> Am 03.08.2024 um 20:14 schrieb Jakub Jelinek <ja...@redhat.com>:
>
> Hi!
>
> I've noticed the following testcase on top of the #embed patchset:
> https://gcc.gnu.org/pipermail/gcc-patches/2024-June/655012.html
>
>
> https://gcc.gnu.org/pipermail/gcc-patches/2024-June/655013.html
>
>
> https://gcc.gnu.org/pipermail/gcc-patches/2024-July/657049.html
>
>
> https://gcc.gnu.org/pipermail/gcc-patches/2024-July/657053.html
> https://gcc.gnu.org/pipermail/gcc-patches/2024-July/658137.html
> hangs during gimplification.
>
> While it is gimplifying an assignment from a VAR_DECL .LCNNN to MEM_REF,
> because the VAR_DECL is TREE_READONLY, it will happily pick its initializer
> and try to gimplify that, which means recursing to the exact same code.
>
> The following patch fixes that by just gimplifying the lhs and building
> assignment, because the code decided that it should use copying from
> a static var.
>
> Bootstrapped/regtested on powerpc64{,le}-linux, ok for trunk?
Ok
Richard
> 2024-08-03 Jakub Jelinek <ja...@redhat.com>
>
> * gimplify.cc (gimplify_init_ctor_eval): For larger RAW_DATA_CST,
> just gimplify cref as lvalue and add gimple assignment of rctor
> to cref instead of going through gimplification of INIT_EXPR, as
> the latter can suffer from infinite recursion.
>
> * c-c++-common/cpp/embed-24.c: New test.
>
> --- gcc/gimplify.cc.jj 2024-08-02 11:34:03.651027803 +0200
> +++ gcc/gimplify.cc 2024-08-03 10:19:47.071916653 +0200
> @@ -5400,9 +5400,10 @@ gimplify_init_ctor_eval (tree object, ve
> cref = build2 (MEM_REF, rtype, addr,
> build_int_cst (ptr_type_node, 0));
> rctor = tree_output_constant_def (rctor);
> - tree init = build2 (INIT_EXPR, rtype, cref, rctor);
> - gimplify_and_add (init, pre_p);
> - ggc_free (init);
> + if (gimplify_expr (&cref, pre_p, NULL, is_gimple_lvalue,
> + fb_lvalue) != GS_ERROR)
> + gimplify_seq_add_stmt (pre_p,
> + gimple_build_assign (cref, rctor));
> }
> }
> else
> --- gcc/testsuite/c-c++-common/cpp/embed-24.c.jj 2024-08-03
> 10:10:42.145076112 +0200
> +++ gcc/testsuite/c-c++-common/cpp/embed-24.c 2024-08-03
> 19:40:58.693297792 +0200
> @@ -0,0 +1,52 @@
> +/* { dg-do run } */
> +/* { dg-options "-O2" } */
> +/* { dg-additional-options "-std=c23" { target c } } */
> +
> +static unsigned char a[] = {
> +#embed __FILE__ limit (125)
> +};
> +
> +void
> +foo (unsigned char *p)
> +{
> + for (int i = 0; i < 128; ++i)
> + if (p[i] != ((i < 64 || i == 127) ? (unsigned char) -1 : i - 64 + 33))
> + __builtin_abort ();
> + if (__builtin_memcmp (p + 128, a, 125))
> + __builtin_abort ();
> + for (int i = 253; i < 256; ++i)
> + if (p[i] != (unsigned char) -1)
> + __builtin_abort ();
> +}
> +
> +#ifdef __cplusplus
> +#define M1 (unsigned char) -1
> +#else
> +#define M1 -1
> +#endif
> +
> +int
> +main ()
> +{
> + unsigned char res[256] = {
> + M1, M1, M1, M1, M1, M1, M1, M1,
> + M1, M1, M1, M1, M1, M1, M1, M1,
> + M1, M1, M1, M1, M1, M1, M1, M1,
> + M1, M1, M1, M1, M1, M1, M1, M1,
> + M1, M1, M1, M1, M1, M1, M1, M1,
> + M1, M1, M1, M1, M1, M1, M1, M1,
> + M1, M1, M1, M1, M1, M1, M1, M1,
> + M1, M1, M1, M1, M1, M1, M1, M1,
> + 33, 34, 35, 36, 37, 38, 39, 40,
> + 41, 42, 43, 44, 45, 46, 47, 48,
> + 49, 50, 51, 52, 53, 54, 55, 56,
> + 57, 58, 59, 60, 61, 62, 63, 64,
> + 65, 66, 67, 68, 69, 70, 71, 72,
> + 73, 74, 75, 76, 77, 78, 79, 80,
> + 81, 82, 83, 84, 85, 86, 87, 88,
> + 89, 90, 91, 92, 93, 94, 95, M1,
> + #embed __FILE__ limit (125) suffix (,)
> + M1, M1, M1
> + };
> + foo (res);
> +}
>
>
> Jakub
>
