[LinkerScript] Support decimal values for filler

[davide]

Summary

Discussed with Rui on IRC

[ruiu]

ELF/LinkerScript.cpp

805

Flip this condition so that you can do early return like this.

if (Tok.startswith("=0x")) {
  next();
  return parseHex(Tok.substr(3));
}

815–818

This can be return { Value }, no?

[davide]

Correct patch (missed one of your comments).

[ruiu]

LGTM with a few nits.

ELF/LinkerScript.cpp

802

At this point, we determined we consume a token whether it's a hexadecimal or decimal, so let's move next() here, so that you can remove the following two next()s.

808

This should be an unsigned int. Otherwise Value > 255 is always false.

809

This can be Tok.substr(1).getAsInteger

[davide]

ELF/LinkerScript.cpp

38

Ignore this #include, it's a leftover from a previous experiment.

ELF/LinkerScript.cpp

   Cmd->Phdrs = readOutputSectionPhdrs();
   Cmd->Filler = readOutputSectionFiller();
 }
 
 std::vector<uint8_t> ScriptParser::readOutputSectionFiller() {
   StringRef Tok = peek();
   if (!Tok.startswith("="))
     return {};
-  if (!Tok.startswith("=0x")) {
-    setError("filler should be a hexadecimal value");
+  if (Tok.startswith("=0x")) {
+    next();
+    return parseHex(Tok.substr(3));
+  }
+  // This must be a decimal.
+  Tok = Tok.substr(1);
+  unsigned char Value;
+  if (Tok.getAsInteger(10, Value)) {
+    setError("filler should be a decimal/hexadecimal value");
     return {};
   }
-  Tok = Tok.substr(3);
+  if (Value > 255)
+    setError("only single bytes decimal are supported for the filler now");
   next();
-  return parseHex(Tok);
+  return {Value};
 }
 
 void ScriptParser::readProvide(bool Hidden) {
   expect("(");
   SymbolAssignment *Cmd = readAssignment(next());
   Cmd->Provide = true;
   Cmd->Hidden = Hidden;
   expect(")");
   expect(";");
 }

test/ELF/linkerscript/linkerscript-sections-padding.s

 # YES2: 00000120  66 88 77 66 55 44 33 22 11 99 88 77 66 55 44
 
 ## Default padding value is 0x00:
 # RUN: echo "SECTIONS { .mysec : { *(.mysec*) } }" > %t.script
 # RUN: ld.lld -o %t.out --script %t.script %t
 # RUN: hexdump -C %t.out | FileCheck -check-prefix=NO %s
 # NO: 00000120  66 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 
-## Filler should be a hex value (1):
+## Decimal value.
 # RUN: echo "SECTIONS { .mysec : { *(.mysec*) } =99 }" > %t.script
-# RUN: not ld.lld -o %t.out --script %t.script %t 2>&1 \
-# RUN:   | FileCheck --check-prefix=ERR %s
-# ERR: filler should be a hexadecimal value
+# RUN: ld.lld -o %t.out --script %t.script %t
+# RUN: hexdump -C %t.out | FileCheck -check-prefix=DEC %s
+# DEC: 00000120  66 63 63 63 63 63 63 63  63 63 63 63 63 63 63 63 
 
-## Filler should be a hex value (2):
+## Invalid hex value:
 # RUN: echo "SECTIONS { .mysec : { *(.mysec*) } =0x99XX }" > %t.script
 # RUN: not ld.lld -o %t.out --script %t.script %t 2>&1 \
 # RUN:   | FileCheck --check-prefix=ERR2 %s
 # ERR2: not a hexadecimal value: XX
 
 .section        .mysec.1,"a"
 .align  16
 .byte   0x66
 
 .section        .mysec.2,"a"
 .align  16
 .byte   0x66
 
 .globl _start
 _start:
  nop