5 Commits

Author SHA1 Message Date
Jun Bum Lim
4d9c93dc3f [CodeGenPrep] Skip merging empty case blocks
This is recommit of r287553 after fixing the invalid loop info after eliminating an empty block and unit test failures in AVR and WebAssembly :

Summary: Merging an empty case block into the header block of switch could cause ISel to add COPY instructions in the header of switch, instead of the case block, if the case block is used as an incoming block of a PHI. This could potentially increase dynamic instructions, especially when the switch is in a loop. I added a test case which was reduced from the benchmark I was targetting.

Reviewers: t.p.northover, mcrosier, manmanren, wmi, joerg, davidxl

Subscribers: joerg, qcolombet, danielcdh, hfinkel, mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D22696

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@289988 91177308-0d34-0410-b5e6-96231b3b80d8
2016-12-16 20:38:39 +00:00
Jun Bum Lim
51900e49f9 Revert "[CodeGenPrep] Skip merging empty case blocks"
This reverts commit r289951.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@289960 91177308-0d34-0410-b5e6-96231b3b80d8
2016-12-16 17:06:14 +00:00
Jun Bum Lim
6db0eaf697 [CodeGenPrep] Skip merging empty case blocks
This is recommit of r287553 after fixing the invalid loop info after eliminating an empty block:

Summary: Merging an empty case block into the header block of switch could cause ISel to add COPY instructions in the header of switch, instead of the case block, if the case block is used as an incoming block of a PHI. This could potentially increase dynamic instructions, especially when the switch is in a loop. I added a test case which was reduced from the benchmark I was targetting.

Reviewers: t.p.northover, mcrosier, manmanren, wmi, joerg, davidxl

Subscribers: joerg, qcolombet, danielcdh, hfinkel, mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D22696

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@289951 91177308-0d34-0410-b5e6-96231b3b80d8
2016-12-16 16:03:31 +00:00
Joerg Sonnenberger
46cc79217b Revert r287553: [CodeGenPrep] Skip merging empty case blocks
It results in assertions in lib/Analysis/BlockFrequencyInfoImpl.cpp line
670 ("Expected irreducible CFG").


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@288052 91177308-0d34-0410-b5e6-96231b3b80d8
2016-11-28 18:56:54 +00:00
Jun Bum Lim
b68036c70c [CodeGenPrep] Skip merging empty case blocks
Summary: Merging an empty case block into the header block of switch could cause
ISel to add COPY instructions in the header of switch, instead of the case
block, if the case block is used as an incoming block of a PHI. This could
potentially increase dynamic instructions, especially when the switch is in a
loop. I added a test case which was reduced from the benchmark I was targetting.

Reviewers: t.p.northover, mcrosier, manmanren, wmi, davidxl

Subscribers: qcolombet, danielcdh, hfinkel, mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D22696

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@287553 91177308-0d34-0410-b5e6-96231b3b80d8
2016-11-21 16:47:28 +00:00