[clang] [llvm] [dwarf] make dwarf fission compatible with RISCV relaxations (PR #164128)

[David Blaikie via llvm-commits]

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@@ -3290,34 +3275,70 @@ static MCSymbol *emitLoclistsTableHeader(AsmPrinter *Asm,
   return TableEnd;
 }
 
-template <typename Ranges, typename PayloadEmitter>
-static void emitRangeList(
-    DwarfDebug &DD, AsmPrinter *Asm, MCSymbol *Sym, const Ranges &R,
-    const DwarfCompileUnit &CU, unsigned BaseAddressx, unsigned OffsetPair,
-    unsigned StartxLength, unsigned EndOfList,
-    StringRef (*StringifyEnum)(unsigned),
-    bool ShouldUseBaseAddress,
-    PayloadEmitter EmitPayload) {
+namespace {
+
+struct DebugLocSpanList {
+  MCSymbol *Label;
+  const DwarfCompileUnit *CU;
+  llvm::ArrayRef<llvm::DebugLocStream::Entry> Ranges;
+};
+
+template <typename DWARFSpanList> struct DwarfRangeListTraits {};
+
+template <> struct DwarfRangeListTraits<DebugLocSpanList> {
+  static constexpr unsigned BaseAddressx = dwarf::DW_LLE_base_addressx;
+  static constexpr unsigned OffsetPair = dwarf::DW_LLE_offset_pair;
+  static constexpr unsigned StartxLength = dwarf::DW_LLE_startx_length;
+  static constexpr unsigned StartxEndx = dwarf::DW_LLE_startx_endx;
+  static constexpr unsigned EndOfList = dwarf::DW_LLE_end_of_list;
+
+  static StringRef StringifyRangeKind(unsigned Encoding) {
+    return llvm::dwarf::LocListEncodingString(Encoding);
+  }
+};
+
+template <> struct DwarfRangeListTraits<RangeSpanList> {
+  static constexpr unsigned BaseAddressx = dwarf::DW_RLE_base_addressx;
+  static constexpr unsigned OffsetPair = dwarf::DW_RLE_offset_pair;
+  static constexpr unsigned StartxLength = dwarf::DW_RLE_startx_length;
+  static constexpr unsigned StartxEndx = dwarf::DW_RLE_startx_endx;
+  static constexpr unsigned EndOfList = dwarf::DW_RLE_end_of_list;
+
+  static StringRef StringifyRangeKind(unsigned Encoding) {
+    return llvm::dwarf::RangeListEncodingString(Encoding);
+  }
+};
+
+} // namespace
+
+template <
+    typename Ranges, typename PayloadEmitter,
+    std::enable_if_t<DwarfRangeListTraits<Ranges>::BaseAddressx, bool> = true>
+static void emitRangeList(DwarfDebug &DD, AsmPrinter *Asm, const Ranges &R,
+                          bool ShouldUseBaseAddress,
+                          PayloadEmitter EmitPayload) {
 
   auto Size = Asm->MAI->getCodePointerSize();
   bool UseDwarf5 = DD.getDwarfVersion() >= 5;
 
   // Emit our symbol so we can find the beginning of the range.
-  Asm->OutStreamer->emitLabel(Sym);
+  Asm->OutStreamer->emitLabel(R.Label);
 
   // Gather all the ranges that apply to the same section so they can share
   // a base address entry.
-  SmallMapVector<const MCSection *, std::vector<decltype(&*R.begin())>, 16>
+  SmallMapVector<const MCSection *, std::vector<decltype(&*R.Ranges.begin())>,
+                 16>
       SectionRanges;
 
-  for (const auto &Range : R)
+  for (const auto &Range : R.Ranges)
     SectionRanges[&Range.Begin->getSection()].push_back(&Range);
 
-  const MCSymbol *CUBase = CU.getBaseAddress();
+  const MCSymbol *CUBase = R.CU->getBaseAddress();
   bool BaseIsSet = false;
   for (const auto &P : SectionRanges) {
     auto *Base = CUBase;
-    if ((Asm->TM.getTargetTriple().isNVPTX() && DD.tuneForGDB())) {
+    if ((Asm->TM.getTargetTriple().isNVPTX() && DD.tuneForGDB()) ||
+        (DD.useSplitDwarf() && P.first->isLinkerRelaxable())) {
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dwblaikie wrote:

Might be worth separating these two changes too - one for DWARFv4 and one for DWARFv5?

https://github.com/llvm/llvm-project/pull/164128