[WebAssembly] Support imports from custom module names

Fixes: https://bugs.llvm.org/show_bug.cgi?id=37168 This is only a first pass at supporting these custom import modules. In the long run we most likely want to treat these kinds of symbols very differently. For example, it should not be possible to resolve such as symbol at static link type. Differential Revision: https://reviews.llvm.org/D45796 llvm-svn: 352828
llvm · Feb 1, 2019 · 7cc0753 · 7cc0753
1 parent 1368022
commit 7cc0753
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Showing 9 changed files with 48 additions and 14 deletions.
diff --git a/lld/test/wasm/import-module.ll b/lld/test/wasm/import-module.ll
@@ -0,0 +1,21 @@
+; RUN: llc -filetype=obj %s -o %t.o
+; RUN: wasm-ld --allow-undefined -o %t.wasm %t.o
+; RUN: obj2yaml %t.wasm | FileCheck %s
+
+target triple = "wasm32-unknown-unknown-wasm"
+
+define void @_start() {
+  call void @foo();
+  ret void
+}
+
+declare void @foo() #0
+
+attributes #0 = { "wasm-import-module"="bar" }
+
+; CHECK:        - Type:            IMPORT
+; CHECK-NEXT:     Imports:         
+; CHECK-NEXT:       - Module:          bar
+; CHECK-NEXT:         Field:           foo
+; CHECK-NEXT:         Kind:            FUNCTION
+; CHECK-NEXT:         SigIndex:        0
diff --git a/lld/wasm/InputFiles.cpp b/lld/wasm/InputFiles.cpp
@@ -378,7 +378,8 @@ Symbol *ObjFile::createUndefined(const WasmSymbol &Sym) {
 
   switch (Sym.Info.Kind) {
   case WASM_SYMBOL_TYPE_FUNCTION:
-    return Symtab->addUndefinedFunction(Name, Flags, this, Sym.Signature);
+    return Symtab->addUndefinedFunction(Name, Sym.Info.Module, Flags, this,
+                                        Sym.Signature);
   case WASM_SYMBOL_TYPE_DATA:
     return Symtab->addUndefinedData(Name, Flags, this);
   case WASM_SYMBOL_TYPE_GLOBAL:
@@ -446,7 +447,7 @@ static Symbol *createBitcodeSymbol(const lto::InputFile::Symbol &ObjSym,
 
   if (ObjSym.isUndefined()) {
     if (ObjSym.isExecutable())
-      return Symtab->addUndefinedFunction(Name, Flags, &F, nullptr);
+      return Symtab->addUndefinedFunction(Name, kDefaultModule, Flags, &F, nullptr);
     return Symtab->addUndefinedData(Name, Flags, &F);
   }
 

diff --git a/lld/wasm/LTO.cpp b/lld/wasm/LTO.cpp
@@ -80,8 +80,8 @@ BitcodeCompiler::~BitcodeCompiler() = default;
 
 static void undefine(Symbol *S) {
   if (auto F = dyn_cast<DefinedFunction>(S))
-    replaceSymbol<UndefinedFunction>(F, F->getName(), 0, F->getFile(),
-                                     F->Signature);
+    replaceSymbol<UndefinedFunction>(F, F->getName(), kDefaultModule, 0,
+                                     F->getFile(), F->Signature);
   else if (isa<DefinedData>(S))
     replaceSymbol<UndefinedData>(S, S->getName(), 0, S->getFile());
   else

diff --git a/lld/wasm/LTO.h b/lld/wasm/LTO.h
@@ -22,6 +22,7 @@
 
 #include "lld/Common/LLVM.h"
 #include "llvm/ADT/SmallString.h"
+#include "Writer.h"
 #include <memory>
 #include <vector>
 

diff --git a/lld/wasm/SymbolTable.cpp b/lld/wasm/SymbolTable.cpp
@@ -315,8 +315,8 @@ Symbol *SymbolTable::addDefinedEvent(StringRef Name, uint32_t Flags,
   return S;
 }
 
