237 lines
7.4 KiB
Diff
237 lines
7.4 KiB
Diff
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From 34088d0a8685defa97754b7ab5d90b9bc536cfaa Mon Sep 17 00:00:00 2001
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From: Yang Yujie <yangyujie@loongson.cn>
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Date: Fri, 8 Dec 2023 18:01:18 +0800
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Subject: [PATCH 066/188] LoongArch: Fix eh_return epilogue for normal returns.
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On LoongArch, the regitsters $r4 - $r7 (EH_RETURN_DATA_REGNO) will be saved
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and restored in the function prologue and epilogue if the given function calls
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__builtin_eh_return. This causes the return value to be overwritten on normal
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return paths and breaks a rare case of libgcc's _Unwind_RaiseException.
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gcc/ChangeLog:
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* config/loongarch/loongarch.cc: Do not restore the saved eh_return
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data registers ($r4-$r7) for a normal return of a function that calls
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__builtin_eh_return elsewhere.
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* config/loongarch/loongarch-protos.h: Same.
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* config/loongarch/loongarch.md: Same.
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gcc/testsuite/ChangeLog:
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* gcc.target/loongarch/eh_return-normal-return.c: New test.
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---
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gcc/config/loongarch/loongarch-protos.h | 2 +-
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gcc/config/loongarch/loongarch.cc | 34 ++++++++++++-----
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gcc/config/loongarch/loongarch.md | 23 ++++++++++-
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.../loongarch/eh_return-normal-return.c | 38 +++++++++++++++++++
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4 files changed, 84 insertions(+), 13 deletions(-)
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create mode 100644 gcc/testsuite/gcc.target/loongarch/eh_return-normal-return.c
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diff --git a/gcc/config/loongarch/loongarch-protos.h b/gcc/config/loongarch/loongarch-protos.h
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index 117669e9f..e5fcf3111 100644
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--- a/gcc/config/loongarch/loongarch-protos.h
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+++ b/gcc/config/loongarch/loongarch-protos.h
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@@ -60,7 +60,7 @@ enum loongarch_symbol_type {
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extern rtx loongarch_emit_move (rtx, rtx);
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extern HOST_WIDE_INT loongarch_initial_elimination_offset (int, int);
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extern void loongarch_expand_prologue (void);
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-extern void loongarch_expand_epilogue (bool);
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+extern void loongarch_expand_epilogue (int);
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extern bool loongarch_can_use_return_insn (void);
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extern bool loongarch_symbolic_constant_p (rtx, enum loongarch_symbol_type *);
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diff --git a/gcc/config/loongarch/loongarch.cc b/gcc/config/loongarch/loongarch.cc
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index 4a3a7a246..7caf04d8d 100644
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--- a/gcc/config/loongarch/loongarch.cc
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+++ b/gcc/config/loongarch/loongarch.cc
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@@ -1012,7 +1012,8 @@ loongarch_save_restore_reg (machine_mode mode, int regno, HOST_WIDE_INT offset,
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static void
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loongarch_for_each_saved_reg (HOST_WIDE_INT sp_offset,
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- loongarch_save_restore_fn fn)
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+ loongarch_save_restore_fn fn,
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+ bool skip_eh_data_regs_p)
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{
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HOST_WIDE_INT offset;
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@@ -1021,7 +1022,14 @@ loongarch_for_each_saved_reg (HOST_WIDE_INT sp_offset,
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for (int regno = GP_REG_FIRST; regno <= GP_REG_LAST; regno++)
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if (BITSET_P (cfun->machine->frame.mask, regno - GP_REG_FIRST))
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{
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- if (!cfun->machine->reg_is_wrapped_separately[regno])
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+ /* Special care needs to be taken for $r4-$r7 (EH_RETURN_DATA_REGNO)
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+ when returning normally from a function that calls
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+ __builtin_eh_return. In this case, these registers are saved but
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+ should not be restored, or the return value may be clobbered. */
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+
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+ if (!(cfun->machine->reg_is_wrapped_separately[regno]
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+ || (skip_eh_data_regs_p
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+ && GP_ARG_FIRST <= regno && regno < GP_ARG_FIRST + 4)))
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loongarch_save_restore_reg (word_mode, regno, offset, fn);
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offset -= UNITS_PER_WORD;
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@@ -1294,7 +1302,7 @@ loongarch_expand_prologue (void)
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GEN_INT (-step1));
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RTX_FRAME_RELATED_P (emit_insn (insn)) = 1;
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size -= step1;
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- loongarch_for_each_saved_reg (size, loongarch_save_reg);
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+ loongarch_for_each_saved_reg (size, loongarch_save_reg, false);
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}
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/* Set up the frame pointer, if we're using one. */
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@@ -1379,11 +1387,13 @@ loongarch_can_use_return_insn (void)
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return reload_completed && cfun->machine->frame.total_size == 0;
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}
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-/* Expand an "epilogue" or "sibcall_epilogue" pattern; SIBCALL_P
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- says which. */
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+/* Expand function epilogue using the following insn patterns:
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+ "epilogue" (style == NORMAL_RETURN)
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+ "sibcall_epilogue" (style == SIBCALL_RETURN)
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+ "eh_return" (style == EXCEPTION_RETURN) */
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void
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-loongarch_expand_epilogue (bool sibcall_p)
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+loongarch_expand_epilogue (int style)
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{
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/* Split the frame into two. STEP1 is the amount of stack we should
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deallocate before restoring the registers. STEP2 is the amount we
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@@ -1400,7 +1410,8 @@ loongarch_expand_epilogue (bool sibcall_p)
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bool need_barrier_p
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= (get_frame_size () + cfun->machine->frame.arg_pointer_offset) != 0;
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- if (!sibcall_p && loongarch_can_use_return_insn ())
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+ /* Handle simple returns. */
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+ if (style == NORMAL_RETURN && loongarch_can_use_return_insn ())
