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[DWARFLinker] Preserve DWARF discriminators while linking #96124

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Merged
merged 4 commits into from
Jun 21, 2024
Merged

[DWARFLinker] Preserve DWARF discriminators while linking #96124

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ce16f6f
[DWARFLinker] Preserve DWARF discriminators while linking
dtellenbach Jun 19, 2024
1172de3
[DWARFLinker] Fix formulation on discriminator test
dtellenbach Jun 19, 2024
acd473d
[DWARFLinker] Fix formulation on discriminator test
dtellenbach Jun 19, 2024
4a7f313
[DWARFLinker] Change objects and test for dsymutil discriminator test
dtellenbach Jun 21, 2024
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17 changes: 13 additions & 4 deletions llvm/lib/DWARFLinker/Classic/DWARFStreamer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1060,6 +1060,7 @@ void DwarfStreamer::emitLineTableRows(
unsigned FileNum = 1;
unsigned LastLine = 1;
unsigned Column = 0;
unsigned Discriminator = 0;
unsigned IsStatement = 1;
unsigned Isa = 0;
uint64_t Address = -1ULL;
Expand Down Expand Up @@ -1098,9 +1099,17 @@ void DwarfStreamer::emitLineTableRows(
MS->emitULEB128IntValue(Column);
LineSectionSize += 1 + getULEB128Size(Column);
}

// FIXME: We should handle the discriminator here, but dsymutil doesn't
// consider it, thus ignore it for now.
if (Discriminator != Row.Discriminator &&
MS->getContext().getDwarfVersion() >= 4) {
Discriminator = Row.Discriminator;
unsigned Size = getULEB128Size(Discriminator);
MS->emitIntValue(dwarf::DW_LNS_extended_op, 1);
MS->emitULEB128IntValue(Size + 1);
MS->emitIntValue(dwarf::DW_LNE_set_discriminator, 1);
MS->emitULEB128IntValue(Discriminator);
LineSectionSize += /* extended op */ 1 + getULEB128Size(Size + 1) +
/* discriminator */ 1 + Size;
}

if (Isa != Row.Isa) {
Isa = Row.Isa;
Expand Down Expand Up @@ -1156,7 +1165,7 @@ void DwarfStreamer::emitLineTableRows(
EncodingBuffer.resize(0);
Address = -1ULL;
LastLine = FileNum = IsStatement = 1;
RowsSinceLastSequence = Column = Isa = 0;
RowsSinceLastSequence = Column = Discriminator = Isa = 0;
}
}

Expand Down
14 changes: 10 additions & 4 deletions llvm/lib/DWARFLinker/Parallel/DebugLineSectionEmitter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -315,6 +315,7 @@ class DebugLineSectionEmitter {
unsigned FileNum = 1;
unsigned LastLine = 1;
unsigned Column = 0;
unsigned Discriminator = 0;
unsigned IsStatement = 1;
unsigned Isa = 0;
uint64_t Address = -1ULL;
Expand Down Expand Up @@ -350,9 +351,14 @@ class DebugLineSectionEmitter {
Section.emitIntVal(dwarf::DW_LNS_set_column, 1);
encodeULEB128(Column, Section.OS);
}

// FIXME: We should handle the discriminator here, but dsymutil doesn't
// consider it, thus ignore it for now.
if (Discriminator != Row.Discriminator && MC->getDwarfVersion() >= 4) {
Discriminator = Row.Discriminator;
unsigned Size = getULEB128Size(Discriminator);
Section.emitIntVal(dwarf::DW_LNS_extended_op, 1);
encodeULEB128(Size + 1, Section.OS);
Section.emitIntVal(dwarf::DW_LNE_set_discriminator, 1);
encodeULEB128(Discriminator, Section.OS);
}

if (Isa != Row.Isa) {
Isa = Row.Isa;
Expand Down Expand Up @@ -397,7 +403,7 @@ class DebugLineSectionEmitter {
EncodingBuffer.resize(0);
Address = -1ULL;
LastLine = FileNum = IsStatement = 1;
RowsSinceLastSequence = Column = Isa = 0;
RowsSinceLastSequence = Column = Discriminator = Isa = 0;
}
}

Expand Down
Binary file added llvm/test/tools/dsymutil/Inputs/discriminator.arm64.dylib
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Binary file added llvm/test/tools/dsymutil/Inputs/discriminator.arm64.o
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23 changes: 23 additions & 0 deletions llvm/test/tools/dsymutil/discriminator.test
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Original file line number Diff line number Diff line change
@@ -0,0 +1,23 @@
; The input at Inputs/discriminator.arm64.dylib[.o] produced by compiling
;
; int foo(int i, int a, int b) {
; return i ? a : a * b;
; }
;
; with -g -fdebug-info-for-profiling -O2.

RUN: dsymutil --flat --linker=classic -oso-prepend-path %p -o - \
RUN: --oso-prepend-path %p/Inputs --verify-dwarf=none \
RUN: %p/Inputs/discriminator.arm64.dylib | llvm-dwarfdump -debug-line - \
RUN: | FileCheck %s

RUN: dsymutil --flat --linker=parallel -oso-prepend-path %p -o - \
RUN: --oso-prepend-path %p/Inputs --verify-dwarf=none \
RUN: %p/Inputs/discriminator.arm64.dylib | llvm-dwarfdump -debug-line - \
RUN: | FileCheck %s

CHECK: Address Line Column File ISA Discriminator OpIndex Flags
CHECK-NEXT: ------------------ ------ ------ ------ --- ------------- ------- -------------
CHECK-NEXT: 0x0000000000003f98 2 10 0 0 0 0 is_stmt prologue_end
CHECK-NEXT: 0x0000000000003fa4 2 3 0 0 6 0
CHECK-NEXT: 0x0000000000003fa8 2 3 0 0 0 0 end_sequence
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