[WebAssembly] Fix getSymbolValue() for data symbols

[sbc100]

Summary

This is mostly a fix for the output of llvm-nm

See Bug 34392: https://bugs.llvm.org//show_bug.cgi?id=34392

[dschuff]

Cool, I guess this fixes PR34392, you should put that in the commit description too.

[dschuff]

ah we raced. LGTM :)

[sbc100]

What do you say "PRXXXXX"? What is PR? I've seen it other commit messages. What is the best way to signal that a bug is fixed by an llvm commit?

[dschuff]

It's just a bug number. PR I guess is a "Problem Report"? Also https://llvm.org/PR34392 is a shortcut to https://bugs.llvm.org/show_bug.cgi?id=34392

[dschuff]

but "Fixes PRNNN" is fine to indicate that a bug is fixed, although now that I think of it, a real link (in either form) is probably even better. Either way there's no auto-linking. Not everyone even uses LLVM's bug tracker anyway.

[hintonda]

llvm/trunk/lib/Object/WasmObjectFile.cpp

794

This is causing buildbot errors on big endian machines when the Opcode is wasm::WASM_OPCODE_I64_CONST, which corresponds to Int64, not Int32, e.g.:

http://lab.llvm.org:8011/builders/clang-ppc64be-linux-lnt/builds/7421

llvm/trunk/lib/Object/WasmObjectFile.cpp

 
 uint64_t WasmObjectFile::getSymbolValueImpl(DataRefImpl Symb) const {
   const WasmSymbol& Sym = getWasmSymbol(Symb);
   switch (Sym.Type) {
   case WasmSymbol::SymbolType::FUNCTION_IMPORT:
   case WasmSymbol::SymbolType::GLOBAL_IMPORT:
     return 0;
   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
-  case WasmSymbol::SymbolType::GLOBAL_EXPORT:
     return Exports[Sym.ElementIndex].Index;
+  case WasmSymbol::SymbolType::GLOBAL_EXPORT: {
+    uint32_t GlobalIndex = Exports[Sym.ElementIndex].Index;
+    assert(GlobalIndex < Globals.size());
+    const wasm::WasmGlobal& Global = Globals[GlobalIndex];
+    return Global.InitExpr.Value.Int32;
+  }
   case WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME:
     return Sym.ElementIndex;
   }
   llvm_unreachable("invalid symbol type");
 }
 
 uint32_t WasmObjectFile::getSymbolAlignment(DataRefImpl Symb) const {
   llvm_unreachable("not yet implemented");

llvm/trunk/test/Object/nm-trivial-object.test

 COFF32-NEXT: 00000000 d L_.str
 COFF32-NEXT:          U _SomeOtherFunction
 COFF32-NEXT: 00000000 T _main
 COFF32-NEXT:          U _puts
 
 WASM:               U SomeOtherFunction
 WASM-NEXT: 00000002 T main
 WASM-NEXT:          U puts
-WASM-NEXT: 00000001 D var
+WASM-NEXT: 00000010 D var
 
 COFF64: 00000000 d .data
 COFF64-NEXT: 00000000 t .text
 COFF64-NEXT: 00000000 r ??__Ex@@YAXXZ
 COFF64-NEXT: 00000000 d L.str
 COFF64-NEXT:          U SomeOtherFunction
 COFF64-NEXT: 00000000 T main
 COFF64-NEXT:          U puts

llvm/trunk/test/tools/llvm-nm/wasm/exports.yaml

- Type:            EXPORT
     Exports:
       - Name:            foo
         Kind:            FUNCTION
         Index:           0x00000004
       - Name:            bar
         Kind:            GLOBAL
         Index:           0x00000002
 
-# CHECK: 00000002 D bar
+# CHECK: 00000400 D bar
 # CHECK: 00000004 T foo

llvm/trunk/test/tools/llvm-nm/wasm/weak-symbols.yaml

SymbolInfo:
         Flags:           1
       - Name:            weak_global_data
         Flags:           1
       - Name:            weak_import_func
         Flags:           1
       - Name:            weak_import_data
         Flags:           1
 
-# CHECK: 00000002 W weak_global_data
+# CHECK: 00000400 W weak_global_data
 # CHECK: 00000004 W weak_global_func
 # CHECK:          w weak_import_data
 # CHECK:          w weak_import_func

llvm/trunk/test/tools/llvm-objdump/WebAssembly/symbol-table.test

 RUN: llvm-objdump -t %p/../Inputs/trivial.obj.wasm | FileCheck %s
 
 CHECK:      SYMBOL TABLE:
 CHECK-NEXT: 00000000 l     F IMPORT puts
 CHECK-NEXT: 00000000 l     F IMPORT SomeOtherFunction
 CHECK-NEXT: 00000002 g     F EXPORT main
-CHECK-NEXT: 00000001 g       EXPORT var
+CHECK-NEXT: 00000010 g       EXPORT var
 CHECK-NEXT: 00000000 l     F name puts
 CHECK-NEXT: 00000001 l     F name SomeOtherFunction
 CHECK-NEXT: 00000002 l     F name main