[Bug target/66609] New: [sh] Relative address expressions bind at as-time, even if symbol is weak
bugdal at aerifal dot cx
gcc-bugzilla@gcc.gnu.org
Fri Jun 19 21:11:00 GMT 2015
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66609
Bug ID: 66609
Summary: [sh] Relative address expressions bind at as-time,
even if symbol is weak
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: bugdal at aerifal dot cx
Target Milestone: ---
Minimal test case (compile with -fPIC and -Os or higher, for sh2 or later):
__attribute__((__weak__,__visibility__("hidden"))) void foo()
{
}
void bar()
{
foo();
}
For the call from bar to foo, gcc generates:
mov.l .L3,r1
braf r1
.LPCS0:
nop
.align 2
.L3:
.long foo-(.LPCS0+2)
Gas in turn ignores the fact that foo is weak and assembles the literal to a
constant with no relocation. This is the following bug I just reported in
binutils:
https://sourceware.org/bugzilla/show_bug.cgi?id=18561
However, GCC can and probably should work around it, by instead generating the
equivalent form that gas assembles correctly:
.long foo@PCREL-(.LPCS0+2-.)
This is easily changed at the following location:
https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/config/sh/sh.c;h=e5fcd7683ef7e06d56a10427d792ba018d1af884;hb=HEAD#l1662
and changing it seems to have solved the problem for me, but I did not yet test
extensively. I'm not sure if the subsequent case for UNSPEC_PCREL_SYMOFF also
needs changes.
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