ping
On Tue, Mar 16, 2021 at 06:13:21PM +0100, Stefan Schulze Frielinghaus wrote:
> [snip]
>
> Please find attached a new version of the patch. A major change compared to
> the previous patch is that I created a separate pass which hopefully makes
> reviewing also easier since it is almost self-contained. After realizing that
> detecting loops which mimic the behavior of rawmemchr/strlen functions does
> not
> really fit into the topic of loop distribution, I created a separate pass.
> Due
> to this I was also able to play around a bit and schedule the pass at
> different
> times. Currently it is scheduled right before loop distribution where loop
> header copying already took place which leads to the following effect.
> Running
> this setup over
>
> char *t (char *p)
> {
> for (; *p; ++p);
> return p;
> }
>
> the new pass transforms
>
> char * t (char * p)
> {
> char _1;
> char _7;
>
> <bb 2> [local count: 118111600]:
> _7 = *p_3(D);
> if (_7 != 0)
> goto <bb 5>; [89.00%]
> else
> goto <bb 7>; [11.00%]
>
> <bb 5> [local count: 105119324]:
>
> <bb 3> [local count: 955630225]:
> # p_8 = PHI <p_6(6), p_3(D)(5)>
> p_6 = p_8 + 1;
> _1 = *p_6;
> if (_1 != 0)
> goto <bb 6>; [89.00%]
> else
> goto <bb 8>; [11.00%]
>
> <bb 8> [local count: 105119324]:
> # p_2 = PHI <p_6(3)>
> goto <bb 4>; [100.00%]
>
> <bb 6> [local count: 850510901]:
> goto <bb 3>; [100.00%]
>
> <bb 7> [local count: 12992276]:
>
> <bb 4> [local count: 118111600]:
> # p_9 = PHI <p_2(8), p_3(D)(7)>
> return p_9;
>
> }
>
> into
>
> char * t (char * p)
> {
> char * _5;
> char _7;
>
> <bb 2> [local count: 118111600]:
> _7 = *p_3(D);
> if (_7 != 0)
> goto <bb 5>; [89.00%]
> else
> goto <bb 4>; [11.00%]
>
> <bb 5> [local count: 105119324]:
> _5 = p_3(D) + 1;
> p_10 = .RAWMEMCHR (_5, 0);
>
> <bb 4> [local count: 118111600]:
> # p_9 = PHI <p_10(5), p_3(D)(2)>
> return p_9;
>
> }
>
> which is fine so far. However, I haven't made up my mind so far whether it is
> worthwhile to spend more time in order to also eliminate the "first unrolling"
> of the loop. I gave it a shot by scheduling the pass prior pass copy header
> and ended up with:
>
> char * t (char * p)
> {
> <bb 2> [local count: 118111600]:
> p_5 = .RAWMEMCHR (p_3(D), 0);
> return p_5;
>
> }
>
> which seems optimal to me. The downside of this is that I have to initialize
> scalar evolution analysis which might be undesired that early.
>
> All this brings me to the question where do you see this peace of code
> running?
> If in a separate pass when would you schedule it? If in an existing pass,
> which one would you choose?
>
> Another topic which came up is whether there exists a more elegant solution to
> my current implementation in order to deal with stores (I'm speaking of the
> `if
> (store_dr)` statement inside of function transform_loop_1). For example,
>
> extern char *p;
> char *t ()
> {
> for (; *p; ++p);
> return p;
> }
>
> ends up as
>
> char * t ()
> {
> char * _1;
> char * _2;
> char _3;
> char * p.1_8;
> char _9;
> char * p.1_10;
> char * p.1_11;
>
> <bb 2> [local count: 118111600]:
> p.1_8 = p;
> _9 = *p.1_8;
> if (_9 != 0)
> goto <bb 5>; [89.00%]
> else
> goto <bb 7>; [11.00%]
>
> <bb 5> [local count: 105119324]:
>
> <bb 3> [local count: 955630225]:
> # p.1_10 = PHI <_1(6), p.1_8(5)>
> _1 = p.1_10 + 1;
> p = _1;
> _3 = *_1;
> if (_3 != 0)
> goto <bb 6>; [89.00%]
> else
> goto <bb 8>; [11.00%]
>
> <bb 8> [local count: 105119324]:
> # _2 = PHI <_1(3)>
> goto <bb 4>; [100.00%]
>
> <bb 6> [local count: 850510901]:
> goto <bb 3>; [100.00%]
>
> <bb 7> [local count: 12992276]:
>
> <bb 4> [local count: 118111600]:
> # p.1_11 = PHI <_2(8), p.1_8(7)>
> return p.1_11;
>
> }
>
> where inside the loop a load and store occurs. For a rawmemchr like loop I
> have to show that we never load from a memory location to which we write.
> Currently I solve this by hard coding those facts which are not generic at
> all.
> I gave compute_data_dependences_for_loop a try which failed to determine the
> fact that stores only happen to p[0] and loads from p[i] where i>0. Maybe
> there are more generic solutions to express this in contrast to my current
> one?
>
> Thanks again for your input so far. Really appreciated.
