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a2029fa58e
In order to set breakpoints on labels and list source code around labels, we need collect debug information for labels, i.e., label name, the function label belong, line number in the file, and the address label located. In order to keep these information in LLVM IR and to allow backend to generate debug information correctly. We create a new kind of metadata for labels, DILabel. The format of DILabel is !DILabel(scope: !1, name: "foo", file: !2, line: 3) We hope to keep debug information as much as possible even the code is optimized. So, we create a new kind of intrinsic for label metadata to avoid the metadata is eliminated with basic block. The intrinsic will keep existing if we keep it from optimized out. The format of the intrinsic is llvm.dbg.label(metadata !1) It has only one argument, that is the DILabel metadata. The intrinsic will follow the label immediately. Backend could get the label metadata through the intrinsic's parameter. We also create DIBuilder API for labels to be used by Frontend. Frontend could use createLabel() to allocate DILabel objects, and use insertLabel() to insert llvm.dbg.label intrinsic in LLVM IR. Differential Revision: https://reviews.llvm.org/D45024 Patch by Hsiangkai Wang. llvm-svn: 331841
91 lines
3.8 KiB
LLVM
91 lines
3.8 KiB
LLVM
; RUN: opt < %s -sample-profile -sample-profile-file=%S/Inputs/discriminator.prof | opt -analyze -branch-prob | FileCheck %s
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; RUN: opt < %s -passes=sample-profile -sample-profile-file=%S/Inputs/discriminator.prof | opt -analyze -branch-prob | FileCheck %s
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; Original code
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;
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; 1 int foo(int i) {
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; 2 int x = 0;
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; 3 while (i < 100) {
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; 4 if (i < 5) x--;
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; 5 i++;
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; 6 }
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; 7 return x;
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; 8 }
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;
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; In this test, if the loop is executed 100 times, the decrement operation
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; at line 4 should only execute 5 times. This is reflected in the profile
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; data for line offset 3. In Inputs/discriminator.prof, we have:
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;
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; 3: 100
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; 3.1: 5
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;
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; This means that the predicate 'i < 5' (line 3) is executed 100 times,
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; but the then branch (line 3.1) is only executed 5 times.
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define i32 @foo(i32 %i) #0 !dbg !4 {
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; CHECK: Printing analysis 'Branch Probability Analysis' for function 'foo':
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entry:
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%i.addr = alloca i32, align 4
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%x = alloca i32, align 4
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store i32 %i, i32* %i.addr, align 4
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store i32 0, i32* %x, align 4, !dbg !10
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br label %while.cond, !dbg !11
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while.cond: ; preds = %if.end, %entry
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%0 = load i32, i32* %i.addr, align 4, !dbg !12
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%cmp = icmp slt i32 %0, 100, !dbg !12
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br i1 %cmp, label %while.body, label %while.end, !dbg !12
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; CHECK: edge while.cond -> while.body probability is 0x7d83ba68 / 0x80000000 = 98.06% [HOT edge]
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; CHECK: edge while.cond -> while.end probability is 0x027c4598 / 0x80000000 = 1.94%
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while.body: ; preds = %while.cond
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%1 = load i32, i32* %i.addr, align 4, !dbg !14
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%cmp1 = icmp slt i32 %1, 50, !dbg !14
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br i1 %cmp1, label %if.then, label %if.end, !dbg !14
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; CHECK: edge while.body -> if.then probability is 0x07878788 / 0x80000000 = 5.88%
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; CHECK: edge while.body -> if.end probability is 0x78787878 / 0x80000000 = 94.12% [HOT edge]
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if.then: ; preds = %while.body
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%2 = load i32, i32* %x, align 4, !dbg !17
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%dec = add nsw i32 %2, -1, !dbg !17
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store i32 %dec, i32* %x, align 4, !dbg !17
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br label %if.end, !dbg !17
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if.end: ; preds = %if.then, %while.body
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%3 = load i32, i32* %i.addr, align 4, !dbg !19
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%inc = add nsw i32 %3, 1, !dbg !19
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store i32 %inc, i32* %i.addr, align 4, !dbg !19
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br label %while.cond, !dbg !20
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while.end: ; preds = %while.cond
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%4 = load i32, i32* %x, align 4, !dbg !21
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ret i32 %4, !dbg !21
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}
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!7, !8}
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!llvm.ident = !{!9}
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!0 = distinct !DICompileUnit(language: DW_LANG_C99, producer: "clang version 3.5 ", isOptimized: false, emissionKind: NoDebug, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
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!1 = !DIFile(filename: "discriminator.c", directory: ".")
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!2 = !{}
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!4 = distinct !DISubprogram(name: "foo", line: 1, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 1, file: !1, scope: !5, type: !6, retainedNodes: !2)
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!5 = !DIFile(filename: "discriminator.c", directory: ".")
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!6 = !DISubroutineType(types: !2)
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!7 = !{i32 2, !"Dwarf Version", i32 4}
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!8 = !{i32 1, !"Debug Info Version", i32 3}
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!9 = !{!"clang version 3.5 "}
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!10 = !DILocation(line: 2, scope: !4)
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!11 = !DILocation(line: 3, scope: !4)
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!12 = !DILocation(line: 3, scope: !13)
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!13 = !DILexicalBlockFile(discriminator: 2, file: !1, scope: !4)
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!14 = !DILocation(line: 4, scope: !15)
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!15 = distinct !DILexicalBlock(line: 4, column: 0, file: !1, scope: !16)
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!16 = distinct !DILexicalBlock(line: 3, column: 0, file: !1, scope: !4)
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!17 = !DILocation(line: 4, scope: !18)
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!18 = !DILexicalBlockFile(discriminator: 2, file: !1, scope: !15)
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!19 = !DILocation(line: 5, scope: !16)
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!20 = !DILocation(line: 6, scope: !16)
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!21 = !DILocation(line: 7, scope: !4)
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