except: Fix __builtin_eh_return_data_regno (-42) expansion [PR101195]
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Commit Message
Hi!
The expansion of this builtin emits an error if the argument is not
INTEGER_CST, otherwise uses tree_to_uhwi on the argument (which is declared
int) and then uses EH_RETURN_DATA_REGNO macro which on most targets returns
INVALID_REGNUM for all values but some small number (2 or 4); if it returns
INVALID_REGNUM, we silently expand to -1.
Now, I think the error for non-INTEGER_CST makes sense to catch when people
unintentionally don't call it with a constant (but, users shouldn't really
use this builtin anyway, it is for the unwinder only). Initially I thought
about emitting an error for the negative values as well on which
tree_to_uhwi otherwise ICEs, but given that the function will silently
expand to -1 for INT_MAX - 1 or INT_MAX - 3 other values, I think treating
the negatives the same silently is fine too.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2024-01-30 Jakub Jelinek <jakub@redhat.com>
PR middle-end/101195
* except.cc (expand_builtin_eh_return_data_regno): If which doesn't
fit into unsigned HOST_WIDE_INT, return constm1_rtx.
* gcc.dg/pr101195.c: New test.
Jakub
Comments
On Tue, 30 Jan 2024, Jakub Jelinek wrote:
> Hi!
>
> The expansion of this builtin emits an error if the argument is not
> INTEGER_CST, otherwise uses tree_to_uhwi on the argument (which is declared
> int) and then uses EH_RETURN_DATA_REGNO macro which on most targets returns
> INVALID_REGNUM for all values but some small number (2 or 4); if it returns
> INVALID_REGNUM, we silently expand to -1.
>
> Now, I think the error for non-INTEGER_CST makes sense to catch when people
> unintentionally don't call it with a constant (but, users shouldn't really
> use this builtin anyway, it is for the unwinder only). Initially I thought
> about emitting an error for the negative values as well on which
> tree_to_uhwi otherwise ICEs, but given that the function will silently
> expand to -1 for INT_MAX - 1 or INT_MAX - 3 other values, I think treating
> the negatives the same silently is fine too.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK
> 2024-01-30 Jakub Jelinek <jakub@redhat.com>
>
> PR middle-end/101195
> * except.cc (expand_builtin_eh_return_data_regno): If which doesn't
> fit into unsigned HOST_WIDE_INT, return constm1_rtx.
>
> * gcc.dg/pr101195.c: New test.
>
> --- gcc/except.cc.jj 2024-01-03 11:51:37.552647625 +0100
> +++ gcc/except.cc 2024-01-29 09:46:09.385299324 +0100
> @@ -2167,6 +2167,9 @@ expand_builtin_eh_return_data_regno (tre
> return constm1_rtx;
> }
>
> + if (!tree_fits_uhwi_p (which))
> + return constm1_rtx;
> +
> iwhich = tree_to_uhwi (which);
> iwhich = EH_RETURN_DATA_REGNO (iwhich);
> if (iwhich == INVALID_REGNUM)
> --- gcc/testsuite/gcc.dg/pr101195.c.jj 2024-01-29 09:48:15.969510457 +0100
> +++ gcc/testsuite/gcc.dg/pr101195.c 2024-01-29 09:48:08.626614220 +0100
> @@ -0,0 +1,8 @@
> +/* PR middle-end/101195 */
> +/* { dg-do compile } */
> +
> +int
> +foo (void)
> +{
> + return __builtin_eh_return_data_regno (-42);
> +}
>
> Jakub
>
>
@@ -2167,6 +2167,9 @@ expand_builtin_eh_return_data_regno (tre
return constm1_rtx;
}
+ if (!tree_fits_uhwi_p (which))
+ return constm1_rtx;
+
iwhich = tree_to_uhwi (which);
iwhich = EH_RETURN_DATA_REGNO (iwhich);
if (iwhich == INVALID_REGNUM)
@@ -0,0 +1,8 @@
+/* PR middle-end/101195 */
+/* { dg-do compile } */
+
+int
+foo (void)
+{
+ return __builtin_eh_return_data_regno (-42);
+}