> Am 26.08.2019 um 15:17 schrieb Ilya Leoshkevich <i...@linux.ibm.com>:
>
>> Am 26.08.2019 um 15:06 schrieb Richard Biener <richard.guent...@gmail.com>:
>>
>> On Mon, Aug 26, 2019 at 1:54 PM Ilya Leoshkevich <i...@linux.ibm.com> wrote:
>>>
>>>> Am 26.08.2019 um 10:49 schrieb Richard Biener <richard.guent...@gmail.com>:
>>>>
>>>> On Fri, Aug 23, 2019 at 1:35 PM Ilya Leoshkevich <i...@linux.ibm.com>
>>>> wrote:
>>>>>
>>>>>> Am 23.08.2019 um 13:24 schrieb Richard Biener
>>>>>> <richard.guent...@gmail.com>:
>>>>>>
>>>>>> On Fri, Aug 23, 2019 at 12:43 PM Richard Sandiford
>>>>>> <richard.sandif...@arm.com> wrote:
>>>>>>>
>>>>>>> Ilya Leoshkevich <i...@linux.ibm.com> writes:
>>>>>>>> @@ -3819,6 +3820,82 @@ can_compare_p (enum rtx_code code, machine_mode
>>>>>>>> mode,
>>>>>>>> return 0;
>>>>>>>> }
>>>>>>>>
>>>>>>>> +/* can_vector_compare_p presents fake rtx binary operations to the
>>>>>>>> the back-end
>>>>>>>> + in order to determine its capabilities. In order to avoid
>>>>>>>> creating fake
>>>>>>>> + operations on each call, values from previous calls are cached in
>>>>>>>> a global
>>>>>>>> + cached_binops hash_table. It contains rtxes, which can be looked
>>>>>>>> up using
>>>>>>>> + binop_keys. */
>>>>>>>> +
>>>>>>>> +struct binop_key {
>>>>>>>> + enum rtx_code code; /* Operation code. */
>>>>>>>> + machine_mode value_mode; /* Result mode. */
>>>>>>>> + machine_mode cmp_op_mode; /* Operand mode. */
>>>>>>>> +};
>>>>>>>> +
>>>>>>>> +struct binop_hasher : pointer_hash_mark<rtx>, ggc_cache_remove<rtx> {
>>>>>>>> + typedef rtx value_type;
>>>>>>>> + typedef binop_key compare_type;
>>>>>>>> +
>>>>>>>> + static hashval_t
>>>>>>>> + hash (enum rtx_code code, machine_mode value_mode, machine_mode
>>>>>>>> cmp_op_mode)
>>>>>>>> + {
>>>>>>>> + inchash::hash hstate (0);
>>>>>>>> + hstate.add_int (code);
>>>>>>>> + hstate.add_int (value_mode);
>>>>>>>> + hstate.add_int (cmp_op_mode);
>>>>>>>> + return hstate.end ();
>>>>>>>> + }
>>>>>>>> +
>>>>>>>> + static hashval_t
>>>>>>>> + hash (const rtx &ref)
>>>>>>>> + {
>>>>>>>> + return hash (GET_CODE (ref), GET_MODE (ref), GET_MODE (XEXP (ref,
>>>>>>>> 0)));
>>>>>>>> + }
>>>>>>>> +
>>>>>>>> + static bool
>>>>>>>> + equal (const rtx &ref1, const binop_key &ref2)
>>>>>>>> + {
>>>>>>>> + return (GET_CODE (ref1) == ref2.code)
>>>>>>>> + && (GET_MODE (ref1) == ref2.value_mode)
>>>>>>>> + && (GET_MODE (XEXP (ref1, 0)) == ref2.cmp_op_mode);
>>>>>>>> + }
>>>>>>>> +};
>>>>>>>> +
>>>>>>>> +static GTY ((cache)) hash_table<binop_hasher> *cached_binops;
>>>>>>>> +
>>>>>>>> +static rtx
>>>>>>>> +get_cached_binop (enum rtx_code code, machine_mode value_mode,
>>>>>>>> + machine_mode cmp_op_mode)
>>>>>>>> +{
>>>>>>>> + if (!cached_binops)
>>>>>>>> + cached_binops = hash_table<binop_hasher>::create_ggc (1024);
>>>>>>>> + binop_key key = { code, value_mode, cmp_op_mode };
>>>>>>>> + hashval_t hash = binop_hasher::hash (code, value_mode, cmp_op_mode);
>>>>>>>> + rtx *slot = cached_binops->find_slot_with_hash (key, hash, INSERT);
>>>>>>>> + if (!*slot)
>>>>>>>> + *slot = gen_rtx_fmt_ee (code, value_mode, gen_reg_rtx
>>>>>>>> (cmp_op_mode),
>>>>>>>> + gen_reg_rtx (cmp_op_mode));
>>>>>>>> + return *slot;
>>>>>>>> +}
>>>>>>>
>>>>>>> Sorry, I didn't mean anything this complicated. I just meant that
>>>>>>> we should have a single cached rtx that we can change via PUT_CODE and
>>>>>>> PUT_MODE_RAW for each new query, rather than allocating a new rtx each
>>>>>>> time.
