Commit Graph

7 Commits

Author SHA1 Message Date
modimo 5caad9b5d3 [InlineAdvisor] Add fallback/format switches and negative remark processing to Replay Inliner
Adds the following switches:

1. --sample-profile-inline-replay-fallback/--cgscc-inline-replay-fallback: controls what the replay advisor does for inline sites that are not present in the replay. Options are:

 1. Original: defers to original advisor
 2. AlwaysInline: inline all sites not in replay
 3. NeverInline: inline no sites not in replay

2. --sample-profile-inline-replay-format/--cgscc-inline-replay-format: controls what format should be generated to match against the replay remarks. Options are:

  1. Line
  2. LineColumn
  3. LineDiscriminator
  4. LineColumnDiscriminator

Adds support for negative inlining decisions. These are denoted by "will not be inlined into" as compared to the positive "inlined into" in the remarks.

All of these together with the previous `--sample-profile-inline-replay-scope/--cgscc-inline-replay-scope` allow tweaking in how to apply replay. In my testing, I'm using:
1. --sample-profile-inline-replay-scope/--cgscc-inline-replay-scope = Function to only replay on a function
2. --sample-profile-inline-replay-fallback/--cgscc-inline-replay-fallback = NeverInline since I'm feeding in only positive remarks to the replay system
3. --sample-profile-inline-replay-format/--cgscc-inline-replay-format = Line since I'm generating the remarks from DWARF information from GCC which can conflict quite heavily in column number compared to Clang

An alternative configuration could be to do Function, AlwaysInline, Line fallback with negative remarks which closer matches the final call-sites. Note that this can lead to unbounded inlining if a negative remark doesn't match/exist for one reason or another.

Updated various tests to cover the new switches and negative remarks

Testing:
ninja check-all

Reviewed By: wenlei, mtrofin

Differential Revision: https://reviews.llvm.org/D112040
2021-10-29 12:32:03 -07:00
Steven Wan 57cb84f5a2 Point replay file to non-existent dummy
Operating systems such as AIX allow open and read on directories, passing in a direcotry as the replay file triggers `Invalid remark format` instead of `Could not open remarks file: Is a directory`. This patch substitutes the directory with a non-existent filename. The current filecheck should still work as-is.

Reviewed By: modimo, Whitney

Differential Revision: https://reviews.llvm.org/D112745
2021-10-29 11:58:40 -04:00
modimo 41f814589f [InlineAdvisor][NFC] Fix tests added in D110658 V2
On Windows there's an *.exe suffix to opt that isn't present in Linux.
Remove the check for opt in the string
2021-10-18 15:27:33 -07:00
modimo 2786dc1096 [InlineAdvisor][NFC] Fix tests added in D110658 on
Windows which outputs "is a directory" rather than "Is a directory" on error compared to linux
2021-10-18 14:21:01 -07:00
modimo 313c657fce [InlineAdvisor] Add -inline-replay-scope=<Function|Module> to control replay scope
The goal is to allow grafting an inline tree from Clang or GCC into a new compilation without affecting other functions. For GCC, we're doing this by extracting the inline tree from dwarf information and generating the equivalent remarks.

This allows easier side-by-side asm analysis and a trial way to see if a particular inlining setup provides benefits by itself.

Testing:
ninja check-all

Reviewed By: wenlei, mtrofin

Differential Revision: https://reviews.llvm.org/D110658
2021-10-18 13:08:39 -07:00
Fangrui Song 76093b1739 [InlineAdvisor] Add single quotes around caller/callee names
Clang diagnostics refer to identifier names in quotes.
This patch makes inline remarks conform to the convention.
New behavior:

```
% clang -O2 -Rpass=inline -Rpass-missed=inline -S a.c
a.c:4:25: remark: 'foo' inlined into 'bar' with (cost=-30, threshold=337) at callsite bar:0:25; [-Rpass=inline]
int bar(int a) { return foo(a); }
                        ^
```

Reviewed By: hoy

Differential Revision: https://reviews.llvm.org/D107791
2021-08-10 11:51:31 -07:00
modimo ce7f9cdb50 [InlineAdvisor] Allow replay of inline decisions for the CGSCC inliner from optimization remarks
This change leverages the work done in D83743 to replay in the SampleProfile inliner to also be used in the CGSCC inliner. NOTE: currently restricted to non-ML advisors only.

The added switch `-cgscc-inline-replay=<remarks file>` will replay the inlining decisions in that file where the remarks file is generated via `-Rpass=inline`. The aim here is to make it easier to analyze changes that would modify inlining heuristics to be separated from this behavior. Doing so allows easier examination of assembly and runtime behavior compared to the baseline rather than trying to dig through the large churn caused by inlining.

In LTO compilation, since inlining is done twice you can separately specify replay by passing the flag to the FE (`-cgscc-inline-replay=`) and to the linker (`-Wl,cgscc-inline-replay=`) with the remarks generated from their respective places.

Testing on mysqld by comparing the inline decisions between base (generates remarks.txt) and diff (replay using identical input/tools with remarks.txt) and examining the inlining sites with `diff` shows 14,000 mismatches out of 247,341 for a ~94% replay accuracy. I believe this gap can be narrowed further though for the general case we may never achieve full accuracy. For my personal use, this is close enough to be representative: I set the baseline as the one generated by the replay on identical input/toolset and compare that to my modified input/toolset using the same replay.

Testing:
ninja check-llvm
newly added test correctly replays CGSCC inlining decisions

Reviewed By: mtrofin, wenlei

Differential Revision: https://reviews.llvm.org/D94334
2021-01-25 15:38:57 -08:00