[clang] [PowerPC] Diagnose invalid combination with Altivec, VSX and soft-float (PR #79109)

[Qiu Chaofan via cfe-commits]

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@@ -442,19 +442,44 @@ void PPCTargetInfo::getTargetDefines(const LangOptions &Opts,
   //   _CALL_DARWIN
 }
 
-// Handle explicit options being passed to the compiler here: if we've
-// explicitly turned off vsx and turned on any of:
-// - power8-vector
-// - direct-move
-// - float128
-// - power9-vector
-// - paired-vector-memops
-// - mma
-// - power10-vector
+// Handle explicit options being passed to the compiler here:
+// - if we've explicitly turned off vsx and turned on any of:
+//   - power8-vector
+//   - direct-move
+//   - float128
+//   - power9-vector
+//   - paired-vector-memops
+//   - mma
+//   - power10-vector
+// - if we've explicitly turned on vsx and turned off altivec.
+// - if we've explicitly turned on soft-float and altivec.
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ecnelises wrote:

Better as `on altivec and off hard-float`? since the feature name is `hard-float` not `soft-float`.

https://github.com/llvm/llvm-project/pull/79109