[PATCH] D42753: [WebAssembly] Add LLD support for defined globals

[Nicholas Wilson via Phabricator via llvm-commits]

ncw created this revision.
ncw added a reviewer: sbc100.
Herald added subscribers: llvm-commits, sunfish, aheejin, jgravelle-google, dschuff, jfb.

Makes use of the new constants added in https://reviews.llvm.org/D42752. Comes after https://reviews.llvm.org/D42585.

Probably should be updated with an extra test - but I'm pretty sure it is working.


Repository:
  rLLD LLVM Linker

https://reviews.llvm.org/D42753

Files:
  wasm/InputChunks.h
  wasm/InputFiles.cpp
  wasm/Writer.cpp


Index: wasm/Writer.cpp
===================================================================
--- wasm/Writer.cpp
+++ wasm/Writer.cpp
@@ -462,6 +462,12 @@
       Comdats[Comdat].emplace_back(
           ComdatEntry{WASM_COMDAT_FUNCTION, F->getOutputIndex()});
   }
+  for (const InputGlobal *G : DefinedGlobals) {
+    StringRef Comdat = G->getComdat();
+    if (!Comdat.empty())
+      Comdats[Comdat].emplace_back(
+          ComdatEntry{WASM_COMDAT_GLOBAL, G->getOutputIndex()});
+  }
   for (uint32_t I = 0; I < Segments.size(); ++I) {
     const auto &InputSegments = Segments[I]->InputSegments;
     if (InputSegments.empty())
Index: wasm/InputFiles.cpp
===================================================================
--- wasm/InputFiles.cpp
+++ wasm/InputFiles.cpp
@@ -296,8 +296,13 @@
     case WasmSymbol::SymbolType::GLOBAL:
       if (WasmSym.WasmIndex >= NumGlobalImports) {
         InputGlobal *Global = getGlobal(WasmSym);
-        S = createDefined(WasmSym, Symbol::Kind::DefinedGlobalKind, Global);
-        break;
+        if (!isExcludedByComdat(Global)) {
+          S = createDefined(WasmSym, Symbol::Kind::DefinedGlobalKind, Global);
+          break;
+        } else {
+          Global->Discarded = true;
+          // Exclude global, and add the symbol as undefined
+        }
       }
       S = createUndefined(WasmSym, Symbol::Kind::UndefinedGlobalKind);
       break;
Index: wasm/InputChunks.h
===================================================================
--- wasm/InputChunks.h
+++ wasm/InputChunks.h
@@ -194,7 +194,7 @@
   }
 
   virtual const WasmInitExpr &initExpr() const { return Global->InitExpr; }
-  StringRef getComdat() const override { return StringRef(); }
+  StringRef getComdat() const override { return Global->Comdat; }
   uint32_t getOutputIndex() const override { return OutputIndex.getValue(); }
   bool hasOutputIndex() const override { return OutputIndex.hasValue(); }
   void setOutputIndex(uint32_t Index);


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