[all-commits] [llvm/llvm-project] 8ffb20: [ELF] Refine LMA offset propagation rule in D76995

[Fangrui Song via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 8ffb2097cc1adf5a0f964006a7633ed1ee4f59d3
      https://github.com/llvm/llvm-project/commit/8ffb2097cc1adf5a0f964006a7633ed1ee4f59d3
  Author: Fangrui Song <maskray at google.com>
  Date:   2020-06-19 (Fri, 19 Jun 2020)

  Changed paths:
    M lld/ELF/LinkerScript.cpp
    M lld/docs/ELF/linker_script.rst
    A lld/test/ELF/linkerscript/lma-offset2.s

  Log Message:
  -----------
  [ELF] Refine LMA offset propagation rule in D76995

If neither AT(lma) nor AT>lma_region is specified,
D76995 keeps `lmaOffset` (LMA - VMA) if the previous section is in the
default LMA region.

This patch additionally checks that the two sections are in the same
memory region.

Add a test case derived from https://bugs.llvm.org/show_bug.cgi?id=45313

  .mdata : AT(0xfb01000) { *(.data); } > TCM
  // It is odd to make .bss inherit lmaOffset, because the two sections
  // are in different memory regions.
  .bss : { *(.bss) } > DDR

With this patch, section VMA/LMA match GNU ld. Note, GNU ld supports
out-of-order (w.r.t sh_offset) sections and places .text and .bss in the
same PT_LOAD. We don't have that behavior.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D81986