[clang] [clang][SYCL] Add SYCL spelling for AS attributes (PR #200849)

[via cfe-commits]

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@@ -312,3 +313,26 @@ void clang::takeAndConcatenateAttrs(ParsedAttributes &First,
   if (Second.Range.getEnd().isValid())
     First.Range.setEnd(Second.Range.getEnd());
 }
+
+LangAS ParsedAttr::asLangAS() const {
+  switch (getParsedKind()) {
+  case ParsedAttr::AT_OffloadGlobalAddressSpace:
+    return OffloadGlobalAddressSpaceAttr::getLangAS(*this);
+  case ParsedAttr::AT_OffloadGlobalDeviceAddressSpace:
+    return OffloadGlobalDeviceAddressSpaceAttr::getLangAS(*this);
+  case ParsedAttr::AT_OffloadGlobalHostAddressSpace:
+    return OffloadGlobalHostAddressSpaceAttr::getLangAS(*this);
+  case ParsedAttr::AT_OffloadLocalAddressSpace:
+    return OffloadLocalAddressSpaceAttr::getLangAS(*this);
+  case ParsedAttr::AT_OffloadPrivateAddressSpace:
+    return OffloadPrivateAddressSpaceAttr::getLangAS(*this);
+  case ParsedAttr::AT_OffloadConstantAddressSpace:
+    return OffloadConstantAddressSpaceAttr::getLangAS(*this);
+  case ParsedAttr::AT_OffloadGenericAddressSpace:
+    return OffloadGenericAddressSpaceAttr::getLangAS(*this);
+  case ParsedAttr::AT_HLSLGroupSharedAddressSpace:
+    return LangAS::hlsl_groupshared;
+  default:
+    return LangAS::Default;
+  }
+}
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elizabethandrews wrote:

>We can't, as far as I know, use the LangOpts declarative approach for the combined OpenCP and SYCL address spaces since that would require differentiation based on spelling, so perhaps that is reasonable motivation for defining distinct attributes (as we discussed earlier today). 

I guess my question is what is the purpose of the new attributes and to be honest also using OpenCL spelling in SYCL code if attribute behavior is semantically similar. Is your concern purely about diagnostics being strange? Because diagnostics can just be reworded to say `global address space` instead of `sycl_global` and `__global`. IMO the differentiation/warnings between spellings (as in done in the second commit of this PR and proposed warnings) for SYCL vs OpenCL  is overkill.  I personally do not see the problem with considering them equivalent with mapping done based on LangOpts. 

https://github.com/llvm/llvm-project/pull/200849