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Revision tags: llvmorg-20.1.0, llvmorg-20.1.0-rc3, llvmorg-20.1.0-rc2, llvmorg-20.1.0-rc1, llvmorg-21-init, llvmorg-19.1.7, llvmorg-19.1.6, llvmorg-19.1.5, llvmorg-19.1.4, llvmorg-19.1.3, llvmorg-19.1.2, llvmorg-19.1.1, llvmorg-19.1.0, llvmorg-19.1.0-rc4, llvmorg-19.1.0-rc3, llvmorg-19.1.0-rc2, llvmorg-19.1.0-rc1, llvmorg-20-init, llvmorg-18.1.8, llvmorg-18.1.7, llvmorg-18.1.6, llvmorg-18.1.5, llvmorg-18.1.4, llvmorg-18.1.3, llvmorg-18.1.2, llvmorg-18.1.1, llvmorg-18.1.0, llvmorg-18.1.0-rc4, llvmorg-18.1.0-rc3, llvmorg-18.1.0-rc2, llvmorg-18.1.0-rc1, llvmorg-19-init, llvmorg-17.0.6, llvmorg-17.0.5, llvmorg-17.0.4, llvmorg-17.0.3, llvmorg-17.0.2, llvmorg-17.0.1, llvmorg-17.0.0, llvmorg-17.0.0-rc4, llvmorg-17.0.0-rc3, llvmorg-17.0.0-rc2, llvmorg-17.0.0-rc1, llvmorg-18-init, llvmorg-16.0.6, llvmorg-16.0.5, llvmorg-16.0.4, llvmorg-16.0.3, llvmorg-16.0.2, llvmorg-16.0.1, llvmorg-16.0.0, llvmorg-16.0.0-rc4, llvmorg-16.0.0-rc3, llvmorg-16.0.0-rc2, llvmorg-16.0.0-rc1, llvmorg-17-init, llvmorg-15.0.7, llvmorg-15.0.6, llvmorg-15.0.5, llvmorg-15.0.4, llvmorg-15.0.3, llvmorg-15.0.2, llvmorg-15.0.1, llvmorg-15.0.0, llvmorg-15.0.0-rc3, llvmorg-15.0.0-rc2, llvmorg-15.0.0-rc1, llvmorg-16-init, llvmorg-14.0.6, llvmorg-14.0.5, llvmorg-14.0.4, llvmorg-14.0.3, llvmorg-14.0.2, llvmorg-14.0.1, llvmorg-14.0.0, llvmorg-14.0.0-rc4, llvmorg-14.0.0-rc3, llvmorg-14.0.0-rc2, llvmorg-14.0.0-rc1, llvmorg-15-init, llvmorg-13.0.1, llvmorg-13.0.1-rc3, llvmorg-13.0.1-rc2, llvmorg-13.0.1-rc1, llvmorg-13.0.0, llvmorg-13.0.0-rc4, llvmorg-13.0.0-rc3, llvmorg-13.0.0-rc2, llvmorg-13.0.0-rc1, llvmorg-14-init, llvmorg-12.0.1, llvmorg-12.0.1-rc4, llvmorg-12.0.1-rc3, llvmorg-12.0.1-rc2, llvmorg-12.0.1-rc1, llvmorg-12.0.0, llvmorg-12.0.0-rc5, llvmorg-12.0.0-rc4, llvmorg-12.0.0-rc3, llvmorg-12.0.0-rc2, llvmorg-11.1.0, llvmorg-11.1.0-rc3, llvmorg-12.0.0-rc1, llvmorg-13-init, llvmorg-11.1.0-rc2, llvmorg-11.1.0-rc1, llvmorg-11.0.1, llvmorg-11.0.1-rc2, llvmorg-11.0.1-rc1, llvmorg-11.0.0, llvmorg-11.0.0-rc6, llvmorg-11.0.0-rc5, llvmorg-11.0.0-rc4, llvmorg-11.0.0-rc3, llvmorg-11.0.0-rc2, llvmorg-11.0.0-rc1, llvmorg-12-init, llvmorg-10.0.1, llvmorg-10.0.1-rc4, llvmorg-10.0.1-rc3, llvmorg-10.0.1-rc2, llvmorg-10.0.1-rc1, llvmorg-10.0.0, llvmorg-10.0.0-rc6, llvmorg-10.0.0-rc5, llvmorg-10.0.0-rc4, llvmorg-10.0.0-rc3, llvmorg-10.0.0-rc2, llvmorg-10.0.0-rc1, llvmorg-11-init, llvmorg-9.0.1, llvmorg-9.0.1-rc3, llvmorg-9.0.1-rc2, llvmorg-9.0.1-rc1, llvmorg-9.0.0, llvmorg-9.0.0-rc6, llvmorg-9.0.0-rc5, llvmorg-9.0.0-rc4, llvmorg-9.0.0-rc3, llvmorg-9.0.0-rc2, llvmorg-9.0.0-rc1, llvmorg-10-init, llvmorg-8.0.1, llvmorg-8.0.1-rc4, llvmorg-8.0.1-rc3
# d2210af3 14-Jun-2019 Guozhi Wei <[email protected]>

