On Tue, 25 Nov 2025, Jakub Jelinek wrote:
> Hi!
>
> The eh pass lowers try { } finally { } stmts and handles
> in there e.g. GIMPLE_GOTOs or GIMPLE_CONDs which jump from
> within the try block out of that by redirecting the jumps
> to an artificial label with code to perform the cleanups/destructors
> and then continuing the goto, ultimately to the original label.
>
> Now, for computed gotos and non-local gotos, we document we don't
> invoke destructors (and cleanups as well), that is something we really
> can't handle, similarly longjmp.
>
> This PR is about asm goto though, and in that case I don't see why
> we shouldn't be performing the cleanups, while the user doesn't
> specify which particular label will be jumped to, so it is more
> like GIMPLE_COND (i.e. conditional goto) rather than unconditional
> GIMPLE_GOTO, even with potentiall more different maybe gotos, there is
> still list of the potential labels and we can adjust some or all of them
> to artificial labels performing cleanups and continuing jump towards the
> user label, we know from where the jumps go (asm goto) and to where
> (the different LABEL_DECLs).
>
> So, the following patch handles asm goto in the eh pass similarly to
> GIMPLE_COND and GIMPLE_GOTO.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
LGTM.
I do wonder whether we want to go this route though - in principle
we have similar info for computed goto. I'm not 100% sure about non-local
goto, but we know all possible targets here as well.
So isn't this inconsistent?
> 2025-11-25 Jakub Jelinek <[email protected]>
>
> PR middle-end/122835
> * tree-eh.cc (replace_goto_queue_1): Handle GIMPLE_ASM.
> (maybe_record_in_goto_queue): Likewise.
> (lower_eh_constructs_2): Likewise.
>
> * gcc.dg/torture/pr122835.c: New test.
>
> --- gcc/tree-eh.cc.jj 2025-09-04 18:51:34.130709784 +0200
> +++ gcc/tree-eh.cc 2025-11-25 17:13:37.724534641 +0100
> @@ -517,6 +517,48 @@ replace_goto_queue_1 (gimple *stmt, stru
> }
> break;
>
> + case GIMPLE_ASM:
> + if (int n = gimple_asm_nlabels (as_a <gasm *> (stmt)))
> + {
> + temp.g = stmt;
> + gasm *asm_stmt = as_a <gasm *> (stmt);
> + location_t loc = gimple_location (stmt);
> + tree bypass_label = NULL_TREE;
> + for (int i = 0; i < n; ++i)
> + {
> + tree elt = gimple_asm_label_op (asm_stmt, i);
> + temp.tp = &TREE_VALUE (elt);
> + seq = find_goto_replacement (tf, temp);
> + if (!seq)
> + continue;
> + if (gimple_seq_singleton_p (seq)
> + && gimple_code (gimple_seq_first_stmt (seq)) == GIMPLE_GOTO)
> + {
> + TREE_VALUE (elt)
> + = gimple_goto_dest (gimple_seq_first_stmt (seq));
> + continue;
> + }
> +
> + if (bypass_label == NULL_TREE)
> + {
> + bypass_label = create_artificial_label (loc);
> + gsi_insert_after (gsi, gimple_build_goto (bypass_label),
> + GSI_CONTINUE_LINKING);
> + }
> +
> + tree label = create_artificial_label (loc);
> + TREE_VALUE (elt) = label;
> + gsi_insert_after (gsi, gimple_build_label (label),
> + GSI_CONTINUE_LINKING);
> + gsi_insert_seq_after (gsi, gimple_seq_copy (seq),
> + GSI_CONTINUE_LINKING);
> + }
