[PATCH] D35479: [CodeGen][mips] Support `long_call/far/near` attributes

John McCall via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Mon Jul 17 15:48:38 PDT 2017

rjmccall added inline comments.

Comment at: include/clang/Basic/Attr.td:1191
+def MipsLongCall : InheritableAttr, TargetSpecificAttr<TargetMips> {
+  let Spellings = [GCC<"long_call">, GCC<"far">, GCC<"near">];
Because this is used for all three attributes, I think you should call it something more general.  Perhaps MipsCallStyle?

Comment at: include/clang/Basic/Attr.td:1195
+  let Accessors = [Accessor<"longCall", [GCC<"long_call">, GCC<"far">]>,
+                   Accessor<"nearCall", [GCC<"near">]>];
+  let Documentation = [MipsLongCallDocs];
This is not the standard naming convention for accessors.  I suggest isLongCall() and isNearCall().

Comment at: include/clang/Basic/AttrDocs.td:1336
+if code compiled using ``-mlong-calls`` switch, it forces compiler to use
+the ``jal`` instruction to call the function.
+  }];
I suggest the following wording:

Clang supports the ``__attribute__((long_call))``, ``__attribute__((far))``, and
``__attribute__((near))`` attributes on MIPS targets.  These attributes may only be
added to function declarations and change the code generated by the compiler when
directly calling the function.  The ``near`` attribute allows calls to the function to
be made using the ``jal`` instruction, which requires the function to be defined in the
same 256MB segment as the caller.  The ``long_call`` and ``far`` attributes are
synonyms and require the use of a different call sequence that works regardless of
the distance between the functions.

These attributes take priority over command line switches such as ``-mlong-calls``.

Comment at: lib/CodeGen/CGCall.cpp:1810
+        FuncAttrs.addAttribute("near-call");
+    }
You should really put this in TargetCodeGenInfo::setTargetAttributes.  Please just add a ForDefinition_t argument to that function and SetFunctionAttributes, then call setTargetAttributes from SetFunctionAttributes.

Comment at: lib/Sema/SemaDeclAttr.cpp:5955
+    handleSimpleAttribute<MipsLongCallAttr>(S, D, Attr);
+    break;
   case AttributeList::AT_AMDGPUFlatWorkGroupSize:
You need to check for conflicts between the different attributes, and please add a test for that.



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