e8209b2486
After performing sink-and-fold over a COPY, the original instruction is
replaced with one that produces its output in the destination of the
copy. Its value is still available (in a hard register), so if there are
debug instructions which refer to the (now deleted) virtual register
they could be updated to refer to the hard register, in principle.
However, it's not clear how to do that, moreover in some cases the debug
instructions may need to be replicated proportionally to the number of
the COPY instructions replaced and in some extreme cases we can end up
with quadratic increase in the number of debug instructions, e.g:
int f(int);
void g(int x) {
int y = x + 1;
int t0 = y;
f(t0);
int t1 = y;
f(t1);
}
143 lines
6.1 KiB
LLVM
143 lines
6.1 KiB
LLVM
; RUN: %llc_dwarf %s -o - -filetype=obj | llvm-dwarfdump - | FileCheck %s -implicit-check-not=DW_TAG
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;
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; Issue #46473
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; XFAIL: target=sparc{{.*}}
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;
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; This tests that we do not create concrete variable DIEs for variables that
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; have no location -- for both ways that LLVM-IR can express a variable with
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; no location. It's possible to:
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; 1) Omit all dbg.values and place the variable in the subprograms retained
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; nodes list,
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; 2) Have a dbg.value with an undef operand, and none with "real" operands.
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; Both of these should produce the same DWARF. In the two functions below
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; (qux and croix) I've modified the IR to represent both scenarios.
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;
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; Original C, LLVM-IR modified afterwards:
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;
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; int foo(int bar) {
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; int baz = 12 + bar;
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; return baz;
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; }
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;
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; int qux(int quux) {
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; int xyzzy = foo(quux);
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; return xyzzy;
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; }
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;
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; int croix(int quux) {
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; int xyzzy = foo(quux);
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; return xyzzy;
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; }
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;
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;; Note the implicit DW_TAG check-not in the FileCheck command line.
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; CHECK: DW_TAG_compile_unit
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;;
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;; First subprogram is attached to the plain "foo" function in the output
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;; object. It should have locations for the two variables in the function,
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;; let's be non-specific as to how.
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; CHECK: DW_TAG_subprogram
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; CHECK: DW_AT_abstract_origin (0x{{[0-9a-f]*}} "foo")
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; CHECK: DW_TAG_formal_parameter
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; CHECK: DW_AT_location
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; CHECK: DW_TAG_variable
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; CHECK: DW_AT_location
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;
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;; Abstract subprogram; should have plain variable declarations
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; CHECK: DW_TAG_subprogram
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; CHECK: DW_AT_name ("foo")
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; CHECK: DW_TAG_formal_parameter
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; CHECK: DW_AT_name ("bar")
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; CHECK: DW_TAG_variable
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; CHECK: DW_AT_name ("baz")
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;
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; CHECK: DW_TAG_base_type
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;
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;; The copy of "foo" inlined into "qux" should have no children.
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; CHECK: DW_TAG_subprogram
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; CHECK: DW_AT_name ("qux")
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; CHECK: DW_TAG_formal_parameter
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; CHECK: DW_TAG_variable
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; CHECK: DW_TAG_inlined_subroutine
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; CHECK: NULL
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;
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;; Same for the copy of foo inlined into "croix"
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; CHECK: DW_TAG_subprogram
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; CHECK: DW_AT_name ("croix")
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; CHECK: DW_TAG_formal_parameter
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; CHECK: DW_TAG_variable
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; CHECK: DW_TAG_inlined_subroutine
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; CHECK: NULL
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; NOTE: Instructions below changed from `add` to `mul` to make them more expensive
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; and unlikely to be sunk to replace COPYs into a return value register.
