Re: [PATCH v4] LoongArch: Fix eh_return epilogue for normal returns
Sorry, this is the wrong patch. I will post it again.
On Fri, Dec 08, 2023 at 05:57:12PM +0800, Yang Yujie wrote:
> Updates:
> v1 -> v2: Add a test case.
> v2 -> v3: Fix code format.
> v3 -> v4: Fix code format. Avoid unwanted optimization in the test.
>
> On Fri, Dec 08, 2023 at 05:54:46PM +0800, Yang Yujie wrote:
> > On LoongArch, the regitsters $r4 - $r7 (EH_RETURN_DATA_REGNO) will be saved
> > and restored in the function prologue and epilogue if the given function
> > calls
> > __builtin_eh_return. This causes the return value to be overwritten on
> > normal
> > return paths and breaks a rare case of libgcc's _Unwind_RaiseException.
> >
> > gcc/ChangeLog:
> >
> > * config/loongarch/loongarch.cc: Do not restore the saved eh_return
> > data registers ($r4-$r7) for a normal return of a function that calls
> > __builtin_eh_return elsewhere.
> > * config/loongarch/loongarch-protos.h: Same.
> > * config/loongarch/loongarch.md: Same.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * gcc.target/loongarch/eh_return-normal-return.c: New test.
> > ---
> > gcc/config/loongarch/loongarch-protos.h | 2 +-
> > gcc/config/loongarch/loongarch.cc | 41 ---
> > gcc/config/loongarch/loongarch.md | 18 +++-
> > .../loongarch/eh_return-normal-return.c | 32 +++
> > 4 files changed, 76 insertions(+), 17 deletions(-)
> > create mode 100644
> > gcc/testsuite/gcc.target/loongarch/eh_return-normal-return.c
> >
> > diff --git a/gcc/config/loongarch/loongarch-protos.h
> > b/gcc/config/loongarch/loongarch-protos.h
> > index cb8fc36b086..af20b5d7132 100644
> > --- a/gcc/config/loongarch/loongarch-protos.h
> > +++ b/gcc/config/loongarch/loongarch-protos.h
> > @@ -60,7 +60,7 @@ enum loongarch_symbol_type {
> > extern rtx loongarch_emit_move (rtx, rtx);
> > extern HOST_WIDE_INT loongarch_initial_elimination_offset (int, int);
> > extern void loongarch_expand_prologue (void);
> > -extern void loongarch_expand_epilogue (bool);
> > +extern void loongarch_expand_epilogue (int);
> > extern bool loongarch_can_use_return_insn (void);
> >
> > extern bool loongarch_symbolic_constant_p (rtx, enum loongarch_symbol_type
> > *);
> > diff --git a/gcc/config/loongarch/loongarch.cc
> > b/gcc/config/loongarch/loongarch.cc
> > index 3545e66a10e..9c0e0dd1b73 100644
> > --- a/gcc/config/loongarch/loongarch.cc
> > +++ b/gcc/config/loongarch/loongarch.cc
> > @@ -1015,20 +1015,30 @@ loongarch_save_restore_reg (machine_mode mode, int
> > regno, HOST_WIDE_INT offset,
> >
> > static void
> > loongarch_for_each_saved_reg (HOST_WIDE_INT sp_offset,
> > - loongarch_save_restore_fn fn)
> > + loongarch_save_restore_fn fn,
> > + bool skip_eh_data_regs_p)
> > {
> >HOST_WIDE_INT offset;
> >
> >/* Save the link register and s-registers. */
> >offset = cfun->machine->frame.gp_sp_offset - sp_offset;
> >for (int regno = GP_REG_FIRST; regno <= GP_REG_LAST; regno++)
> > -if (BITSET_P (cfun->machine->frame.mask, regno - GP_REG_FIRST))
> > - {
> > - if (!cfun->machine->reg_is_wrapped_separately[regno])
> > - loongarch_save_restore_reg (word_mode, regno, offset, fn);
> > +{
> > + /* Special care needs to be taken for $r4-$r7 (EH_RETURN_DATA_REGNO)
> > +when returning normally from a function that calls __builtin_eh_return.
