[WebAssembly] Fix typo in relocation checking

[sbc100]

Summary

Runtime relocation are generated for relocations of type
R_WASM_MEMORY_ADDR_I32 when in PIC mode (either -shared or -pie).

Followup on https://reviews.llvm.org/D60882.

[ruiu]

LGTM

It is a good idea to add a test to catch this though.

[sbc100]

• add test

lld/trunk/test/wasm/pie.ll

+; RUN: llc -relocation-model=pic -filetype=obj %s -o %t.o
+; RUN: wasm-ld --no-gc-sections --allow-undefined -pie -o %t.wasm %t.o
+; RUN: obj2yaml %t.wasm | FileCheck %s
+
+target triple = "wasm32-unknown-unknown"
+
+@data = global i32 2, align 4
+@data_external = external global i32
+@indirect_func = local_unnamed_addr global i32 ()* @foo, align 4
+
+@data_addr = local_unnamed_addr global i32* @data, align 4
+@data_addr_external = local_unnamed_addr global i32* @data_external, align 4
+
+define i32 @foo() {
+entry:
+  ; To ensure we use __stack_pointer
+  %ptr = alloca i32
+  %0 = load i32, i32* @data, align 4
+  %1 = load i32 ()*, i32 ()** @indirect_func, align 4
+  call i32 %1()
+  ret i32 %0
+}
+
+define default i32** @get_data_address() {
+entry:
+  ret i32** @data_addr_external
+}
+
+define void @_start() {
+  ret void
+}
+
+; CHECK:        - Type:            IMPORT
+; CHECK-NEXT:     Imports:
+; CHECK-NEXT:       - Module:          env
+; CHECK-NEXT:         Field:           __indirect_function_table
+; CHECK-NEXT:         Kind:            TABLE
+; CHECK-NEXT:         Table:
+; CHECK-NEXT:           ElemType:        FUNCREF
+; CHECK-NEXT:           Limits:
+; CHECK-NEXT:             Initial:         0x00000001
+; CHECK-NEXT:       - Module:          env
+; CHECK-NEXT:         Field:           __memory_base
+; CHECK-NEXT:         Kind:            GLOBAL
+; CHECK-NEXT:         GlobalType:      I32
+; CHECK-NEXT:         GlobalMutable:   false
+; CHECK-NEXT:       - Module:          env
+; CHECK-NEXT:         Field:           __table_base
+; CHECK-NEXT:         Kind:            GLOBAL
+; CHECK-NEXT:         GlobalType:      I32
+; CHECK-NEXT:         GlobalMutable:   false
+
+

lld/trunk/wasm/InputFiles.cpp

if (Reloc.Type != R_WASM_TYPE_INDEX_LEB) {
     if ((isa<FunctionSymbol>(Sym) || isa<DataSymbol>(Sym)) && !Sym->isLive())
       return 0;
 
     // Special handling for undefined data symbols.  Most relocations against
     // such symbols cannot be resolved.
     if (isa<DataSymbol>(Sym) && Sym->isUndefined()) {
       if (Sym->isWeak() || Config->Relocatable)
         return 0;
-      if (Config->Shared && Reloc.Type == R_WASM_MEMORY_ADDR_I32)
+      // R_WASM_MEMORY_ADDR_I32 relocations in PIC code are turned into runtime
+      // fixups in __wasm_apply_relocs
+      if (Config->Pic && Reloc.Type == R_WASM_MEMORY_ADDR_I32)
         return 0;
       if (Reloc.Type != R_WASM_GLOBAL_INDEX_LEB) {
         llvm_unreachable(
           ("invalid relocation against undefined data symbol: " + toString(*Sym))
               .c_str());
       }
     }
   }