[DWARF] Suppress split line tables more carefully.
If a given split type unit does not have source locations, don't have
it refer to the split line table.
If no split type unit refers to the split line table, don't emit the
line table at all.
This will save a little space on rare occasions, but also refactors
things a bit to improve which class is responsible for what.
Responding to review comments on r326395.
Differential Revision: https://reviews.llvm.org/D44220
llvm-svn: 328670
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index b392586..024472d 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2122,11 +2122,9 @@
void DwarfDebug::emitDebugLineDWO() {
assert(useSplitDwarf() && "No split dwarf?");
- if (!HasSplitTypeUnits)
- return;
- Asm->OutStreamer->SwitchSection(
+ SplitTypeUnitFileTable.Emit(
+ *Asm->OutStreamer, MCDwarfLineTableParams(),
Asm->getObjFileLowering().getDwarfLineDWOSection());
- SplitTypeUnitFileTable.Emit(*Asm->OutStreamer, MCDwarfLineTableParams());
}
void DwarfDebug::emitStringOffsetsTableHeaderDWO() {
@@ -2200,8 +2198,9 @@
if (useSplitDwarf())
NewTU.setSection(Asm->getObjFileLowering().getDwarfTypesDWOSection());
else {
- CU.applyStmtList(UnitDie);
NewTU.setSection(Asm->getObjFileLowering().getDwarfTypesSection(Signature));
+ // Non-split type units reuse the compile unit's line table.
+ CU.applyStmtList(UnitDie);
}
// Add DW_AT_str_offsets_base to the type unit DIE, but not for split type
@@ -2239,7 +2238,6 @@
InfoHolder.computeSizeAndOffsetsForUnit(TU.first.get());
InfoHolder.emitUnit(TU.first.get(), useSplitDwarf());
}
- HasSplitTypeUnits = useSplitDwarf();
}
CU.addDIETypeSignature(RefDie, Signature);
}
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 52b9206..3ee7871 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -280,10 +280,6 @@
/// a monolithic sequence of string offsets.
bool UseSegmentedStringOffsetsTable;
- /// Whether we have emitted any type units with split DWARF (and therefore
- /// need to emit a line table to the .dwo file).
- bool HasSplitTypeUnits = false;
-
/// Separated Dwarf Variables
/// In general these will all be for bits that are left in the
/// original object file, rather than things that are meant
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index 16ce3d7..811112a 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -85,8 +85,6 @@
MCDwarfDwoLineTable *SplitLineTable)
: DwarfUnit(dwarf::DW_TAG_type_unit, CU.getCUNode(), A, DW, DWU), CU(CU),
SplitLineTable(SplitLineTable) {
- if (SplitLineTable)
- addSectionOffset(getUnitDie(), dwarf::DW_AT_stmt_list, 0);
}
DwarfUnit::~DwarfUnit() {
@@ -300,12 +298,15 @@
}
unsigned DwarfTypeUnit::getOrCreateSourceID(const DIFile *File) {
- return SplitLineTable
- ? SplitLineTable->getFile(File->getDirectory(),
- File->getFilename(),
- getMD5AsBytes(File),
- File->getSource())
- : getCU().getOrCreateSourceID(File);
+ if (!SplitLineTable)
+ return getCU().getOrCreateSourceID(File);
+ if (!UsedLineTable) {
+ UsedLineTable = true;
+ // This is a split type unit that needs a line table.
+ addSectionOffset(getUnitDie(), dwarf::DW_AT_stmt_list, 0);
+ }
+ return SplitLineTable->getFile(File->getDirectory(), File->getFilename(),
+ getMD5AsBytes(File), File->getSource());
}
void DwarfUnit::addOpAddress(DIELoc &Die, const MCSymbol *Sym) {
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
index 5de3963..328e354 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -367,6 +367,7 @@
const DIE *Ty;
DwarfCompileUnit &CU;
MCDwarfDwoLineTable *SplitLineTable;
+ bool UsedLineTable = false;
unsigned getOrCreateSourceID(const DIFile *File) override;
bool isDwoUnit() const override;