[lld][WebAssembly] Report unsupported PIC relocations as errors

lld/test/wasm/unsupported-pic-relocations.s

@@ -0,0 +1,39 @@
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t.o %s
+
+# RUN: not wasm-ld --experimental-pic -shared %t.o -o /dev/null 2>&1 | \
+# RUN:   FileCheck %s
+
+# RUN: not wasm-ld --experimental-pic -shared %t.o -o /dev/null  --unresolved-symbols=report-all 2>&1 | \
+# RUN:   FileCheck %s
+
+# RUN: not wasm-ld --experimental-pic -shared %t.o -o /dev/null  --warn-unresolved-symbols 2>&1 | \
+# RUN:   FileCheck %s
+
+# RUN: not wasm-ld --experimental-pic -shared %t.o -o /dev/null  --unresolved-symbols=ignore-all 2>&1 | \
+# RUN:   FileCheck %s
+
+# RUN: not wasm-ld --experimental-pic -shared %t.o -o /dev/null  --unresolved-symbols=import-dynamic 2>&1 | \
+# RUN:   FileCheck %s
+
+.functype external_func () -> ()
+
+use_undefined_function:
+    .functype use_undefined_function () -> ()
+    i32.const external_func@TBREL
+    # CHECK: error: {{.*}}.o: relocation R_WASM_TABLE_INDEX_REL_SLEB is not supported against an undefined symbol `external_func`
+    drop
+    end_function
+
+use_undefined_data:
+    .functype use_undefined_data () -> ()
+    i32.const external_data@MBREL
+    # CHECK: error: {{.*}}.o: relocation R_WASM_MEMORY_ADDR_REL_SLEB is not supported against an undefined symbol `external_data`
+    drop
+    end_function
+
+.globl _start
+_start:
+    .functype _start () -> ()
+    call use_undefined_function
+    call use_undefined_data
+    end_function

lld/test/wasm/unsupported-pic-relocations64.s

@@ -0,0 +1,39 @@
+# RUN: llvm-mc -filetype=obj -triple=wasm64-unknown-unknown -o %t.o %s
+
+# RUN: not wasm-ld -mwasm64 --experimental-pic -shared %t.o -o /dev/null 2>&1 | \
+# RUN:   FileCheck %s
+
+# RUN: not wasm-ld -mwasm64 --experimental-pic -shared %t.o -o /dev/null  --unresolved-symbols=report-all 2>&1 | \
+# RUN:   FileCheck %s
+
+# RUN: not wasm-ld -mwasm64 --experimental-pic -shared %t.o -o /dev/null  --warn-unresolved-symbols 2>&1 | \
+# RUN:   FileCheck %s
+
+# RUN: not wasm-ld -mwasm64 --experimental-pic -shared %t.o -o /dev/null  --unresolved-symbols=ignore-all 2>&1 | \
+# RUN:   FileCheck %s
+
+# RUN: not wasm-ld -mwasm64 --experimental-pic -shared %t.o -o /dev/null  --unresolved-symbols=import-dynamic 2>&1 | \
+# RUN:   FileCheck %s
+
+.functype external_func () -> ()
+
+use_undefined_function:
+    .functype use_undefined_function () -> ()
+    i64.const external_func@TBREL
+    # CHECK: error: {{.*}}.o: relocation R_WASM_TABLE_INDEX_REL_SLEB64 is not supported against an undefined symbol `external_func`
+    drop
+    end_function
+
+use_undefined_data:
+    .functype use_undefined_data () -> ()
+    i64.const external_data@MBREL
+    # CHECK: error: {{.*}}.o: relocation R_WASM_MEMORY_ADDR_REL_SLEB64 is not supported against an undefined symbol `external_data`
+    drop
+    end_function
+
+.globl _start
+_start:
+    .functype _start () -> ()
+    call use_undefined_function
+    call use_undefined_data
+    end_function

lld/wasm/Relocations.cpp

@@ -173,6 +173,22 @@ void scanRelocations(InputChunk *chunk) {
       }
     }
 
+    if (sym->isUndefined()) {
+      switch (reloc.Type) {
+      case R_WASM_TABLE_INDEX_REL_SLEB:
+      case R_WASM_TABLE_INDEX_REL_SLEB64:
+      case R_WASM_MEMORY_ADDR_REL_SLEB:
+      case R_WASM_MEMORY_ADDR_REL_SLEB64:
+        // These relocation types are for symbols that exists relative to
+        // `__memory_base` or `__table_base` and as such only make sense for
+        // defined symbols.
+        error(toString(file) + ": relocation " + relocTypeToString(reloc.Type) +
+              " is not supported against an undefined symbol `" +
+              toString(*sym) + "`");
+        break;
+      }
+    }
+
     if (sym->isUndefined() && !config->relocatable && !sym->isWeak()) {
       // Report undefined symbols
       reportUndefined(file, sym);