> > +In this case, these registers are saved but should not be restored,
> > +or the return value may be clobbered. */
> >
> > - offset -= UNITS_PER_WORD;
> > - }
> > + if (BITSET_P (cfun->machine->frame.mask, regno - GP_REG_FIRST))
> > + {
> > + if (!(cfun->machine->reg_is_wrapped_separately[regno]
> > + || (skip_eh_data_regs_p
> > + && GP_ARG_FIRST <= regno && regno < GP_ARG_FIRST + 4)))
> > + loongarch_save_restore_reg (word_mode, regno, offset, fn);
> > +
> > + offset -= UNITS_PER_WORD;
> > + }
> > +}
> >
> >/* This loop must iterate over the same space as its companion in
> > loongarch_compute_frame_info. */
> > @@ -1297,7 +1307,7 @@ loongarch_expand_prologue (void)
> > GEN_INT (-step1));
> >RTX_FRAME_RELATED_P (emit_insn (insn)) = 1;
> >size -= step1;
> > - loongarch_for_each_saved_reg (size, loongarch_save_reg);
> > + loongarch_for_each_saved_reg (size, loongarch_save_reg, false);
> > }
> >
> >/* Set up the frame pointer, if we're using one. */
> > @@ -1382,11 +1392,11 @@ loongarch_can_use_return_insn (void)
> >return reload_completed && cfun->machine->frame.total_size == 0;
> > }
> >
> > -/* Expand an "epilogue" or "sibcall_epilogue" pattern; SIBCALL_P
> > - says which. */
> > +/* Expand function epilogue for the following insn patterns:
> > + "epilogue" (style == 0) / "sibcall_epilogue" (1) / "eh_return" (2). */
> >
> > void
> > -loongarch_expand_epilogue (bool
Re: [PATCH v4] LoongArch: Fix eh_return epilogue for normal returns
Updates:
v1 -> v2: Add a test case.
v2 -> v3: Fix code format.
v3 -> v4: Fix code format. Avoid unwanted optimization in the test.
On Fri, Dec 08, 2023 at 05:54:46PM +0800, Yang Yujie wrote:
> On LoongArch, the regitsters $r4 - $r7 (EH_RETURN_DATA_REGNO) will be saved
> and restored in the function prologue and epilogue if the given function calls
> __builtin_eh_return. This causes the return value to be overwritten on normal
> return paths and breaks a rare case of libgcc's _Unwind_RaiseException.
>
> gcc/ChangeLog:
>
> * config/loongarch/loongarch.cc: Do not restore the saved eh_return
> data registers ($r4-$r7) for a normal return of a function that calls
> __builtin_eh_return elsewhere.
> * config/loongarch/loongarch-protos.h: Same.
> * config/loongarch/loongarch.md: Same.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/loongarch/eh_return-normal-return.c: New test.
> ---
> gcc/config/loongarch/loongarch-protos.h | 2 +-
> gcc/config/loongarch/loongarch.cc | 41 ---
> gcc/config/loongarch/loongarch.md | 18 +++-
> .../loongarch/eh_return-normal-return.c | 32 +++
> 4 files changed, 76 insertions(+), 17 deletions(-)
> create mode 100644
> gcc/testsuite/gcc.target/loongarch/eh_return-normal-return.c
>
> diff --git a/gcc/config/loongarch/loongarch-protos.h
> b/gcc/config/loongarch/loongarch-protos.h
> index cb8fc36b086..af20b5d7132 100644
> --- a/gcc/config/loongarch/loongarch-protos.h
> +++ b/gcc/config/loongarch/loongarch-protos.h
> @@ -60,7 +60,7 @@ enum loongarch_symbol_type {
> extern rtx loongarch_emit_move (rtx, rtx);
> extern HOST_WIDE_INT loongarch_initial_elimination_offset (int, int);
> extern void loongarch_expand_prologue (void);
> -extern void loongarch_expand_epilogue (bool);
> +extern void loongarch_expand_epilogue (int);
> extern bool loongarch_can_use_return_insn (void);
>
> extern bool loongarch_symbolic_constant_p (rtx, enum loongarch_symbol_type
> *);
> diff --git a/gcc/config/loongarch/loongarch.cc
> b/gcc/config/loongarch/loongarch.cc
> index 3545e66a10e..9c0e0dd1b73 100644
> --- a/gcc/config/loongarch/loongarch.cc
> +++ b/gcc/config/loongarch/loongarch.cc
> @@ -1015,20 +1015,30 @@ loongarch_save_restore_reg (machine_mode mode, int
> regno, HOST_WIDE_INT offset,
>
> static void
> loongarch_for_each_saved_reg (HOST_WIDE_INT sp_offset,
> - loongarch_save_restore_fn fn)
> + loongarch_save_restore_fn fn,
> + bool skip_eh_data_regs_p)
> {
>HOST_WIDE_INT offset;
>
>/* Save the link register and s-registers. */
>offset = cfun->machine->frame.gp_sp_offset - sp_offset;
>for (int regno = GP_REG_FIRST; regno <= GP_REG_LAST; regno++)
> -if (BITSET_P (cfun->machine->frame.mask, regno - GP_REG_FIRST))
> - {
> - if (!cfun->machine->reg_is_wrapped_separately[regno])
> - loongarch_save_restore_reg (word_mode, regno, offset, fn);
> +{
> + /* Special care needs to be taken for $r4-$r7 (EH_RETURN_DATA_REGNO)
> + when returning normally from a function that calls __builtin_eh_return.
