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Introduce gcc_qsort 

* sort.cc: New file.
	* system.h [!CHECKING_P] (qsort): Redirect to gcc_qsort.
	* vec.c (qsort_chk): Use gcc_qsort.
	* Makefile.in (OBJS-libcommon): Add sort.o.
	(build/sort.o): New target.  Use it...
	(BUILD_RTL): ... here, and...
	(build/gencfn-macros): ... here, and...
	(build/genmatch): ... here.

From-SVN: r260216
This commit is contained in:
Alexander Monakov 2018-05-13 21:23:06 +03:00 committed by Alexander Monakov
parent 628332f85d
commit 82a04cd1d3
5 changed files with 254 additions and 7 deletions
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11
gcc/ChangeLog
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@ -1,3 +1,14 @@
2018-05-13 Alexander Monakov <amonakov@ispras.ru>
* sort.cc: New file.
* system.h [!CHECKING_P] (qsort): Redirect to gcc_qsort.
* vec.c (qsort_chk): Use gcc_qsort.
* Makefile.in (OBJS-libcommon): Add sort.o.
(build/sort.o): New target. Use it...
(BUILD_RTL): ... here, and...
(build/gencfn-macros): ... here, and...
(build/genmatch): ... here.
2018-05-13 Kito Cheng <kito.cheng@gmail.com>
Chung-Ju Wu <jasonwucj@gmail.com>

9
gcc/Makefile.in
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@ -1076,7 +1076,7 @@ BUILD_LIBS = $(BUILD_LIBIBERTY)
BUILD_RTL = build/rtl.o build/read-rtl.o build/ggc-none.o \
build/vec.o build/min-insn-modes.o build/gensupport.o \
build/print-rtl.o build/hash-table.o
build/print-rtl.o build/hash-table.o build/sort.o
BUILD_MD = build/read-md.o
BUILD_ERRORS = build/errors.o
@ -1611,7 +1611,7 @@ OBJS-libcommon = diagnostic.o diagnostic-color.o diagnostic-show-locus.o \
pretty-print.o intl.o \
sbitmap.o \
vec.o input.o version.o hash-table.o ggc-none.o memory-block.o \
selftest.o selftest-diagnostic.o
selftest.o selftest-diagnostic.o sort.o
# Objects in libcommon-target.a, used by drivers and by the core
# compiler and containing target-dependent code.
@ -2681,6 +2681,7 @@ build/vec.o : vec.c $(BCONFIG_H) $(SYSTEM_H) $(CORETYPES_H) $(VEC_H) \
$(GGC_H) toplev.h $(DIAGNOSTIC_CORE_H)
build/hash-table.o : hash-table.c $(BCONFIG_H) $(SYSTEM_H) \
$(CORETYPES_H) $(HASH_TABLE_H) $(GGC_H) toplev.h $(DIAGNOSTIC_CORE_H)
build/sort.o : sort.cc $(BCONFIG_H) $(SYSTEM_H)
build/inchash.o : inchash.c $(BCONFIG_H) $(SYSTEM_H) $(CORETYPES_H) \
$(HASHTAB_H) inchash.h
build/gencondmd.o : build/gencondmd.c $(BCONFIG_H) $(SYSTEM_H) \
@ -2817,7 +2818,7 @@ build/genautomata$(build_exeext) : BUILD_LIBS += -lm
build/genrecog$(build_exeext) : build/hash-table.o build/inchash.o
build/gencfn-macros$(build_exeext) : build/hash-table.o build/vec.o \
build/ggc-none.o
build/ggc-none.o build/sort.o
# For stage1 and when cross-compiling use the build libcpp which is
# built with NLS disabled. For stage2+ use the host library and
@ -2831,7 +2832,7 @@ build/genmatch$(build_exeext): BUILD_LIBS += $(LIBINTL) $(LIBICONV)
endif
build/genmatch$(build_exeext) : $(BUILD_CPPLIB) \
$(BUILD_ERRORS) build/vec.o build/hash-table.o
$(BUILD_ERRORS) build/vec.o build/hash-table.o build/sort.o
# These programs are not linked with the MD reader.
build/gengtype$(build_exeext) : build/gengtype-lex.o build/gengtype-parse.o \