[MBP] Move a latch block with conditional exit and multi predecessors to top of loop

Current findBestLoopTop can find and move one kind of block to top, a latch block has one successor. Another comm

[MBP] Move a latch block with conditional exit and multi predecessors to top of loop

Current findBestLoopTop can find and move one kind of block to top, a latch block has one successor. Another common case is:

* a latch block
* it has two successors, one is loop header, another is exit
* it has more than one predecessors

If it is below one of its predecessors P, only P can fall through to it, all other predecessors need a jump to it, and another conditional jump to loop header. If it is moved before loop header, all its predecessors jump to it, then fall through to loop header. So all its predecessors except P can reduce one taken branch.

Differential Revision: https://reviews.llvm.org/D43256

llvm-svn: 363471

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Revision tags: llvmorg-8.0.1-rc2, llvmorg-8.0.1-rc1, llvmorg-8.0.0, llvmorg-8.0.0-rc5, llvmorg-8.0.0-rc4, llvmorg-8.0.0-rc3, llvmorg-7.1.0, llvmorg-7.1.0-rc1, llvmorg-8.0.0-rc2, llvmorg-8.0.0-rc1, llvmorg-7.0.1, llvmorg-7.0.1-rc3, llvmorg-7.0.1-rc2, llvmorg-7.0.1-rc1, llvmorg-7.0.0, llvmorg-7.0.0-rc3, llvmorg-7.0.0-rc2, llvmorg-7.0.0-rc1, llvmorg-6.0.1, llvmorg-6.0.1-rc3, llvmorg-6.0.1-rc2, llvmorg-6.0.1-rc1, llvmorg-5.0.2, llvmorg-5.0.2-rc2, llvmorg-5.0.2-rc1, llvmorg-6.0.0, llvmorg-6.0.0-rc3, llvmorg-6.0.0-rc2, llvmorg-6.0.0-rc1, llvmorg-5.0.1, llvmorg-5.0.1-rc3, llvmorg-5.0.1-rc2, llvmorg-5.0.1-rc1, llvmorg-5.0.0, llvmorg-5.0.0-rc5, llvmorg-5.0.0-rc4, llvmorg-5.0.0-rc3, llvmorg-5.0.0-rc2, llvmorg-5.0.0-rc1
# 0e831c99 11-Jul-2017 Serguei Katkov <[email protected]>

Revert Revert [MBP] do not rotate loop if it creates extra branch

This is a second attempt to land this patch.

The first one resulted in a crash of clang sanitizer buildbot.
The fix is here and reg

Revert Revert [MBP] do not rotate loop if it creates extra branch

This is a second attempt to land this patch.

The first one resulted in a crash of clang sanitizer buildbot.
The fix is here and regression test is added.

This is a last fix for the corner case of PR32214. Actually this is not really corner case in general.

We should not do a loop rotation if we create an additional branch due to it.
Consider the case where we have a loop chain H, M, B, C , where
H is header with viable fallthrough from pre-header and exit from the loop
M - some middle block
B - backedge to Header but with exit from the loop also.
C - some cold block of the loop.

Let's H is determined as a best exit. If we do a loop rotation M, B, C, H we can introduce the extra branch.
Let's compute the change in number of branches:
+1 branch from pre-header to header
-1 branch from header to exit
+1 branch from header to middle block if there is such
-1 branch from cold bock to header if there is one

So if C is not a predecessor of H then we introduce extra branch.

This change actually prohibits rotation of the loop if both true
Best Exit has next element in chain as successor.
Last element in chain is not a predecessor of first element of chain.

