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[thinlto] Basic thinlto fdo heuristic

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Summary:
This patch improves thinlto importer
by importing 3x larger functions that are called from hot block.

I compared performance with the trunk on spec, and there
were about 2% on povray and 3.33% on milc. These results seems
to be consistant and match the results Teresa got with her simple
heuristic. Some benchmarks got slower but I think they are just
noisy (mcf, xalancbmki, omnetpp)- running the benchmarks again with
more iterations to confirm. Geomean of all benchmarks including the noisy ones
were about +0.02%.

I see much better improvement on google branch with Easwaran patch
for pgo callsite inlining (the inliner actually inline those big functions)
Over all I see +0.5% improvement, and I get +8.65% on povray.
So I guess we will see much bigger change when Easwaran patch will land
(it depends on new pass manager), but it is still worth putting this to trunk
before it.

Implementation details changes:
- Removed CallsiteCount.
- ProfileCount got replaced by Hotness
- hot-import-multiplier is set to 3.0 for now,
didn't have time to tune it up, but I see that we get most of the interesting
functions with 3, so there is no much performance difference with higher, and
binary size doesn't grow as much as with 10.0.

Reviewers: eraman, mehdi_amini, tejohnson

Subscribers: mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D24638

llvm-svn: 282437
This commit is contained in:
Piotr Padlewski
2016-09-26 20:37:32 +00:00
parent 2cd84c905d
commit d9830eb79f
21 changed files with 422 additions and 80 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
llvm/test/Bitcode/thinlto-function-summary-refgraph.ll
View File

@@ -11,20 +11,20 @@
; llvm.ctpop.i8.
; CHECK: <GLOBALVAL_SUMMARY_BLOCK
; Function main contains call to func, as well as address reference to func:
; CHECK-DAG: <PERMODULE {{.*}} op0=[[MAINID:[0-9]+]] op1=0 {{.*}} op3=1 op4=[[FUNCID:[0-9]+]] op5=[[FUNCID]] op6=1/>
; CHECK-DAG: <PERMODULE {{.*}} op0=[[MAINID:[0-9]+]] op1=0 {{.*}} op3=1 op4=[[FUNCID:[0-9]+]] op5=[[FUNCID]]/>
; Function W contains a call to func3 as well as a reference to globalvar:
; CHECK-DAG: <PERMODULE {{.*}} op0=[[WID:[0-9]+]] op1=5 {{.*}} op3=1 op4=[[GLOBALVARID:[0-9]+]] op5=[[FUNC3ID:[0-9]+]] op6=1/>
; CHECK-DAG: <PERMODULE {{.*}} op0=[[WID:[0-9]+]] op1=5 {{.*}} op3=1 op4=[[GLOBALVARID:[0-9]+]] op5=[[FUNC3ID:[0-9]+]]/>
; Function X contains call to foo, as well as address reference to foo
; which is in the same instruction as the call:
; CHECK-DAG: <PERMODULE {{.*}} op0=[[XID:[0-9]+]] op1=1 {{.*}} op3=1 op4=[[FOOID:[0-9]+]] op5=[[FOOID]] op6=1/>
; CHECK-DAG: <PERMODULE {{.*}} op0=[[XID:[0-9]+]] op1=1 {{.*}} op3=1 op4=[[FOOID:[0-9]+]] op5=[[FOOID]]/>
; Function Y contains call to func2, and ensures we don't incorrectly add
; a reference to it when reached while earlier analyzing the phi using its
; return value:
; CHECK-DAG: <PERMODULE {{.*}} op0=[[YID:[0-9]+]] op1=8 {{.*}} op3=0 op4=[[FUNC2ID:[0-9]+]] op5=1/>
; CHECK-DAG: <PERMODULE {{.*}} op0=[[YID:[0-9]+]] op1=8 {{.*}} op3=0 op4=[[FUNC2ID:[0-9]+]]/>
; Function Z contains call to func2, and ensures we don't incorrectly add
; a reference to it when reached while analyzing subsequent use of its return
; value:
; CHECK-DAG: <PERMODULE {{.*}} op0=[[ZID:[0-9]+]] op1=3 {{.*}} op3=0 op4=[[FUNC2ID:[0-9]+]] op5=1/>
; CHECK-DAG: <PERMODULE {{.*}} op0=[[ZID:[0-9]+]] op1=3 {{.*}} op3=0 op4=[[FUNC2ID:[0-9]+]]/>
; Variable bar initialization contains address reference to func:
; CHECK-DAG: <PERMODULE_GLOBALVAR_INIT_REFS {{.*}} op0=[[BARID:[0-9]+]] op1=0 op2=[[FUNCID]]/>
; CHECK: </GLOBALVAL_SUMMARY_BLOCK>