Hi,
I got a bit lost in this thread – but the
commit r11-2663-g82c4b78dbef6f03838e3040688c934360a09513f
"Replace std::vector<> usage in ipa-fnsummary.c with GCC's vec<>."
Causes here:
gcc-mainline/gcc/vec.h:1287:3: error: static assertion failed:
static_assert (alignof (vec_embedded) == alignof(vec), "");
^
for a '--build=i686-pc-linux-gnu --host=powerpc64le-linux-gnu
--target=nvptx-none'
build.
Tobias
On 8/7/20 8:04 PM, Aldy Hernandez via Gcc-patches wrote:
Is the attached patch what y'all suggest?
The patch reverts the GCC vec<> usage in ipa-fnsummary.c and
implements the above suggestion.
Bootstraps, tests running...
If tests pass, is this OK?
Thanks.
Aldy
On Fri, Aug 7, 2020 at 11:17 AM Jonathan Wakely via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
On 07/08/20 10:55 +0200, Jakub Jelinek wrote:
On Fri, Aug 07, 2020 at 09:34:38AM +0100, Jonathan Wakely via Gcc-patches wrote:
Now that you say it, vec has a T[1] member so depending on T
there might be a side-effect as invoking its CTOR? Or it might
even not compile if there is no default CTOR available... Ick :/
Right.
Does the GTY stuff add members to the struct, or otherwise alter its
layout?
Or perhaps use offsetof on an alternate structure that should have the same
layout.
Yes that's what I was going to suggest next.
So instead of
typedef vec<T, A, vl_embed> vec_embedded;
return offsetof (vec_embedded, m_vecdata) + alloc * sizeof (T);
use
struct alignas (T) U { char data[sizeof (T)]; };
typedef vec<U, A, vl_embed> vec_embedded;
static_assert(sizeof(vec_embedded) == sizeof(vec), "");
static_assert(alignof(vec_embedded) == alignof(vec), "");
return offsetof (vec_embedded, m_vecdata) + alloc * sizeof (T);
where vec_embedded should have the same offset of m_vecdata as vec.
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