Reviewers: iteratee, xur, sammccall, chandlerc
Reviewed By: iteratee
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34745

llvm-svn: 307631

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# 0e70206c 26-Jun-2017 Serguei Katkov <[email protected]>

This reverts commit r306272.

Revert "[MBP] do not rotate loop if it creates extra branch"

It breaks the sanitizer build bots. Need to fix this.

llvm-svn: 306276


# b01fff06 26-Jun-2017 Serguei Katkov <[email protected]>

[MBP] do not rotate loop if it creates extra branch

This is a last fix for the corner case of PR32214. Actually this is not really corner case in general.

We should not do a loop rotation if we cre

[MBP] do not rotate loop if it creates extra branch

This is a last fix for the corner case of PR32214. Actually this is not really corner case in general.

We should not do a loop rotation if we create an additional branch due to it.
Consider the case where we have a loop chain H, M, B, C , where
H is header with viable fallthrough from pre-header and exit from the loop
M - some middle block
B - backedge to Header but with exit from the loop also.
C - some cold block of the loop.

Let's H is determined as a best exit. If we do a loop rotation M, B, C, H we can introduce the extra branch.
Let's compute the change in number of branches:
+1 branch from pre-header to header
-1 branch from header to exit
+1 branch from header to middle block if there is such
-1 branch from cold bock to header if there is one

So if C is not a predecessor of H then we introduce extra branch.

This change actually prohibits rotation of the loop if both true
1) Best Exit has next element in chain as successor.
2) Last element in chain is not a predecessor of first element of chain.

Reviewers: iteratee, xur
Reviewed By: iteratee
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34271

llvm-svn: 306272

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Revision tags: llvmorg-4.0.1, llvmorg-4.0.1-rc3, llvmorg-4.0.1-rc2, llvmorg-4.0.1-rc1, llvmorg-4.0.0, llvmorg-4.0.0-rc4, llvmorg-4.0.0-rc3, llvmorg-4.0.0-rc2, llvmorg-4.0.0-rc1, llvmorg-3.9.1, llvmorg-3.9.1-rc3, llvmorg-3.9.1-rc2, llvmorg-3.9.1-rc1, llvmorg-3.9.0, llvmorg-3.9.0-rc3, llvmorg-3.9.0-rc2, llvmorg-3.9.0-rc1, llvmorg-3.8.1, llvmorg-3.8.1-rc1
# 029a0567 19-Apr-2016 Mandeep Singh Grang <[email protected]>

[LLVM] Remove unwanted --check-prefix=CHECK from unit tests. NFC.

Summary: Removed unwanted --check-prefix=CHECK from numerous unit tests.

Reviewers: t.p.northover, dblaikie, uweigand, MatzeB, tste

[LLVM] Remove unwanted --check-prefix=CHECK from unit tests. NFC.

Summary: Removed unwanted --check-prefix=CHECK from numerous unit tests.

Reviewers: t.p.northover, dblaikie, uweigand, MatzeB, tstellarAMD, mcrosier

Subscribers: mcrosier, dsanders

Differential Revision: http://reviews.llvm.org/D19279

llvm-svn: 266834

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Revision tags: llvmorg-3.8.0, llvmorg-3.8.0-rc3, llvmorg-3.8.0-rc2, llvmorg-3.8.0-rc1, llvmorg-3.7.1, llvmorg-3.7.1-rc2, llvmorg-3.7.1-rc1
# b90b9e05 02-Nov-2015 Cong Hou <[email protected]>

In MachineBlockPlacement, filter cold blocks off the loop chain when profile data is available.

In the current BB placement algorithm, a loop chain always contains all loop blocks. This has a drawba

In MachineBlockPlacement, filter cold blocks off the loop chain when profile data is available.

In the current BB placement algorithm, a loop chain always contains all loop blocks. This has a drawback that cold blocks in the loop may be inserted on a hot function path, hence increasing branch cost and also reducing icache locality.

Consider a simple example shown below:

A
|
B⇆C
|
D

When B->C is quite cold, the best BB-layout should be A,B,D,C. But the current implementation produces A,C,B,D.

This patch filters those cold blocks off from the loop chain by comparing the ratio:

LoopBBFreq / LoopFreq

to 20%: if it is less than 20%, we don't include this BB to the loop chain. Here LoopFreq is the frequency of the loop when we reduce the loop into a single node. In general we have more cold blocks when the loop has few iterations. And vice versa.


Differential revision: http://reviews.llvm.org/D11662

llvm-svn: 251833

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