>
> Cheers,
> Stefan
> diff --git a/gcc/Makefile.in b/gcc/Makefile.in
> index 8a5fb3fd99c..7b2d7405277 100644
> --- a/gcc/Makefile.in
> +++ b/gcc/Makefile.in
> @@ -1608,6 +1608,7 @@ OBJS = \
> tree-into-ssa.o \
> tree-iterator.o \
> tree-loop-distribution.o \
> + tree-loop-pattern.o \
> tree-nested.o \
> tree-nrv.o \
> tree-object-size.o \
> diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
> index dd7173126fb..957e96a46a4 100644
> --- a/gcc/internal-fn.c
> +++ b/gcc/internal-fn.c
> @@ -2917,6 +2917,33 @@ expand_VEC_CONVERT (internal_fn, gcall *)
> gcc_unreachable ();
> }
>
> +void
> +expand_RAWMEMCHR (internal_fn, gcall *stmt)
> +{
> + expand_operand ops[3];
> +
> + tree lhs = gimple_call_lhs (stmt);
> + if (!lhs)
> + return;
> + tree lhs_type = TREE_TYPE (lhs);
> + rtx lhs_rtx = expand_expr (lhs, NULL_RTX, VOIDmode, EXPAND_WRITE);
> + create_output_operand (&ops[0], lhs_rtx, TYPE_MODE (lhs_type));
> +
> + for (unsigned int i = 0; i < 2; ++i)
> + {
> + tree rhs = gimple_call_arg (stmt, i);
> + tree rhs_type = TREE_TYPE (rhs);
> + rtx rhs_rtx = expand_normal (rhs);
> + create_input_operand (&ops[i + 1], rhs_rtx, TYPE_MODE (rhs_type));
> + }
> +
> + insn_code icode = direct_optab_handler (rawmemchr_optab, ops[2].mode);
> +
> + expand_insn (icode, 3, ops);
> + if (!rtx_equal_p (lhs_rtx, ops[0].value))
> + emit_move_insn (lhs_rtx, ops[0].value);
> +}
> +
> /* Expand the IFN_UNIQUE function according to its first argument. */
>
> static void
> diff --git a/gcc/internal-fn.def b/gcc/internal-fn.def
> index daeace7a34e..95c76795648 100644
> --- a/gcc/internal-fn.def
> +++ b/gcc/internal-fn.def
> @@ -348,6 +348,7 @@ DEF_INTERNAL_FN (MUL_OVERFLOW, ECF_CONST | ECF_LEAF |
> ECF_NOTHROW, NULL)
> DEF_INTERNAL_FN (TSAN_FUNC_EXIT, ECF_NOVOPS | ECF_LEAF | ECF_NOTHROW, NULL)
> DEF_INTERNAL_FN (VA_ARG, ECF_NOTHROW | ECF_LEAF, NULL)
> DEF_INTERNAL_FN (VEC_CONVERT, ECF_CONST | ECF_LEAF | ECF_NOTHROW, NULL)
> +DEF_INTERNAL_FN (RAWMEMCHR, ECF_PURE | ECF_LEAF | ECF_NOTHROW, NULL)
>
> /* An unduplicable, uncombinable function. Generally used to preserve
> a CFG property in the face of jump threading, tail merging or
> diff --git a/gcc/optabs.def b/gcc/optabs.def
> index b192a9d070b..f7c69f914ce 100644
> --- a/gcc/optabs.def
> +++ b/gcc/optabs.def
> @@ -267,6 +267,7 @@ OPTAB_D (cpymem_optab, "cpymem$a")
> OPTAB_D (movmem_optab, "movmem$a")
> OPTAB_D (setmem_optab, "setmem$a")
> OPTAB_D (strlen_optab, "strlen$a")
> +OPTAB_D (rawmemchr_optab, "rawmemchr$I$a")
>
> OPTAB_DC(fma_optab, "fma$a4", FMA)
> OPTAB_D (fms_optab, "fms$a4")
> diff --git a/gcc/passes.def b/gcc/passes.def
> index e9ed3c7bc57..280e8fc0cde 100644
> --- a/gcc/passes.def
> +++ b/gcc/passes.def
> @@ -274,6 +274,7 @@ along with GCC; see the file COPYING3. If not see
> empty loops. Remove them now. */
> NEXT_PASS (pass_cd_dce, false /* update_address_taken_p */);
> NEXT_PASS (pass_iv_canon);
> + NEXT_PASS (pass_lpat);
> NEXT_PASS (pass_loop_distribution);
> NEXT_PASS (pass_linterchange);
> NEXT_PASS (pass_copy_prop);
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/lpat-rawmemchr-1.c
> b/gcc/testsuite/gcc.dg/tree-ssa/lpat-rawmemchr-1.c
> new file mode 100644
> index 00000000000..b4133510fca
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/lpat-rawmemchr-1.c
> @@ -0,0 +1,72 @@
> +/* { dg-do run { target s390x-*-* } } */
> +/* { dg-options "-O2 -fdump-tree-lpat-details" } */
> +/* { dg-final { scan-tree-dump-times "generated rawmemchrqi" 2 "lpat" {
> target s390x-*-* } } } */
> +/* { dg-final { scan-tree-dump-times "generated rawmemchrhi" 2 "lpat" {
> target s390x-*-* } } } */
> +/* { dg-final { scan-tree-dump-times "generated rawmemchrsi" 2 "lpat" {
> target s390x-*-* } } } */
> +
> +/* Rawmemchr pattern: reduction stmt but no store */
> +
> +#include <stdint.h>
> +#include <assert.h>
> +
> +typedef __SIZE_TYPE__ size_t;
> +extern void* malloc (size_t);
> +extern void* memset (void*, int, size_t);
> +
> +#define test(T, pattern) \
> +__attribute__((noinline)) \
> +T *test_##T (T *p) \
> +{ \
> + while (*p != (T)pattern) \
> + ++p; \
> + return p; \
> +}
> +
> +test (uint8_t, 0xab)
> +test (uint16_t, 0xabcd)
> +test (uint32_t, 0xabcdef15)
> +
> +test (int8_t, 0xab)
> +test (int16_t, 0xabcd)
> +test (int32_t, 0xabcdef15)
> +
> +#define run(T, pattern, i) \
> +{ \
> +T *q = p; \
> +q[i] = (T)pattern; \
> +assert (test_##T (p) == &q[i]); \
> +q[i] = 0; \
> +}
> +
> +int main(void)
> +{
> + void *p = malloc (1024);
> + assert (p);
> + memset (p, 0, 1024);
> +
> + run (uint8_t, 0xab, 0);
> + run (uint8_t, 0xab, 1);
> + run (uint8_t, 0xab, 13);
> +
> + run (uint16_t, 0xabcd, 0);
> + run (uint16_t, 0xabcd, 1);
> + run (uint16_t, 0xabcd, 13);
> +
> + run (uint32_t, 0xabcdef15, 0);
> + run (uint32_t, 0xabcdef15, 1);
