[CodeGen]: BlockPlacement: Apply const liberally. NFC

Anything that needs to be passed to AnalyzeBranch unfortunately can't be const,
or more would be const. Added const_iterator to BlockChain to al

[CodeGen]: BlockPlacement: Apply const liberally. NFC

Anything that needs to be passed to AnalyzeBranch unfortunately can't be const,
or more would be const. Added const_iterator to BlockChain to allow
BlockChain to be const when we don't expect to change it.

llvm-svn: 294085

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[PGO] internal option cleanups

1. Added comments for options
2. Added missing option cl::desc field
3. Uniified function filter option for graph viewing.
Now PGO count/raw-counts share the same

[PGO] internal option cleanups

1. Added comments for options
2. Added missing option cl::desc field
3. Uniified function filter option for graph viewing.
Now PGO count/raw-counts share the same
filter option: -view-bfi-func-name=.

llvm-svn: 293938

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[PGO] make graph view internal options available for all builds

Differential Revision: https://reviews.llvm.org/D29259

llvm-svn: 293921

CodeGen: Allow small copyable blocks to "break" the CFG.

When choosing the best successor for a block, ordinarily we would have preferred
a block that preserves the CFG unless there is a strong prob

CodeGen: Allow small copyable blocks to "break" the CFG.

When choosing the best successor for a block, ordinarily we would have preferred
a block that preserves the CFG unless there is a strong probability the other
direction. For small blocks that can be duplicated we now skip that requirement
as well, subject to some simple frequency calculations.

Differential Revision: https://reviews.llvm.org/D28583

llvm-svn: 293716

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Add support to dump dot graph block layout after MBP

Differential Revision: https://reviews.llvm.org/D29141

llvm-svn: 293408

Revert "CodeGen: Allow small copyable blocks to "break" the CFG."

This reverts commit ada6595a526d71df04988eb0a4b4fe84df398ded.

This needs a simple probability check because there are some cases wh

Revert "CodeGen: Allow small copyable blocks to "break" the CFG."

This reverts commit ada6595a526d71df04988eb0a4b4fe84df398ded.

This needs a simple probability check because there are some cases where it is
not profitable.

llvm-svn: 291695

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CodeGen: Allow small copyable blocks to "break" the CFG.

When choosing the best successor for a block, ordinarily we would have preferred
a block that preserves the CFG unless there is a strong prob

CodeGen: Allow small copyable blocks to "break" the CFG.

When choosing the best successor for a block, ordinarily we would have preferred
a block that preserves the CFG unless there is a strong probability the other
direction. For small blocks that can be duplicated we now skip that requirement
as well.

Differential revision: https://reviews.llvm.org/D27742

llvm-svn: 291609

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Trying to fix NDEBUG build after r289764

llvm-svn: 289766

[MachineBlockPlacement] Don't make blocks "uneditable"

Summary:
This fixes an issue with MachineBlockPlacement due to a badly timed call
to `analyzeBranch` with `AllowModify` set to true. The timel

[MachineBlockPlacement] Don't make blocks "uneditable"

Summary:
This fixes an issue with MachineBlockPlacement due to a badly timed call
to `analyzeBranch` with `AllowModify` set to true. The timeline is as
follows:

1. `MachineBlockPlacement::maybeTailDuplicateBlock` calls
`TailDup.shouldTailDuplicate` on its argument, which in turn calls
`analyzeBranch` with `AllowModify` set to true.

2. This `analyzeBranch` call edits the terminator sequence of the block
based on the physical layout of the machine function, turning an
unanalyzable non-fallthrough block to a unanalyzable fallthrough
block. Normally MBP bails out of rearranging such blocks, but this
block was unanalyzable non-fallthrough (and thus rearrangeable) the
first time MBP looked at it, and so it goes ahead and decides where
it should be placed in the function.

3. When placing this block MBP fails to analyze and thus update the
block in keeping with the new physical layout.

Concretely, before (1) we have something like:

```
LBL0:
< unknown terminator op that may branch to LBL1 >
jmp LBL1

LBL1:
... A

LBL2:
... B
```

In (2), analyze branch simplifies this to

```
LBL0:
< unknown terminator op that may branch to LBL2 >
;; jmp LBL1 <- redundant jump removed

LBL1:
... A

LBL2:
... B
```

In (3), MachineBlockPlacement goes ahead with its plan of putting LBL2
after the first block since that is profitable.

```
LBL0:
< unknown terminator op that may branch to LBL2 >
;; jmp LBL1 <- redundant jump

LBL2:
... B

LBL1:
... A
```

and the program now has incorrect behavior (we no longer fall-through
from `LBL0` to `LBL1`) because MBP can no longer edit LBL0.

There are several possible solutions, but I went with removing the teeth
off of the `analyzeBranch` calls in TailDuplicator. That makes thinking
about the result of these calls easier, and breaks nothing in the lit
test suite.

I've also added some bookkeeping to the MachineBlockPlacement pass and
used that to write an assert that would have caught this.