-Symbol *SymbolTable::addUndefinedFunction(StringRef Name, uint32_t Flags,
-                                          InputFile *File,
+Symbol *SymbolTable::addUndefinedFunction(StringRef Name, StringRef Module,
+                                          uint32_t Flags, InputFile *File,
                                           const WasmSignature *Sig) {
   LLVM_DEBUG(dbgs() << "addUndefinedFunction: " << Name <<
              " [" << (Sig ? toString(*Sig) : "none") << "]\n");
@@ -326,7 +326,7 @@ Symbol *SymbolTable::addUndefinedFunction(StringRef Name, uint32_t Flags,
   std::tie(S, WasInserted) = insert(Name, File);
 
   if (WasInserted)
-    replaceSymbol<UndefinedFunction>(S, Name, Flags, File, Sig);
+    replaceSymbol<UndefinedFunction>(S, Name, Module, Flags, File, Sig);
   else if (auto *Lazy = dyn_cast<LazySymbol>(S))
     Lazy->fetch();
   else

diff --git a/lld/wasm/SymbolTable.h b/lld/wasm/SymbolTable.h
@@ -58,8 +58,8 @@ class SymbolTable {
   Symbol *addDefinedEvent(StringRef Name, uint32_t Flags, InputFile *File,
                           InputEvent *E);
 
-  Symbol *addUndefinedFunction(StringRef Name, uint32_t Flags, InputFile *File,
-                               const WasmSignature *Signature);
+  Symbol *addUndefinedFunction(StringRef Name, StringRef Module, uint32_t Flags,
+                               InputFile *File, const WasmSignature *Signature);
   Symbol *addUndefinedData(StringRef Name, uint32_t Flags, InputFile *File);
   Symbol *addUndefinedGlobal(StringRef Name, uint32_t Flags, InputFile *File,
                              const WasmGlobalType *Type);

diff --git a/lld/wasm/Symbols.h b/lld/wasm/Symbols.h
@@ -155,13 +155,17 @@ class DefinedFunction : public FunctionSymbol {
 
 class UndefinedFunction : public FunctionSymbol {
 public:
-  UndefinedFunction(StringRef Name, uint32_t Flags, InputFile *File = nullptr,
+  UndefinedFunction(StringRef Name, StringRef Module, uint32_t Flags,
+                    InputFile *File = nullptr,
                     const WasmSignature *Type = nullptr)
-      : FunctionSymbol(Name, UndefinedFunctionKind, Flags, File, Type) {}
+      : FunctionSymbol(Name, UndefinedFunctionKind, Flags, File, Type),
+        Module(Module) {}
 
   static bool classof(const Symbol *S) {
     return S->kind() == UndefinedFunctionKind;
   }
+
+  StringRef Module;
 };
 
 class SectionSymbol : public Symbol {

diff --git a/lld/wasm/Writer.cpp b/lld/wasm/Writer.cpp
@@ -41,6 +41,7 @@ using namespace lld::wasm;
 
 static constexpr int kStackAlignment = 16;
 static constexpr const char *kFunctionTableName = "__indirect_function_table";
+const char *lld::wasm::kDefaultModule = "env";
 
 namespace {
 
@@ -156,7 +157,7 @@ void Writer::createImportSection() {
 
   if (Config->ImportMemory) {
     WasmImport Import;
-    Import.Module = "env";
+    Import.Module = kDefaultModule;
     Import.Field = "memory";
     Import.Kind = WASM_EXTERNAL_MEMORY;
     Import.Memory.Flags = 0;
@@ -173,7 +174,7 @@ void Writer::createImportSection() {
   if (Config->ImportTable) {
     uint32_t TableSize = TableBase + IndirectFunctions.size();
     WasmImport Import;
-    Import.Module = "env";
+    Import.Module = kDefaultModule;
     Import.Field = kFunctionTableName;
     Import.Kind = WASM_EXTERNAL_TABLE;
     Import.Table.ElemType = WASM_TYPE_FUNCREF;
@@ -183,7 +184,11 @@ void Writer::createImportSection() {
 
   for (const Symbol *Sym : ImportedSymbols) {
     WasmImport Import;
-    Import.Module = "env";
+    if (auto *F = dyn_cast<UndefinedFunction>(Sym))
+      Import.Module = F->Module;
+    else
+      Import.Module = kDefaultModule;
+
     Import.Field = Sym->getName();
     if (auto *FunctionSym = dyn_cast<FunctionSymbol>(Sym)) {
       Import.Kind = WASM_EXTERNAL_FUNCTION;

diff --git a/lld/wasm/Writer.h b/lld/wasm/Writer.h
@@ -14,6 +14,8 @@ namespace wasm {
 
 void writeResult();
 
+extern const char *kDefaultModule;
+
 } // namespace wasm
 } // namespace lld