> + run (uint32_t, 0xabcdef15, 13);
> +
> + run (int8_t, 0xab, 0);
> + run (int8_t, 0xab, 1);
> + run (int8_t, 0xab, 13);
> +
> + run (int16_t, 0xabcd, 0);
> + run (int16_t, 0xabcd, 1);
> + run (int16_t, 0xabcd, 13);
> +
> + run (int32_t, 0xabcdef15, 0);
> + run (int32_t, 0xabcdef15, 1);
> + run (int32_t, 0xabcdef15, 13);
> +
> + return 0;
> +}
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/lpat-rawmemchr-2.c
> b/gcc/testsuite/gcc.dg/tree-ssa/lpat-rawmemchr-2.c
> new file mode 100644
> index 00000000000..9bebec11db0
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/lpat-rawmemchr-2.c
> @@ -0,0 +1,83 @@
> +/* { dg-do run { target s390x-*-* } } */
> +/* { dg-options "-O2 -fdump-tree-lpat-details" } */
> +/* { dg-final { scan-tree-dump-times "generated rawmemchrqi" 2 "lpat" {
> target s390x-*-* } } } */
> +/* { dg-final { scan-tree-dump-times "generated rawmemchrhi" 2 "lpat" {
> target s390x-*-* } } } */
> +/* { dg-final { scan-tree-dump-times "generated rawmemchrsi" 2 "lpat" {
> target s390x-*-* } } } */
> +
> +/* Rawmemchr pattern: reduction stmt and store */
> +
> +#include <stdint.h>
> +#include <assert.h>
> +
> +typedef __SIZE_TYPE__ size_t;
> +extern void* malloc (size_t);
> +extern void* memset (void*, int, size_t);
> +
> +uint8_t *p_uint8_t;
> +uint16_t *p_uint16_t;
> +uint32_t *p_uint32_t;
> +
> +int8_t *p_int8_t;
> +int16_t *p_int16_t;
> +int32_t *p_int32_t;
> +
> +#define test(T, pattern) \
> +__attribute__((noinline)) \
> +T *test_##T (void) \
> +{ \
> + while (*p_##T != pattern) \
> + ++p_##T; \
> + return p_##T; \
> +}
> +
> +test (uint8_t, 0xab)
> +test (uint16_t, 0xabcd)
> +test (uint32_t, 0xabcdef15)
> +
> +test (int8_t, (int8_t)0xab)
> +test (int16_t, (int16_t)0xabcd)
> +test (int32_t, (int32_t)0xabcdef15)
> +
> +#define run(T, pattern, i) \
> +{ \
> +T *q = p; \
> +q[i] = pattern; \
> +p_##T = p; \
> +T *r = test_##T (); \
> +assert (r == p_##T); \
> +assert (r == &q[i]); \
> +q[i] = 0; \
> +}
> +
> +int main(void)
> +{
> + void *p = malloc (1024);
> + assert (p);
> + memset (p, '\0', 1024);
> +
> + run (uint8_t, 0xab, 0);
> + run (uint8_t, 0xab, 1);
> + run (uint8_t, 0xab, 13);
> +
> + run (uint16_t, 0xabcd, 0);
> + run (uint16_t, 0xabcd, 1);
> + run (uint16_t, 0xabcd, 13);
> +
> + run (uint32_t, 0xabcdef15, 0);
> + run (uint32_t, 0xabcdef15, 1);
> + run (uint32_t, 0xabcdef15, 13);
> +
> + run (int8_t, (int8_t)0xab, 0);
> + run (int8_t, (int8_t)0xab, 1);
> + run (int8_t, (int8_t)0xab, 13);
> +
> + run (int16_t, (int16_t)0xabcd, 0);
> + run (int16_t, (int16_t)0xabcd, 1);
> + run (int16_t, (int16_t)0xabcd, 13);
> +
> + run (int32_t, (int32_t)0xabcdef15, 0);
> + run (int32_t, (int32_t)0xabcdef15, 1);
> + run (int32_t, (int32_t)0xabcdef15, 13);
> +
> + return 0;
> +}
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/lpat-strlen-1.c
> b/gcc/testsuite/gcc.dg/tree-ssa/lpat-strlen-1.c
> new file mode 100644
> index 00000000000..b02509c2c8c
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/lpat-strlen-1.c
> @@ -0,0 +1,100 @@
> +/* { dg-do run } */
> +/* { dg-options "-O2 -fdump-tree-lpat-details" } */
> +/* { dg-final { scan-tree-dump-times "generated strlen\n" 4 "lpat" } } */
> +/* { dg-final { scan-tree-dump-times "generated strlen using rawmemchrhi\n"
> 4 "lpat" { target s390x-*-* } } } */
> +/* { dg-final { scan-tree-dump-times "generated strlen using rawmemchrsi\n"
> 4 "lpat" { target s390x-*-* } } } */
> +
> +#include <stdint.h>
> +#include <assert.h>
> +
> +typedef __SIZE_TYPE__ size_t;
> +extern void* malloc (size_t);
> +extern void* memset (void*, int, size_t);
> +
> +#define test(T, U) \
> +__attribute__((noinline)) \
> +U test_##T##U (T *s) \
> +{ \
> + U i; \
> + for (i=0; s[i]; ++i); \
> + return i; \
> +}
> +
> +test (uint8_t, size_t)
> +test (uint16_t, size_t)
> +test (uint32_t, size_t)
> +test (uint8_t, int)
> +test (uint16_t, int)
> +test (uint32_t, int)
> +
> +test (int8_t, size_t)
> +test (int16_t, size_t)
> +test (int32_t, size_t)
> +test (int8_t, int)
> +test (int16_t, int)
> +test (int32_t, int)
> +
> +#define run(T, U, i) \
> +{ \
> +T *q = p; \
> +q[i] = 0; \
> +assert (test_##T##U (p) == i); \
> +memset (&q[i], 0xf, sizeof (T)); \
> +}
> +
> +int main(void)
> +{
> + void *p = malloc (1024);
> + assert (p);
> + memset (p, 0xf, 1024);
> +
> + run (uint8_t, size_t, 0);
> + run (uint8_t, size_t, 1);
> + run (uint8_t, size_t, 13);
> +
> + run (int8_t, size_t, 0);
> + run (int8_t, size_t, 1);
> + run (int8_t, size_t, 13);
> +
> + run (uint8_t, int, 0);
> + run (uint8_t, int, 1);
> + run (uint8_t, int, 13);
> +
> + run (int8_t, int, 0);
> + run (int8_t, int, 1);
> + run (int8_t, int, 13);
> +
> + run (uint16_t, size_t, 0);
> + run (uint16_t, size_t, 1);
> + run (uint16_t, size_t, 13);
> +
> + run (int16_t, size_t, 0);
> + run (int16_t, size_t, 1);
