[ELF] - Linkerscript: accept space between '=' and expression in section filler.

[grimar]

Summary

Previously we failed to parse next scripts because disallowed
a space between filler value and '=':

  .text : {
...
  } :text = 0x9090

Found it in the wild here: https://searchcode.com/file/61508112/xen/arch/x86/xen.lds.S

[ruiu]

ELF/LinkerScript.cpp

1220 ↗

(On Diff #72183)

Probably this is better.

if (skip("="))
  Cmd->Filler = next();
else if (peek().startswith("="))
  Cmd->Filler = readOutputSectionFiller(next().drop_front());

[grimar]

• Addressed review comments.

[ruiu]

LGTM.

You probably cannot make the lexer split '=' as a separate token because that can be used in filenames.

lld/trunk/ELF/LinkerScript.cpp

while (!Error && !skip("}")) {
     else if (Tok == "SORT")
       readSort();
     else if (peek() == "(")
       Cmd->Commands.emplace_back(readInputSectionDescription(Tok));
     else
       setError("unknown command " + Tok);
   }
   Cmd->Phdrs = readOutputSectionPhdrs();
-  if (peek().startswith("="))
+
+  if (skip("="))
+    Cmd->Filler = readOutputSectionFiller(next());
+  else if (peek().startswith("="))
     Cmd->Filler = readOutputSectionFiller(next().drop_front());
+
   return Cmd;
 }
 
 // Read "=<number>" where <number> is an octal/decimal/hexadecimal number.
 // https://sourceware.org/binutils/docs/ld/Output-Section-Fill.html
 //
 // ld.gold is not fully compatible with ld.bfd. ld.bfd handles
 // hexstrings as blobs of arbitrary sizes, while ld.gold handles them

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

 # DEC: 66000309 00000309 00000309 00000309
 
 ## 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: invalid filler expression: 0x99XX
 
+## Check case with space between '=' and expression:
+# RUN: echo "SECTIONS { .mysec : { *(.mysec*) } = 0x1122 }" > %t.script
+# RUN: ld.lld -o %t.out --script %t.script %t
+# RUN: llvm-objdump -s %t.out | FileCheck -check-prefix=YES %s
+
 .section        .mysec.1,"a"
 .align  16
 .byte   0x66
 
 .section        .mysec.2,"a"
 .align  16
 .byte   0x66
 
 .globl _start
 _start:
  nop