[WebAssembly] MC: Don't generate extra types for weak alias

[sbc100]

Summary

Previously we were generated a void(void) function type
for a weak alias. Update the weak-alias test case to
catch this.

Also, fix type if relocation index to be unsigned inline
with the spec (Linking.md)

[dschuff]

lib/MC/WasmObjectWriter.cpp

962

so a weak alias both isVariable() and isFunction()?

[sbc100]

lib/MC/WasmObjectWriter.cpp

962

Yup

[sbc100]

• [WebAssembly] Fix types for address taken functions

[sbc100]

• [WebAssembly] Fix types for address taken functions

[sbc100]

• Revert

[dschuff]

lib/MC/WasmObjectWriter.cpp

962

That's.... fun. Maybe should add a comment here about that.

[sbc100]

• add comment

include/llvm/BinaryFormat/Wasm.h

 struct WasmElemSegment {
   uint32_t TableIndex;
   WasmInitExpr Offset;
   std::vector<uint32_t> Functions;
 };
 
 struct WasmRelocation {
   uint32_t Type;   // The type of the relocation.
-  int32_t Index;   // Index into function to global index space.
+  uint32_t Index;  // Index into function to global index space.
   uint64_t Offset; // Offset from the start of the section.
   int64_t Addend;  // A value to add to the symbol.
 };
 
 struct WasmLinkingData {
   uint32_t DataSize;
   uint32_t DataAlignment;
 };

lib/MC/WasmObjectWriter.cpp

case wasm::R_WEBASSEMBLY_GLOBAL_ADDR_I32:
       break;
     default:
       break;
     }
   }
 
   // Populate the Imports set.
   for (const MCSymbol &S : Asm.symbols()) {
+    if (S.isVariable())
+      continue;
+
     const auto &WS = static_cast<const MCSymbolWasm &>(S);
     int32_t Type;
 
     if (WS.isFunction()) {
       // Prepare the function's type, if we haven't seen it yet.
       WasmFunctionType F;
       F.Returns = WS.getReturns();
       F.Params = WS.getParams();

test/MC/WebAssembly/weak-alias.ll

 ; RUN: llc -mtriple wasm32-unknown-unknown-wasm -filetype=obj %s -o - | obj2yaml | FileCheck %s
 
 ; foo_alias() function is weak alias of function foo()
 ; Generates two exports of the same function, one of them weak
 
 @foo_alias = weak hidden alias i32 (...), bitcast (i32 ()* @foo to i32 (...)*)
 
 define hidden i32 @foo() #0 {
 entry:
   ret i32 0
 }
 
+; CHECK:        - Type:            TYPE
+; CHECK-NEXT:     Signatures:      
+; CHECK-NEXT:       - Index:           0
+; CHECK-NEXT:         ReturnType:      I32
+; CHECK-NEXT:         ParamTypes:      
+; CHECK-NEXT:   - Type:            FUNCTION
+; CHECK-NEXT:     FunctionTypes:   [ 0 ]
+
 ; CHECK:        - Type:            EXPORT
 ; CHECK-NEXT:     Exports:         
 ; CHECK-NEXT:       - Name:            foo
 ; CHECK-NEXT:         Kind:            FUNCTION
 ; CHECK-NEXT:         Index:           0
 ; CHECK-NEXT:       - Name:            foo_alias
 ; CHECK-NEXT:         Kind:            FUNCTION
 ; CHECK-NEXT:         Index:           0
 
-
 ; CHECK:        - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            name
 ; CHECK-NEXT:     FunctionNames:   
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Name:            foo
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
 ; CHECK-NEXT:     DataSize:        0
 ; CHECK-NEXT:     DataAlignment:   0
 ; CHECK-NEXT:     SymbolInfo:      
 ; CHECK-NEXT:       - Name:            foo_alias
 ; CHECK-NEXT:         Flags:           1
 ; CHECK-NEXT: ...