> + run (int16_t, size_t, 13);
> +
> + run (uint16_t, int, 0);
> + run (uint16_t, int, 1);
> + run (uint16_t, int, 13);
> +
> + run (int16_t, int, 0);
> + run (int16_t, int, 1);
> + run (int16_t, int, 13);
> +
> + run (uint32_t, size_t, 0);
> + run (uint32_t, size_t, 1);
> + run (uint32_t, size_t, 13);
> +
> + run (int32_t, size_t, 0);
> + run (int32_t, size_t, 1);
> + run (int32_t, size_t, 13);
> +
> + run (uint32_t, int, 0);
> + run (uint32_t, int, 1);
> + run (uint32_t, int, 13);
> +
> + run (int32_t, int, 0);
> + run (int32_t, int, 1);
> + run (int32_t, int, 13);
> +
> + return 0;
> +}
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/lpat-strlen-2.c
> b/gcc/testsuite/gcc.dg/tree-ssa/lpat-strlen-2.c
> new file mode 100644
> index 00000000000..e71dad8ed2e
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/lpat-strlen-2.c
> @@ -0,0 +1,58 @@
> +/* { dg-do run } */
> +/* { dg-options "-O2 -fdump-tree-lpat-details" } */
> +/* { dg-final { scan-tree-dump-times "generated strlen\n" 3 "lpat" } } */
> +
> +#include <assert.h>
> +
> +typedef __SIZE_TYPE__ size_t;
> +extern void* malloc (size_t);
> +extern void* memset (void*, int, size_t);
> +
> +__attribute__((noinline))
> +int test_pos (char *s)
> +{
> + int i;
> + for (i=42; s[i]; ++i);
> + return i;
> +}
> +
> +__attribute__((noinline))
> +int test_neg (char *s)
> +{
> + int i;
> + for (i=-42; s[i]; ++i);
> + return i;
> +}
> +
> +__attribute__((noinline))
> +int test_including_null_char (char *s)
> +{
> + int i;
> + for (i=1; s[i-1]; ++i);
> + return i;
> +}
> +
> +int main(void)
> +{
> + void *p = malloc (1024);
> + assert (p);
> + memset (p, 0xf, 1024);
> + char *s = (char *)p + 100;
> +
> + s[42+13] = 0;
> + assert (test_pos (s) == 42+13);
> + s[42+13] = 0xf;
> +
> + s[13] = 0;
> + assert (test_neg (s) == 13);
> + s[13] = 0xf;
> +
> + s[-13] = 0;
> + assert (test_neg (s) == -13);
> + s[-13] = 0xf;
> +
> + s[13] = 0;
> + assert (test_including_null_char (s) == 13+1);
> +
> + return 0;
> +}
> diff --git a/gcc/timevar.def b/gcc/timevar.def
> index 63c0b3306de..bdefc85fbb4 100644
> --- a/gcc/timevar.def
> +++ b/gcc/timevar.def
> @@ -307,6 +307,7 @@ DEFTIMEVAR (TV_TREE_UBSAN , "tree ubsan")
> DEFTIMEVAR (TV_INITIALIZE_RTL , "initialize rtl")
> DEFTIMEVAR (TV_GIMPLE_LADDRESS , "address lowering")
> DEFTIMEVAR (TV_TREE_LOOP_IFCVT , "tree loop if-conversion")
> +DEFTIMEVAR (TV_LPAT , "tree loop pattern")
>
> /* Everything else in rest_of_compilation not included above. */
> DEFTIMEVAR (TV_EARLY_LOCAL , "early local passes")
> diff --git a/gcc/tree-loop-distribution.c b/gcc/tree-loop-distribution.c
> index 7ee19fc8677..f7aafd0d0dc 100644
> --- a/gcc/tree-loop-distribution.c
> +++ b/gcc/tree-loop-distribution.c
> @@ -890,7 +890,7 @@ loop_distribution::partition_merge_into (struct graph
> *rdg,
> /* Returns true when DEF is an SSA_NAME defined in LOOP and used after
> the LOOP. */
>
> -static bool
> +bool
> ssa_name_has_uses_outside_loop_p (tree def, loop_p loop)
> {
> imm_use_iterator imm_iter;
> @@ -912,7 +912,7 @@ ssa_name_has_uses_outside_loop_p (tree def, loop_p loop)
> /* Returns true when STMT defines a scalar variable used after the
> loop LOOP. */
>
> -static bool
> +bool
> stmt_has_scalar_dependences_outside_loop (loop_p loop, gimple *stmt)
> {
> def_operand_p def_p;
> @@ -1234,7 +1234,7 @@ generate_memcpy_builtin (class loop *loop, partition
> *partition)
>
> /* Remove and destroy the loop LOOP. */
>
> -static void
> +void
> destroy_loop (class loop *loop)
> {
> unsigned nbbs = loop->num_nodes;
> diff --git a/gcc/tree-loop-pattern.c b/gcc/tree-loop-pattern.c
> new file mode 100644
> index 00000000000..a9c984d5e53
> --- /dev/null
> +++ b/gcc/tree-loop-pattern.c
> @@ -0,0 +1,588 @@
> +#include "config.h"
> +#include "system.h"
> +#include "coretypes.h"
> +#include "backend.h"
> +#include "intl.h"
> +#include "tree.h"
> +#include "gimple.h"
> +#include "cfghooks.h"
> +#include "tree-pass.h"
> +#include "ssa.h"
> +#include "fold-const.h"
> +#include "gimple-iterator.h"
> +#include "gimplify-me.h"
> +#include "tree-cfg.h"
> +#include "tree-ssa.h"
> +#include "tree-ssanames.h"
> +#include "tree-ssa-loop.h"
> +#include "tree-ssa-loop-manip.h"
> +#include "tree-into-ssa.h"
> +#include "cfgloop.h"
> +#include "tree-scalar-evolution.h"
> +#include "tree-vectorizer.h"
> +#include "tree-eh.h"
> +#include "gimple-fold.h"
> +#include "rtl.h"
> +#include "memmodel.h"
> +#include "insn-codes.h"
> +#include "optabs.h"
> +
> +/* This pass detects loops which mimic the effects of builtins and replaces
> them
> + accordingly. For example, a loop of the form
> +
> + for (; *p != 42; ++p);
> +
> + is replaced by
> +
> + p = rawmemchr (p, 42);
> +
> + under the assumption that rawmemchr is available for a particular mode.