232
gcc/sort.cc Normal file
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@ -0,0 +1,232 @@
/* Platform-independent deterministic sort function.
Copyright (C) 2018 Free Software Foundation, Inc.
Contributed by Alexander Monakov.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3, or (at your option) any
later version.
GCC is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
/* This implements a sort function suitable for GCC use cases:
- signature-compatible to C qsort, but relaxed contract:
- may apply the comparator to elements in a temporary buffer
- may abort on allocation failure
- deterministic (but not necessarily stable)
- fast, especially for common cases (0-5 elements of size 8 or 4)
The implementation uses a network sort for up to 5 elements and
a merge sort on top of that. Neither stage has branches depending on
comparator result, trading extra arithmetic for branch mispredictions. */
#ifdef GENERATOR_FILE
#include "bconfig.h"
#else
#include "config.h"
#endif
#include "system.h"
#define likely(cond) __builtin_expect ((cond), 1)
#ifdef __GNUC__
#define noinline __attribute__ ((__noinline__))
#else
#define noinline
#endif
/* C-style qsort comparator function type. */
typedef int cmp_fn (const void *, const void *);
/* Structure holding read-mostly (read-only in netsort) context. */
struct sort_ctx
{
cmp_fn *cmp; // pointer to comparator
char *out; // output buffer
size_t n; // number of elements
size_t size; // element size
};
/* Helper for netsort. Permute, possibly in-place, 2 or 3 elements,
placing E0 to C->OUT, E1 to C->OUT + C->SIZE, and so on. */
static void
reorder23 (sort_ctx *c, char *e0, char *e1, char *e2)
{
#define REORDER_23(SIZE, STRIDE, OFFSET) \
do { \
size_t t0, t1; \
memcpy (&t0, e0 + OFFSET, SIZE); \
memcpy (&t1, e1 + OFFSET, SIZE); \
char *out = c->out + OFFSET; \
if (likely (c->n == 3)) \
memcpy (out + 2*STRIDE, e2 + OFFSET, SIZE); \
memcpy (out, &t0, SIZE); out += STRIDE; \
memcpy (out, &t1, SIZE); \
} while (0)
if (sizeof (size_t) == 8 && likely (c->size == 8))
REORDER_23 (8, 8, 0);
else if (likely (c->size == 4))
REORDER_23 (4, 4, 0);
else
{
size_t offset = 0, step = sizeof (size_t);
for (; offset + step <= c->size; offset += step)
REORDER_23 (step, c->size, offset);
for (; offset < c->size; offset++)
REORDER_23 (1, c->size, offset);
}
}
/* Like reorder23, but permute 4 or 5 elements. */
static void
reorder45 (sort_ctx *c, char *e0, char *e1, char *e2, char *e3, char *e4)
{
#define REORDER_45(SIZE, STRIDE, OFFSET) \
do { \
size_t t0, t1, t2, t3; \
memcpy (&t0, e0 + OFFSET, SIZE); \
memcpy (&t1, e1 + OFFSET, SIZE); \
memcpy (&t2, e2 + OFFSET, SIZE); \
memcpy (&t3, e3 + OFFSET, SIZE); \
char *out = c->out + OFFSET; \
if (likely (c->n == 5)) \
memcpy (out + 4*STRIDE, e4 + OFFSET, SIZE); \
memcpy (out, &t0, SIZE); out += STRIDE; \
memcpy (out, &t1, SIZE); out += STRIDE; \
memcpy (out, &t2, SIZE); out += STRIDE; \
memcpy (out, &t3, SIZE); \
} while (0)
if (sizeof (size_t) == 8 && likely (c->size == 8))
REORDER_45 (8, 8, 0);
else if (likely(c->size == 4))
REORDER_45 (4, 4, 0);
else
{
size_t offset = 0, step = sizeof (size_t);
