[clang] Revert "[Driver] Default riscv*- triples to -fdebug-default-version=4" (PR #84119)

[Fangrui Song via cfe-commits]

https://github.com/MaskRay created https://github.com/llvm/llvm-project/pull/84119

This reverts commit bbc0f99f3bc96f1db16f649fc21dd18e5b0918f6
(https://reviews.llvm.org/D157663).

With this change, the next major release 19.1 will generate
R_RISCV_SET_ULEB128/R_RISCV_SUB_ULEB128 relocations, which require
lld>=18 or binutils>=2.41.
binutils 2.41 is relatively new, but GCC has been producing
R_RISCV_SET_ULEB128/R_RISCV_SUB_ULEB128 for some time now.


>From 7d55c2a4673ff3419a39a4eb2a8c18efb554a497 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Tue, 5 Mar 2024 20:57:25 -0800
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Created using spr 1.3.5-bogner
---
 clang/include/clang/Driver/ToolChain.h | 2 +-
 clang/lib/Driver/ToolChain.cpp         | 6 ------
 clang/test/Driver/clang-g-opts.c       | 5 -----
 3 files changed, 1 insertion(+), 12 deletions(-)

diff --git a/clang/include/clang/Driver/ToolChain.h b/clang/include/clang/Driver/ToolChain.h
index fbe2e8fe8e88d8..a4f9cad98aa8b1 100644
--- a/clang/include/clang/Driver/ToolChain.h
+++ b/clang/include/clang/Driver/ToolChain.h
@@ -580,7 +580,7 @@ class ToolChain {
 
   // Return the DWARF version to emit, in the absence of arguments
   // to the contrary.
-  virtual unsigned GetDefaultDwarfVersion() const;
+  virtual unsigned GetDefaultDwarfVersion() const { return 5; }
 
   // Some toolchains may have different restrictions on the DWARF version and
   // may need to adjust it. E.g. NVPTX may need to enforce DWARF2 even when host
diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index 08b1fd01b3c0ac..03450fc0f57b93 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -453,12 +453,6 @@ ToolChain::getDefaultUnwindTableLevel(const ArgList &Args) const {
   return UnwindTableLevel::None;
 }
 
-unsigned ToolChain::GetDefaultDwarfVersion() const {
-  // TODO: Remove the RISC-V special case when R_RISCV_SET_ULEB128 linker
-  // support becomes more widely available.
-  return getTriple().isRISCV() ? 4 : 5;
-}
-
 Tool *ToolChain::getClang() const {
   if (!Clang)
     Clang.reset(new tools::Clang(*this, useIntegratedBackend()));
diff --git a/clang/test/Driver/clang-g-opts.c b/clang/test/Driver/clang-g-opts.c
index b73602a155b009..fdbe0b96420c51 100644
--- a/clang/test/Driver/clang-g-opts.c
+++ b/clang/test/Driver/clang-g-opts.c
@@ -42,8 +42,3 @@
 
 // CHECK-WITH-G-STANDALONE: "-debug-info-kind=standalone"
 // CHECK-WITH-G-STANDALONE: "-dwarf-version=2"
-
-/// TODO: Special case before R_RISCV_SET_ULEB128 linker support becomes more widely available.
-// RUN: %clang -### -S %s -g --target=riscv64-linux-gnu 2>&1 | FileCheck --check-prefix=VERSION4 %s
-// RUN: %clang -### -S %s -g --target=riscv64-unknown-elf 2>&1 | FileCheck --check-prefix=VERSION4 %s
-// VERSION4: "-dwarf-version=4"