f9193f3b18
This patch introduces a new option `-preserve-merged-debug-info` to preserve an arbitrary but deterministic version of debug information when DILocations are merged. This is intended to be used in production environments from which sample based profiles are derived such as AutoFDO and MemProf. With this patch we have see a 0.2% improvement on an internal workload at Google when generating AutoFDO profiles. It also significantly improves the ability for MemProf by preserving debug info for merged call instructions used in the contextual profile. --------- Co-authored-by: Krzysztof Pszeniczny <kpszeniczny@google.com>
78 lines
4.0 KiB
LLVM
78 lines
4.0 KiB
LLVM
;; This test verifies that we assign a deterministic location for merged
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;; instructions when -pick-merged-source-locations is enabled. We use the
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;; simplifycfg pass to test this behaviour since it was a common source of
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;; merged instructions, however we intend this to apply to all users of the
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;; getMergedLocation API.
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;; Run simplifycfg and check that only 1 call to bar remains and it's debug
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;; location has a valid line number (lexicographically smallest).
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; RUN: opt %s -passes=simplifycfg -hoist-common-insts -pick-merged-source-locations -S | FileCheck %s --check-prefix=ENABLED
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; ENABLED: call i32 @bar{{.*!dbg !}}[[TAG:[0-9]+]]
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; ENABLED-NOT: call i32 @bar
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; ENABLED: ![[TAG]] = !DILocation(line: 9, column: 16, scope: !9)
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;; Run simplifycfg without the pass to ensure that we don't spuriously start
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;; passing the test if simplifycfg behaviour changes.
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; RUN: opt %s -passes=simplifycfg -hoist-common-insts -pick-merged-source-locations=false -S | FileCheck %s --check-prefix=DISABLED
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; DISABLED: call i32 @bar{{.*!dbg !}}[[TAG:[0-9]+]]
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; DISABLED-NOT: call i32 @bar
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; DISABLED: ![[TAG]] = !DILocation(line: 0, scope: !9)
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; ModuleID = '../llvm/test/DebugInfo/Inputs/debug-info-merge-call.c'
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source_filename = "../llvm/test/DebugInfo/Inputs/debug-info-merge-call.c"
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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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; Function Attrs: nounwind uwtable
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define dso_local i32 @test(i32 %n) !dbg !9 {
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entry:
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%call = call i32 @foo(i32 %n), !dbg !12
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%cmp1 = icmp sgt i32 %n, 100, !dbg !13
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br i1 %cmp1, label %if.then, label %if.else, !dbg !13
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if.then: ; preds = %entry
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%call2 = call i32 @bar(i32 %n), !dbg !14
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%add = add nsw i32 %call2, %call, !dbg !15
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br label %if.end, !dbg !16
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if.else: ; preds = %entry
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%call4 = call i32 @bar(i32 %n), !dbg !17
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br label %if.end
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if.end: ; preds = %if.else, %if.then
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%r.0 = phi i32 [ %add, %if.then ], [ %call4, %if.else ], !dbg !18
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ret i32 %r.0, !dbg !19
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}
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declare !dbg !20 i32 @foo(i32)
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declare !dbg !21 i32 @bar(i32)
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!2, !3, !4, !5, !6, !7}
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!llvm.ident = !{!8}
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!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 21.0.0git (git@github.com:snehasish/llvm-project.git 6ce41db6b0275d060d6e60f88b96a1657024345c)", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly, splitDebugInlining: false, nameTableKind: None)
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!1 = !DIFile(filename: "../llvm/test/DebugInfo/Inputs/debug-info-merge-call.c", directory: "/usr/local/google/home/snehasishk/working/llvm-project/build-assert", checksumkind: CSK_MD5, checksum: "ac1be6c40dad11691922d600f9d55c55")
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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 = !{!"clang version 21.0.0git (git@github.com:snehasish/llvm-project.git 6ce41db6b0275d060d6e60f88b96a1657024345c)"}
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!9 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 5, type: !10, scopeLine: 5, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0)
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!10 = !DISubroutineType(types: !11)
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!11 = !{}
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!12 = !DILocation(line: 7, column: 13, scope: !9)
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!13 = !DILocation(line: 8, column: 8, scope: !9)
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!14 = !DILocation(line: 9, column: 16, scope: !9)
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!15 = !DILocation(line: 9, column: 14, scope: !9)
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!16 = !DILocation(line: 10, column: 3, scope: !9)
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!17 = !DILocation(line: 11, column: 10, scope: !9)
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!18 = !DILocation(line: 0, scope: !9)
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!19 = !DILocation(line: 13, column: 3, scope: !9)
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!20 = !DISubprogram(name: "foo", scope: !1, file: !1, line: 2, type: !10, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
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!21 = !DISubprogram(name: "bar", scope: !1, file: !1, line: 1, type: !10, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
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