[WebAssembly] Fix expected contents of relocations with addends

[sbc100]

Summary

This fixes issues found on the wasm waterfall related to relocations
with addends. Undefined symbols, even those with addends should
always have a provisional value of zero. At least this is what llvm
emits for wasm today (and I believe this is true for ELF too).

[sbc100]

• add test

[dschuff]

LGTM, and confirmed that it makes libcxx configure successfully.

[ncw]

Looks good, well caught

[ruiu]

LGTM

test/wasm/data-layout.ll

 ; RUN: llc -filetype=obj %p/Inputs/hello.ll -o %t.hello.o
 ; RUN: llc -filetype=obj %s -o %t.o
 
 target triple = "wasm32-unknown-unknown-wasm"
 
 @foo = hidden global i32 1, align 4
 @aligned_bar = hidden global i32 3, align 16
 
 @hello_str = external global i8*
 @external_ref = global i8** @hello_str, align 8
 
+%struct.s = type { i32, i32 }
+@local_struct = hidden global %struct.s zeroinitializer, align 4
+@local_struct_internal_ptr = hidden local_unnamed_addr global i32* getelementptr inbounds (%struct.s, %struct.s* @local_struct, i32 0, i32 1), align 4
+
 ; RUN: wasm-ld -no-gc-sections --check-signatures --allow-undefined -o %t.wasm %t.o %t.hello.o
 ; RUN: obj2yaml %t.wasm | FileCheck %s
 
 ; CHECK:        - Type:            GLOBAL
 ; CHECK-NEXT:     Globals:
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Type:            I32
 ; CHECK-NEXT:         Mutable:         true

 
 ; CHECK:         - Type:            DATA
 ; CHECK-NEXT:     Segments:
 ; CHECK-NEXT:       - SectionOffset:   7
 ; CHECK-NEXT:         MemoryIndex:     0
 ; CHECK-NEXT:         Offset:
 ; CHECK-NEXT:           Opcode:          I32_CONST
 ; CHECK-NEXT:           Value:           1024
-; CHECK-NEXT:         Content:         0100000000000000000000000000000003000000000000001C040000
-; CHECK-NEXT:       - SectionOffset:   41
+; CHECK-NEXT:         Content:         '0100000000000000000000000000000003000000000000002804000024040000'
+; CHECK-NEXT:       - SectionOffset:   45
+; CHECK-NEXT:         MemoryIndex:     0
+; CHECK-NEXT:         Offset:
+; CHECK-NEXT:           Opcode:          I32_CONST
+; CHECK-NEXT:           Value:           1056
+; CHECK-NEXT:         Content:         '0000000000000000'
+; CHECK-NEXT:       - SectionOffset:   59
 ; CHECK-NEXT:         MemoryIndex:     0
-; CHECK-NEXT:         Offset:
+; CHECK-NEXT:         Offset:          
 ; CHECK-NEXT:           Opcode:          I32_CONST
-; CHECK-NEXT:           Value:           1052
+; CHECK-NEXT:           Value:           1064
 ; CHECK-NEXT:         Content:         68656C6C6F0A00
+; CHECK-NEXT:    - Type:            CUSTOM
 
 
 ; RUN: wasm-ld --check-signatures --relocatable -o %t_reloc.wasm %t.o %t.hello.o
 ; RUN: obj2yaml %t_reloc.wasm | FileCheck %s -check-prefix=RELOC
 
 ; RELOC:       - Type:            DATA
 ; RELOC-NEXT:     Relocations:
 ; RELOC-NEXT:       - Type:            R_WEBASSEMBLY_MEMORY_ADDR_I32
-; RELOC-NEXT:         Index:           4
+; RELOC-NEXT:         Index:           6
 ; RELOC-NEXT:         Offset:          0x00000018
+; RELOC-NEXT:       - Type:            R_WEBASSEMBLY_MEMORY_ADDR_I32
+; RELOC-NEXT:         Index:           3
+; RELOC-NEXT:         Offset:          0x0000002E
+; RELOC-NEXT:         Addend:          4
 ; RELOC-NEXT:     Segments:
 ; RELOC-NEXT:       - SectionOffset:   6
 ; RELOC-NEXT:         MemoryIndex:     0
 ; RELOC-NEXT:         Offset:
 ; RELOC-NEXT:           Opcode:          I32_CONST
 ; RELOC-NEXT:           Value:           0
 ; RELOC-NEXT:         Content:         '01000000'
 ; RELOC-NEXT:       - SectionOffset:   15
 ; RELOC-NEXT:         MemoryIndex:     0
 ; RELOC-NEXT:         Offset:
 ; RELOC-NEXT:           Opcode:          I32_CONST
 ; RELOC-NEXT:           Value:           16
 ; RELOC-NEXT:         Content:         '03000000'
 ; RELOC-NEXT:       - SectionOffset:   24
 ; RELOC-NEXT:         MemoryIndex:     0
 ; RELOC-NEXT:         Offset:
 ; RELOC-NEXT:           Opcode:          I32_CONST
 ; RELOC-NEXT:           Value:           24
-; RELOC-NEXT:         Content:         1C000000
+; RELOC-NEXT:         Content:         '28000000'
 ; RELOC-NEXT:       - SectionOffset:   33
 ; RELOC-NEXT:         MemoryIndex:     0
-; RELOC-NEXT:         Offset:
+; RELOC-NEXT:         Offset:          
 ; RELOC-NEXT:           Opcode:          I32_CONST
 ; RELOC-NEXT:           Value:           28
+; RELOC-NEXT:         Content:         '0000000000000000'
+; RELOC-NEXT:       - SectionOffset:   46
+; RELOC-NEXT:         MemoryIndex:     0
+; RELOC-NEXT:         Offset:          
+; RELOC-NEXT:           Opcode:          I32_CONST
+; RELOC-NEXT:           Value:           36
+; RELOC-NEXT:         Content:         '20000000'
+; RELOC-NEXT:       - SectionOffset:   55
+; RELOC-NEXT:         MemoryIndex:     0
+; RELOC-NEXT:         Offset:
+; RELOC-NEXT:           Opcode:          I32_CONST
+; RELOC-NEXT:           Value:           40
 ; RELOC-NEXT:         Content:         68656C6C6F0A00
 
