add some comments on how this is *supposed* to work. We don't
need the PreferredEHDataFormat hook, but I have yet-more refactoring to
do before I can zap it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77742 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/AsmPrinter/DwarfException.cpp b/lib/CodeGen/AsmPrinter/DwarfException.cpp
index 0c710fc..8eb97af 100644
--- a/lib/CodeGen/AsmPrinter/DwarfException.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfException.cpp
@@ -539,6 +539,9 @@
unsigned SizeAlign = (4 - TotalSize) & 3;
// Begin the exception table.
+ //MCSection *LSDASection = TAI->getLSDASection();
+ //Asm->SwitchToSection(LSDASection);
+
Asm->SwitchToDataSection(TAI->getDwarfExceptionSection());
Asm->EmitAlignment(2, 0, 0, false);
O << "GCC_except_table" << SubprogramCount << ":\n";
@@ -560,8 +563,32 @@
Asm->EmitInt8(dwarf::DW_EH_PE_omit);
Asm->EOL("TType format (DW_EH_PE_omit)");
} else {
+ // FIXME: Instead of using "PreferredEHDataFormat", we should use a simple
+ // approach to determine what needs to happen. Basically, if the target
+ // wants the LSDA to be emitted into a read-only segment (like .text) then
+ // (unless in static mode) it can't output direct pointers to the typeinfo
+ // objects, which may be in an arbitrary locations. Instead, it has to use
+ // and indirect stub pointer to get to the typeinfo.
+ //
+ // If the target wants to dump the LSDA's into a segment writable by the
+ // dynamic linker, then it can just use a normal pointer, and the dynamic
+ // linker will fix it up.
+
+ // TODO: Replace the getDwarfExceptionSection() callback on TAI with a new
+ // getLSDASection() method on TLOF. Merge and sanitize the implementations,
+ // and figure out what the ".gcc_except_table" directive expands to on elf
+ // systems.
+
+ //
+ //if (LSDASection->isWritable()) {
+ //Asm->EmitInt8(DW_EH_PE_absptr);
+ //} else {
+ //Asm->EmitInt8(DW_EH_PE_pcrel | DW_EH_PE_indirect | DW_EH_PE_sdata4);
+ //}
+
Asm->EmitInt8(TAI->PreferredEHDataFormat());
+
// FIXME: The comment here should correspond with what PreferredEHDataFormat
// returned.
Asm->EOL("TType format (DW_EH_PE_xxxxx)");