[libcxxabi][mips] Correct float_data::mangled_size for all ABI's.

[dsanders]

Summary

Patch by Nitesh Jain and Jaydeep Patil with a small revision to use ABIs rather
than Architecture Revisions (which currently imply particular ABIs).

Fixes test_demangle.pass.cpp (PR24149).

[dsanders]

@mclow.lists: I couldn't find a libcxxabi code owner in CODE_OWNERS.txt. Do you cover libcxxabi as well as libcxx?

[hans]

Ping? This on my 3.7 hotlist.

[hans]

Ping?

[dsanders]

libc++abi is outside my area of knowledge but seeing as no other reviewers have come forward and the patch is MIPS specific I'd like to LGTM this on the basis that I've tested it and found that it fixes the bug in the release.

Hans: After committing, the process still needs the code owner to approve the merge. We haven't heard anything from the person we think is the code-owner so I'm not sure how to proceed. Would you be willing to approve it without the code-owner or would you prefer to wait?

[dsanders]

I'd like to LGTM this on the basis

Scratch that. I'm one of the authors (albeit as a minor revision on Jaydeep+Nitesh's patch) and I can't approve my own patches :-).

Hans: Are you willing to LGTM it?

[mclow.lists]

I have no objections to this change; but I have no way to test it.

[hans]

In D11483#215120, @dsanders wrote:

I'd like to LGTM this on the basis

Scratch that. I'm one of the authors (albeit as a minor revision on Jaydeep+Nitesh's patch) and I can't approve my own patches :-).

Hans: Are you willing to LGTM it?

I don't know enough here to be a good review. What's mangled_size used for?

In D11483#215133, @mclow.lists wrote:

I have no objections to this change; but I have no way to test it.

Is that an lgtm or call for some kind of test? :-)

[mclow.lists]

In D11483#215138, @hans wrote:

In D11483#215133, @mclow.lists wrote:

I have no objections to this change; but I have no way to test it.

Is that an lgtm or call for some kind of test? :-)

It looks good to me, but I don't have access to a MIPS or MIPS_n64 system.
If people with access to those systems are OK with this, I am as well.

[dsanders]

Thanks Marshall. Committed in r243645.

libcxxabi/trunk/src/cxa_demangle.cpp

struct float_data<double>
     static constexpr const char* spec = "%a";
 };
 
 constexpr const char* float_data<double>::spec;
 
 template <>
 struct float_data<long double>
 {
-#if defined(__arm__)
+#if defined(__mips__) && defined(__mips_n64)
+    static const size_t mangled_size = 32;
+#elif defined(__arm__) || defined(__mips__)
     static const size_t mangled_size = 16;
 #else
     static const size_t mangled_size = 20;  // May need to be adjusted to 16 or 24 on other platforms
 #endif
     static const size_t max_demangled_size = 40;
     static constexpr const char* spec = "%LaL";
 };