[lld] r325046 - [WebAssembly] Unify concepts of discarded and non-live input chunks. NFC.

[Sam Clegg via llvm-commits]

Author: sbc
Date: Tue Feb 13 12:29:38 2018
New Revision: 325046

URL: http://llvm.org/viewvc/llvm-project?rev=325046&view=rev
Log:
[WebAssembly] Unify concepts of discarded and non-live input chunks. NFC.

It seems redundant to store this information twice.  None of the
locations where this bit is checked care about the distinction.

Differential Revision: https://reviews.llvm.org/D43250

Modified:
    lld/trunk/wasm/InputChunks.h
    lld/trunk/wasm/InputFiles.cpp
    lld/trunk/wasm/Writer.cpp

Modified: lld/trunk/wasm/InputChunks.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/wasm/InputChunks.h?rev=325046&r1=325045&r2=325046&view=diff
==============================================================================
--- lld/trunk/wasm/InputChunks.h (original)
+++ lld/trunk/wasm/InputChunks.h Tue Feb 13 12:29:38 2018
@@ -57,12 +57,12 @@ public:
   virtual StringRef getComdat() const = 0;
   virtual StringRef getName() const = 0;
 
-  bool Discarded = false;
   std::vector<OutputRelocation> OutRelocations;
   ObjFile *File;
 
-  // The garbage collector sets sections' Live bits.
-  // If GC is disabled, all sections are considered live by default.
+  // Signals that the section is part of the output.  The garbage collector,
+  // and COMDAT handling can set a sections' Live bit.
+  // If GC is disabled, all sections start out as live by default.
   unsigned Live : 1;
 
 protected:

Modified: lld/trunk/wasm/InputFiles.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/wasm/InputFiles.cpp?rev=325046&r1=325045&r2=325046&view=diff
==============================================================================
--- lld/trunk/wasm/InputFiles.cpp (original)
+++ lld/trunk/wasm/InputFiles.cpp Tue Feb 13 12:29:38 2018
@@ -252,7 +252,7 @@ void ObjFile::initializeSymbols() {
         S = createDefined(WasmSym, Symbol::Kind::DefinedFunctionKind, Function);
         break;
       } else {
-        Function->Discarded = true;
+        Function->Live = false;
         LLVM_FALLTHROUGH; // Exclude function, and add the symbol as undefined
       }
     }
@@ -267,7 +267,7 @@ void ObjFile::initializeSymbols() {
                           getGlobalValue(WasmSym));
         break;
       } else {
-        Segment->Discarded = true;
+        Segment->Live = false;
         LLVM_FALLTHROUGH; // Exclude global, and add the symbol as undefined
       }
     }

Modified: lld/trunk/wasm/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/wasm/Writer.cpp?rev=325046&r1=325045&r2=325046&view=diff
==============================================================================
--- lld/trunk/wasm/Writer.cpp (original)
+++ lld/trunk/wasm/Writer.cpp Tue Feb 13 12:29:38 2018
@@ -662,14 +662,11 @@ void Writer::calculateExports() {
         continue;
       if (Sym->isGlobal())
         continue;
-      if (Sym->getChunk()->Discarded)
+      if (!Sym->getChunk()->Live)
         continue;
 
       if ((Sym->isHidden() || Sym->isLocal()) && !ExportHidden)
         continue;
-
-      // We should never be exporting a non-live symbol
-      assert(Sym->getChunk()->Live);
       ExportedSymbols.emplace_back(WasmExportEntry{Sym, BudgeLocalName(Sym)});
     }
   }
@@ -759,7 +756,7 @@ void Writer::assignIndexes() {
   for (ObjFile *File : Symtab->ObjectFiles) {
     DEBUG(dbgs() << "Functions: " << File->getName() << "\n");
     for (InputFunction *Func : File->Functions) {
-      if (Func->Discarded || !Func->Live)
+      if (!Func->Live)
         continue;
       DefinedFunctions.emplace_back(Func);
       Func->setOutputIndex(FunctionIndex++);
@@ -769,7 +766,7 @@ void Writer::assignIndexes() {
   for (ObjFile *File : Symtab->ObjectFiles) {
     DEBUG(dbgs() << "Handle relocs: " << File->getName() << "\n");
     auto HandleRelocs = [&](InputChunk *Chunk) {
-      if (Chunk->Discarded)
+      if (!Chunk->Live)
         return;
       ArrayRef<WasmSignature> Types = File->getWasmObj()->types();
       for (const WasmRelocation& Reloc : Chunk->getRelocations()) {
@@ -813,7 +810,7 @@ static StringRef getOutputDataSegmentNam
 void Writer::createOutputSegments() {
   for (ObjFile *File : Symtab->ObjectFiles) {
     for (InputSegment *Segment : File->Segments) {
-      if (Segment->Discarded || !Segment->Live)
+      if (!Segment->Live)
         continue;
       StringRef Name = getOutputDataSegmentName(Segment->getName());
       OutputSegment *&S = SegmentMap[Name];