[WebAssembly] Fix imported function symbol names that differ from their import names in the .o format

Add a flag to allow symbols to have a wasm import name which differs from the
linker symbol name, allowing the linker to link code using the import_module
attribute.

This is the MC/Object portion of the patch.

Differential Revision: https://reviews.llvm.org/D57632

llvm-svn: 353474

1 files changed, 18 insertions, 4 deletions

diff --git a/llvm/lib/Object/WasmObjectFile.cpp b/llvm/lib/Object/WasmObjectFile.cpp
index 7423dc9726a..e5b6a9b6e35 100644
--- a/llvm/lib/Object/WasmObjectFile.cpp
+++ b/llvm/lib/Object/WasmObjectFile.cpp
@@ -505,9 +505,13 @@ Error WasmObjectFile::parseLinkingSectionSymtab(ReadContext &Ctx) {
           Function.SymbolName = Info.Name;
       } else {
         wasm::WasmImport &Import = *ImportedFunctions[Info.ElementIndex];
+        if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0)
+          Info.Name = readString(Ctx);
+        else
+          Info.Name = Import.Field;
         Signature = &Signatures[Import.SigIndex];
-        Info.Name = Import.Field;
-        Info.Module = Import.Module;
+        Info.ImportName = Import.Field;
+        Info.ImportModule = Import.Module;
       }
       break;
 
@@ -530,8 +534,13 @@ Error WasmObjectFile::parseLinkingSectionSymtab(ReadContext &Ctx) {
           Global.SymbolName = Info.Name;
       } else {
         wasm::WasmImport &Import = *ImportedGlobals[Info.ElementIndex];
-        Info.Name = Import.Field;
+        if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0)
+          Info.Name = readString(Ctx);
+        else
+          Info.Name = Import.Field;
         GlobalType = &Import.Global;
+        Info.ImportName = Import.Field;
+        Info.ImportModule = Import.Module;
       }
       break;
 
@@ -585,9 +594,14 @@ Error WasmObjectFile::parseLinkingSectionSymtab(ReadContext &Ctx) {
 
       } else {
         wasm::WasmImport &Import = *ImportedEvents[Info.ElementIndex];
+        if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0)
+          Info.Name = readString(Ctx);
+        else
+          Info.Name = Import.Field;
         EventType = &Import.Event;
         Signature = &Signatures[EventType->SigIndex];
-        Info.Name = Import.Field;
+        Info.ImportName = Import.Field;
+        Info.ImportModule = Import.Module;
       }
       break;
     }