On Tue, Aug 27, 2019 at 9:01 AM Richard Sandiford
<richard.sandif...@arm.com> wrote:
>
> Ilya Leoshkevich <i...@linux.ibm.com> writes:
> >> 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);
>
> Might as well remove this comment while you're there. RTX_HDR_SIZE
> has long ceased to be sizeof (int) for any host.
>
> > 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.
>
> Sounds good to me, but rtx_init should probably be an inline function.
Sounds good to me, too.
Richard.
> Thanks,
> Richard
