[PATCH] D42752: [WebAssembly] Add LLVM stub support for defined globals

[Nicholas Wilson via Phabricator via llvm-commits]

ncw added inline comments.


================
Comment at: lib/MC/WasmObjectWriter.cpp:1213-1221
+        WasmIndex = NumGlobalImports + Globals.size();
+        WasmGlobal G;
+        G.Type = WS.getGlobalType();
+        // TODO G.InitialValue should come from somewhere, maybe the MCSymbol.
+        // This code is waiting to be used though; I expect thread-local-storage
+        // will want to declare Wasm globals.
+        G.InitialValue = 0;
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Not really needed for anything -yet  :)

I wanted to add the COMDAT_GLOBAL enum value to the header, and implement it in LLD - otherwise the LLD code just looks "lopsided". And moreover we can test it in LLD.

So having put the COMDAT_GLOBAL enum value in place, it needs supporting in obj2yaml etc... And all that code can be tested.

This chunk of code here where we handle defined global MCSymbolWasms is the only bit of truly "dead" code. It's just five lines of fairly sensible filler code, here to save somebody else some time later when they actually come to make use of global syms. If someone wants to add support in the frontend, now they won't need to worry about how to feed the globals into the object file, because it's handled here already.

We'll need a compiler intrinsic quite soon to declare/read/write globals, as something to use for implementing thread-local storage.


Repository:
  rL LLVM

https://reviews.llvm.org/D42752