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: 308531d148a ("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.
---
I am sending this as RFC as I think there should be a better way to handle
this but I am not sure how that would be.
An earlier patch I tried was to store the link register to a temporary register
then pass the temporary register as an argument to _mcount, however
optimizations caused the link register to still get clobbered.
Any thoughts will be helpful.
-Stafford
gcc/config/or1k/or1k-protos.h | 1 +
gcc/config/or1k/or1k.c | 49 ++++++++++++++++++++++++++++-------
gcc/config/or1k/or1k.h | 8 +-----
3 files changed, 42 insertions(+), 16 deletions(-)
diff --git a/gcc/config/or1k/or1k-protos.h b/gcc/config/or1k/or1k-protos.h
index bbb54c8f790..56554f2937f 100644
--- a/gcc/config/or1k/or1k-protos.h
+++ b/gcc/config/or1k/or1k-protos.h
@@ -20,6 +20,7 @@ along with GCC; see the file COPYING3. If not see
extern HOST_WIDE_INT or1k_initial_elimination_offset (int, int);
extern void or1k_expand_prologue (void);
extern void or1k_expand_epilogue (void);
+extern void or1k_profile_hook (void);
extern void or1k_expand_eh_return (rtx);
extern rtx or1k_initial_frame_addr (void);
extern rtx or1k_dynamic_chain_addr (rtx);
diff --git a/gcc/config/or1k/or1k.c b/gcc/config/or1k/or1k.c
index e772a7addea..335c4c5decf 100644
--- a/gcc/config/or1k/or1k.c
+++ b/gcc/config/or1k/or1k.c
@@ -73,6 +73,10 @@ struct GTY(()) machine_function
/* Remember where the set_got_placeholder is located. */
rtx_insn *set_got_insn;
+
+ /* Remember where mcount args are stored so we can insert set_got_insn
+ after. */
+ rtx_insn *set_mcount_arg_insn;
};
/* Zero initialization is OK for all current fields. */
@@ -415,6 +419,25 @@ or1k_expand_epilogue (void)
EH_RETURN_STACKADJ_RTX));
}
+/* Worker for PROFILE_HOOK.
+ The OpenRISC profile hook uses the link register which will get clobbered by
+ the GOT setup RTX. This sets up a placeholder to allow injecting of the GOT
+ setup RTX to avoid clobbering. */
+
+void
+or1k_profile_hook (void)
+{
+ rtx a1 = gen_rtx_REG (Pmode, 3);
+ rtx ra = get_hard_reg_initial_val (Pmode, LR_REGNUM);
+ rtx fun = gen_rtx_SYMBOL_REF (Pmode, "_mcount");
+
+ /* Keep track of where we setup the _mcount argument so we can insert the
+ GOT setup RTX after it. */
+ cfun->machine->set_mcount_arg_insn = emit_move_insn (a1, ra);
+
+ emit_library_call (fun, LCT_NORMAL, VOIDmode, a1, Pmode);
+}
+
/* Worker for TARGET_INIT_PIC_REG.
Initialize the cfun->machine->set_got_insn rtx and insert it at the entry
of the current function. The rtx is just a temporary placeholder for
@@ -423,17 +446,25 @@ or1k_expand_epilogue (void)
static void
or1k_init_pic_reg (void)
{
- start_sequence ();
- cfun->machine->set_got_insn
- = emit_insn (gen_set_got_tmp (pic_offset_table_rtx));
+ if (crtl->profile)
+ cfun->machine->set_got_insn =
+ emit_insn_after (gen_set_got_tmp (pic_offset_table_rtx),
+ cfun->machine->set_mcount_arg_insn);
+ else
+ {
+ start_sequence ();
+
+ cfun->machine->set_got_insn =
+ emit_insn (gen_set_got_tmp (pic_offset_table_rtx));
- rtx_insn *seq = get_insns ();
- end_sequence ();
+ rtx_insn *seq = get_insns ();
+ end_sequence ();
- edge entry_edge = single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun));
- insert_insn_on_edge (seq, entry_edge);
- commit_one_edge_insertion (entry_edge);
+ edge entry_edge = single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun));
+ insert_insn_on_edge (seq, entry_edge);
+ commit_one_edge_insertion (entry_edge);
+ }
}
#undef TARGET_INIT_PIC_REG
@@ -480,7 +511,7 @@ or1k_frame_pointer_required ()
{
/* ??? While IRA checks accesses_prior_frames, reload does not.
We do want the frame pointer for this case. */
- return (crtl->accesses_prior_frames || crtl->profile);
+ return (crtl->accesses_prior_frames);
}
/* Expand the "eh_return" pattern.
diff --git a/gcc/config/or1k/or1k.h b/gcc/config/or1k/or1k.h
index 4603cb67160..ce0a47dfa66 100644
--- a/gcc/config/or1k/or1k.h
+++ b/gcc/config/or1k/or1k.h
@@ -385,13 +385,7 @@ do { \
/* Emit rtl for profiling. Output assembler code to call "_mcount" for
profiling a function entry. */
-#define PROFILE_HOOK(LABEL) \
- { \
- rtx fun, ra; \
- ra = get_hard_reg_initial_val (Pmode, LR_REGNUM); \
- fun = gen_rtx_SYMBOL_REF (Pmode, "_mcount"); \
- emit_library_call (fun, LCT_NORMAL, VOIDmode, ra, Pmode); \
- }
+#define PROFILE_HOOK(LABEL) or1k_profile_hook()
/* All the work is done in PROFILE_HOOK, but this is still required. */
#define FUNCTION_PROFILER(STREAM, LABELNO) do { } while (0)
--
2.31.1