> + Another example is
> +
> + int i;
> + for (i = 42; s[i]; ++i);
> +
> + which is replaced by
> +
> + i = (int)strlen (&s[42]) + 42;
> +
> + for some character array S. In case array S is not of a character array
> + type, we end up with
> +
> + i = (int)(rawmemchr (&s[42], 0) - &s[42]) + 42;
> +
> + assuming that rawmemchr is available for a particular mode. Note,
> detecting
> + strlen like loops also depends on whether the type for the resulting
> length
> + is compatible with size type or overflow is undefined. */
> +
> +/* TODO Quick and dirty imports from tree-loop-distribution pass. */
> +void destroy_loop (class loop *loop);
> +bool stmt_has_scalar_dependences_outside_loop (loop_p loop, gimple *stmt);
> +bool ssa_name_has_uses_outside_loop_p (tree def, loop_p loop);
> +
> +static void
> +generate_rawmemchr_builtin (loop_p loop, tree reduction_var,
> + data_reference_p store_dr, tree base, tree pattern,
> + location_t loc)
> +{
> + gcc_checking_assert (POINTER_TYPE_P (TREE_TYPE (base))
> + && TREE_TYPE (TREE_TYPE (base)) == TREE_TYPE (pattern));
> + gcc_checking_assert (TREE_TYPE (reduction_var) == TREE_TYPE (base));
> +
> + /* The new statements will be placed before LOOP. */
> + gimple_stmt_iterator gsi = gsi_last_bb (loop_preheader_edge (loop)->src);
> +
> + tree mem = force_gimple_operand_gsi (&gsi, base, true, NULL_TREE, false,
> + GSI_CONTINUE_LINKING);
> + gimple *fn_call = gimple_build_call_internal (IFN_RAWMEMCHR, 2, mem,
> pattern);
> + tree reduction_var_new = copy_ssa_name (reduction_var);
> + gimple_call_set_lhs (fn_call, reduction_var_new);
> + gimple_set_location (fn_call, loc);
> + gsi_insert_after (&gsi, fn_call, GSI_CONTINUE_LINKING);
> +
> + if (store_dr)
> + {
> + gassign *g = gimple_build_assign (DR_REF (store_dr),
> reduction_var_new);
> + gsi_insert_after (&gsi, g, GSI_CONTINUE_LINKING);
> + }
> +
> + imm_use_iterator iter;
> + gimple *stmt;
> + use_operand_p use_p;
> + FOR_EACH_IMM_USE_STMT (stmt, iter, reduction_var)
> + {
> + FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
> + SET_USE (use_p, reduction_var_new);
> +
> + update_stmt (stmt);
> + }
> +
> + fold_stmt (&gsi);
> +
> + if (dump_file && (dump_flags & TDF_DETAILS))
> + switch (TYPE_MODE (TREE_TYPE (pattern)))
> + {
> + case QImode:
> + fprintf (dump_file, "generated rawmemchrqi\n");
> + break;
> +
> + case HImode:
> + fprintf (dump_file, "generated rawmemchrhi\n");
> + break;
> +
> + case SImode:
> + fprintf (dump_file, "generated rawmemchrsi\n");
> + break;
> +
> + default:
> + gcc_unreachable ();
> + }
> +}
> +
> +static void
> +generate_strlen_builtin (loop_p loop, tree reduction_var, tree base,
> + tree start_len, location_t loc)
> +{
> + gcc_checking_assert (POINTER_TYPE_P (TREE_TYPE (base)));
> + gcc_checking_assert (TREE_TYPE (reduction_var) == TREE_TYPE (start_len));
> +
> + /* The new statements will be placed before LOOP. */
> + gimple_stmt_iterator gsi = gsi_last_bb (loop_preheader_edge (loop)->src);
> +
> + tree reduction_var_new = make_ssa_name (size_type_node);
> +
> + tree mem = force_gimple_operand_gsi (&gsi, base, true, NULL_TREE, false,
> + GSI_CONTINUE_LINKING);
> + tree fn = build_fold_addr_expr (builtin_decl_implicit (BUILT_IN_STRLEN));
> + gimple *fn_call = gimple_build_call (fn, 1, mem);
> + gimple_call_set_lhs (fn_call, reduction_var_new);
> + gimple_set_location (fn_call, loc);
> + gsi_insert_after (&gsi, fn_call, GSI_CONTINUE_LINKING);
> +
> + /* In case reduction type is not compatible with size type, then
> + conversion is sound even in case an overflow occurs since we previously
> + ensured that for reduction type an overflow is undefined. */
> + tree convert = fold_convert (TREE_TYPE (reduction_var), reduction_var_new);
> + reduction_var_new = force_gimple_operand_gsi (&gsi, convert, true,
> NULL_TREE,
> + false, GSI_CONTINUE_LINKING);
> +
> + /* Loops of the form `for (i=42; s[i]; ++i);` have an additional start
> + length. */
> + if (!integer_zerop (start_len))
> + {
> + tree fn_result = reduction_var_new;
> + reduction_var_new = make_ssa_name (TREE_TYPE (reduction_var));
> + gimple *add_stmt = gimple_build_assign (reduction_var_new, PLUS_EXPR,
> + fn_result, start_len);
> + gsi_insert_after (&gsi, add_stmt, GSI_CONTINUE_LINKING);
> + }
> +
> + imm_use_iterator iter;
> + gimple *stmt;
> + use_operand_p use_p;
> + FOR_EACH_IMM_USE_STMT (stmt, iter, reduction_var)
> + {
> + FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
> + SET_USE (use_p, reduction_var_new);
> +
> + update_stmt (stmt);
> + }
> +
> + fold_stmt (&gsi);
> +
> + if (dump_file && (dump_flags & TDF_DETAILS))
> + fprintf (dump_file, "generated strlen\n");
> +}
> +
> +static void
> +generate_strlen_builtin_using_rawmemchr (loop_p loop, tree reduction_var,
> + tree base, tree start_len,
> + location_t loc)
> +{