> + In this case, these registers are saved but should not be restored,
> + or the return value may be clobbered. */
>
> - offset -= UNITS_PER_WORD;
> - }
> + if (BITSET_P (cfun->machine->frame.mask, regno - GP_REG_FIRST))
> + {
> + if (!(cfun->machine->reg_is_wrapped_separately[regno]
> + || (skip_eh_data_regs_p
> + && GP_ARG_FIRST <= regno && regno < GP_ARG_FIRST + 4)))
> + loongarch_save_restore_reg (word_mode, regno, offset, fn);
> +
> + offset -= UNITS_PER_WORD;
> + }
> +}
>
>/* This loop must iterate over the same space as its companion in
> loongarch_compute_frame_info. */
> @@ -1297,7 +1307,7 @@ loongarch_expand_prologue (void)
> GEN_INT (-step1));
>RTX_FRAME_RELATED_P (emit_insn (insn)) = 1;
>size -= step1;
> - loongarch_for_each_saved_reg (size, loongarch_save_reg);
> + loongarch_for_each_saved_reg (size, loongarch_save_reg, false);
> }
>
>/* Set up the frame pointer, if we're using one. */
> @@ -1382,11 +1392,11 @@ loongarch_can_use_return_insn (void)
>return reload_completed && cfun->machine->frame.total_size == 0;
> }
>
> -/* Expand an "epilogue" or "sibcall_epilogue" pattern; SIBCALL_P
> - says which. */
> +/* Expand function epilogue for the following insn patterns:
> + "epilogue" (style == 0) / "sibcall_epilogue" (1) / "eh_return" (2). */
>
> void
> -loongarch_expand_epilogue (bool sibcall_p)
> +loongarch_expand_epilogue (int style)
> {
>/* Split the frame into two. STEP1 is the amount of stack we should
> deallocate before restoring the registers. STEP2 is the amount we
> @@ -1403,7 +1413,8 @@ loongarch_expand_epilogue (bool sibcall_p)
>bool need_barrier_p
>
[PATCH v4] LoongArch: Fix eh_return epilogue for normal returns
On LoongArch, the regitsters $r4 - $r7 (EH_RETURN_DATA_REGNO) will be saved
and restored in the function prologue and epilogue if the given function calls
__builtin_eh_return. This causes the return value to be overwritten on normal
return paths and breaks a rare case of libgcc's _Unwind_RaiseException.
gcc/ChangeLog:
* config/loongarch/loongarch.cc: Do not restore the saved eh_return
data registers ($r4-$r7) for a normal return of a function that calls
__builtin_eh_return elsewhere.
* config/loongarch/loongarch-protos.h: Same.
* config/loongarch/loongarch.md: Same.
gcc/testsuite/ChangeLog:
* gcc.target/loongarch/eh_return-normal-return.c: New test.