> + if (bypass_label)
> + gsi_insert_after (gsi, gimple_build_label (bypass_label),
> + GSI_CONTINUE_LINKING);
> + }
> + break;
> +
> case GIMPLE_COND:
> replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 2), tf, gsi);
> replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 3), tf, gsi);
> @@ -685,12 +727,28 @@ maybe_record_in_goto_queue (struct leh_s
> EXPR_LOCATION (*new_stmt.tp));
> }
> break;
> +
> case GIMPLE_GOTO:
> new_stmt.g = stmt;
> record_in_goto_queue_label (tf, new_stmt, gimple_goto_dest (stmt),
> gimple_location (stmt));
> break;
>
> + case GIMPLE_ASM:
> + if (int n = gimple_asm_nlabels (as_a <gasm *> (stmt)))
> + {
> + new_stmt.g = stmt;
> + gasm *asm_stmt = as_a <gasm *> (stmt);
> + for (int i = 0; i < n; ++i)
> + {
> + tree elt = gimple_asm_label_op (asm_stmt, i);
> + new_stmt.tp = &TREE_VALUE (elt);
> + record_in_goto_queue_label (tf, new_stmt, TREE_VALUE (elt),
> + gimple_location (stmt));
> + }
> + }
> + break;
> +
> case GIMPLE_RETURN:
> tf->may_return = true;
> new_stmt.g = stmt;
> @@ -2082,6 +2140,7 @@ lower_eh_constructs_2 (struct leh_state
> case GIMPLE_COND:
> case GIMPLE_GOTO:
> case GIMPLE_RETURN:
> + case GIMPLE_ASM:
> maybe_record_in_goto_queue (state, stmt);
> break;
>
> --- gcc/testsuite/gcc.dg/torture/pr122835.c.jj 2025-11-25
> 17:26:19.533199921 +0100
> +++ gcc/testsuite/gcc.dg/torture/pr122835.c 2025-11-25 19:11:01.639094677
> +0100
> @@ -0,0 +1,79 @@
> +/* PR middle-end/122835 */
> +/* { dg-do run { target i?86-*-* x86_64-*-* aarch64-*-* arm*-*-*
> powerpc*-*-* s390*-*-* } } */
> +
> +#if defined(__x86_64__) || defined(__i386__)
> +#define JMP "jmp"
> +#elif defined(__aarch64__) || defined(__arm__) || defined(__powerpc__)
> +#define JMP "b"
> +#elif defined(__s390__)
> +#define JMP "j"
> +#endif
> +
> +int cnt;
> +
> +static void
> +my_cleanup (int *p)
> +{
> + ++cnt;
> +}
> +
> +__attribute__((noipa)) static void
> +my_abort (void)
> +{
> + __builtin_abort ();
> +}
> +
> +int
> +main ()
> +{
> + {
> + int x __attribute__((cleanup (my_cleanup))) = 0;
> +
> + asm goto (JMP "\t%l0" :::: l1);
> +
> + my_abort ();
> + }
> +
> +l1:
> + if (cnt != 1)
> + __builtin_abort ();
> +
> + {
> + int x __attribute__((cleanup (my_cleanup))) = 0;
> +
> + {
> + int y __attribute__((cleanup (my_cleanup))) = 0;
> +
> + asm goto (JMP "\t%l1" :::: l2, l3);
> +
> + my_abort ();
> + }
> +l2:
> + __builtin_abort ();
> + }
> +l3:
> + if (cnt != 3)
> + __builtin_abort ();
> +
> + {
> + int x __attribute__((cleanup (my_cleanup))) = 0;
> +
> + {
> + int y __attribute__((cleanup (my_cleanup))) = 0;
> +
> + asm goto (JMP "\t%l0" :::: l4, l5);
> +
> + my_abort ();
> + }
> +l4:
> + if (cnt != 4)
> + __builtin_abort ();
> + }
> + if (0)
> + {
> +l5:
> + __builtin_abort ();
> + }
> + if (cnt != 5)
> + __builtin_abort ();
> +}
>
>
> 2025-11-25 Jakub Jelinek <[email protected]>
>
> PR middle-end/122835
> * tree-eh.cc (replace_goto_queue_1): Handle GIMPLE_ASM.
> (maybe_record_in_goto_queue): Likewise.
> (lower_eh_constructs_2): Likewise.
>
> * gcc.dg/torture/pr122835.c: New test.
