ae8b560899
By default we were marking some contexts as hot, and adding hot hints to unambiguously hot allocations. However, there is not yet support for cloning to expose hot allocation contexts, and none is planned for the forseeable future. While we convert hot contexts to notcold contexts during the cloning step, their existence was greatly limiting the context trimming performed when we add the MemProf profile to the IR. This change simply disables the generation of hot contexts / hints by default, as few allocations were unambiguously hot. A subsequent change will address the issue when hot hints are optionally enabled. See PR124219 for details. This change resulted in significant overhead reductions for a large target: ~48% reduction in the per-module ThinLTO bitcode summary sizes ~72% reduction in the distributed ThinLTO bitcode combined summary sizes ~68% reduction in thin link time ~34% reduction in thin link peak memory
104 lines
5.3 KiB
LLVM
104 lines
5.3 KiB
LLVM
;; Tests memprof when contains loop unroll of allocation, where the unrolled
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;; allocations have the same context but different allocation types.
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;; Avoid failures on big-endian systems that can't read the profile properly
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; REQUIRES: x86_64-linux
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;; TODO: Use text profile inputs once that is available for memprof.
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;; # To update the Inputs below, run Inputs/update_memprof_inputs.sh.
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;; # To generate below LLVM IR for use in matching.
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;; $ clang++ -gmlt -fdebug-info-for-profiling -S %S/Inputs/memprof_loop_unroll_b.cc -emit-llvm
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; RUN: llvm-profdata merge %S/Inputs/memprof_loop_unroll.memprofraw --profiled-binary %S/Inputs/memprof_loop_unroll.exe -o %t.memprofdata
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;; Set the minimum lifetime threshold to 0 to ensure that one context is
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;; considered cold (the other will be notcold).
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; RUN: opt < %s -passes='memprof-use<profile-filename=%t.memprofdata>' -S -memprof-report-hinted-sizes -memprof-ave-lifetime-cold-threshold=0 2>&1 | FileCheck %s
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;; Conservatively annotate as not cold. We get two messages as there are two
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;; unrolled copies of the allocation.
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; CHECK: MemProf hinting: Total size for full allocation context hash {{.*}} and indistinguishable alloc type notcold: 4
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; CHECK: MemProf hinting: Total size for full allocation context hash {{.*}} and indistinguishable alloc type notcold: 4
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; CHECK: call {{.*}} @_Znam{{.*}} #[[ATTR:[0-9]+]]
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; CHECK: attributes #[[ATTR]] = { builtin allocsize(0) "memprof"="notcold" }
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; CHECK-NOT: stackIds: ()
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; ModuleID = 'memprof_loop_unroll_b.cc'
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source_filename = "memprof_loop_unroll_b.cc"
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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@a = external global [2 x ptr], align 16
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; Function Attrs: mustprogress noinline optnone uwtable
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define dso_local void @_Z3foov() #0 !dbg !10 {
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entry:
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%i = alloca i32, align 4
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store i32 0, ptr %i, align 4, !dbg !13
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br label %for.cond, !dbg !14
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for.cond: ; preds = %for.inc, %entry
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%0 = load i32, ptr %i, align 4, !dbg !15
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%cmp = icmp slt i32 %0, 2, !dbg !17
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br i1 %cmp, label %for.body, label %for.end, !dbg !18
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for.body: ; preds = %for.cond
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%call = call noalias noundef nonnull ptr @_Znam(i64 noundef 4) #2, !dbg !19
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%1 = load i32, ptr %i, align 4, !dbg !20
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%idxprom = sext i32 %1 to i64, !dbg !21
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%arrayidx = getelementptr inbounds [2 x ptr], ptr @a, i64 0, i64 %idxprom, !dbg !21
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store ptr %call, ptr %arrayidx, align 8, !dbg !22
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br label %for.inc, !dbg !23
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for.inc: ; preds = %for.body
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%2 = load i32, ptr %i, align 4, !dbg !24
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%inc = add nsw i32 %2, 1, !dbg !24
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store i32 %inc, ptr %i, align 4, !dbg !24
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br label %for.cond, !dbg !26, !llvm.loop !27
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for.end: ; preds = %for.cond
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ret void, !dbg !30
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}
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; Function Attrs: nobuiltin allocsize(0)
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declare noundef nonnull ptr @_Znam(i64 noundef) #1
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attributes #0 = { mustprogress noinline optnone uwtable "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
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attributes #1 = { nobuiltin allocsize(0) "frame-pointer"="all" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
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attributes #2 = { builtin allocsize(0) }
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!2, !3, !4, !5, !6, !7, !8}
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!llvm.ident = !{!9}
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!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 18.0.0", isOptimized: false, runtimeVersion: 0, emissionKind: LineTablesOnly, splitDebugInlining: false, debugInfoForProfiling: true, nameTableKind: None)
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!1 = !DIFile(filename: "memprof_loop_unroll_b.cc", directory: "/", checksumkind: CSK_MD5, checksum: "00276e590d606451dc54f3ff5f4bba25")
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!2 = !{i32 7, !"Dwarf Version", i32 5}
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!3 = !{i32 2, !"Debug Info Version", i32 3}
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!4 = !{i32 1, !"wchar_size", i32 4}
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!5 = !{i32 8, !"PIC Level", i32 2}
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!6 = !{i32 7, !"PIE Level", i32 2}
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!7 = !{i32 7, !"uwtable", i32 2}
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!8 = !{i32 7, !"frame-pointer", i32 2}
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!9 = !{!"clang version 18.0.0"}
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!10 = distinct !DISubprogram(name: "foo", linkageName: "_Z3foov", scope: !1, file: !1, line: 4, type: !11, scopeLine: 4, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
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!11 = !DISubroutineType(types: !12)
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!12 = !{}
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!13 = !DILocation(line: 5, column: 14, scope: !10)
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!14 = !DILocation(line: 5, column: 10, scope: !10)
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!15 = !DILocation(line: 5, column: 21, scope: !16)
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!16 = !DILexicalBlockFile(scope: !10, file: !1, discriminator: 2)
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!17 = !DILocation(line: 5, column: 23, scope: !16)
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!18 = !DILocation(line: 5, column: 5, scope: !16)
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!19 = !DILocation(line: 6, column: 16, scope: !10)
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!20 = !DILocation(line: 6, column: 11, scope: !10)
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!21 = !DILocation(line: 6, column: 9, scope: !10)
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!22 = !DILocation(line: 6, column: 14, scope: !10)
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!23 = !DILocation(line: 7, column: 5, scope: !10)
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!24 = !DILocation(line: 5, column: 28, scope: !25)
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!25 = !DILexicalBlockFile(scope: !10, file: !1, discriminator: 4)
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!26 = !DILocation(line: 5, column: 5, scope: !25)
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!27 = distinct !{!27, !28, !23, !29}
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!28 = !DILocation(line: 5, column: 5, scope: !10)
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!29 = !{!"llvm.loop.mustprogress"}
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!30 = !DILocation(line: 8, column: 1, scope: !10)
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