> + gcc_checking_assert (POINTER_TYPE_P (TREE_TYPE (base)));
> + gcc_checking_assert (TREE_TYPE (reduction_var) == TREE_TYPE (start_len));
> +
> + /* The new statements will be placed before LOOP. */
> + gimple_stmt_iterator gsi = gsi_last_bb (loop_preheader_edge (loop)->src);
> +
> + tree mem = force_gimple_operand_gsi (&gsi, base, true, NULL_TREE, false,
> + GSI_CONTINUE_LINKING);
> + tree zero = build_zero_cst (TREE_TYPE (TREE_TYPE (mem)));
> + gimple *fn_call = gimple_build_call_internal (IFN_RAWMEMCHR, 2, mem, zero);
> + tree end = make_ssa_name (TREE_TYPE (base));
> + gimple_call_set_lhs (fn_call, end);
> + gimple_set_location (fn_call, loc);
> + gsi_insert_after (&gsi, fn_call, GSI_CONTINUE_LINKING);
> +
> + tree diff = make_ssa_name (ptrdiff_type_node);
> + gimple *diff_stmt = gimple_build_assign (diff, POINTER_DIFF_EXPR, end,
> mem);
> + gsi_insert_after (&gsi, diff_stmt, GSI_CONTINUE_LINKING);
> +
> + tree convert = fold_convert (ptrdiff_type_node,
> + TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (mem))));
> + tree size = force_gimple_operand_gsi (&gsi, convert, true, NULL_TREE,
> false,
> + GSI_CONTINUE_LINKING);
> +
> + tree count = make_ssa_name (ptrdiff_type_node);
> + gimple *count_stmt = gimple_build_assign (count, TRUNC_DIV_EXPR, diff,
> size);
> + gsi_insert_after (&gsi, count_stmt, GSI_CONTINUE_LINKING);
> +
> + convert = fold_convert (TREE_TYPE (reduction_var), count);
> + tree reduction_var_new = force_gimple_operand_gsi (&gsi, convert, true,
> + NULL_TREE, false,
> + GSI_CONTINUE_LINKING);
> +
> + /* Loops of the form `for (i=42; s[i]; ++i);` have an additional start
> + length. */
> + if (!integer_zerop (start_len))
> + {
> + tree lhs = make_ssa_name (TREE_TYPE (reduction_var_new));
> + gimple *g = gimple_build_assign (lhs, PLUS_EXPR, reduction_var_new,
> + start_len);
> + gsi_insert_after (&gsi, g, GSI_CONTINUE_LINKING);
> + reduction_var_new = lhs;
> + }
> +
> + imm_use_iterator iter;
> + gimple *stmt;
> + use_operand_p use_p;
> + FOR_EACH_IMM_USE_STMT (stmt, iter, reduction_var)
> + {
> + FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
> + SET_USE (use_p, reduction_var_new);
> +
> + update_stmt (stmt);
> + }
> +
> + fold_stmt (&gsi);
> +
> + if (dump_file && (dump_flags & TDF_DETAILS))
> + switch (TYPE_MODE (TREE_TYPE (zero)))
> + {
> + case HImode:
> + fprintf (dump_file, "generated strlen using rawmemchrhi\n");
> + break;
> +
> + case SImode:
> + fprintf (dump_file, "generated strlen using rawmemchrsi\n");
> + break;
> +
> + default:
> + gcc_unreachable ();
> + }
> +}
> +
> +static bool
> +transform_loop_1 (loop_p loop,
> + data_reference_p load_dr,
> + data_reference_p store_dr,
> + tree reduction_var)
> +{
> + tree load_ref = DR_REF (load_dr);
> + tree load_type = TREE_TYPE (load_ref);
> + tree load_access_base = build_fold_addr_expr (load_ref);
> + tree load_access_size = TYPE_SIZE_UNIT (load_type);
> + affine_iv load_iv, reduction_iv;
> + tree pattern;
> +
> + /* A limitation of the current implementation is that we only support
> + constant patterns. */
> + edge e = single_exit (loop);
> + gcond *cond_stmt = safe_dyn_cast <gcond *> (last_stmt (e->src));
> + if (!cond_stmt)
> + return false;
> + pattern = gimple_cond_rhs (cond_stmt);
> + if (gimple_cond_code (cond_stmt) != NE_EXPR
> + || gimple_cond_lhs (cond_stmt) != gimple_assign_lhs (DR_STMT (load_dr))
> + || TREE_CODE (pattern) != INTEGER_CST)
> + return false;
> +
> + /* Bail out if no affine induction variable with constant step can be
> + determined. */
> + if (!simple_iv (loop, loop, load_access_base, &load_iv, false))
> + return false;
> +
> + /* Bail out if memory accesses are not consecutive or not growing. */
> + if (!operand_equal_p (load_iv.step, load_access_size, 0))
> + return false;
> +
> + if (!INTEGRAL_TYPE_P (load_type)
> + || !type_has_mode_precision_p (load_type))
> + return false;
> +
> + if (!simple_iv (loop, loop, reduction_var, &reduction_iv, false))
> + return false;
> +
> + /* Handle rawmemchr like loops. */
> + if (operand_equal_p (load_iv.base, reduction_iv.base)
> + && operand_equal_p (load_iv.step, reduction_iv.step))
> + {
> + if (store_dr)
> + {
> + /* Ensure that we store to X and load from X+I where I>0. */
> + if (TREE_CODE (load_iv.base) != POINTER_PLUS_EXPR
> + || !integer_onep (TREE_OPERAND (load_iv.base, 1)))
> + return false;
> + tree ptr_base = TREE_OPERAND (load_iv.base, 0);
> + if (TREE_CODE (ptr_base) != SSA_NAME)
> + return false;
> + gimple *def = SSA_NAME_DEF_STMT (ptr_base);
> + if (!gimple_assign_single_p (def)
> + || gimple_assign_rhs1 (def) != DR_REF (store_dr))
> + return false;
> + /* Ensure that the reduction value is stored. */
> + if (gimple_assign_rhs1 (DR_STMT (store_dr)) != reduction_var)
> + return false;
> + }
> + /* Bail out if target does not provide rawmemchr for a certain mode.
