[lld] r277680 - Make filler expression compatible with gold.

[Rafael Espíndola via llvm-commits]

Note that gold also parses the hex string as a 32 bit value.

Cheers,
Rafael


On 3 August 2016 at 19:25, Rui Ueyama via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Author: ruiu
> Date: Wed Aug  3 18:25:15 2016
> New Revision: 277680
>
> URL: http://llvm.org/viewvc/llvm-project?rev=277680&view=rev
> Log:
> Make filler expression compatible with gold.
>
> Previously, a decimal filler expression is interpreted as a byte value.
> Gold on the other hand use it as a 32-bit big-endian value.
> This patch fixes the compatibility issue.
>
> Differential Revision: https://reviews.llvm.org/D23142
>
> Modified:
>     lld/trunk/ELF/LinkerScript.cpp
>     lld/trunk/test/ELF/linkerscript/linkerscript-sections-padding.s
>
> Modified: lld/trunk/ELF/LinkerScript.cpp
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/LinkerScript.cpp?rev=277680&r1=277679&r2=277680&view=diff
> ==============================================================================
> --- lld/trunk/ELF/LinkerScript.cpp (original)
> +++ lld/trunk/ELF/LinkerScript.cpp Wed Aug  3 18:25:15 2016
> @@ -843,18 +843,19 @@ std::vector<uint8_t> ScriptParser::readO
>    if (!Tok.startswith("="))
>      return {};
>    next();
> +
> +  // Read a hexstring of arbitrary length.
>    if (Tok.startswith("=0x"))
>      return parseHex(Tok.substr(3));
>
> -  // This must be a decimal.
> -  unsigned int Value;
> -  if (Tok.substr(1).getAsInteger(10, Value)) {
> -    setError("filler should be a decimal/hexadecimal value");
> +  // Read a decimal or octal value as a big-endian 32 bit value.
> +  // Why do this? I don't know, but that's what gold does.
> +  uint32_t V;
> +  if (Tok.substr(1).getAsInteger(0, V)) {
> +    setError("invalid filler expression: " + Tok);
>      return {};
>    }
> -  if (Value > 255)
> -    setError("only single bytes decimal are supported for the filler now");
> -  return {static_cast<unsigned char>(Value)};
> +  return { uint8_t(V >> 24), uint8_t(V >> 16), uint8_t(V >> 8), uint8_t(V) };
>  }
>
>  void ScriptParser::readProvide(bool Hidden) {
>
> Modified: lld/trunk/test/ELF/linkerscript/linkerscript-sections-padding.s
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/linkerscript/linkerscript-sections-padding.s?rev=277680&r1=277679&r2=277680&view=diff
> ==============================================================================
> --- lld/trunk/test/ELF/linkerscript/linkerscript-sections-padding.s (original)
> +++ lld/trunk/test/ELF/linkerscript/linkerscript-sections-padding.s Wed Aug  3 18:25:15 2016
> @@ -20,10 +20,10 @@
>  # NO: 00000120  66 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>
>  ## Decimal value.
> -# RUN: echo "SECTIONS { .mysec : { *(.mysec*) } =99 }" > %t.script
> +# RUN: echo "SECTIONS { .mysec : { *(.mysec*) } =777 }" > %t.script
>  # 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
> +# DEC: 00000120  66 00 03 09 00 00 03 09 00 00 03 09 00 00 03 09
>
>  ## Invalid hex value:
>  # RUN: echo "SECTIONS { .mysec : { *(.mysec*) } =0x99XX }" > %t.script
>
>
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