Summary:
Currently we skip merging when extra moves may be added in the header of switch instead of the case block, if the case block is used as an incoming
block of a PHI. If all the incoming values of the PHIs are non-constants and the destination block is dominated by the switch block then extra moves are likely not added by ISel, so there is no need to skip merging in this case.
Reviewers: efriedma, junbuml, davidxl, hfinkel, qcolombet
Reviewed By: efriedma
Subscribers: dberlin, kuhar, mcrosier, llvm-commits
Differential Revision: https://reviews.llvm.org/D37343
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316711 91177308-0d34-0410-b5e6-96231b3b80d8
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
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
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
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
