Re: [pushed][PATCH][gcc-12] LoongArch: Fix eh_return epilogue for normal returns.
Pushed to r12-10403.
在 2024/4/29 下午4:09, Lulu Cheng 写道:
From: Yang Yujie
On LoongArch, the regitsters $r4 - $r7 (EH_RETURN_DATA_REGNO) will be saved
and restored in the function prologue and epilogue if the given function calls
__builtin_eh_return. This causes the return value to be overwritten on normal
return paths and breaks a rare case of libgcc's _Unwind_RaiseException.
gcc/ChangeLog:
PR target/114848
* config/loongarch/loongarch.cc: Do not restore the saved eh_return
data registers ($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.
(cherry picked from commit 4b421728289e6f1caa0dfaa953a11698ab95d37d)
---
gcc/config/loongarch/loongarch-protos.h | 2 +-
gcc/config/loongarch/loongarch.cc | 35 -
gcc/config/loongarch/loongarch.md | 23 ++-
.../loongarch/eh_return-normal-return.c | 38 +++
4 files changed, 85 insertions(+), 13 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 2144c2421ed..8af82ffaa20 100644
--- a/gcc/config/loongarch/loongarch-protos.h
+++ b/gcc/config/loongarch/loongarch-protos.h
@@ -47,7 +47,7 @@ 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 33b1919e7a3..a0e11f2fc66 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -1008,7 +1008,8 @@ 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;
@@ -1017,7 +1018,15 @@ loongarch_for_each_saved_reg (HOST_WIDE_INT sp_offset,
for (int regno = GP_REG_FIRST; regno <= GP_REG_LAST; regno++)
if (BITSET_P (cfun->machine->frame.mask, regno - GP_REG_FIRST))
{
- 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. */
+
+ if (!(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;
}
@@ -1289,7 +1298,7 @@ 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);
}
@@ -1336,11 +1345,13 @@ 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 using the following insn patterns:
+ "epilogue" (style == NORMAL_RETURN)
+ "sibcall_epilogue" (style == SIBCALL_RETURN)
+ "eh_return" (style == EXCEPTION_RETURN) */
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
@@ -1357,7 +1368,8 @@ 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 == NORMAL_RETURN && loongarch_can_use_return_insn ())
{
emit_jump_insn (gen_return ());
return;
@@ -1433,7 +1445,9 @@ loongarch_expand_epilogue (bool sibcall_p)
/* Restore the registers. */
loongarch_for_each_saved_reg (frame->total_size - step2,
- loongarch_restore_reg);
+
[PATCH][gcc-12] LoongArch: Fix eh_return epilogue for normal returns.
From: Yang Yujie
On LoongArch, the regitsters $r4 - $r7 (EH_RETURN_DATA_REGNO) will be saved
and restored in the function prologue and epilogue if the given function calls
__builtin_eh_return. This causes the return value to be overwritten on normal
return paths and breaks a rare case of libgcc's _Unwind_RaiseException.
gcc/ChangeLog:
PR target/114848
* config/loongarch/loongarch.cc: Do not restore the saved eh_return
data registers ($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.
(cherry picked from commit 4b421728289e6f1caa0dfaa953a11698ab95d37d)
---
gcc/config/loongarch/loongarch-protos.h | 2 +-
gcc/config/loongarch/loongarch.cc | 35 -
gcc/config/loongarch/loongarch.md | 23 ++-
.../loongarch/eh_return-normal-return.c | 38 +++
4 files changed, 85 insertions(+), 13 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 2144c2421ed..8af82ffaa20 100644
--- a/gcc/config/loongarch/loongarch-protos.h
+++ b/gcc/config/loongarch/loongarch-protos.h
@@ -47,7 +47,7 @@ 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 33b1919e7a3..a0e11f2fc66 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -1008,7 +1008,8 @@ 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;
@@ -1017,7 +1018,15 @@ loongarch_for_each_saved_reg (HOST_WIDE_INT sp_offset,
for (int regno = GP_REG_FIRST; regno <= GP_REG_LAST; regno++)
if (BITSET_P (cfun->machine->frame.mask, regno - GP_REG_FIRST))
{
- 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. */
+
+ if (!(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;
}
@@ -1289,7 +1298,7 @@ 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);
}
@@ -1336,11 +1345,13 @@ 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 using the following insn patterns:
+ "epilogue"(style == NORMAL_RETURN)
+ "sibcall_epilogue" (style == SIBCALL_RETURN)
+ "eh_return" (style == EXCEPTION_RETURN) */
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
@@ -1357,7 +1368,8 @@ 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 == NORMAL_RETURN && loongarch_can_use_return_insn ())
{
emit_jump_insn (gen_return ());
return;
@@ -1433,7 +1445,9 @@ loongarch_expand_epilogue (bool sibcall_p)
/* Restore the registers. */
loongarch_for_each_saved_reg (frame->total_size - step2,
- loongarch_restore_reg);
+ loongarch_restore_reg,
+ crtl->calls_eh_return
+