> */
> + machine_mode mode = TYPE_MODE (load_type);
> + if (direct_optab_handler (rawmemchr_optab, mode) == CODE_FOR_nothing)
> + return false;
> + location_t loc = gimple_location (DR_STMT (load_dr));
> + generate_rawmemchr_builtin (loop, reduction_var, store_dr,
> load_iv.base,
> + pattern, loc);
> + return true;
> + }
> +
> + /* Handle strlen like loops. */
> + if (store_dr == NULL
> + && integer_zerop (pattern)
> + && TREE_CODE (reduction_iv.base) == INTEGER_CST
> + && TREE_CODE (reduction_iv.step) == INTEGER_CST
> + && integer_onep (reduction_iv.step)
> + && (types_compatible_p (TREE_TYPE (reduction_var), size_type_node)
> + || TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (reduction_var))))
> + {
> + location_t loc = gimple_location (DR_STMT (load_dr));
> + if (TYPE_MODE (load_type) == TYPE_MODE (char_type_node)
> + && TYPE_PRECISION (load_type) == TYPE_PRECISION (char_type_node))
> + generate_strlen_builtin (loop, reduction_var, load_iv.base,
> + reduction_iv.base, loc);
> + else if (direct_optab_handler (rawmemchr_optab, TYPE_MODE (load_type))
> + != CODE_FOR_nothing)
> + generate_strlen_builtin_using_rawmemchr (loop, reduction_var,
> + load_iv.base,
> + reduction_iv.base, loc);
> + else
> + return false;
> + if (TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (reduction_var)))
> + {
> + const char *msg = G_("assuming signed overflow does not occur "
> + "when optimizing strlen like loop");
> + fold_overflow_warning (msg, WARN_STRICT_OVERFLOW_MISC);
> + }
> + return true;
> + }
> +
> + return false;
> +}
> +
> +static bool
> +transform_loop (loop_p loop)
> +{
> + gimple *reduction_stmt = NULL;
> + data_reference_p load_dr = NULL, store_dr = NULL;
> +
> + basic_block *bbs = get_loop_body (loop);
> +
> + for (unsigned i = 0, ninsns = 0; i < loop->num_nodes; ++i)
> + {
> + basic_block bb = bbs[i];
> +
> + for (gphi_iterator bsi = gsi_start_phis (bb); !gsi_end_p (bsi);
> + gsi_next (&bsi), ++ninsns)
> + {
> + /* Bail out early for loops which are unlikely to match. */
> + if (ninsns > 16)
> + return false;
> + gphi *phi = bsi.phi ();
> + if (gimple_has_volatile_ops (phi))
> + return false;
> + if (gimple_clobber_p (phi))
> + continue;
> + if (virtual_operand_p (gimple_phi_result (phi)))
> + continue;
> + if (stmt_has_scalar_dependences_outside_loop (loop, phi))
> + {
> + if (reduction_stmt)
> + return false;
> + reduction_stmt = phi;
> + }
> + }
> +
> + for (gimple_stmt_iterator bsi = gsi_start_bb (bb); !gsi_end_p (bsi);
> + gsi_next (&bsi), ++ninsns)
> + {
> + /* Bail out early for loops which are unlikely to match. */
> + if (ninsns > 16)
> + return false;
> +
> + gimple *stmt = gsi_stmt (bsi);
> +
> + if (gimple_clobber_p (stmt))
> + continue;
> +
> + if (gimple_code (stmt) == GIMPLE_LABEL || is_gimple_debug (stmt))
> + continue;
> +
> + if (gimple_has_volatile_ops (stmt))
> + return false;
> +
> + if (stmt_has_scalar_dependences_outside_loop (loop, stmt))
> + {
> + if (reduction_stmt)
> + return false;
> + reduction_stmt = stmt;
> + }
> +
> + /* Any scalar stmts are ok. */
> + if (!gimple_vuse (stmt))
> + continue;
> +
> + /* Otherwise just regular loads/stores. */
> + if (!gimple_assign_single_p (stmt))
> + return false;
> +
> + auto_vec<data_reference_p, 2> dr_vec;
> + if (!find_data_references_in_stmt (loop, stmt, &dr_vec))
> + return false;
> + data_reference_p dr;
> + unsigned j;
> + FOR_EACH_VEC_ELT (dr_vec, j, dr)
> + {
> + tree type = TREE_TYPE (DR_REF (dr));
> + if (!ADDR_SPACE_GENERIC_P (TYPE_ADDR_SPACE (type)))
> + return false;
> + if (DR_IS_READ (dr))
> + {
> + if (load_dr != NULL)
> + return false;
> + load_dr = dr;
> + }
> + else
> + {
> + if (store_dr != NULL)
> + return false;
> + store_dr = dr;
> + }
> + }
> + }
> + }
> +
> + /* A limitation of the current implementation is that we require a
> reduction
> + statement which does not occur in cases like
> + extern int *p;
> + void foo (void) { for (; *p; ++p); } */
> + if (load_dr == NULL || reduction_stmt == NULL)
> + return false;
> +
> + /* Note, reduction variables are guaranteed to be SSA names. */
> + tree reduction_var;
> + switch (gimple_code (reduction_stmt))
> + {
> + case GIMPLE_PHI:
> + reduction_var = gimple_phi_result (reduction_stmt);
> + break;
