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gcc: try latest available snapshot (NOT TO BE MERGED) #9034

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gcc: try latest available snapshot (NOT TO BE MERGED) #9034

wants to merge 4 commits into from

Commits on Jul 3, 2021

  1. gcc: migrate to 11.1 applying msys2#8320

    Oscar Fuentes committed Jul 3, 2021
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  2. gcc: use the latest development snapshot

    Oscar Fuentes committed Jul 3, 2021
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  3. gcc: apply patch from upstream 

    Change EH pointer encodings to PC relative on Windows
author	Eric Botcazou <[email protected]>
	Fri, 2 Jul 2021 08:21:11 +0000 (10:21 +0200)
committer	Eric Botcazou <[email protected]>
	Fri, 2 Jul 2021 08:27:41 +0000 (10:27 +0200)
commit	014e6aa467b1648d09eab9897ca367bfec5e6b76

Change EH pointer encodings to PC relative on Windows

A big difference between ELF and PE-COFF is that, with the latter, you can
build position-independent executables or DLLs without generating PIC; as
a  matter of fact, flag_pic has historically been forced to 0 for 32-bit:

/* Don't allow flag_pic to propagate since gas may produce invalid code
   otherwise.  */

\
do {
        \
  flag_pic = TARGET_64BIT ? 1 : 0; \
} while (0)

The reason is that the linker builds a .reloc section that collects the
absolute relocations in the generated binary, and the loader uses them to
relocate it at load time if need be (e.g. if --dynamicbase is enabled).

Up to binutils 2.35, the GNU linker didn't build the .reloc section for
executables and defaulted to --enable-auto-image-base for DLLs, which means
that DLLs had an essentially unique load address and, therefore, need not
be relocated by the loader in most cases.

With binutils 2.36 and later, the GNU linker builds a .reloc section for
executables (thus making them PIE), --enable-auto-image-base is disabled
and --dynamicbase is enabled by default, which means that essentially all
the binaries are relocated at load time.

This badly breaks the 32-bit compiler configured to use DWARF-2 EH because
the loader corrupts the .eh_frame section when processing the relocations
contained in the .reloc section.

gcc/
* config/i386/i386.c (asm_preferred_eh_data_format): Always use the
PIC encodings for PE-COFF targets.
    Oscar Fuentes committed Jul 3, 2021
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  4. gcc: drop patch already present on snapshot

    Oscar Fuentes committed Jul 3, 2021
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