[ELF] Drop '>>> defined in ' for locations of linker synthesized symbols

[grimar]

LGTM with or without my suggestion.

lld/ELF/Relocations.cpp

82

return ""; might look cleaner here, because a string is returned.

Also, I'd get probably rid of msg variable, because it is not used for all paths now:

static std::string getDefinedLocation(const Symbol &sym) {
  if (sym.file)
    return "\n>>> defined in " + toString(sym.file);
  if (Optional<std::string> loc = getLinkerScriptLocation(sym))
    return "\n>>> defined in " + *loc;
  return "";
}

lld/ELF/Relocations.cpp

static Optional<std::string> getLinkerScriptLocation(const Symbol &sym) {
   for (BaseCommand *base : script->sectionCommands)
     if (auto *cmd = dyn_cast<SymbolAssignment>(base))
       if (cmd->sym == &sym)
         return cmd->location;
   return None;
 }
 
 static std::string getDefinedLocation(const Symbol &sym) {
-  std::string msg = "\n>>> defined in ";
+  const char msg[] = "\n>>> defined in ";
   if (sym.file)
-    msg += toString(sym.file);
-  else if (Optional<std::string> loc = getLinkerScriptLocation(sym))
-    msg += *loc;
-  return msg;
+    return msg + toString(sym.file);
+  if (Optional<std::string> loc = getLinkerScriptLocation(sym))
+    return msg + *loc;
+  return "";
 }
 
 // Construct a message in the following format.
 //
 // >>> defined in /home/alice/src/foo.o
 // >>> referenced by bar.c:12 (/home/alice/src/bar.c:12)
 // >>>               /home/alice/src/bar.o:(.text+0x1)
 static std::string getLocation(InputSectionBase &s, const Symbol &sym,

lld/test/ELF/x86-64-gotpc-err.s

 # REQUIRES: x86
 # RUN: split-file %s %t
 # RUN: llvm-mc -filetype=obj -triple=x86_64 %t/a.s -o %t/a.o
 # RUN: not ld.lld -T %t/lds %t/a.o -o /dev/null 2>&1 | FileCheck %s
 
-# CHECK:     error: {{.*}}:(.text+0x2): relocation R_X86_64_GOTPCRELX out of range: 2147483655 is not in [-2147483648, 2147483647]; references data
-# CHECK:     error: {{.*}}:(.text+0x9): relocation R_X86_64_REX_GOTPCRELX out of range: 2147483648 is not in [-2147483648, 2147483647]; references data
+## Test diagnostics for GOTPCRELX overflows. In addition, test that there is no
+## `>>> defined in` for linker synthesized __stop_* symbols (there is no
+## associated file or linker script line number).
+
+# CHECK:      error: {{.*}}:(.text+0x2): relocation R_X86_64_GOTPCRELX out of range: 2147483655 is not in [-2147483648, 2147483647]; references __stop_data
+# CHECK-NEXT: error: {{.*}}:(.text+0x9): relocation R_X86_64_REX_GOTPCRELX out of range: 2147483648 is not in [-2147483648, 2147483647]; references __stop_data
 # CHECK-NOT: error:
 
 #--- a.s
-  movl data@GOTPCREL(%rip), %eax  # out of range
-  movq data@GOTPCREL(%rip), %rax  # out of range
-  movq data@GOTPCREL(%rip), %rax  # in range
+  movl __stop_data@GOTPCREL(%rip), %eax  # out of range
+  movq __stop_data@GOTPCREL(%rip), %rax  # out of range
+  movq __stop_data@GOTPCREL(%rip), %rax  # in range
 
-.data
+.section data,"aw",@progbits
 .space 13
-.globl data
-data:
-  .long 0
 
 #--- lds
 SECTIONS {
   .text 0x200000 : { *(.text) }
-  .data 0x80200000 : { *(.data) }
+  data 0x80200000 : { *(data) }
 }