[clang] [SPARC][clang] Add -m(no-)v8plus flags handling (PR #98713)

[Sergei Barannikov via cfe-commits]

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@@ -179,6 +179,13 @@ void sparc::getSparcTargetFeatures(const Driver &D, const ArgList &Args,
       Features.push_back("-hard-quad-float");
   }
 
+  if (Arg *A = Args.getLastArg(options::OPT_mv8plus, options::OPT_mno_v8plus)) {
+    if (A->getOption().matches(options::OPT_mv8plus))
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s-barannikov wrote:

This is quite confusing.
`-m[no]-v8plus` is an environment option, similar to X86's `-mx32`, but imposes more restrictions.
`-mcpu=v9 -mno-v8plus` should be equivalent to just `-mcpu=v9` because 64-bit environment is the default for 64-bit ISA.
`-mv8plus` enables 32-bit environment and therefore should restrict the compiler from using the whole set of V9 features. That is, I would expect it to disable something rather than to enable `v9`, which should already be set by `-mcpu=v9`.


https://github.com/llvm/llvm-project/pull/98713