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; Function Attrs: norecurse nounwind readnone uwtable willreturn
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define dso_local i32 @foo(i32 %bar) local_unnamed_addr !dbg !7 {
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entry:
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call void @llvm.dbg.value(metadata i32 %bar, metadata !12, metadata !DIExpression()), !dbg !14
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%add = mul nsw i32 %bar, 12, !dbg !15
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call void @llvm.dbg.value(metadata i32 %add, metadata !13, metadata !DIExpression()), !dbg !14
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ret i32 %add, !dbg !16
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}
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; Function Attrs: norecurse nounwind readnone uwtable willreturn
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define dso_local i32 @qux(i32 %quux) local_unnamed_addr !dbg !17 {
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entry:
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%add.i = mul nsw i32 %quux, 12, !dbg !24
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ret i32 %add.i, !dbg !25
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}
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; Function Attrs: norecurse nounwind readnone uwtable willreturn
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define dso_local i32 @croix(i32 %quux) local_unnamed_addr !dbg !26 {
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entry:
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call void @llvm.dbg.value(metadata i32 undef, metadata !28, metadata !DIExpression()), !dbg !30
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call void @llvm.dbg.value(metadata i32 undef, metadata !12, metadata !DIExpression()), !dbg !31
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%add.i = mul nsw i32 %quux, 12, !dbg !33
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call void @llvm.dbg.value(metadata i32 undef, metadata !13, metadata !DIExpression()), !dbg !31
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call void @llvm.dbg.value(metadata i32 undef, metadata !29, metadata !DIExpression()), !dbg !30
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ret i32 %add.i, !dbg !34
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}
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; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
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declare void @llvm.dbg.value(metadata, metadata, metadata)
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!3, !4, !5}
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!llvm.ident = !{!6}
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!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
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!1 = !DIFile(filename: "test.c", directory: ".")
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!2 = !{}
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!3 = !{i32 7, !"Dwarf Version", i32 4}
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!4 = !{i32 2, !"Debug Info Version", i32 3}
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!5 = !{i32 1, !"wchar_size", i32 4}
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!6 = !{!"clang"}
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!7 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
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!8 = !DISubroutineType(types: !9)
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!9 = !{!10, !10}
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!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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!11 = !{!12, !13}
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!12 = !DILocalVariable(name: "bar", arg: 1, scope: !7, file: !1, line: 1, type: !10)
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!13 = !DILocalVariable(name: "baz", scope: !7, file: !1, line: 2, type: !10)
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!14 = !DILocation(line: 0, scope: !7)
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!15 = !DILocation(line: 2, column: 16, scope: !7)
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!16 = !DILocation(line: 3, column: 3, scope: !7)
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!17 = distinct !DISubprogram(name: "qux", scope: !1, file: !1, line: 6, type: !8, scopeLine: 6, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !18)
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!18 = !{!19, !20}
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!19 = !DILocalVariable(name: "quux", arg: 1, scope: !17, file: !1, line: 6, type: !10)
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!20 = !DILocalVariable(name: "xyzzy", scope: !17, file: !1, line: 7, type: !10)
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!21 = !DILocation(line: 0, scope: !17)
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!22 = !DILocation(line: 0, scope: !7, inlinedAt: !23)
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!23 = distinct !DILocation(line: 7, column: 15, scope: !17)
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!24 = !DILocation(line: 2, column: 16, scope: !7, inlinedAt: !23)
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!25 = !DILocation(line: 8, column: 3, scope: !17)
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!26 = distinct !DISubprogram(name: "croix", scope: !1, file: !1, line: 11, type: !8, scopeLine: 11, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !27)
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!27 = !{!28, !29}
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!28 = !DILocalVariable(name: "quux", arg: 1, scope: !26, file: !1, line: 11, type: !10)
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!29 = !DILocalVariable(name: "xyzzy", scope: !26, file: !1, line: 12, type: !10)
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!30 = !DILocation(line: 0, scope: !26)
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!31 = !DILocation(line: 0, scope: !7, inlinedAt: !32)
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!32 = distinct !DILocation(line: 12, column: 15, scope: !26)
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!33 = !DILocation(line: 2, column: 16, scope: !7, inlinedAt: !32)
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!34 = !DILocation(line: 13, column: 3, scope: !26)
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