Hi, I tried both the following patches:
Patch1:
[opc@qinzhao-ol8u3-x86 gcc]$ git diff
diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
index 0cba95411a6..ca49d2b4514 100644
--- a/gcc/internal-fn.c
+++ b/gcc/internal-fn.c
@@ -3073,12 +3073,14 @@ expand_DEFERRED_INIT (internal_fn, gcall *stmt)
/* If this variable is in a register use expand_assignment.
For boolean scalars force zero-init. */
tree init;
+ scalar_int_mode var_mode;
if (TREE_CODE (TREE_TYPE (lhs)) != BOOLEAN_TYPE
&& tree_fits_uhwi_p (var_size)
&& (init_type == AUTO_INIT_PATTERN
|| !is_gimple_reg_type (var_type))
&& int_mode_for_size (tree_to_uhwi (var_size) * BITS_PER_UNIT,
- 0).exists ())
+ 0).exists (&var_mode)
+ && targetm.scalar_mode_supported_p (var_mode))
{
unsigned HOST_WIDE_INT total_bytes = tree_to_uhwi (var_size);
unsigned char *buf = (unsigned char *) xmalloc (total_bytes);
AND
Patch2:
diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
index 0cba95411a6..7f129655926 100644
--- a/gcc/internal-fn.c
+++ b/gcc/internal-fn.c
@@ -3073,12 +3073,14 @@ expand_DEFERRED_INIT (internal_fn, gcall *stmt)
/* If this variable is in a register use expand_assignment.
For boolean scalars force zero-init. */
tree init;
+ scalar_int_mode var_mode;
if (TREE_CODE (TREE_TYPE (lhs)) != BOOLEAN_TYPE
&& tree_fits_uhwi_p (var_size)
&& (init_type == AUTO_INIT_PATTERN
|| !is_gimple_reg_type (var_type))
&& int_mode_for_size (tree_to_uhwi (var_size) * BITS_PER_UNIT,
- 0).exists ())
+ 0).exists (&var_mode)
+ && have_insn_for (SET, var_mode))
{
unsigned HOST_WIDE_INT total_bytes = tree_to_uhwi (var_size);
unsigned char *buf = (unsigned char *) xmalloc (total_bytes);
Have the same effect:
1. Resolved the ICE in gcc11;
2. For _Complex long double variables, both return FALSE, as a result, for
PATTERN initialization of _Complex long double variables, now they are
initialization with ZEROs instead of FEs.
Let me know you opinion on this, If the above 2 is okay, then I might pick the
above Patch 1 for the final patch to this issue.
Thanks.
Qing
> On Nov 8, 2021, at 2:41 AM, Richard Biener <richard.guent...@gmail.com> wrote:
>
> On Sat, Nov 6, 2021 at 10:56 AM Jakub Jelinek <ja...@redhat.com> wrote:
>>
>> On Fri, Nov 05, 2021 at 05:37:25PM +0000, Qing Zhao wrote:
>>>> On Nov 5, 2021, at 11:17 AM, Jakub Jelinek <ja...@redhat.com> wrote:
>>>>
>>>> On Fri, Nov 05, 2021 at 04:11:36PM +0000, Qing Zhao wrote:
>>>>> 3076 if (TREE_CODE (TREE_TYPE (lhs)) != BOOLEAN_TYPE
>>>>> 3077 && tree_fits_uhwi_p (var_size)
>>>>> 3078 && (init_type == AUTO_INIT_PATTERN
>>>>> 3079 || !is_gimple_reg_type (var_type))
>>>>> 3080 && int_mode_for_size (tree_to_uhwi (var_size) *
>>>>> BITS_PER_UNIT,
>>>>> 3081 0).exists ())
>>>>> 3082 {
>>>>> 3083 unsigned HOST_WIDE_INT total_bytes = tree_to_uhwi
>>>>> (var_size);
>>>>> 3084 unsigned char *buf = (unsigned char *) xmalloc
>>>>> (total_bytes);
>>>>> 3085 memset (buf, (init_type == AUTO_INIT_PATTERN
>>>>> 3086 ? INIT_PATTERN_VALUE : 0), total_bytes);
>>>>> 3087 tree itype = build_nonstandard_integer_type
>>>>> 3088 (total_bytes * BITS_PER_UNIT, 1);
>>>>>
>>>>> The exact failing point is at function
>>>>> “set_min_and_max_values_for_integral_type”:
>>>>>
>>>>> 2851 gcc_assert (precision <= WIDE_INT_MAX_PRECISION);
>>>>>
>>>>> For _Complex long double, “precision” is 256.
>>>>> In GCC11, “WIDE_INT_MAX_PRECISION” is 192, in GCC12, it’s 512.
>>>>> As a result, the above assertion failed on GCC11.
>>>>>
>>>>> I am wondering what’s the best fix for this issue in gcc11?
>>>>
>>>> Even for gcc 12 the above is wrong, you can't blindly assume that
>>>> build_nonstandard_integer_type will work for arbitrary precisions,
>>>> and even if it works that it will actually work.
>>>> The fact that such a mode exist is one thing, but
>>>> targetm.scalar_mode_supported_p should be tested for whether the mode
>>>> is actually supported.
>>>
>>> You mean “int_mode_for_size().exists()” is not enough to make sure
>>> “build_nonstandard_integer_type” to be valid? We should add
>>> “targetm.scalar_mode_supported_p” too ?
>>
>> Yeah. The former says whether the backend has that mode at all.
>> But some modes may be there only in some specific patterns but
>> without support for mov, add, etc. Only for
>> targetm.scalar_mode_supported_p modes the backend guarantees that
>> one can use them e.g. in mode attribute and can expect expansion
>> to expand everything with that mode that is needed in some way.
>> E.g. only if targetm.scalar_mode_supported_p (TImode) the FEs
>> support __int128_t type, etc.
>
> The memcpy folding code now checks
>
> scalar_int_mode mode;
> if (int_mode_for_size (ilen * 8, 0).exists (&mode)
> && GET_MODE_SIZE (mode) * BITS_PER_UNIT == ilen * 8
> && have_insn_for (SET, mode)
>
> thus specifically only have_insn_for (SET, mode), which I guess is
> good enough for this case as well?
>
>> Jakub
