[HCS] Externd to outline overlapping sub/super cold regions (#80732)

Currently, with hot cold splitting, when a cold region is identified, it
is added to the region list of ColdBlocks. Then when an

[HCS] Externd to outline overlapping sub/super cold regions (#80732)

Currently, with hot cold splitting, when a cold region is identified, it
is added to the region list of ColdBlocks. Then when another cold region
(B) identified overlaps with a ColdBlocks region (A) already added to
the list, the region B is not added to the list because of the
overlapping with region A. The splitting analysis is performed, and the
region A may not get split, for example, if it’s considered too
expansive. This is to improve the handling the overlapping case when the
region A is not considered good for splitting, while the region B is
good for splitting.
 
The change is to move the cold region splitting analysis earlier to
allow more cold region splitting. If an identified region cannot be
split, it will not be added to the candidate list of ColdBlocks for
overlapping check.

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[NFC] Port all (but one) HotColdSplit tests to `-passes=` syntax

HotColdSplit: Convert tests to opaque pointers

For some reason the script was deleting the assume declaration in
assumption-cache-invalidation.ll, so fixed that manually.

HotColdSplit: Don't use anonymous values in test

These were interfering with the conversion to opaque pointers

[HotColdSplit] Reflect full cost of parameters in split penalty

Make the penalty for splitting a region more accurately reflect the cost
of materializing all of the inputs/outputs to/from the region

[HotColdSplit] Reflect full cost of parameters in split penalty

Make the penalty for splitting a region more accurately reflect the cost
of materializing all of the inputs/outputs to/from the region.

This almost entirely eliminates code growth within functions which
undergo splitting in key internal frameworks, and reduces the size of
those frameworks between 2.6% to 3%.

rdar://49167240

Patch by: Vedant Kumar(@vsk)
Reviewers: hiraditya,rjf,t.p.northover
Reviewed By: hiraditya,rjf

Differential Revision: https://reviews.llvm.org/D59715

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Revert "[PM/CC1] Add -f[no-]split-cold-code CC1 option to toggle splitting"

This broke Chromium's PGO build, it seems because hot-cold-splitting got turned
on unintentionally. See comment on the cod

Revert "[PM/CC1] Add -f[no-]split-cold-code CC1 option to toggle splitting"

This broke Chromium's PGO build, it seems because hot-cold-splitting got turned
on unintentionally. See comment on the code review for repro etc.

> This patch adds -f[no-]split-cold-code CC1 options to clang. This allows
> the splitting pass to be toggled on/off. The current method of passing
> `-mllvm -hot-cold-split=true` to clang isn't ideal as it may not compose
> correctly (say, with `-O0` or `-Oz`).
>
> To implement the -fsplit-cold-code option, an attribute is applied to
> functions to indicate that they may be considered for splitting. This
> removes some complexity from the old/new PM pipeline builders, and
> behaves as expected when LTO is enabled.
>
> Co-authored by: Saleem Abdulrasool <compnerd@compnerd.org>
> Differential Revision: https://reviews.llvm.org/D57265
> Reviewed By: Aditya Kumar, Vedant Kumar
> Reviewers: Teresa Johnson, Aditya Kumar, Fedor Sergeev, Philip Pfaffe, Vedant Kumar

This reverts commit 273c299d5d649a0222fbde03c9a41e41913751b4.

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[PM/CC1] Add -f[no-]split-cold-code CC1 option to toggle splitting

This patch adds -f[no-]split-cold-code CC1 options to clang. This allows
the splitting pass to be toggled on/off. The current metho

[PM/CC1] Add -f[no-]split-cold-code CC1 option to toggle splitting

This patch adds -f[no-]split-cold-code CC1 options to clang. This allows
the splitting pass to be toggled on/off. The current method of passing
`-mllvm -hot-cold-split=true` to clang isn't ideal as it may not compose
correctly (say, with `-O0` or `-Oz`).

To implement the -fsplit-cold-code option, an attribute is applied to
functions to indicate that they may be considered for splitting. This
removes some complexity from the old/new PM pipeline builders, and
behaves as expected when LTO is enabled.

Co-authored by: Saleem Abdulrasool <compnerd@compnerd.org>
Differential Revision: https://reviews.llvm.org/D57265
Reviewed By: Aditya Kumar, Vedant Kumar
Reviewers: Teresa Johnson, Aditya Kumar, Fedor Sergeev, Philip Pfaffe, Vedant Kumar

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[CodeExtractor] Remove stale llvm.assume calls from extracted region

During extraction, stale llvm.assume handles may be retained in the
original function. The setup is:

1) CodeExtractor unregister

[CodeExtractor] Remove stale llvm.assume calls from extracted region

During extraction, stale llvm.assume handles may be retained in the
original function. The setup is:

1) CodeExtractor unregisters assumptions in the blocks that are to be
extracted.

2) Extraction happens. There are now two functions: f1 and f1.extracted.

3) Leftover assumptions in f1 (/not/ removed as they were not in the set of
blocks to be extracted) now have affected-value llvm.assume handles in
f1.extracted.

When assumptions for a value used in f1 are looked up, ValueTracking can assert
as some of the handles are in the wrong function. To fix this, simply erase the
llvm.assume calls in the extracted function.

Alternatives include flushing the assumption cache in the original function, or
walking all values used in the original function to prune stale affected-value
handles. Both seem more expensive.

Testing: check-llvm, LNT run with -mllvm -hot-cold-split enabled

rdar://58460728

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Invalidate assumption cache before outlining.

Subscribers: llvm-commits

Tags: #llvm

Reviewers: compnerd, vsk, sebpop, fhahn, tejohnson

Reviewed by: vsk

Differential Revision: https://reviews.llv

Invalidate assumption cache before outlining.

Subscribers: llvm-commits

Tags: #llvm

Reviewers: compnerd, vsk, sebpop, fhahn, tejohnson

Reviewed by: vsk

Differential Revision: https://reviews.llvm.org/D68478

llvm-svn: 373807

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HotColdSplitting: invalidate the AssumptionCache on split

When a cold path is outlined, the value tracking in the assumption cache may be
invalidated due to the code motion. We would previously tri

HotColdSplitting: invalidate the AssumptionCache on split

When a cold path is outlined, the value tracking in the assumption cache may be
invalidated due to the code motion. We would previously trip an assertion in
subsequent passes (but required the passes to happen in a single run as the
assumption cache is shared across the passes). Invalidating the cache ensures
that we get the correct information when needed with the legacy pass manager as
well.

llvm-svn: 372667

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