Revert [Driver] Error for -gsplit-dwarf with RISC-V linker relaxation (llvm#169653)

This patch reverts 80a4e6f

After the relevant patches clang now supports dwarf fission with RISC-V
linker relaxations, so we can remove the related driver error.

Author: daniilavdeev

clang/include/clang/Basic/DiagnosticDriverKinds.td

@@ -851,9 +851,6 @@ def warn_drv_sarif_format_unstable : Warning<
   "diagnostic formatting in SARIF mode is currently unstable">,
   InGroup<DiagGroup<"sarif-format-unstable">>;
 
-def err_drv_riscv_unsupported_with_linker_relaxation : Error<
-  "%0 is unsupported with RISC-V linker relaxation (-mrelax)">;
-
 def warn_drv_loongarch_conflicting_implied_val : Warning<
   "ignoring '%0' as it conflicts with that implied by '%1' (%2)">,
   InGroup<OptionIgnored>;

clang/lib/Driver/ToolChains/Arch/RISCV.cpp

@@ -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)
-      D.Diag(clang::diag::err_drv_riscv_unsupported_with_linker_relaxation)
-          << A->getAsString(Args);
-  } else {
+  else
     Features.push_back("-relax");
-  }
 
   // If -mstrict-align, -mno-strict-align, -mscalar-strict-align, or
   // -mno-scalar-strict-align is passed, use it. Otherwise, the

clang/test/Driver/riscv-features.c

@@ -68,13 +68,6 @@
 // DEFAULT-LINUX-SAME: "-target-feature" "+d"
 // DEFAULT-LINUX-SAME: "-target-feature" "+c"
 
-// RUN: not %clang -c --target=riscv64-linux-gnu -gsplit-dwarf %s 2>&1 | FileCheck %s --check-prefix=ERR-SPLIT-DWARF
-// RUN: not %clang -c --target=riscv64 -gsplit-dwarf=single %s 2>&1 | FileCheck %s --check-prefix=ERR-SPLIT-DWARF
-// RUN: %clang -### -c --target=riscv64 -mno-relax -g -gsplit-dwarf %s 2>&1 | FileCheck %s --check-prefix=SPLIT-DWARF
-
-// ERR-SPLIT-DWARF: error: -gsplit-dwarf{{.*}} is unsupported with RISC-V linker relaxation (-mrelax)
-// SPLIT-DWARF:     "-split-dwarf-file"
-
 // RUN: %clang -mabi=lp64d --target=riscv64-unknown-fuchsia -### %s -fsyntax-only 2>&1 | FileCheck %s -check-prefixes=FUCHSIA
 // FUCHSIA: "-target-feature" "+m"
 // FUCHSIA-SAME: "-target-feature" "+a"