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[PGO] Fix select instruction annotation

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Summary:
Select instruction annotation in IR PGO uses the edge count to infer the
branch count. It's currently placed in setInstrumentedCounts() where
no all the BB counts have been computed. This leads to wrong branch weights.
Move the annotation after all BB counts are populated.

Reviewers: davidxl

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D25961

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@285128 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rong Xu 2016-10-25 21:47:24 +00:00
parent 908c768e1c
commit 0eba98aa7d
3 changed files with 61 additions and 4 deletions
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17
lib/Transforms/Instrumentation/PGOInstrumentation.cpp
View File

@ -642,7 +642,7 @@ public:
BranchProbabilityInfo *BPI = nullptr,
BlockFrequencyInfo *BFI = nullptr)
: F(Func), M(Modu), FuncInfo(Func, ComdatMembers, false, BPI, BFI),
FreqAttr(FFA_Normal) {}
CountPosition(0), ProfileCountSize(0), FreqAttr(FFA_Normal) {}
// Read counts for the instrumented BB from profile.
bool readCounters(IndexedInstrProfReader *PGOReader);
@ -682,6 +682,12 @@ private:
// compilation.
uint64_t ProgramMaxCount;
// Position of counter that remains to be read.
uint32_t CountPosition;
// Total size of the profile count for this function.
uint32_t ProfileCountSize;
// ProfileRecord for this function.
InstrProfRecord ProfileRecord;
@ -750,9 +756,8 @@ void PGOUseFunc::setInstrumentedCounts(
NewEdge1.InMST = true;
getBBInfo(InstrBB).setBBInfoCount(CountValue);
}
// Now annotate select instructions
FuncInfo.SIVisitor.annotateSelects(F, this, &I);
assert(I == CountFromProfile.size());
ProfileCountSize = CountFromProfile.size();
CountPosition = I;
}
// Set the count value for the unknown edge. There should be one and only one
@ -892,6 +897,10 @@ void PGOUseFunc::populateCounters() {
FuncMaxCount = std::max(FuncMaxCount, getBBInfo(&BB).CountValue);
markFunctionAttributes(FuncEntryCount, FuncMaxCount);
// Now annotate select instructions
FuncInfo.SIVisitor.annotateSelects(F, this, &CountPosition);
assert(CountPosition == ProfileCountSize);
DEBUG(FuncInfo.dumpInfo("after reading profile."));
}

11
test/Transforms/PGOProfile/Inputs/select2.proftext Normal file
View File

@ -0,0 +1,11 @@
# IR level Instrumentation Flag
:ir
foo
# Func Hash:
72057628175588252
# Num Counters:
3
# Counter Values:
800
3
300

37
test/Transforms/PGOProfile/select2.ll Normal file
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@ -0,0 +1,37 @@
; RUN: llvm-profdata merge %S/Inputs/select2.proftext -o %t.profdata
; RUN: opt < %s -pgo-instr-use -pgo-test-profile-file=%t.profdata -pgo-instr-select=true -S | FileCheck %s --check-prefix=USE
; RUN: opt < %s -passes=pgo-instr-use -pgo-test-profile-file=%t.profdata -pgo-instr-select=true -S | FileCheck %s --check-prefix=USE
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
define i32 @foo(i32 %n) {
;USE: define i32 @foo(i32 %n) !prof ![[ENTRY_COUNT:[0-9]+]] {
entry:
br label %for.cond
for.cond:
%i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
%sum.0 = phi i32 [ 0, %entry ], [ %add, %for.inc ]
%cmp = icmp slt i32 %i.0, %n
br i1 %cmp, label %for.body, label %for.end
;USE: br i1 %cmp, label %for.body, label %for.end, !prof ![[BW_FOR_BR:[0-9]+]]
for.body:
%cmp1 = icmp sgt i32 %sum.0, 10
%cond = select i1 %cmp1, i32 20, i32 -10
;USE: %cond = select i1 %cmp1, i32 20, i32 -10, !prof ![[BW_FOR_SELECT:[0-9]+]]
%add = add nsw i32 %sum.0, %cond
br label %for.inc
for.inc:
%inc = add nsw i32 %i.0, 1
br label %for.cond
for.end:
ret i32 %sum.0
}
;USE: ![[ENTRY_COUNT]] = !{!"function_entry_count", i64 3}
;USE: ![[BW_FOR_BR]] = !{!"branch_weights", i32 800, i32 3}
;USE: ![[BW_FOR_SELECT]] = !{!"branch_weights", i32 300, i32 500}