[llgo] Increment "Debug Info Version"

[cierniak]

Summary

This patch increments the "Debug Info Version" from 2 to 3. This is a nop if you just want to generate binaries. I verified that with and without this patch, when I run llgo -g on a Go source file, I get exactly the same binary.
The purpose of the patch is to make it possible to run the llvm-dis tool. Without the patch, it is impossible to disassemble files generated with llgo:

$ llgo -c -g -emit-llvm src/hello.go
$ llvm-dis hello.o
llvm-dis: warning: ignoring debug info with an invalid version (2) in hello.o

[axw]

LGTM, thanks. One of these days we should expose llvm::DEBUG_METADATA_VERSION to the C API.

[cierniak]

In D18355#380939, @axw wrote:

LGTM, thanks. One of these days we should expose llvm::DEBUG_METADATA_VERSION to the C API.

I don't have commit access to LLVM yet (this is my first patch ever). Could you commit it for me?

[axw]

In D18355#381860, @cierniak wrote:

In D18355#380939, @axw wrote:

LGTM, thanks. One of these days we should expose llvm::DEBUG_METADATA_VERSION to the C API.

I don't have commit access to LLVM yet (this is my first patch ever). Could you commit it for me?

Done, congratulations ;)

[cierniak]

In D18355#382077, @axw wrote:

In D18355#381860, @cierniak wrote:

In D18355#380939, @axw wrote:

LGTM, thanks. One of these days we should expose llvm::DEBUG_METADATA_VERSION to the C API.

I don't have commit access to LLVM yet (this is my first patch ever). Could you commit it for me?

Done, congratulations ;)

Thank you!

llgo/trunk/debug/debug.go

llvm.GlobalContext().MDNode([]llvm.Metadata{
       llvm.ConstInt(llvm.Int32Type(), 4, false).ConstantAsMetadata(),
     }),
   )
   d.module.AddNamedMetadataOperand(
     "llvm.module.flags",
     llvm.GlobalContext().MDNode([]llvm.Metadata{
       llvm.ConstInt(llvm.Int32Type(), 1, false).ConstantAsMetadata(), // Error on mismatch
       llvm.GlobalContext().MDString("Debug Info Version"),
-      llvm.ConstInt(llvm.Int32Type(), 2, false).ConstantAsMetadata(),
+      llvm.ConstInt(llvm.Int32Type(), 3, false).ConstantAsMetadata(),
     }),
   )
   d.builder.Finalize()
 }
 
 // DIType maps a Go type to DIType debug metadata value.
 func (d *DIBuilder) DIType(t types.Type) llvm.Metadata {
   return d.typeDebugDescriptor(t, types.TypeString(nil, t))