Reviewers: chandlerc, gberry, MatzeB, iteratee

Subscribers: mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D27783

llvm-svn: 289764

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Make block placement deterministic

We fail to produce bit-to-bit matching stage2 and stage3 compiler in PGO
bootstrap build. The reason is because LoopBlockSet is of SmallPtrSet type
whose iterating

Make block placement deterministic

We fail to produce bit-to-bit matching stage2 and stage3 compiler in PGO
bootstrap build. The reason is because LoopBlockSet is of SmallPtrSet type
whose iterating order depends on the pointer value.

This patch fixes this issue by changing to use SmallSetVector.

Differential Revision: http://reviews.llvm.org/D26634

llvm-svn: 287148

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Move the initialization of PreferredLoopExit into runOnMachineFunction to be near the other function specific initializations.

llvm-svn: 285758

Fix uninitialized access in MachineBlockPlacement.

Summary:
Currently PreferredLoopExit is set only in buildLoopChains, which is
never called if there are no MachineLoops.

MSan is currently broken

Fix uninitialized access in MachineBlockPlacement.

Summary:
Currently PreferredLoopExit is set only in buildLoopChains, which is
never called if there are no MachineLoops.

MSan is currently broken by this:
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast/builds/145/steps/check-llvm%20msan/logs/stdio

This is a naive fix to get things green again. iteratee: you may have a better fix.

This change will also mean PreferredLoopExit will not carry over if
buildCFGChains() is called a second time in runOnMachineFunction, this
appears to be the right thing.

Reviewers: bkramer, iteratee, echristo

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D26069

llvm-svn: 285757

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CodeGen: Handle missed case of block removal during BlockPlacement.

There is a use after free bug in the existing code. Loop layout selects
a preferred exit block, and then lays out the loop. If thi

CodeGen: Handle missed case of block removal during BlockPlacement.

There is a use after free bug in the existing code. Loop layout selects
a preferred exit block, and then lays out the loop. If this block is
removed during layout, it needs to be invalidated to prevent a use after
free.

llvm-svn: 285348

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Codegen: Tail-duplicate during placement.

The tail duplication pass uses an assumed layout when making duplication
decisions. This is fine, but passes up duplication opportunities that
may arise whe

Codegen: Tail-duplicate during placement.

The tail duplication pass uses an assumed layout when making duplication
decisions. This is fine, but passes up duplication opportunities that
may arise when blocks are outlined. Because we want the updated CFG to
affect subsequent placement decisions, this change must occur during
placement.

In order to achieve this goal, TailDuplicationPass is split into a
utility class, TailDuplicator, and the pass itself. The pass delegates
nearly everything to the TailDuplicator object, except for looping over
the blocks in a function. This allows the same code to be used for tail
duplication in both places.

This change, in concert with outlining optional branches, allows
triangle shaped code to perform much better, esepecially when the
taken/untaken branches are correlated, as it creates a second spine when
the tests are small enough.

Issue from previous rollback fixed, and a new test was added for that
case as well. Issue was worklist/scheduling/taildup issue in layout.

Issue from 2nd rollback fixed, with 2 additional tests. Issue was
tail merging/loop info/tail-duplication causing issue with loops that share
a header block.

Issue with early tail-duplication of blocks that branch to a fallthrough
predecessor fixed with test case: tail-dup-branch-to-fallthrough.ll

Differential revision: https://reviews.llvm.org/D18226

llvm-svn: 283934

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Revert "Codegen: Tail-duplicate during placement."

This reverts commit r283842.

test/CodeGen/X86/tail-dup-repeat.ll causes and llc crash with our
internal testing. I'll share a link with you.

llvm

Revert "Codegen: Tail-duplicate during placement."

This reverts commit r283842.

test/CodeGen/X86/tail-dup-repeat.ll causes and llc crash with our
internal testing. I'll share a link with you.

llvm-svn: 283857

show more ...

Codegen: Tail-duplicate during placement.

The tail duplication pass uses an assumed layout when making duplication
decisions. This is fine, but passes up duplication opportunities that
may arise whe

Codegen: Tail-duplicate during placement.

The tail duplication pass uses an assumed layout when making duplication
decisions. This is fine, but passes up duplication opportunities that
may arise when blocks are outlined. Because we want the updated CFG to
affect subsequent placement decisions, this change must occur during
placement.

In order to achieve this goal, TailDuplicationPass is split into a
utility class, TailDuplicator, and the pass itself. The pass delegates
nearly everything to the TailDuplicator object, except for looping over
the blocks in a function. This allows the same code to be used for tail
duplication in both places.

This change, in concert with outlining optional branches, allows
triangle shaped code to perform much better, esepecially when the
taken/untaken branches are correlated, as it creates a second spine when
the tests are small enough.

Issue from previous rollback fixed, and a new test was added for that
case as well. Issue was worklist/scheduling/taildup issue in layout.