>>>>>>>
>>>>>>> Something like:
>>>>>>>
>>>>>>> static GTY ((cache)) rtx cached_binop;
>>>>>>>
>>>>>>> rtx
>>>>>>> get_cached_binop (machine_mode mode, rtx_code code, machine_mode
>>>>>>> op_mode)
>>>>>>> {
>>>>>>> if (cached_binop)
>>>>>>> {
>>>>>>> PUT_CODE (cached_binop, code);
>>>>>>> PUT_MODE_RAW (cached_binop, mode);
>>>>>>> PUT_MODE_RAW (XEXP (cached_binop, 0), op_mode);
>>>>>>> PUT_MODE_RAW (XEXP (cached_binop, 1), op_mode);
>>>>>>> }
>>>>>>> else
>>>>>>> {
>>>>>>> rtx reg1 = gen_raw_REG (op_mode, LAST_VIRTUAL_REGISTER + 1);
>>>>>>> rtx reg2 = gen_raw_REG (op_mode, LAST_VIRTUAL_REGISTER + 2);
>>>>>>> cached_binop = gen_rtx_fmt_ee (code, mode, reg1, reg2);
>>>>>>> }
>>>>>>> return cached_binop;
>>>>>>> }
>>>>>>
>>>>>> Hmm, maybe we need auto_rtx (code) that constructs such
>>>>>> RTX on the stack instead of wasting a GC root (and causing
>>>>>> issues for future threading of GCC ;)).
>>>>>
>>>>> Do you mean something like this?
>>>>>
>>>>> union {
>>>>> char raw[rtx_code_size[code]];
>>>>> rtx rtx;
>>>>> } binop;
>>>>>
>>>>> Does this exist already (git grep auto.*rtx / rtx.*auto doesn't show
>>>>> anything useful), or should I implement this?
>>>>
>>>> It doesn't exist AFAIK, I thought about using alloca like
>>>>
>>>> rtx tem;
>>>> rtx_alloca (tem, PLUS);
>>>>
>>>> and due to using alloca rtx_alloca has to be a macro like
>>>>
>>>> #define rtx_alloca(r, code) r = (rtx)alloca (RTX_CODE_SIZE(code));
>>>> memset (r, 0, RTX_HDR_SIZE); PUT_CODE (r, code);
>>>>
>>>> maybe C++ can help making this prettier but of course
>>>> since we use alloca we have to avoid opening new scopes.
>>>>
>>>> I guess templates like with auto_vec doesn't work unless
>>>> we can make RTX_CODE_SIZE constant-evaluated.
>>>>
>>>> Richard.
>>>
>>> I ended up with the following change:
>>>
>>> diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
>>> index a667cdab94e..97aa2144e95 100644
>>> --- a/gcc/emit-rtl.c
>>> +++ b/gcc/emit-rtl.c
>>> @@ -466,17 +466,25 @@ set_mode_and_regno (rtx x, machine_mode mode,
>>> unsigned int regno)
>>> set_regno_raw (x, regno, nregs);
>>> }
>>>
>>> -/* Generate a new REG rtx. Make sure ORIGINAL_REGNO is set properly, and
>>> +/* Initialize a REG rtx. Make sure ORIGINAL_REGNO is set properly, and
>>> don't attempt to share with the various global pieces of rtl (such as
>>> frame_pointer_rtx). */
>>>
>>> -rtx
>>> -gen_raw_REG (machine_mode mode, unsigned int regno)
>>> +void
>>> +init_raw_REG (rtx x, machine_mode mode, unsigned int regno)
>>> {
>>> - rtx x = rtx_alloc (REG MEM_STAT_INFO);
>>> set_mode_and_regno (x, mode, regno);
>>> REG_ATTRS (x) = NULL;
>>> ORIGINAL_REGNO (x) = regno;
>>> +}
>>> +
>>> +/* Generate a new REG rtx. */
>>> +
>>> +rtx
>>> +gen_raw_REG (machine_mode mode, unsigned int regno)
>>> +{
>>> + rtx x = rtx_alloc (REG MEM_STAT_INFO);
>>> + init_raw_REG (x, mode, regno);
>>> return x;
>>> }
>>>
>>> diff --git a/gcc/gengenrtl.c b/gcc/gengenrtl.c
>>> index 5c78fabfb50..bb2087da258 100644
>>> --- a/gcc/gengenrtl.c
>>> +++ b/gcc/gengenrtl.c
>>> @@ -231,8 +231,7 @@ genmacro (int idx)
>>> puts (")");
>>> }
>>>
>>> -/* Generate the code for the function to generate RTL whose
>>> - format is FORMAT. */
>>> +/* Generate the code for functions to generate RTL whose format is FORMAT.
