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llvm-mirror/test/DebugInfo/X86/stack-args.ll

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EmitFuncArgumentDbgValue: Prefer stack slots over registers for stack arguments While investigating LLVM PR22316 (http://llvm.org/bugs/show_bug.cgi?id=22316) I started wondering if it were not always preferable to emit the initial DBG_VALUEs for stack arguments as FI locations instead of describing the first register they get copied into. The advantage of doing this is that the arguments will be available as soon as the stack is setup. As illustrated by the testcase in the PR, the first copy of the FI into a register may be sunk by MachineSink.cpp into a later basic block. By describing the argument on the stack, we nicely circumvent this problem. <rdar://problem/19583723> Differential Revision: https://reviews.llvm.org/D41135 llvm-svn: 320758
2017-12-14 23:55:06 +01:00
; RUN: llc -filetype=obj -o - %s | llvm-dwarfdump - | FileCheck %s
; Generated from:
; void * __attribute__ (( regparm(2) )) f(void *, void *);
; void * __attribute__ (( regparm(0) )) g(void *, void *);
;
; void *g(void *t, void *k) {
; if (k == (void *)0)
; return (void *)0;
; return f(t, k);
; }
; CHECK: DW_TAG_formal_parameter
; CHECK-NEXT: DW_AT_location (DW_OP_fbreg +4)
; CHECK-NEXT: DW_AT_name ("t")
; CHECK: DW_TAG_formal_parameter
; CHECK-NEXT: DW_AT_location (DW_OP_fbreg +8)
; CHECK-NEXT: DW_AT_name ("k")
source_filename = "t.c"
target datalayout = "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128"
target triple = "i386--linux-gnu"
; Function Attrs: nounwind
define i8* @g(i8* %t, i8* %k) local_unnamed_addr #0 !dbg !10 {
entry:
call void @llvm.dbg.value(metadata i8* %t, metadata !14, metadata !DIExpression()), !dbg !16
call void @llvm.dbg.value(metadata i8* %k, metadata !15, metadata !DIExpression()), !dbg !17
%cmp = icmp eq i8* %k, null, !dbg !18
br i1 %cmp, label %return, label %if.end, !dbg !20
if.end: ; preds = %entry
%call = tail call i8* @f(i8* inreg %t, i8* inreg nonnull %k) #3, !dbg !21
br label %return, !dbg !22
return: ; preds = %entry, %if.end
%retval.0 = phi i8* [ %call, %if.end ], [ null, %entry ]
ret i8* %retval.0, !dbg !23
}
declare i8* @f(i8* inreg, i8* inreg) local_unnamed_addr
; Function Attrs: nounwind readnone speculatable
declare void @llvm.dbg.value(metadata, metadata, metadata) #2
attributes #0 = { nounwind }
attributes #2 = { nounwind readnone speculatable }
attributes #3 = { nounwind }
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!5, !6, !7, !8}
!llvm.ident = !{!9}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 6.0.0 (llvm/trunk 319230)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3)
!1 = !DIFile(filename: "t.c", directory: "/")
!2 = !{}
!3 = !{!4}
!4 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: null, size: 32)
!5 = !{i32 1, !"NumRegisterParameters", i32 0}
!6 = !{i32 2, !"Dwarf Version", i32 4}
!7 = !{i32 2, !"Debug Info Version", i32 3}
!8 = !{i32 1, !"wchar_size", i32 4}
!9 = !{!"clang version 6.0.0 (llvm/trunk 319230)"}
[DebugInfo] Add DILabel metadata and intrinsic llvm.dbg.label. 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
2018-05-09 04:40:45 +02:00
!10 = distinct !DISubprogram(name: "g", scope: !1, file: !1, line: 4, type: !11, isLocal: false, isDefinition: true, scopeLine: 4, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !13)
EmitFuncArgumentDbgValue: Prefer stack slots over registers for stack arguments While investigating LLVM PR22316 (http://llvm.org/bugs/show_bug.cgi?id=22316) I started wondering if it were not always preferable to emit the initial DBG_VALUEs for stack arguments as FI locations instead of describing the first register they get copied into. The advantage of doing this is that the arguments will be available as soon as the stack is setup. As illustrated by the testcase in the PR, the first copy of the FI into a register may be sunk by MachineSink.cpp into a later basic block. By describing the argument on the stack, we nicely circumvent this problem. <rdar://problem/19583723> Differential Revision: https://reviews.llvm.org/D41135 llvm-svn: 320758
2017-12-14 23:55:06 +01:00
!11 = !DISubroutineType(types: !12)
!12 = !{!4, !4, !4}
!13 = !{!14, !15}
!14 = !DILocalVariable(name: "t", arg: 1, scope: !10, file: !1, line: 4, type: !4)
!15 = !DILocalVariable(name: "k", arg: 2, scope: !10, file: !1, line: 4, type: !4)
!16 = !DILocation(line: 4, column: 15, scope: !10)
!17 = !DILocation(line: 4, column: 24, scope: !10)
!18 = !DILocation(line: 5, column: 9, scope: !19)
!19 = distinct !DILexicalBlock(scope: !10, file: !1, line: 5, column: 7)
!20 = !DILocation(line: 5, column: 7, scope: !10)
!21 = !DILocation(line: 7, column: 10, scope: !10)
!22 = !DILocation(line: 7, column: 3, scope: !10)
!23 = !DILocation(line: 8, column: 1, scope: !10)
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