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

[Sam Elliott via llvm-commits]

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@@ -130,17 +130,10 @@ void riscv::getRISCVTargetFeatures(const Driver &D, const llvm::Triple &Triple,
 #undef RESERVE_REG
 
   // -mrelax is default, unless -mno-relax is specified.
-  if (Args.hasFlag(options::OPT_mrelax, options::OPT_mno_relax, true)) {
+  if (Args.hasFlag(options::OPT_mrelax, options::OPT_mno_relax, true))
     Features.push_back("+relax");
-    // -gsplit-dwarf -mrelax requires DW_AT_high_pc/DW_AT_ranges/... indexing
-    // into .debug_addr, which is currently not implemented.
-    Arg *A;
-    if (getDebugFissionKind(D, Args, A) != DwarfFissionKind::None)
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lenary wrote:

RISC-V has relocations for PC offsets in debug info. IIRC, `R_RISCV_SET6` and `R_RISCV_SUB6` would be placed as a pair on the relevant part of the debug info. There are variants of this for ulebs too, which came later.

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