[AMDGPU][HIP] Change default DWARF version to 4

[scott.linder]

Summary

Tooling around DWARF 5 is still not mature enough for this to be a sane
default, and the AMDGPU and HIP toolchains should agree on a single
default.

[yaxunl]

LGTM. Thanks.

clang/lib/Driver/ToolChains/AMDGPU.h

const StringRef getOptionDefault(options::ID OptID) const {
     auto opt = OptionsDefault.find(OptID);
     assert(opt != OptionsDefault.end() && "No Default for Option");
     return opt->second;
   }
 
 public:
   AMDGPUToolChain(const Driver &D, const llvm::Triple &Triple,
                   const llvm::opt::ArgList &Args);
-  unsigned GetDefaultDwarfVersion() const override { return 5; }
+  unsigned GetDefaultDwarfVersion() const override { return 4; }
   bool IsIntegratedAssemblerDefault() const override { return true; }
   bool IsMathErrnoDefault() const override { return false; }
 
   llvm::opt::DerivedArgList *
   TranslateArgs(const llvm::opt::DerivedArgList &Args, StringRef BoundArch,
                 Action::OffloadKind DeviceOffloadKind) const override;
 
   void addClangTargetOptions(const llvm::opt::ArgList &DriverArgs,

clang/lib/Driver/ToolChains/HIP.h

void AddIAMCUIncludeArgs(const llvm::opt::ArgList &DriverArgs,
                            llvm::opt::ArgStringList &CC1Args) const override;
 
   SanitizerMask getSupportedSanitizers() const override;
 
   VersionTuple
   computeMSVCVersion(const Driver *D,
                      const llvm::opt::ArgList &Args) const override;
 
-  unsigned GetDefaultDwarfVersion() const override { return 2; }
+  unsigned GetDefaultDwarfVersion() const override { return 4; }
 
   const ToolChain &HostTC;
 
 protected:
   Tool *buildLinker() const override;
 };
 
 } // end namespace toolchains
 } // end namespace driver
 } // end namespace clang
 
 #endif // LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_HIP_H

clang/test/Driver/amdgpu-toolchain.c

 // RUN: %clang -### -target amdgcn--amdhsa -x assembler -mcpu=kaveri %s 2>&1 | FileCheck -check-prefix=AS_LINK %s
 // RUN: %clang -### -g -target amdgcn--amdhsa -mcpu=kaveri %s 2>&1 | FileCheck -check-prefix=DWARF_VER %s
 // RUN: %clang -### -target amdgcn-amd-amdpal -x assembler -mcpu=kaveri %s 2>&1 | FileCheck -check-prefix=AS_LINK %s
 // RUN: %clang -### -g -target amdgcn-amd-amdpal -mcpu=kaveri %s 2>&1 | FileCheck -check-prefix=DWARF_VER %s
 // RUN: %clang -### -target amdgcn-mesa-mesa3d -x assembler -mcpu=kaveri %s 2>&1 | FileCheck -check-prefix=AS_LINK %s
 // RUN: %clang -### -g -target amdgcn-mesa-mesa3d -mcpu=kaveri %s 2>&1 | FileCheck -check-prefix=DWARF_VER %s
 
 // AS_LINK: clang{{.*}} "-cc1as"
 // AS_LINK: ld.lld{{.*}} "-shared"
 
-// DWARF_VER: "-dwarf-version=5"
+// DWARF_VER: "-dwarf-version=4"

clang/test/Driver/hip-toolchain-dwarf.hip

+// REQUIRES: clang-driver
+// REQUIRES: x86-registered-target
+// REQUIRES: amdgpu-registered-target
+
+// RUN: %clang -### -c -target x86_64-linux-gnu -fgpu-rdc \
+// RUN:   -x hip --cuda-gpu-arch=gfx803 %s \
+// RUN:   -Xarch_gfx803 -g 2>&1 | FileCheck %s -check-prefix=DWARF_VER
+
+// DWARF_VER: "-dwarf-version=4"