Recently we changed the PROFILE_HOOK _mcount call to pass in the link
register as an argument. This actually does not work when the _mcount
call uses a PLT because the GOT register setup code ends up getting
inserted before the PROFILE_HOOK and clobbers the link register
argument.
These glibc tests are failing:
gmon/tst-gmon-pie-gprof
gmon/tst-gmon-static-gprof
This patch fixes this by saving the instruction that stores the Link
Register to the _mcount argument and then inserts the GOT register setup
instructions after that.
For example:
main.c:
extern int e;
int f2(int a) {
return a + e;
}
int f1(int a) {
return f2 (a + a);
}
int main(int argc, char ** argv) {
return f1 (argc);
}
Compiled:
or1k-smh-linux-gnu-gcc -Wall -c -O2 -fPIC -pg -S main.c
Before Fix:
main:
l.addi r1, r1, -16
l.sw 8(r1), r2
l.sw 0(r1), r16
l.addi r2, r1, 16 # Keeping FP, but not needed
l.sw 4(r1), r18
l.sw 12(r1), r9
l.jal 8 # GOT Setup clobbers r9 (Link Register)
l.movhi r16, gotpchi(_GLOBAL_OFFSET_TABLE_-4)
l.ori r16, r16, gotpclo(_GLOBAL_OFFSET_TABLE_+0)
l.add r16, r16, r9
l.or r18, r3, r3
l.or r3, r9, r9 # This is not the original LR
l.jal plt(_mcount)
l.nop
l.jal plt(f1)
l.or r3, r18, r18
l.lwz r9, 12(r1)
l.lwz r16, 0(r1)
l.lwz r18, 4(r1)
l.lwz r2, 8(r1)
l.jr r9
l.addi r1, r1, 16
After the fix:
main:
l.addi r1, r1, -12
l.sw 0(r1), r16
l.sw 4(r1), r18
l.sw 8(r1), r9
l.or r18, r3, r3
l.or r3, r9, r9 # We now have r9 (LR) set early
l.jal 8 # Clobbers r9 (Link Register)
l.movhi r16, gotpchi(_GLOBAL_OFFSET_TABLE_-4)
l.ori r16, r16, gotpclo(_GLOBAL_OFFSET_TABLE_+0)
l.add r16, r16, r9
l.jal plt(_mcount)
l.nop
l.jal plt(f1)
l.or r3, r18, r18
l.lwz r9, 8(r1)
l.lwz r16, 0(r1)
l.lwz r18, 4(r1)
l.jr r9
l.addi r1, r1, 12
Fixes: 308531d148 ("or1k: Add return address argument to _mcount call")
gcc/ChangeLog:
* config/or1k/or1k-protos.h (or1k_profile_hook): New function.
* config/or1k/or1k.h (PROFILE_HOOK): Change macro to reference
new function or1k_profile_hook.
* config/or1k/or1k.c (struct machine_function): Add new field
set_mcount_arg_insn.
(or1k_profile_hook): New function.
(or1k_init_pic_reg): Update to inject pic rtx after _mcount arg
when profiling.
(or1k_frame_pointer_required): Frame pointer no longer needed
when profiling.
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