[lld][WebAssembly] Don't force the export symbols assiged internal/dummy GOT entries

[sbc100]

Summary

Symbols with regular GOT entries do need to be exported, but those
that are internalized (and have internal GOT entries) should not
be exported.

This happens to fix the failures on the emscripten waterfall where
extra symbols were being exported by the linker (and then later
removed by wasm-opt).

[dschuff]

can-haz test?

[sbc100]

• add test

lld/test/wasm/tls-non-shared-memory.s

.section  .custom_section.target_features,"",@
   .int8 43
   .int8 11
   .ascii  "bulk-memory"
 
 # RUN: wasm-ld --no-gc-sections --no-entry -o %t.wasm %t.o
 # RUN: obj2yaml %t.wasm | FileCheck %s
 
 # RUN: wasm-ld --experimental-pic -shared -o %t.so %t.o
-# RUN: obj2yaml %t.so | FileCheck %s --check-prefix=PIC
+# RUN: obj2yaml %t.so | FileCheck %s --check-prefixes=SHARED,PIC
 
 # RUN: wasm-ld --experimental-pic --no-gc-sections --no-entry -pie -o %t-pie.wasm %t.o
-# RUN: obj2yaml %t.so | FileCheck %s --check-prefix=PIC
+# RUN: obj2yaml %t-pie.wasm | FileCheck %s --check-prefixes=PIE,PIC
 
 #      CHECK:   - Type:            GLOBAL
 # __stack_pointer
 # CHECK-NEXT:     Globals:
 # CHECK-NEXT:       - Index:           0
 # CHECK-NEXT:         Type:            I32
 # CHECK-NEXT:         Mutable:         true
 # CHECK-NEXT:         InitExpr:

 # CHECK-NEXT:          Value:           1028
 # CHECK-NEXT:        Content:         2A000000
 # CHECK-NEXT:  - Type:            CUSTOM
 
 
 # In PIC mode we expect TLS data and non-TLS data to be merged into
 # a single segment which is initialized via the  __memory_base import
 
-#      PIC:  - Type:            IMPORT
-# PIC-NEXT:    Imports:
-# PIC-NEXT:      - Module:          env
-# PIC-NEXT:        Field:           memory
-# PIC-NEXT:        Kind:            MEMORY
-# PIC-NEXT:        Memory:
-# PIC-NEXT:          Minimum:         0x1
-# PIC-NEXT:      - Module:          env
-# PIC-NEXT:        Field:           __memory_base
-# PIC-NEXT:        Kind:            GLOBAL
-# PIC-NEXT:        GlobalType:      I32
+#      SHARED:  - Type:            IMPORT
+# SHARED-NEXT:    Imports:
+# SHARED-NEXT:      - Module:          env
+# SHARED-NEXT:        Field:           memory
+# SHARED-NEXT:        Kind:            MEMORY
+# SHARED-NEXT:        Memory:
+# SHARED-NEXT:          Minimum:         0x1
+# SHARED-NEXT:      - Module:          env
+# SHARED-NEXT:        Field:           __memory_base
+# SHARED-NEXT:        Kind:            GLOBAL
+# SHARED-NEXT:        GlobalType:      I32
+
+# In SHARED mode we export the address of all data symbols.
+#      SHARED:   - Type:            EXPORT
+# SHARED-NEXT:     Exports:
+#      SHARED:     - Name:            tls1
+# SHARED-NEXT:       Kind:            GLOBAL
+#      SHARED:     - Name:            no_tls
+# SHARED-NEXT:       Kind:            GLOBAL
+
+# In PIE mode we don't export data address by default.
+#      PIE:   - Type:            EXPORT
+# PIE-NEXT:     Exports:
+# PIE-NEXT:       - Name:            memory
+# PIE-NEXT:         Kind:            MEMORY
+# PIE-NEXT:         Index:           0
+# PIE-NEXT:   - Type:
 
 # .tdata and .data are combined into single segment in PIC mode.
 #      PIC:  - Type:            DATA
 # PIC-NEXT:    Segments:
 # PIC-NEXT:      - SectionOffset:   6
 # PIC-NEXT:        InitFlags:       0
 # PIC-NEXT:        Offset:
 # PIC-NEXT:          Opcode:          GLOBAL_GET
-# PIC-NEXT:          Index:           0
+# PIC-NEXT:          Index:           {{\d*}}
 # PIC-NEXT:        Content:         2B0000002A000000
 # PIC-NEXT:  - Type:            CUSTOM

lld/wasm/Symbols.cpp

LLVM_DEBUG(dbgs() << "setOutputSymbolIndex " << name << " -> " << index
                     << "\n");
   assert(outputSymbolIndex == INVALID_INDEX);
   outputSymbolIndex = index;
 }
 
 void Symbol::setGOTIndex(uint32_t index) {
   LLVM_DEBUG(dbgs() << "setGOTIndex " << name << " -> " << index << "\n");
   assert(gotIndex == INVALID_INDEX);
-  if (config->isPic) {
-    // Any symbol that is assigned a GOT entry must be exported otherwise the
-    // dynamic linker won't be able create the entry that contains it.
-    forceExport = true;
-  }
   gotIndex = index;
 }
 
 bool Symbol::isWeak() const {
   return (flags & WASM_SYMBOL_BINDING_MASK) == WASM_SYMBOL_BINDING_WEAK;
 }
 
 bool Symbol::isLocal() const {

lld/wasm/SyntheticSections.cpp

 }
 
 void ImportSection::addGOTEntry(Symbol *sym) {
   assert(!isSealed);
   if (sym->hasGOTIndex())
     return;
   LLVM_DEBUG(dbgs() << "addGOTEntry: " << toString(*sym) << "\n");
   sym->setGOTIndex(numImportedGlobals++);
+  if (config->isPic) {
+    // Any symbol that is assigned an normal GOT entry must be exported
+    // otherwise the dynamic linker won't be able create the entry that contains
+    // it.
+    sym->forceExport = true;
+  }
   gotSymbols.push_back(sym);
 }
 
 void ImportSection::addImport(Symbol *sym) {
   assert(!isSealed);
   StringRef module = sym->importModule.getValueOr(defaultModule);
   StringRef name = sym->importName.getValueOr(sym->getName());
   if (auto *f = dyn_cast<FunctionSymbol>(sym)) {