[PATCH] D52296: [Clang] - Add '-gsplit-dwarf[=split, =single]' version for '-gsplit-dwarf' option.

[George Rimar via Phabricator via cfe-commits]

grimar added inline comments.


================
Comment at: lib/Driver/ToolChains/CommonArgs.cpp:813-830
+  if (Arg *A = Args.getLastArg(options::OPT_gsplit_dwarf_EQ))
+    if (StringRef(A->getValue()) == "single")
+      return Args.MakeArgString(Output.getFilename());
+
   Arg *FinalOutput = Args.getLastArg(options::OPT_o);
   if (FinalOutput && Args.hasArg(options::OPT_c)) {
     SmallString<128> T(FinalOutput->getValue());
----------------
dblaikie wrote:
> If this function now takes the output file name - could it be simplified to just always use that, rather than the conditional code that follows and tests whether -o is specified and builds up something like the output file name & uses the dwo suffix?
I am investigating this.


================
Comment at: test/CodeGen/split-debug-single-file.c:12
+//  RUN:   -enable-split-dwarf=split -split-dwarf-file %t.o -emit-obj -o %t.o %s
+//  RUN: llvm-objdump -section-headers %t.o | FileCheck --check-prefix=MODE-SPLIT %s
+//  MODE-SPLIT-NOT: .dwo
----------------
dblaikie wrote:
> This looks like an end-to-end test, which we don't usually do in Clang (or in the LLVM project in general).
> 
> For example, the previous testing for split-dwarf had a driver test (that tested only that the driver produced the right cc1 invocation) and a CodeGen test (that tested that the right IR was produced), but I don't see any test like this (that tested the resulting object file)?
> 
> I know there's a narrow gap in IR testing - things that don't go in the IR, but instead go through MCOptions  & that the SplitDwarfFile is one of those.
> 
> So, yeah, in this case it's a bit of a test hole - if you're going to keep this test, perhaps it could test assembly, rather than the object file? Since it doesn't need complex parsing, etc, perhaps?
> So, yeah, in this case it's a bit of a test hole - if you're going to keep this test, perhaps it could test assembly, rather than the object file? Since it doesn't need complex parsing, etc, perhaps?

I am not sure assembly can help here. For example
`clang main.c -S -g -gsplit-dwarf` would create single asm file output anyways
and what I tried to check here is that we can either place .dwo sections into the
same output or into a different one depending on new option.

> For example, the previous testing for split-dwarf had a driver test (that tested only that the driver produced the right cc1 invocation) and a CodeGen test (that tested that the right IR was produced), but I don't see any test like this (that tested the resulting object file)?

I think `split-debug-filename.c` do that?
See: https://github.com/llvm-mirror/clang/blob/master/test/CodeGen/split-debug-filename.c#L18

Also, `relax.c`: https://github.com/llvm-mirror/clang/blob/master/test/CodeGen/relax.c
And `mips-inline-asm-abi.c`:  https://github.com/llvm-mirror/clang/blob/master/test/CodeGen/mips-inline-asm-abi.c

Seems it is not common, but still acceptable?


https://reviews.llvm.org/D52296