Issue from 2nd rollback fixed, with 2 additional tests. Issue was
tail merging/loop info/tail-duplication causing issue with loops that share
a header block.

Issue with early tail-duplication of blocks that branch to a fallthrough
predecessor fixed with test case: tail-dup-branch-to-fallthrough.ll

Differential revision: https://reviews.llvm.org/D18226

llvm-svn: 283842

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Revert "Codegen: Tail-duplicate during placement."

This reverts commit 71c312652c10f1855b28d06697c08d47e7a243e4.

llvm-svn: 283647

Codegen: Tail-duplicate during placement.

The tail duplication pass uses an assumed layout when making duplication
decisions. This is fine, but passes up duplication opportunities that
may arise whe

Codegen: Tail-duplicate during placement.

The tail duplication pass uses an assumed layout when making duplication
decisions. This is fine, but passes up duplication opportunities that
may arise when blocks are outlined. Because we want the updated CFG to
affect subsequent placement decisions, this change must occur during
placement.

In order to achieve this goal, TailDuplicationPass is split into a
utility class, TailDuplicator, and the pass itself. The pass delegates
nearly everything to the TailDuplicator object, except for looping over
the blocks in a function. This allows the same code to be used for tail
duplication in both places.

This change, in concert with outlining optional branches, allows
triangle shaped code to perform much better, esepecially when the
taken/untaken branches are correlated, as it creates a second spine when
the tests are small enough.

Issue from previous rollback fixed, and a new test was added for that
case as well. Issue was worklist/scheduling/taildup issue in layout.

Issue from 2nd rollback fixed, with 2 additional tests. Issue was
tail merging/loop info/tail-duplication causing issue with loops that share
a header block.

Differential revision: https://reviews.llvm.org/D18226

llvm-svn: 283619

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Revert "Codegen: Tail-duplicate during placement."

This reverts commit 062ace9764953e9769142c1099281a345f9b6bdc.

Issue with loop info and block removal revealed by polly.
I have a fix for this issu

Revert "Codegen: Tail-duplicate during placement."

This reverts commit 062ace9764953e9769142c1099281a345f9b6bdc.

Issue with loop info and block removal revealed by polly.
I have a fix for this issue already in another patch, I'll re-roll this
together with that fix, and a test case.

llvm-svn: 283292

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Codegen: Tail-duplicate during placement.

The tail duplication pass uses an assumed layout when making duplication
decisions. This is fine, but passes up duplication opportunities that
may arise whe

Codegen: Tail-duplicate during placement.

The tail duplication pass uses an assumed layout when making duplication
decisions. This is fine, but passes up duplication opportunities that
may arise when blocks are outlined. Because we want the updated CFG to
affect subsequent placement decisions, this change must occur during
placement.

In order to achieve this goal, TailDuplicationPass is split into a
utility class, TailDuplicator, and the pass itself. The pass delegates
nearly everything to the TailDuplicator object, except for looping over
the blocks in a function. This allows the same code to be used for tail
duplication in both places.

This change, in concert with outlining optional branches, allows
triangle shaped code to perform much better, esepecially when the
taken/untaken branches are correlated, as it creates a second spine when
the tests are small enough.

Issue from previous rollback fixed, and a new test was added for that
case as well.

Differential revision: https://reviews.llvm.org/D18226

llvm-svn: 283274

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Revert "Codegen: Tail-duplicate during placement."

This reverts commit ff234efbe23528e4f4c80c78057b920a51f434b2.

Causing crashes on aarch64 build.

llvm-svn: 283172

Codegen: Tail-duplicate during placement.

The tail duplication pass uses an assumed layout when making duplication
decisions. This is fine, but passes up duplication opportunities that
may arise whe

Codegen: Tail-duplicate during placement.

The tail duplication pass uses an assumed layout when making duplication
decisions. This is fine, but passes up duplication opportunities that
may arise when blocks are outlined. Because we want the updated CFG to
affect subsequent placement decisions, this change must occur during
placement.

In order to achieve this goal, TailDuplicationPass is split into a
utility class, TailDuplicator, and the pass itself. The pass delegates
nearly everything to the TailDuplicator object, except for looping over
the blocks in a function. This allows the same code to be used for tail
duplication in both places.

This change, in concert with outlining optional branches, allows
triangle shaped code to perform much better, esepecially when the
taken/untaken branches are correlated, as it creates a second spine when
the tests are small enough.

llvm-svn: 283164

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Finish renaming remaining analyzeBranch functions

llvm-svn: 281535

Make analyzeBranch family of instruction names consistent

analyzeBranch was renamed to use lowercase first, rename
the related set to match.

llvm-svn: 281506

Branch Folding: Accept explicit threshold for tail merge size.

This is prep work for allowing the threshold to be different during layout,
and to enforce a single threshold between merging and dupli

Branch Folding: Accept explicit threshold for tail merge size.

This is prep work for allowing the threshold to be different during layout,
and to enforce a single threshold between merging and duplicating during
layout. No observable change intended.

llvm-svn: 279117

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