[Bug gold/13214] New: Gold does emit mapping symbols for stubs

[mgretton at sourceware dot org]

http://sourceware.org/bugzilla/show_bug.cgi?id=13214

             Bug #: 13214
           Summary: Gold does emit mapping symbols for stubs
           Product: binutils
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gold
        AssignedTo: address@hidden
        ReportedBy: address@hidden
    Classification: Unclassified
            Target: arm-none-eabi


Given the following testcase:

@tmp.s
    .syntax unified
    .thumb
    .section sect1, "ax"
    .globl _start
_start:
    bl bar

    .section sect2, "ax"
    .globl bar
    .arm
bar:
    bx lr
@end of tmp.s

Doing the following:

arm-none-eabi-as -march=armv5t tmp.s -o tmp.o
arm-none-eabi-ld.gold tmp.o -o tmp --section-start sect2=0x1000 \
    --section-start sect1=0x04000000
arm-none-eabi-objdump -d tmp

Produces the following output:

00001000 <_start>:
    1000:       f000 e800       blx     1004 <_start+0x4>
    1004:       f004 e51f                       ; <UNDEFINED> instruction:
0xf004e51f
    1008:       0000            movs    r0, r0
    100a:       0400            lsls    r0, r0, #16

The instruction at 0x1004 is actually an ARM instruction (and so should have a
$a mapping symbol).  The 'instructions' at 0x1008 and 0x100a are actually a
word of data, and so should have a $d mapping symbol.

Not emitting these mapping symbols is technically in contravention of the ABI,
and makes disassembly harder to read, but in the majority of cases won't impact
correct execution of images.

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