[clang] [llvm] [PowerPC] Diagnose musttail instead of crash inside backend (PR #93267)

[Eli Friedman via cfe-commits]

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@@ -743,6 +743,20 @@ bool Sema::checkMustTailAttr(const Stmt *St, const Attr &MTA) {
     CallerType.Func = CallerDecl->getType()->getAs<FunctionProtoType>();
   }
 
+  if (Context.getTargetInfo().getTriple().isPPC()) {
+    if (Context.getTargetInfo().getTriple().isOSAIX())
+      return Diag(St->getBeginLoc(), diag::err_aix_musttail_unsupported);
+    else if (!Context.getTargetInfo().hasFeature("pcrelative-memops")) {
+      if (Context.getTargetInfo().hasFeature("longcall"))
+        return Diag(St->getBeginLoc(), diag::err_ppc_impossible_musttail) << 0;
+      else if (!CE->getDirectCallee())
+        return Diag(St->getBeginLoc(), diag::err_ppc_impossible_musttail) << 1;
+      else if (isa_and_nonnull<FunctionDecl>(CE->getCalleeDecl()) &&
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efriedma-quic wrote:

For the weak definitions, you can look at GVALinkage or something like that, yes.

For the ordering issue, you probably need to do the analysis at the end of the translation unit, or something like that.

https://github.com/llvm/llvm-project/pull/93267