>>> */
>>>
>>> static void
>>> gendef (const char *format)
>>> @@ -240,22 +239,18 @@ gendef (const char *format)
>>> const char *p;
>>> int i, j;
>>>
>>> - /* Start by writing the definition of the function name and the types
>>> + /* Write the definition of the init function name and the types
>>> of the arguments. */
>>>
>>> - printf ("static inline rtx\ngen_rtx_fmt_%s_stat (RTX_CODE code,
>>> machine_mode mode", format);
>>> + puts ("static inline void");
>>> + printf ("init_rtx_fmt_%s (rtx rt, machine_mode mode", format);
>>> for (p = format, i = 0; *p != 0; p++)
>>> if (*p != '0')
>>> printf (",\n\t%sarg%d", type_from_format (*p), i++);
>>> + puts (")");
>>>
>>> - puts (" MEM_STAT_DECL)");
>>> -
>>> - /* Now write out the body of the function itself, which allocates
>>> - the memory and initializes it. */
>>> + /* Now write out the body of the init function itself. */
>>> puts ("{");
>>> - puts (" rtx rt;");
>>> - puts (" rt = rtx_alloc (code PASS_MEM_STAT);\n");
>>> -
>>> puts (" PUT_MODE_RAW (rt, mode);");
>>>
>>> for (p = format, i = j = 0; *p ; ++p, ++i)
>>> @@ -266,16 +261,56 @@ gendef (const char *format)
>>> else
>>> printf (" %s (rt, %d) = arg%d;\n", accessor_from_format (*p), i, j++);
>>>
>>> - puts ("\n return rt;\n}\n");
>>> + puts ("}\n");
>>> +
>>> + /* Write the definition of the gen function name and the types
>>> + of the arguments. */
>>> +
>>> + puts ("static inline rtx");
>>> + printf ("gen_rtx_fmt_%s_stat (RTX_CODE code, machine_mode mode", format);
>>> + for (p = format, i = 0; *p != 0; p++)
>>> + if (*p != '0')
>>> + printf (",\n\t%sarg%d", type_from_format (*p), i++);
>>> + puts (" MEM_STAT_DECL)");
>>> +
>>> + /* Now write out the body of the function itself, which allocates
>>> + the memory and initializes it. */
>>> + puts ("{");
>>> + puts (" rtx rt;\n");
>>> +
>>> + puts (" rt = rtx_alloc (code PASS_MEM_STAT);");
>>> + printf (" init_rtx_fmt_%s (rt, mode", format);
>>> + for (p = format, i = 0; *p != 0; p++)
>>> + if (*p != '0')
>>> + printf (", arg%d", i++);
>>> + puts (");\n");
>>> +
>>> + puts (" return rt;\n}\n");
>>> +
>>> + /* Write the definition of gen macro. */
>>> +
>>> printf ("#define gen_rtx_fmt_%s(c, m", format);
>>> for (p = format, i = 0; *p != 0; p++)
>>> if (*p != '0')
>>> - printf (", p%i",i++);
>>> - printf (")\\\n gen_rtx_fmt_%s_stat (c, m", format);
>>> + printf (", arg%d", i++);
>>> + printf (") \\\n gen_rtx_fmt_%s_stat ((c), (m)", format);
>>> for (p = format, i = 0; *p != 0; p++)
>>> if (*p != '0')
>>> - printf (", p%i",i++);
>>> + printf (", (arg%d)", i++);
>>> printf (" MEM_STAT_INFO)\n\n");
>>> +
>>> + /* Write the definition of alloca macro. */
>>> +
>>> + printf ("#define alloca_rtx_fmt_%s(rt, c, m", format);
>>> + for (p = format, i = 0; *p != 0; p++)
>>> + if (*p != '0')
>>> + printf (", arg%d", i++);
>>> + printf (") \\\n rtx_alloca ((rt), (c)); \\\n");
>>> + printf (" init_rtx_fmt_%s ((rt), (m)", format);
>>> + for (p = format, i = 0; *p != 0; p++)
>>> + if (*p != '0')
>>> + printf (", (arg%d)", i++);
>>> + printf (")\n\n");
>>> }
>>>
>>> /* Generate the documentation header for files we write. */
>>> diff --git a/gcc/rtl.h b/gcc/rtl.h