---
gcc/config/loongarch/loongarch-protos.h | 2 +-
gcc/config/loongarch/loongarch.cc | 41 ---
gcc/config/loongarch/loongarch.md | 18 +++-
.../loongarch/eh_return-normal-return.c | 32 +++
4 files changed, 76 insertions(+), 17 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/loongarch/eh_return-normal-return.c
diff --git a/gcc/config/loongarch/loongarch-protos.h
b/gcc/config/loongarch/loongarch-protos.h
index cb8fc36b086..af20b5d7132 100644
--- a/gcc/config/loongarch/loongarch-protos.h
+++ b/gcc/config/loongarch/loongarch-protos.h
@@ -60,7 +60,7 @@ enum loongarch_symbol_type {
extern rtx loongarch_emit_move (rtx, rtx);
extern HOST_WIDE_INT loongarch_initial_elimination_offset (int, int);
extern void loongarch_expand_prologue (void);
-extern void loongarch_expand_epilogue (bool);
+extern void loongarch_expand_epilogue (int);
extern bool loongarch_can_use_return_insn (void);
extern bool loongarch_symbolic_constant_p (rtx, enum loongarch_symbol_type *);
diff --git a/gcc/config/loongarch/loongarch.cc
b/gcc/config/loongarch/loongarch.cc
index 3545e66a10e..9c0e0dd1b73 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -1015,20 +1015,30 @@ loongarch_save_restore_reg (machine_mode mode, int
regno, HOST_WIDE_INT offset,
static void
loongarch_for_each_saved_reg (HOST_WIDE_INT sp_offset,
- loongarch_save_restore_fn fn)
+ loongarch_save_restore_fn fn,
+ bool skip_eh_data_regs_p)
{
HOST_WIDE_INT offset;
/* Save the link register and s-registers. */
offset = cfun->machine->frame.gp_sp_offset - sp_offset;
for (int regno = GP_REG_FIRST; regno <= GP_REG_LAST; regno++)
-if (BITSET_P (cfun->machine->frame.mask, regno - GP_REG_FIRST))
- {
- if (!cfun->machine->reg_is_wrapped_separately[regno])
- loongarch_save_restore_reg (word_mode, regno, offset, fn);
+{
+ /* Special care needs to be taken for $r4-$r7 (EH_RETURN_DATA_REGNO)
+when returning normally from a function that calls __builtin_eh_return.
+In this case, these registers are saved but should not be restored,
+or the return value may be clobbered. */
- offset -= UNITS_PER_WORD;
- }
+ if (BITSET_P (cfun->machine->frame.mask, regno - GP_REG_FIRST))
+ {
+ if (!(cfun->machine->reg_is_wrapped_separately[regno]
+ || (skip_eh_data_regs_p
+ && GP_ARG_FIRST <= regno && regno < GP_ARG_FIRST + 4)))
+ loongarch_save_restore_reg (word_mode, regno, offset, fn);
+
+ offset -= UNITS_PER_WORD;
+ }
+}
/* This loop must iterate over the same space as its companion in
loongarch_compute_frame_info. */
@@ -1297,7 +1307,7 @@ loongarch_expand_prologue (void)
GEN_INT (-step1));
RTX_FRAME_RELATED_P (emit_insn (insn)) = 1;
size -= step1;
- loongarch_for_each_saved_reg (size, loongarch_save_reg);
+ loongarch_for_each_saved_reg (size, loongarch_save_reg, false);
}
/* Set up the frame pointer, if we're using one. */
@@ -1382,11 +1392,11 @@ loongarch_can_use_return_insn (void)
return reload_completed && cfun->machine->frame.total_size == 0;
}
-/* Expand an "epilogue" or "sibcall_epilogue" pattern; SIBCALL_P
- says which. */
+/* Expand function epilogue for the following insn patterns:
+ "epilogue" (style == 0) / "sibcall_epilogue" (1) / "eh_return" (2). */
void
-loongarch_expand_epilogue (bool sibcall_p)
+loongarch_expand_epilogue (int style)
{
/* Split the frame into two. STEP1 is the amount of stack we should
deallocate before restoring the registers. STEP2 is the amount we
@@ -1403,7 +1413,8 @@ loongarch_expand_epilogue (bool sibcall_p)
bool need_barrier_p
= (get_frame_size () + cfun->machine->frame.arg_pointer_offset) != 0;
- if (!sibcall_p && loongarch_can_use_return_insn ())
+ /* Handle simple returns. */
+ if (style == 0 && loongarch_can_use_return_insn ())
{
emit_jump_insn (gen_return ());
return;
@@ -1479,7 +1490,8 @@ loongarch_expand_epilogue (bool sibcall_p)
/* Restore the
