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Add function entry counts from sample profiles.

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This patch uses the new function profile metadata "function_entry_count"
to annotate entry counts from sample profiles.

In a sampling profile, the total samples collected at the function entry
are an approximation for the number of times that function was invoked.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237265 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Diego Novillo 2015-05-13 17:04:29 +00:00
parent 552cd98683
commit 0e0929ed98
3 changed files with 31 additions and 0 deletions
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4
lib/Transforms/Scalar/SampleProfile.cpp
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@ -580,6 +580,10 @@ void SampleProfileLoader::propagateWeights(Function &F) {
bool Changed = true;
unsigned i = 0;
// Add an entry count to the function using the samples gathered
// at the function entry.
F.setEntryCount(Samples->getHeadSamples());
// Before propagation starts, build, for each block, a list of
// unique predecessors and successors. This is necessary to handle
// identical edges in multiway branches. Since we visit all blocks and all

3
test/Transforms/SampleProfile/Inputs/entry_counts.prof Normal file
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@ -0,0 +1,3 @@
empty:100:13293
0: 0
1: 100

24
test/Transforms/SampleProfile/entry_counts.ll Normal file
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@ -0,0 +1,24 @@
; RUN: opt < %s -sample-profile -sample-profile-file=%S/Inputs/entry_counts.prof -S | FileCheck %s
; According to the profile, function empty() was called 13,293 times.
; CHECK: {{.*}} = !{!"function_entry_count", i64 13293}
define void @empty() {
entry:
ret void, !dbg !9
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!6, !7}
!llvm.ident = !{!8}
!0 = !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.7.0 (trunk 237249) (llvm/trunk 237261)", isOptimized: false, runtimeVersion: 0, emissionKind: 2, enums: !2, retainedTypes: !2, subprograms: !3, globals: !2, imports: !2)
!1 = !DIFile(filename: "entry_counts.c", directory: "/usr/local/google/home/dnovillo/llvm/test/pgo")
!2 = !{}
!3 = !{!4}
!4 = !DISubprogram(name: "empty", scope: !1, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true, scopeLine: 1, isOptimized: false, function: void ()* @empty, variables: !2)
!5 = !DISubroutineType(types: !2)
!6 = !{i32 2, !"Dwarf Version", i32 4}
!7 = !{i32 2, !"Debug Info Version", i32 3}
!8 = !{!"clang version 3.7.0 (trunk 237249) (llvm/trunk 237261)"}
!9 = !DILocation(line: 1, column: 15, scope: !4)