>>> index efb9b3ce40d..44733d8a39e 100644
>>> --- a/gcc/rtl.h
>>> +++ b/gcc/rtl.h
>>> @@ -2933,6 +2933,10 @@ extern HOST_WIDE_INT get_stack_check_protect (void);
>>>
>>> /* In rtl.c */
>>> extern rtx rtx_alloc (RTX_CODE CXX_MEM_STAT_INFO);
>>> +#define rtx_alloca(rt, code) \
>>> + (rt) = (rtx) alloca (RTX_CODE_SIZE ((code))); \
>>> + memset ((rt), 0, RTX_HDR_SIZE); \
>>> + PUT_CODE ((rt), (code));
>>> extern rtx rtx_alloc_stat_v (RTX_CODE MEM_STAT_DECL, int);
>>> #define rtx_alloc_v(c, SZ) rtx_alloc_stat_v (c MEM_STAT_INFO, SZ)
>>> #define const_wide_int_alloc(NWORDS) \
>>> @@ -3797,7 +3801,11 @@ gen_rtx_INSN (machine_mode mode, rtx_insn
>>> *prev_insn, rtx_insn *next_insn,
>>> extern rtx gen_rtx_CONST_INT (machine_mode, HOST_WIDE_INT);
>>> extern rtx gen_rtx_CONST_VECTOR (machine_mode, rtvec);
>>> extern void set_mode_and_regno (rtx, machine_mode, unsigned int);
>>> +extern void init_raw_REG (rtx, machine_mode, unsigned int);
>>> extern rtx gen_raw_REG (machine_mode, unsigned int);
>>> +#define alloca_raw_REG(rt, mode, regno) \
>>> + rtx_alloca ((rt), REG); \
>>> + init_raw_REG ((rt), (mode), (regno))
>>> extern rtx gen_rtx_REG (machine_mode, unsigned int);
>>> extern rtx gen_rtx_SUBREG (machine_mode, rtx, poly_uint64);
>>> extern rtx gen_rtx_MEM (machine_mode, rtx);
>>>
>>> which now allows me to write:
>>>
>>> rtx reg1, reg2, test;
>>> alloca_raw_REG (reg1, cmp_op_mode, LAST_VIRTUAL_REGISTER + 1);
>>> alloca_raw_REG (reg2, cmp_op_mode, LAST_VIRTUAL_REGISTER + 2);
>>> alloca_rtx_fmt_ee (test, code, value_mode, reg1, reg2);
>>>
>>> If that looks ok, I'll resend the series.
>>
>> that looks OK to me - please leave Richard S. time to comment. Also while
>> I'd like to see
>>
>> rtx reg1 = alloca_raw_REG (cmp_op_mode, LAST_VIRTUAL_REGISTER + 1);
>>
>> I don't really see a way to write that portably (or at all), do you all
>> agree?
>> GCC doesn't seem to convert alloca() calls to __builtin_stack_save/restore
>> nor place CLOBBERs to end their lifetime. But is it guaranteed that the
>> alloca result is valid until frame termination?
>
> Hmm, the alloca man page says:
>
> The alloca() function allocates size bytes of space in the stack
> frame of the caller. This temporary space is automatically freed
> when the function that called alloca() returns to its caller.
> ...
> The space allocated by alloca() is not automatically deallocated if
> the pointer that refers to it simply goes out of scope.
>
> A quick experiment with gcc and clang confirms this. I think this means
> I can make alloca_raw_REG macro return the allocated pointer using the
> return-from-block GNU extension.
What do you think about the following approach?
extern rtx rtx_init (rtx, RTX_CODE);
#define rtx_alloca(code) \
rtx_init ((rtx) alloca (RTX_CODE_SIZE ((code))), (code))
...
rtx
rtx_init (rtx rt, RTX_CODE code)
{
/* We want to clear everything up to the FLD array. Normally, this
is one int, but we don't want to assume that and it isn't very
portable anyway; this is. */
memset (rt, 0, RTX_HDR_SIZE);
PUT_CODE (rt, code);
return rt;
}
with similar changes to alloca_raw_REG and gengenrtl. This way we don't
even need a GNU extension.
