Summary:
(This is a second attempt as https://reviews.llvm.org/D34822 was reverted.)
LazyValueInfo currently computes the constant value of the switch condition through case edges, which allows the constant value to be propagated through the case edges.
But we have seen a case where a zero-extended value of the switch condition is used past case edges for which the constant propagation doesn't occur.
This patch adds a small logic to handle such a case in getEdgeValueLocal().
This is motivated by the Python 2.7 eval loop in PyEval_EvalFrameEx() where the lack of the constant propagation causes longer live ranges and more spill code than necessary.
With this patch, we see that the code size of PyEval_EvalFrameEx() decreases by ~5.4% and a performance test improves by ~4.6%.
Reviewers: sanjoy
Reviewed By: sanjoy
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D36247
llvm-svn: 309986
This causes assertion failures in (a somewhat old version of) SpiderMonkey.
I have already forwarded reproduction instructions to the patch author.
llvm-svn: 309659
Summary:
LazyValueInfo currently computes the constant value of the switch condition through case edges, which allows the constant value to be propagated through the case edges.
But we have seen a case where a zero-extended value of the switch condition is used past case edges for which the constant propagation doesn't occur.
This patch adds a small logic to handle such a case in getEdgeValueLocal().
This is motivated by the Python 2.7 eval loop in PyEval_EvalFrameEx() where the lack of the constant propagation causes longer live ranges and more spill code than necessary.
With this patch, we see that the code size of PyEval_EvalFrameEx() decreases by ~5.4% and a performance test improves by ~4.6%.
Reviewers: wmi, dberlin, sanjoy
Reviewed By: sanjoy
Subscribers: davide, davidxl, llvm-commits
Differential Revision: https://reviews.llvm.org/D34822
llvm-svn: 309415
Take range metadata into account for conditions like this:
%length = load i32, i32* %length_ptr, !range !{i32 0, i32 2147483647}
%cmp = icmp ult i32 %a, %length
This is a common pattern for range checks where the length of the array is dynamically loaded.
Reviewed By: sanjoy
Differential Revision: https://reviews.llvm.org/D23267
llvm-svn: 278496
Currently LVI can only gather value constraints from comparisons like:
* icmp <pred> Val, ...
* icmp ult (add Val, Offset), ...
In fact we can handle any predicate in latter comparisons.
Reviewed By: sanjoy
Differential Revision: https://reviews.llvm.org/D23357
llvm-svn: 278493
The diff is relatively large since I took a chance to rearrange the code I had to touch in a more obvious way, but the key bit is merely using the !range metadata when we can't analyze the instruction further. The previous !range metadata code was essentially just dead since no binary operator or cast will have !range metadata (per Verifier) and it was otherwise dropped on the floor.
llvm-svn: 262751
Somewhat shockingly for an analysis pass which is computing constant ranges, LVI did not understand the ranges provided by range metadata.
As part of this change, I included a change to CVP primarily because doing so made it much easier to write small self contained test cases. CVP was previously only handling the non-local operand case, but given that LVI can sometimes figure out information about instructions standalone, I don't see any reason to restrict this. There could possibly be a compile time impact from this, but I suspect it should be minimal. If anyone has an example which substaintially regresses, please let me know. I could restrict the block local handling to ICmps feeding Terminator instructions if needed.
Note that this patch continues a somewhat bad practice in LVI. In many cases, we know facts about values, and separate context sensitive facts about values. LVI makes no effort to distinguish and will frequently cache the same value fact repeatedly for different contexts. I would like to change this, but that's a large enough change that I want it to go in separately with clear documentation of what's changing. Other examples of this include the non-null handling, and arguments.
As a meta comment: the entire motivation of this change was being able to write smaller (aka reasonable sized) test cases for a future patch teaching LVI about select instructions.
Differential Revision: http://reviews.llvm.org/D13543
llvm-svn: 251606
This update was done with the following bash script:
find test/Transforms -name "*.ll" | \
while read NAME; do
echo "$NAME"
if ! grep -q "^; *RUN: *llc" $NAME; then
TEMP=`mktemp -t temp`
cp $NAME $TEMP
sed -n "s/^define [^@]*@\([A-Za-z0-9_]*\)(.*$/\1/p" < $NAME | \
while read FUNC; do
sed -i '' "s/;\(.*\)\([A-Za-z0-9_]*\):\( *\)@$FUNC\([( ]*\)\$/;\1\2-LABEL:\3@$FUNC(/g" $TEMP
done
mv $TEMP $NAME
fi
done
llvm-svn: 186268
This could probably be made a lot smarter, but this is a common case and doesn't require LVI to scan a lot
of code. With this change CVP can optimize away the "shift == 0" case in Hashing.h that only gets hit when
"shift" is in a range not containing 0.
llvm-svn: 151919
Hiroshi Yamauchi