>
> --- gcc/tree-eh.cc.jj 2025-09-04 18:51:34.130709784 +0200
> +++ gcc/tree-eh.cc 2025-11-25 17:13:37.724534641 +0100
> @@ -517,6 +517,48 @@ replace_goto_queue_1 (gimple *stmt, stru
> }
> break;
>
> + case GIMPLE_ASM:
> + if (int n = gimple_asm_nlabels (as_a <gasm *> (stmt)))
> + {
> + temp.g = stmt;
> + gasm *asm_stmt = as_a <gasm *> (stmt);
> + location_t loc = gimple_location (stmt);
> + tree bypass_label = NULL_TREE;
> + for (int i = 0; i < n; ++i)
> + {
> + tree elt = gimple_asm_label_op (asm_stmt, i);
> + temp.tp = &TREE_VALUE (elt);
> + seq = find_goto_replacement (tf, temp);
> + if (!seq)
> + continue;
> + if (gimple_seq_singleton_p (seq)
> + && gimple_code (gimple_seq_first_stmt (seq)) == GIMPLE_GOTO)
> + {
> + TREE_VALUE (elt)
> + = gimple_goto_dest (gimple_seq_first_stmt (seq));
> + continue;
> + }
> +
> + if (bypass_label == NULL_TREE)
> + {
> + bypass_label = create_artificial_label (loc);
> + gsi_insert_after (gsi, gimple_build_goto (bypass_label),
> + GSI_CONTINUE_LINKING);
> + }
> +
> + tree label = create_artificial_label (loc);
> + TREE_VALUE (elt) = label;
> + gsi_insert_after (gsi, gimple_build_label (label),
> + GSI_CONTINUE_LINKING);
> + gsi_insert_seq_after (gsi, gimple_seq_copy (seq),
> + GSI_CONTINUE_LINKING);
> + }
> + if (bypass_label)
> + gsi_insert_after (gsi, gimple_build_label (bypass_label),
> + GSI_CONTINUE_LINKING);
> + }
> + break;
> +
> case GIMPLE_COND:
> replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 2), tf, gsi);
> replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 3), tf, gsi);
> @@ -685,12 +727,28 @@ maybe_record_in_goto_queue (struct leh_s
> EXPR_LOCATION (*new_stmt.tp));
> }
> break;
> +
> case GIMPLE_GOTO:
> new_stmt.g = stmt;
> record_in_goto_queue_label (tf, new_stmt, gimple_goto_dest (stmt),
> gimple_location (stmt));
> break;
>
> + case GIMPLE_ASM:
> + if (int n = gimple_asm_nlabels (as_a <gasm *> (stmt)))
> + {
> + new_stmt.g = stmt;
> + gasm *asm_stmt = as_a <gasm *> (stmt);
> + for (int i = 0; i < n; ++i)
> + {
> + tree elt = gimple_asm_label_op (asm_stmt, i);
> + new_stmt.tp = &TREE_VALUE (elt);
> + record_in_goto_queue_label (tf, new_stmt, TREE_VALUE (elt),
> + gimple_location (stmt));
> + }
> + }
> + break;
> +
> case GIMPLE_RETURN:
> tf->may_return = true;
> new_stmt.g = stmt;
> @@ -2082,6 +2140,7 @@ lower_eh_constructs_2 (struct leh_state
> case GIMPLE_COND:
> case GIMPLE_GOTO:
> case GIMPLE_RETURN:
> + case GIMPLE_ASM:
> maybe_record_in_goto_queue (state, stmt);
> break;
>
> --- gcc/testsuite/gcc.dg/torture/pr122835.c.jj 2025-11-25
> 17:26:19.533199921 +0100
> +++ gcc/testsuite/gcc.dg/torture/pr122835.c 2025-11-25 19:11:01.639094677
> +0100
> @@ -0,0 +1,79 @@
> +/* PR middle-end/122835 */
> +/* { dg-do run { target i?86-*-* x86_64-*-* aarch64-*-* arm*-*-*
> powerpc*-*-* s390*-*-* } } */
> +
> +#if defined(__x86_64__) || defined(__i386__)
> +#define JMP "jmp"
> +#elif defined(__aarch64__) || defined(__arm__) || defined(__powerpc__)
> +#define JMP "b"
> +#elif defined(__s390__)
> +#define JMP "j"
> +#endif
> +
> +int cnt;
> +
> +static void
> +my_cleanup (int *p)
> +{
> + ++cnt;
> +}
> +
> +__attribute__((noipa)) static void
> +my_abort (void)
> +{
> + __builtin_abort ();
> +}
> +
> +int
> +main ()
> +{
> + {
> + int x __attribute__((cleanup (my_cleanup))) = 0;
> +
> + asm goto (JMP "\t%l0" :::: l1);
> +
> + my_abort ();
> + }
> +
> +l1:
> + if (cnt != 1)
> + __builtin_abort ();
> +
> + {
> + int x __attribute__((cleanup (my_cleanup))) = 0;
> +
> + {
> + int y __attribute__((cleanup (my_cleanup))) = 0;
> +
> + asm goto (JMP "\t%l1" :::: l2, l3);
> +
> + my_abort ();
> + }
> +l2:
> + __builtin_abort ();
> + }
> +l3:
> + if (cnt != 3)
> + __builtin_abort ();
> +
> + {
> + int x __attribute__((cleanup (my_cleanup))) = 0;
> +
> + {
> + int y __attribute__((cleanup (my_cleanup))) = 0;
> +
> + asm goto (JMP "\t%l0" :::: l4, l5);
> +
> + my_abort ();
> + }
> +l4:
> + if (cnt != 4)
> + __builtin_abort ();
> + }
> + if (0)
> + {
> +l5:
> + __builtin_abort ();
> + }
> + if (cnt != 5)
> + __builtin_abort ();
> +}
>
> Jakub
>
>
--
Richard Biener <[email protected]>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
