3]
line += ", "
line += match.groups()[1]
line += "\n"
return line
for line in sys.stdin:
if line.find("getelementptr ") == line.find("getelementptr inbounds"):
if line.find("getelementptr inbounds") != line.find("getelementptr inbounds ("):
line = conv(re.match(ibrep, line), line)
elif line.find("getelementptr ") != line.find("getelementptr ("):
line = conv(re.match(normrep, line), line)
sys.stdout.write(line)
apply.sh:
for name in "$@"
do
python3 `dirname "$0"`/update.py < "$name" > "$name.tmp" && mv "$name.tmp" "$name"
rm -f "$name.tmp"
done
The actual commands:
From llvm/src:
find test/ -name *.ll | xargs ./apply.sh
From llvm/src/tools/clang:
find test/ -name *.mm -o -name *.m -o -name *.cpp -o -name *.c | xargs -I '{}' ../../apply.sh "{}"
From llvm/src/tools/polly:
find test/ -name *.ll | xargs ./apply.sh
After that, check-all (with llvm, clang, clang-tools-extra, lld,
compiler-rt, and polly all checked out).
The extra 'rm' in the apply.sh script is due to a few files in clang's test
suite using interesting unicode stuff that my python script was throwing
exceptions on. None of those files needed to be migrated, so it seemed
sufficient to ignore those cases.
Reviewers: rafael, dexonsmith, grosser
Differential Revision: http://reviews.llvm.org/D7636
llvm-svn: 230786
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Quentin Colombet
|
a799e2e014 |
[RegAllocGreedy] Introduce a late pass to repair broken hints.
A broken hint is a copy where both ends are assigned different colors. When a variable gets evicted in the neighborhood of such copies, it is likely we can reconcile some of them. ** Context ** Copies are inserted during the register allocation via splitting. These split points are required to relax the constraints on the allocation problem. When such a point is inserted, both ends of the copy would not share the same color with respect to the current allocation problem. When variables get evicted, the allocation problem becomes different and some split point may not be required anymore. However, the related variables may already have been colored. This usually shows up in the assembly with pattern like this: def A ... save A to B def A use A restore A from B ... use B Whereas we could simply have done: def B ... def A use A ... use B ** Proposed Solution ** A variable having a broken hint is marked for late recoloring if and only if selecting a register for it evict another variable. Indeed, if no eviction happens this is pointless to look for recoloring opportunities as it means the situation was the same as the initial allocation problem where we had to break the hint. Finally, when everything has been allocated, we look for recoloring opportunities for all the identified candidates. The recoloring is performed very late to rely on accurate copy cost (all involved variables are allocated). The recoloring is simple unlike the last change recoloring. It propagates the color of the broken hint to all its copy-related variables. If the color is available for them, the recoloring uses it, otherwise it gives up on that hint even if a more complex coloring would have worked. The recoloring happens only if it is profitable. The profitability is evaluated using the expected frequency of the copies of the currently recolored variable with a) its current color and b) with the target color. If a) is greater or equal than b), then it is profitable and the recoloring happen. ** Example ** Consider the following example: BB1: a = b = BB2: ... = b = a Let us assume b gets split: BB1: a = b = BB2: c = b ... d = c = d = a Because of how the allocation work, b, c, and d may be assigned different colors. Now, if a gets evicted to make room for c, assuming b and d were assigned to something different than a. We end up with: BB1: a = st a, SpillSlot b = BB2: c = b ... d = c = d e = ld SpillSlot = e This is likely that we can assign the same register for b, c, and d, getting rid of 2 copies. ** Performances ** Both ARM64 and x86_64 show performance improvements of up to 3% for the llvm-testsuite + externals with Os and O3. There are a few regressions too that comes from the (in)accuracy of the block frequency estimate. <rdar://problem/18312047> llvm-svn: 225422 |