> + case GIMPLE_ASSIGN:
> + reduction_var = gimple_assign_lhs (reduction_stmt);
> + break;
> + default:
> + /* Bail out e.g. for GIMPLE_CALL. */
> + return false;
> + }
> + if (reduction_var == NULL)
> + return false;
> +
> + /* Bail out if this is a bitfield memory reference. */
> + if (TREE_CODE (DR_REF (load_dr)) == COMPONENT_REF
> + && DECL_BIT_FIELD (TREE_OPERAND (DR_REF (load_dr), 1)))
> + return false;
> +
> + /* Data reference must be executed exactly once per iteration of each
> + loop in the loop nest. We only need to check dominance information
> + against the outermost one in a perfect loop nest because a bb can't
> + dominate outermost loop's latch without dominating inner loop's. */
> + basic_block load_bb = gimple_bb (DR_STMT (load_dr));
> + if (!dominated_by_p (CDI_DOMINATORS, loop->latch, load_bb))
> + return false;
> +
> + if (store_dr)
> + {
> + /* Bail out if this is a bitfield memory reference. */
> + if (TREE_CODE (DR_REF (store_dr)) == COMPONENT_REF
> + && DECL_BIT_FIELD (TREE_OPERAND (DR_REF (store_dr), 1)))
> + return false;
> +
> + /* Data reference must be executed exactly once per iteration of each
> + loop in the loop nest. We only need to check dominance information
> + against the outermost one in a perfect loop nest because a bb can't
> + dominate outermost loop's latch without dominating inner loop's. */
> + basic_block store_bb = gimple_bb (DR_STMT (store_dr));
> + if (!dominated_by_p (CDI_DOMINATORS, loop->latch, store_bb))
> + return false;
> +
> + /* Load and store must be in the same loop nest. */
> + if (store_bb->loop_father != load_bb->loop_father)
> + return false;
> +
> + edge e = single_exit (store_bb->loop_father);
> + if (!e)
> + return false;
> + bool load_dom = dominated_by_p (CDI_DOMINATORS, e->src, load_bb);
> + bool store_dom = dominated_by_p (CDI_DOMINATORS, e->src, store_bb);
> + if (load_dom != store_dom)
> + return false;
> + }
> +
> + return transform_loop_1 (loop, load_dr, store_dr, reduction_var);
> +}
> +
> +namespace {
> +
> +const pass_data pass_data_lpat =
> +{
> + GIMPLE_PASS, /* type */
> + "lpat", /* name */
> + OPTGROUP_LOOP, /* optinfo_flags */
> + TV_LPAT, /* tv_id */
> + ( PROP_cfg | PROP_ssa ), /* properties_required */
> + 0, /* properties_provided */
> + 0, /* properties_destroyed */
> + 0, /* todo_flags_start */
> + 0, /* todo_flags_finish */
> +};
> +
> +class pass_lpat : public gimple_opt_pass
> +{
> +public:
> + pass_lpat (gcc::context *ctxt)
> + : gimple_opt_pass (pass_data_lpat, ctxt)
> + {}
> +
> + bool
> + gate (function *) OVERRIDE
> + {
> + return optimize != 0;
> + }
> +
> + unsigned int
> + execute (function *f) OVERRIDE
> + {
> + loop_p loop;
> + auto_vec<loop_p> loops_to_be_destroyed;
> +
> + FOR_EACH_LOOP_FN (f, loop, LI_ONLY_INNERMOST)
> + {
> + if (!single_exit (loop)
> + || (!flag_tree_loop_distribute_patterns // TODO
> + && !optimize_loop_for_speed_p (loop)))
> + continue;
> +
> + if (transform_loop (loop))
> + loops_to_be_destroyed.safe_push (loop);
> + }
> +
> + if (loops_to_be_destroyed.length () > 0)
> + {
> + unsigned i;
> + FOR_EACH_VEC_ELT (loops_to_be_destroyed, i, loop)
> + destroy_loop (loop);
> +
> + scev_reset_htab ();
> + mark_virtual_operands_for_renaming (f);
> + rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa);
> +
> + return TODO_cleanup_cfg;
> + }
> + else
> + return 0;
> + }
> +}; // class pass_lpat
> +
> +} // anon namespace
> +
> +gimple_opt_pass *
> +make_pass_lpat (gcc::context *ctxt)
> +{
> + return new pass_lpat (ctxt);
> +}
> diff --git a/gcc/tree-pass.h b/gcc/tree-pass.h
> index 15693fee150..2d71a12039e 100644
> --- a/gcc/tree-pass.h
> +++ b/gcc/tree-pass.h
> @@ -380,6 +380,7 @@ extern gimple_opt_pass *make_pass_graphite (gcc::context
> *ctxt);
> extern gimple_opt_pass *make_pass_graphite_transforms (gcc::context *ctxt);
> extern gimple_opt_pass *make_pass_if_conversion (gcc::context *ctxt);
> extern gimple_opt_pass *make_pass_if_to_switch (gcc::context *ctxt);
> +extern gimple_opt_pass *make_pass_lpat (gcc::context *ctxt);
> extern gimple_opt_pass *make_pass_loop_distribution (gcc::context *ctxt);
> extern gimple_opt_pass *make_pass_vectorize (gcc::context *ctxt);
> extern gimple_opt_pass *make_pass_simduid_cleanup (gcc::context *ctxt);