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{
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emit_jump_insn (gen_return ());
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return;
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@@ -1476,7 +1487,9 @@ loongarch_expand_epilogue (bool sibcall_p)
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/* Restore the registers. */
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loongarch_for_each_saved_reg (frame->total_size - step2,
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- loongarch_restore_reg);
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+ loongarch_restore_reg,
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+ crtl->calls_eh_return
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+ && style != EXCEPTION_RETURN);
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if (need_barrier_p)
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loongarch_emit_stack_tie ();
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@@ -1497,11 +1510,12 @@ loongarch_expand_epilogue (bool sibcall_p)
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}
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/* Add in the __builtin_eh_return stack adjustment. */
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- if (crtl->calls_eh_return)
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+ if (crtl->calls_eh_return && style == EXCEPTION_RETURN)
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emit_insn (gen_add3_insn (stack_pointer_rtx, stack_pointer_rtx,
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EH_RETURN_STACKADJ_RTX));
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- if (!sibcall_p)
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+ /* Emit return unless doing sibcall. */
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+ if (style != SIBCALL_RETURN)
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emit_jump_insn (gen_simple_return_internal (ra));
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}
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diff --git a/gcc/config/loongarch/loongarch.md b/gcc/config/loongarch/loongarch.md
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index c6edd1dda..222f1ae83 100644
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--- a/gcc/config/loongarch/loongarch.md
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+++ b/gcc/config/loongarch/loongarch.md
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@@ -125,6 +125,11 @@
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(T1_REGNUM 13)
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(S0_REGNUM 23)
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+ ;; Return path styles
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+ (NORMAL_RETURN 0)
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+ (SIBCALL_RETURN 1)
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+ (EXCEPTION_RETURN 2)
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+
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;; PIC long branch sequences are never longer than 100 bytes.
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(MAX_PIC_BRANCH_LENGTH 100)
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])
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@@ -3276,7 +3281,7 @@
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[(const_int 2)]
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""
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{
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- loongarch_expand_epilogue (false);
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+ loongarch_expand_epilogue (NORMAL_RETURN);
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DONE;
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})
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@@ -3284,7 +3289,7 @@
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[(const_int 2)]
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""
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{
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- loongarch_expand_epilogue (true);
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+ loongarch_expand_epilogue (SIBCALL_RETURN);
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DONE;
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})
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@@ -3341,6 +3346,20 @@
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emit_insn (gen_eh_set_ra_di (operands[0]));
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else
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emit_insn (gen_eh_set_ra_si (operands[0]));
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+
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+ emit_jump_insn (gen_eh_return_internal ());
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+ emit_barrier ();
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+ DONE;
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+})
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+
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+(define_insn_and_split "eh_return_internal"
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+ [(eh_return)]
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+ ""
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+ "#"
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+ "epilogue_completed"
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+ [(const_int 0)]
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+{
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+ loongarch_expand_epilogue (EXCEPTION_RETURN);
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DONE;
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})
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diff --git a/gcc/testsuite/gcc.target/loongarch/eh_return-normal-return.c b/gcc/testsuite/gcc.target/loongarch/eh_return-normal-return.c
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new file mode 100644
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index 000000000..f8f3965f8
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--- /dev/null
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+++ b/gcc/testsuite/gcc.target/loongarch/eh_return-normal-return.c
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@@ -0,0 +1,38 @@
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+/* { dg-do run } */
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+/* { dg-options "-O2" } */
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+
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+#include <stdlib.h>
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+
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+int foo () __attribute__((noinline));
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+int main ();
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+
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+int
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+foo () {
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+
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+ int t;
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+
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+ /* prevent optimization using asm */
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+ asm ("" : "=r" (t) : "0" (-1));
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+ asm ("" : "=r" (t) : "0" (t ? 1 : 0));
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+
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+ if (t == 0)
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+ /* never reached */
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+ __builtin_eh_return (0, __builtin_return_address (0));
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+
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+ else if (t == 1)
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+ /* return here */
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+ return 202312;
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+
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+ else
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+ /* never reached: prevent vrp optimization in main */
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+ return 0;
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+}
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+
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+int
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+main ()
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+{
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+ if (foo() == 202312)
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+ return 0;
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+ else
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+ abort ();
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+}
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--
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2.43.0
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