dwarfgen: Add support for generating the debug_str_offsets section, take 2
This recommits r337910 after fixing an "ambiguous call to addAttribute"
error with some compilers (gcc circa 4.9 and MSVC). It seems that these
compilers will consider a "false -> pointer" conversion during overload
resolution. This creates ambiguity because one I added an overload which
takes a MCExpr * as an argument.
I fix this by making the new overload take MCExpr&, which avoids the
conversion. It also documents the fact that we expect a valid MCExpr
object.
Original commit message follows:
The motivation for this is D49493, where we'd like to test details of
debug_str_offsets behavior which is difficult to trigger from a
traditional test.
This adds the plubming necessary for dwarfgen to generate this section.
The more interesting changes are:
- I've moved emitStringOffsetsTableHeader function from DwarfFile to
DwarfStringPool, so I can generate the section header more easily from
the unit test.
- added a new addAttribute overload taking an MCExpr*. This is used to
generate the DW_AT_str_offsets_base, which links a compile unit to the
offset table.
I've also added a basic test for reading and writing DW_form_strx forms.
Reviewers: dblaikie, JDevlieghere, probinson
Subscribers: llvm-commits, aprantl
Differential Revision: https://reviews.llvm.org/D49670
llvm-svn: 337933
diff --git a/llvm/unittests/DebugInfo/DWARF/DwarfGenerator.cpp b/llvm/unittests/DebugInfo/DWARF/DwarfGenerator.cpp
index b93b0cc..7f9f03e 100644
--- a/llvm/unittests/DebugInfo/DWARF/DwarfGenerator.cpp
+++ b/llvm/unittests/DebugInfo/DWARF/DwarfGenerator.cpp
@@ -54,16 +54,36 @@
}
void dwarfgen::DIE::addAttribute(uint16_t A, dwarf::Form Form,
+ const MCExpr &Expr) {
+ auto &DG = CU->getGenerator();
+ Die->addValue(DG.getAllocator(), static_cast<dwarf::Attribute>(A), Form,
+ DIEExpr(&Expr));
+}
+
+void dwarfgen::DIE::addAttribute(uint16_t A, dwarf::Form Form,
StringRef String) {
auto &DG = CU->getGenerator();
- if (Form == DW_FORM_string) {
+ switch (Form) {
+ case DW_FORM_string:
Die->addValue(DG.getAllocator(), static_cast<dwarf::Attribute>(A), Form,
new (DG.getAllocator())
DIEInlineString(String, DG.getAllocator()));
- } else {
+ break;
+
+ case DW_FORM_strp:
+ case DW_FORM_GNU_str_index:
+ case DW_FORM_strx:
+ case DW_FORM_strx1:
+ case DW_FORM_strx2:
+ case DW_FORM_strx3:
+ case DW_FORM_strx4:
Die->addValue(
DG.getAllocator(), static_cast<dwarf::Attribute>(A), Form,
DIEString(DG.getStringPool().getEntry(*DG.getAsmPrinter(), String)));
+ break;
+
+ default:
+ llvm_unreachable("Unhandled form!");
}
}
@@ -427,6 +447,7 @@
Asm->setDwarfVersion(Version);
StringPool = llvm::make_unique<DwarfStringPool>(Allocator, *Asm, StringRef());
+ StringOffsetsStartSym = Asm->createTempSymbol("str_offsets_base");
return Error::success();
}
@@ -448,7 +469,12 @@
CU->setLength(CUOffset - 4);
}
Abbreviations.Emit(Asm.get(), MOFI->getDwarfAbbrevSection());
- StringPool->emit(*Asm, MOFI->getDwarfStrSection());
+
+ StringPool->emitStringOffsetsTableHeader(*Asm, MOFI->getDwarfStrOffSection(),
+ StringOffsetsStartSym);
+ StringPool->emit(*Asm, MOFI->getDwarfStrSection(),
+ MOFI->getDwarfStrOffSection());
+
MS->SwitchSection(MOFI->getDwarfInfoSection());
for (auto &CU : CompileUnits) {
uint16_t Version = CU->getVersion();