On Thu, Mar 19, 2020 at 4:10 AM Richard Sandiford
<richard.sandif...@arm.com> wrote:
>
> In this PR we had a 512-bit VECTOR_TYPE whose mode is XImode
> (an integer mode used for four 128-bit vectors). When trying
> to expand a zero constant for it, we hit code in expand_expr_real_1
> that tries to use the associated integer type instead. The code used
> type_for_mode (XImode, 1) to get this integer type.
>
> However, the c-family implementation of type_for_mode checks for
> any registered built-in type that matches the mode and has the
> right signedness. This meant that it could return a built-in
> vector type when given an integer mode (particularly if, as here,
> the vector type isn't supported by the current subtarget and so
> TYPE_MODE != TYPE_MODE_RAW). The expand code would then cycle
> endlessly trying to use this "new" type instead of the original
> vector type.
>
> The search loop is probably too lax in other ways -- e.g. it could
> return records that just happen to have the right mode -- but this
> seems like a safe, incremental improvement.
>
> Tested on aarch64-linux-gnu and x86_64-linux-gnu. OK to install?
>
> Richard
>
>
> 2020-03-18 Richard Sandiford <richard.sandif...@arm.com>
>
> gcc/c-family/
> PR middle-end/94072
> * c-common.c (c_common_type_for_mode): Before using a registered
> built-in type, check that the vectorness of the type matches
> the vectorness of the mode.
>
> gcc/testsuite/
> PR middle-end/94072
> * gcc.target/aarch64/pr94072.c: New test.
> ---
> gcc/c-family/c-common.c | 11 +++++++----
> gcc/testsuite/gcc.target/aarch64/pr94072.c | 9 +++++++++
> 2 files changed, 16 insertions(+), 4 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/aarch64/pr94072.c
>
> diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
> index 25020bf1415..8e5a9243827 100644
> --- a/gcc/c-family/c-common.c
> +++ b/gcc/c-family/c-common.c
> @@ -2387,10 +2387,13 @@ c_common_type_for_mode (machine_mode mode, int
> unsignedp)
> }
>
> for (t = registered_builtin_types; t; t = TREE_CHAIN (t))
> - if (TYPE_MODE (TREE_VALUE (t)) == mode
> - && !!unsignedp == !!TYPE_UNSIGNED (TREE_VALUE (t)))
> - return TREE_VALUE (t);
> -
> + {
> + tree type = TREE_VALUE (t);
> + if (TYPE_MODE (type) == mode
> + && VECTOR_TYPE_P (type) == VECTOR_MODE_P (mode)
> + && !!unsignedp == !!TYPE_UNSIGNED (type))
> + return type;
> + }
> return NULL_TREE;
> }
>
> diff --git a/gcc/testsuite/gcc.target/aarch64/pr94072.c
> b/gcc/testsuite/gcc.target/aarch64/pr94072.c
> new file mode 100644
> index 00000000000..2aa72eb7a16
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/pr94072.c
> @@ -0,0 +1,9 @@
> +/* { dg-options "-msve-vector-bits=512" } */
> +
> +#pragma GCC target "+nosve"
> +
> +void
> +foo (void)
> +{
> + (int __attribute__ ((__vector_size__ (64)))){};
> +}
Shouldn't this test also be enabled for AVX512F?
--
H.J.
