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Teresa Johnson c3a521efd8 [PGO] Function section hotness prefix should look at all blocks
Summary:
The function section prefix for PGO based layout (e.g. hot/unlikely)
should look at the hotness of all blocks not just the entry BB.
A function with a cold entry but a very hot loop should be placed in the
hot section, for example, so that it is located close to other hot
functions it may call. For SamplePGO it was already looking at the
branch weights on calls, and I made that code conditional on whether
this is SamplePGO since it was essentially a noop for instrumentation
PGO anyway.

Reviewers: davidxl

Subscribers: eraman, llvm-commits

Differential Revision: https://reviews.llvm.org/D41395

llvm-svn: 321197
2017-12-20 17:53:10 +00:00

85 lines
2.4 KiB
LLVM

; RUN: opt < %s -codegenprepare -S | FileCheck %s
target triple = "x86_64-pc-linux-gnu"
; This tests that hot/cold functions get correct section prefix assigned
; CHECK: hot_func1{{.*}}!section_prefix ![[HOT_ID:[0-9]+]]
; The entry is hot
define void @hot_func1() !prof !15 {
ret void
}
; CHECK: hot_func2{{.*}}!section_prefix ![[HOT_ID:[0-9]+]]
; Entry is cold but inner block is hot
define void @hot_func2(i32 %n) !prof !16 {
entry:
%n.addr = alloca i32, align 4
%i = alloca i32, align 4
store i32 %n, i32* %n.addr, align 4
store i32 0, i32* %i, align 4
br label %for.cond
for.cond:
%0 = load i32, i32* %i, align 4
%1 = load i32, i32* %n.addr, align 4
%cmp = icmp slt i32 %0, %1
br i1 %cmp, label %for.body, label %for.end, !prof !19
for.body:
%2 = load i32, i32* %i, align 4
%inc = add nsw i32 %2, 1
store i32 %inc, i32* %i, align 4
br label %for.cond
for.end:
ret void
}
; For instrumentation based PGO, we should only look at block counts,
; not call site VP metadata (which can exist on value profiled memcpy,
; or possibly left behind after static analysis based devirtualization).
; CHECK: cold_func1{{.*}}!section_prefix ![[COLD_ID:[0-9]+]]
define void @cold_func1() !prof !16 {
call void @hot_func1(), !prof !17
call void @hot_func1(), !prof !17
ret void
}
; CHECK: cold_func2{{.*}}!section_prefix ![[COLD_ID]]
define void @cold_func2() !prof !16 {
call void @hot_func1(), !prof !17
call void @hot_func1(), !prof !18
call void @hot_func1(), !prof !18
ret void
}
; CHECK: cold_func3{{.*}}!section_prefix ![[COLD_ID]]
define void @cold_func3() !prof !16 {
call void @hot_func1(), !prof !18
ret void
}
; CHECK: ![[HOT_ID]] = !{!"function_section_prefix", !".hot"}
; CHECK: ![[COLD_ID]] = !{!"function_section_prefix", !".unlikely"}
!llvm.module.flags = !{!1}
!1 = !{i32 1, !"ProfileSummary", !2}
!2 = !{!3, !4, !5, !6, !7, !8, !9, !10}
!3 = !{!"ProfileFormat", !"InstrProf"}
!4 = !{!"TotalCount", i64 10000}
!5 = !{!"MaxCount", i64 1000}
!6 = !{!"MaxInternalCount", i64 1}
!7 = !{!"MaxFunctionCount", i64 1000}
!8 = !{!"NumCounts", i64 3}
!9 = !{!"NumFunctions", i64 3}
!10 = !{!"DetailedSummary", !11}
!11 = !{!12, !13, !14}
!12 = !{i32 10000, i64 100, i32 1}
!13 = !{i32 999000, i64 100, i32 1}
!14 = !{i32 999999, i64 1, i32 2}
!15 = !{!"function_entry_count", i64 1000}
!16 = !{!"function_entry_count", i64 1}
!17 = !{!"branch_weights", i32 80}
!18 = !{!"branch_weights", i32 1}
!19 = !{!"branch_weights", i32 1000, i32 1}