[WebAssembly] Fix getSymbolValue for exported globals

The code wasn't previously taking into account that the
global index space is not same as the into in the Globals
array since the latter does not include imported globals.

This fixes the WebAssembly waterfall failures.

Differential Revision: https://reviews.llvm.org/D37384

llvm-svn: 312340

lib/Object/WasmObjectFile.cpp

@@ -788,7 +788,7 @@ uint64_t WasmObjectFile::getSymbolValueImpl(DataRefImpl Symb) const {
   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
     return Exports[Sym.ElementIndex].Index;
   case WasmSymbol::SymbolType::GLOBAL_EXPORT: {
-    uint32_t GlobalIndex = Exports[Sym.ElementIndex].Index;
+    uint32_t GlobalIndex = Exports[Sym.ElementIndex].Index - NumImportedGlobals;
     assert(GlobalIndex < Globals.size());
     const wasm::WasmGlobal& Global = Globals[GlobalIndex];
     return Global.InitExpr.Value.Int32;

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

@@ -1,4 +1,4 @@
-# RUN: yaml2obj < %s | llvm-nm - | FileCheck %s
+# RUN: yaml2obj < %s | llvm-nm - | FileCheck -strict-whitespace %s
 
 # That wasm exports of functions and globals are displayed as global data and
 # code symbols.
@@ -31,6 +31,17 @@ Sections:
         InitExpr:
           Opcode:          I64_CONST
           Value:           1024
+  - Type:            IMPORT
+    Imports:
+      - Module:          env
+        Field:           fimport
+        Kind:            FUNCTION
+        SigIndex:        0
+      - Module:          env
+        Field:           gimport
+        Kind:            GLOBAL
+        GlobalType:      I32
+        GlobalMutable:   false
   - Type:            EXPORT
     Exports:
       - Name:            foo
@@ -38,7 +49,9 @@ Sections:
         Index:           0x00000004
       - Name:            bar
         Kind:            GLOBAL
-        Index:           0x00000002
+        Index:           0x00000003
 
-# CHECK: 00000400 D bar
-# CHECK: 00000004 T foo
+# CHECK:      00000400 D bar
+# CHECK-NEXT:          U fimport
+# CHECK-NEXT: 00000004 T foo
+# CHECK-NEXT:          U gimport

test/tools/llvm-nm/wasm/imports.yaml

@@ -1,4 +1,4 @@
-# RUN: yaml2obj < %s | llvm-nm - | FileCheck %s
+# RUN: yaml2obj < %s | llvm-nm - | FileCheck -strict-whitespace %s
 
 --- !WASM
 FileHeader:

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

@@ -1,4 +1,4 @@
-# RUN: yaml2obj < %s | llvm-nm - | FileCheck %s
+# RUN: yaml2obj < %s | llvm-nm - | FileCheck -strict-whitespace %s
 
 # That wasm exports of functions and globals are displayed as global data and
 # code symbols.
@@ -49,7 +49,7 @@ Sections:
         Index:           0x00000004
       - Name:            weak_global_data
         Kind:            GLOBAL
-        Index:           0x00000002
+        Index:           0x00000003
   - Type:            CUSTOM
     Name:            linking
     DataSize:        0