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

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.

Subscribers: kzhuravl, jvesely, wdng, nhaehnle, yaxunl, aprantl, dstuttard, tpr, t-tye, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70191

Author: slinder1

clang/lib/Driver/ToolChains/AMDGPU.h

@@ -55,7 +55,7 @@ class LLVM_LIBRARY_VISIBILITY AMDGPUToolChain : public Generic_ELF {
 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; }
 

clang/lib/Driver/ToolChains/HIP.h

@@ -113,7 +113,7 @@ class LLVM_LIBRARY_VISIBILITY HIPToolChain : public ToolChain {
   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;
 

clang/test/Driver/amdgpu-toolchain.c

@@ -8,4 +8,4 @@
 // 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

@@ -0,0 +1,9 @@
+// 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"