[AMDGPU] Switch default dwarf version to 5

[scott.linder]

Summary

Reverts r337612. The issues that cropped up with the last attempt appear to have gone away.

[scott.linder]

Ping

[t-tye]

LGTM

Do we know the state of split DWARF and DWARF compression for DWARF 5 (compared to DWARF 2)?

[dblaikie]

In D59008#1441903, @t-tye wrote:

LGTM

Do we know the state of split DWARF and DWARF compression for DWARF 5 (compared to DWARF 2)?

State of them in what sense? Compression is pretty orthogonal to any DWARF version - it's more about the container (ELF, etc) you use. Split DWARF is non-standardly supported in pre-v5, and I think it's functioning in the standards conformant v5 mode too.

[t-tye]

In D59008#1442014, @dblaikie wrote:

In D59008#1441903, @t-tye wrote:

LGTM

Do we know the state of split DWARF and DWARF compression for DWARF 5 (compared to DWARF 2)?

State of them in what sense? Compression is pretty orthogonal to any DWARF version - it's more about the container (ELF, etc) you use. Split DWARF is non-standardly supported in pre-v5, and I think it's functioning in the standards conformant v5 mode too.

I had heard mention that at least split DWARF may not be fully supported yet for DWARF 5 in LLVM. But maybe that is old news:-)

[kzhuravl]

LGTM

[dblaikie]

In D59008#1442256, @t-tye wrote:

In D59008#1442014, @dblaikie wrote:

In D59008#1441903, @t-tye wrote:

LGTM

Do we know the state of split DWARF and DWARF compression for DWARF 5 (compared to DWARF 2)?

State of them in what sense? Compression is pretty orthogonal to any DWARF version - it's more about the container (ELF, etc) you use. Split DWARF is non-standardly supported in pre-v5, and I think it's functioning in the standards conformant v5 mode too.

I had heard mention that at least split DWARF may not be fully supported yet for DWARF 5 in LLVM. But maybe that is old news:-)

Might be - nothing I know of right now. (type units aren't fully supported in DWARFv5 - but that's the only big thing on my list)

[probinson]

In D59008#1442515, @dblaikie wrote:

In D59008#1442256, @t-tye wrote:

In D59008#1442014, @dblaikie wrote:

In D59008#1441903, @t-tye wrote:

LGTM

Do we know the state of split DWARF and DWARF compression for DWARF 5 (compared to DWARF 2)?

State of them in what sense? Compression is pretty orthogonal to any DWARF version - it's more about the container (ELF, etc) you use. Split DWARF is non-standardly supported in pre-v5, and I think it's functioning in the standards conformant v5 mode too.

I had heard mention that at least split DWARF may not be fully supported yet for DWARF 5 in LLVM. But maybe that is old news:-)

Might be - nothing I know of right now. (type units aren't fully supported in DWARFv5 - but that's the only big thing on my list)

Anything having to do with section format and placement ought to be correct at this point. Certainly I see v5 type units coming out in the .debug_info section per spec, and the .dwo files look right. If there's something missing please file a bug and CC me.

There was certainly a release where split-dwarf and type units didn't work yet, but that's all done now.

[dblaikie]

In D59008#1442962, @probinson wrote:

In D59008#1442515, @dblaikie wrote:

In D59008#1442256, @t-tye wrote:

In D59008#1442014, @dblaikie wrote:

In D59008#1441903, @t-tye wrote:

LGTM

Do we know the state of split DWARF and DWARF compression for DWARF 5 (compared to DWARF 2)?

State of them in what sense? Compression is pretty orthogonal to any DWARF version - it's more about the container (ELF, etc) you use. Split DWARF is non-standardly supported in pre-v5, and I think it's functioning in the standards conformant v5 mode too.

I had heard mention that at least split DWARF may not be fully supported yet for DWARF 5 in LLVM. But maybe that is old news:-)

Might be - nothing I know of right now. (type units aren't fully supported in DWARFv5 - but that's the only big thing on my list)

Anything having to do with section format and placement ought to be correct at this point. Certainly I see v5 type units coming out in the .debug_info section per spec, and the .dwo files look right. If there's something missing please file a bug and CC me.

There was certainly a release where split-dwarf and type units didn't work yet, but that's all done now.

Ah, thanks for the correction - I thought that was the case, and then I thought I'd tested it a couple of weeks ago and seen it wasn't (when I'd expected it was)... must've messed up my test, maybe used an old compiler build I had lying around.

Good stuff!

[scott.linder]

Add a test to confirm split-dwarf is supported for the amdhsa OS in the driver.

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 2; }
+  unsigned GetDefaultDwarfVersion() const override { return 5; }
   bool IsIntegratedAssemblerDefault() const override { return true; }
   llvm::opt::DerivedArgList *
   TranslateArgs(const llvm::opt::DerivedArgList &Args, StringRef BoundArch,
                 Action::OffloadKind DeviceOffloadKind) const override;
 
   void addClangTargetOptions(const llvm::opt::ArgList &DriverArgs,
                              llvm::opt::ArgStringList &CC1Args,
                              Action::OffloadKind DeviceOffloadKind) const override;
 };
 
 } // end namespace toolchains
 } // end namespace driver
 } // end namespace clang
 
 #endif // LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_AMDGPU_H

test/Driver/amdgpu-toolchain.c

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

test/Driver/split-debug.c

 // CHECK-BAD-NOT: "Bad.dwo"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -gsplit-dwarf -c -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-OPTION < %t %s
 //
 // RUN: %clang -target x86_64-pc-freebsd12 -gsplit-dwarf -c -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-OPTION < %t %s
 //
+// RUN: %clang -target amdgcn-amd-amdhsa -gsplit-dwarf -c -### %s 2> %t
+// RUN: FileCheck -check-prefix=CHECK-OPTION < %t %s
+//
 // CHECK-OPTION: "-split-dwarf-file" "split-debug.dwo"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -gsplit-dwarf -S -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-ASM < %t %s
 //
 // CHECK-ASM-NOT: objcopy
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -no-integrated-as -gsplit-dwarf -c -### %s 2> %t