 ; RELOC:        - Type:            CUSTOM
 ; RELOC-NEXT:     Name:            linking
 ; RELOC-NEXT:     SymbolTable:
 ; RELOC-NEXT:       - Index:           0
 ; RELOC-NEXT:         Kind:            DATA
 ; RELOC-NEXT:         Name:            foo
 ; RELOC-NEXT:         Flags:           [ VISIBILITY_HIDDEN ]
 ; RELOC-NEXT:         Segment:         0
 ; RELOC-NEXT:         Size:            4
 ; RELOC-NEXT:       - Index:           1
 ; RELOC-NEXT:         Kind:            DATA
 ; RELOC-NEXT:         Name:            aligned_bar
 ; RELOC-NEXT:         Flags:           [ VISIBILITY_HIDDEN ]
 ; RELOC-NEXT:         Segment:         1
 ; RELOC-NEXT:         Size:            4
 ; RELOC-NEXT:       - Index:           2
 ; RELOC-NEXT:         Kind:            DATA
 ; RELOC-NEXT:         Name:            external_ref
 ; RELOC-NEXT:         Flags:           [  ]
 ; RELOC-NEXT:         Segment:         2
 ; RELOC-NEXT:         Size:            4
-; RELOC:            - Index:           4
+; RELOC:            - Index:           6
 ; RELOC-NEXT:         Kind:            DATA
 ; RELOC-NEXT:         Name:            hello_str
 ; RELOC-NEXT:         Flags:           [  ]
-; RELOC-NEXT:         Segment:         3
+; RELOC-NEXT:         Segment:         5
 ; RELOC-NEXT:         Size:            7

wasm/InputChunks.cpp

 void InputChunk::writeTo(uint8_t *Buf) const {
   // Copy contents
   memcpy(Buf + OutputOffset, data().data(), data().size());
 
   // Apply relocations
   if (Relocations.empty())
     return;
 
-  DEBUG(dbgs() << "applying relocations: count=" << Relocations.size() << "\n");
+  DEBUG(dbgs() << "applying relocations: " << getName()
+               << " count=" << Relocations.size() << "\n");
   int32_t Off = OutputOffset - getInputSectionOffset();
 
   for (const WasmRelocation &Rel : Relocations) {
     uint8_t *Loc = Buf + Rel.Offset + Off;
     uint32_t Value = File->calcNewValue(Rel);
     uint32_t ExistingValue;
     DEBUG(dbgs() << "apply reloc: type=" << ReloctTypeToString(Rel.Type)
                  << " addend=" << Rel.Addend << " index=" << Rel.Index

wasm/InputFiles.cpp

uint32_t ObjFile::calcExpectedValue(const WasmRelocation &Reloc) const {
   }
   case R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
   case R_WEBASSEMBLY_MEMORY_ADDR_I32:
   case R_WEBASSEMBLY_MEMORY_ADDR_LEB: {
     const WasmSymbol& Sym = WasmObj->syms()[Reloc.Index];
     if (Sym.isUndefined())
       return 0;
     const WasmSegment& Segment = WasmObj->dataSegments()[Sym.Info.DataRef.Segment];
-    return Segment.Data.Offset.Value.Int32 + Sym.Info.DataRef.Offset;
+    return Segment.Data.Offset.Value.Int32 + Sym.Info.DataRef.Offset +
+           Reloc.Addend;
   }
   case R_WEBASSEMBLY_TYPE_INDEX_LEB:
     return Reloc.Index;
   case R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
   case R_WEBASSEMBLY_GLOBAL_INDEX_LEB: {
     const WasmSymbol& Sym = WasmObj->syms()[Reloc.Index];
     return Sym.Info.ElementIndex;
   }
   default:
     llvm_unreachable("unknown relocation type");
   }
 }
 
 // Translate from the relocation's index into the final linked output value.
 uint32_t ObjFile::calcNewValue(const WasmRelocation &Reloc) const {
   switch (Reloc.Type) {
   case R_WEBASSEMBLY_TABLE_INDEX_I32:
   case R_WEBASSEMBLY_TABLE_INDEX_SLEB:
     return getFunctionSymbol(Reloc.Index)->getTableIndex();
   case R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
   case R_WEBASSEMBLY_MEMORY_ADDR_I32:
   case R_WEBASSEMBLY_MEMORY_ADDR_LEB:
     if (auto *Sym = dyn_cast<DefinedData>(getDataSymbol(Reloc.Index)))
       return Sym->getVirtualAddress() + Reloc.Addend;
-    return Reloc.Addend;
+    return 0;
   case R_WEBASSEMBLY_TYPE_INDEX_LEB:
     return TypeMap[Reloc.Index];
   case R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
     return getFunctionSymbol(Reloc.Index)->getFunctionIndex();
   case R_WEBASSEMBLY_GLOBAL_INDEX_LEB:
     return getGlobalSymbol(Reloc.Index)->getGlobalIndex();
   default:
     llvm_unreachable("unknown relocation type");