for (; offset + step <= c->size; offset += step)
REORDER_45 (step, c->size, offset);
for (; offset < c->size; offset++)
REORDER_45 (1, c->size, offset);
}
}
/* Helper for netsort. Invoke comparator CMP on E0 and E1.
Return E0^E1 if E0 compares less than E1, zero otherwise.
This is noinline to avoid code growth and confine invocation
to a single call site, assisting indirect branch prediction. */
noinline static intptr_t
cmp1 (char *e0, char *e1, cmp_fn *cmp)
{
intptr_t x = (intptr_t)e0 ^ (intptr_t)e1;
return x & (cmp (e0, e1) >> 31);
}
/* Execute network sort on 2 to 5 elements from IN, placing them into C->OUT.
IN may be equal to C->OUT, in which case elements are sorted in place. */
static void
netsort (char *in, sort_ctx *c)
{
#define CMP(e0, e1) \
do { \
intptr_t x = cmp1 (e1, e0, c->cmp); \
e0 = (char *)((intptr_t)e0 ^ x); \
e1 = (char *)((intptr_t)e1 ^ x); \
} while (0)
char *e0 = in, *e1 = e0 + c->size, *e2 = e1 + c->size;
CMP (e0, e1);
if (likely (c->n == 3))
{
CMP (e1, e2);
CMP (e0, e1);
}
if (c->n <= 3)
return reorder23 (c, e0, e1, e2);
char *e3 = e2 + c->size, *e4 = e3 + c->size;
if (likely (c->n == 5))
{
CMP (e3, e4);
CMP (e2, e4);
}
CMP (e2, e3);
if (likely (c->n == 5))
{
CMP (e0, e3);
CMP (e1, e4);
}
CMP (e0, e2);
CMP (e1, e3);
CMP (e1, e2);
reorder45 (c, e0, e1, e2, e3, e4);
}
/* Execute merge sort on N elements from IN, placing them into OUT,
using TMP as temporary storage if IN is equal to OUT.
This is a stable sort if netsort is used only for 2 or 3 elements. */
static void
mergesort (char *in, sort_ctx *c, size_t n, char *out, char *tmp)
{
if (likely (n <= 5))
{
c->out = out;
c->n = n;
return netsort (in, c);
}
size_t nl = n / 2, nr = n - nl, sz = nl * c->size;
char *mid = in + sz, *r = out + sz, *l = in == out ? tmp : in;
/* Sort the right half, outputting to right half of OUT. */
mergesort (mid, c, nr, r, tmp);
/* Sort the left half, leaving left half of OUT free. */
mergesort (in, c, nl, l, mid);
/* Merge sorted halves given by L, R to [OUT, END). */
#define MERGE_ELTSIZE(SIZE) \
do { \
intptr_t mr = c->cmp (r, l) >> 31; \
intptr_t lr = (intptr_t)l ^ (intptr_t)r; \
lr = (intptr_t)l ^ (lr & mr); \
out = (char *)memcpy (out, (char *)lr, SIZE); \
out += SIZE; \
r += mr & SIZE; \
if (r == out) return; \
l += ~mr & SIZE; \
} while (r != end)
if (likely (c->cmp(r, l + (r - out) - c->size) < 0))
{
char *end = out + n * c->size;
if (sizeof (size_t) == 8 && likely (c->size == 8))
MERGE_ELTSIZE (8);
else if (likely (c->size == 4))
MERGE_ELTSIZE (4);
else
MERGE_ELTSIZE (c->size);
}
memcpy (out, l, r - out);
}
void
gcc_qsort (void *vbase, size_t n, size_t size, cmp_fn *cmp)
{
if (n < 2)
return;
char *base = (char *)vbase;
sort_ctx c = {cmp, base, n, size};
long long scratch[32];
size_t bufsz = (n / 2) * size;
void *buf = bufsz <= sizeof scratch ? scratch : xmalloc (bufsz);
mergesort (base, &c, n, base, (char *)buf);
if (buf != scratch)
free (buf);
}

7
gcc/system.h
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@ -1202,11 +1202,14 @@ helper_const_non_const_cast (const char *p)
/* qsort comparator consistency checking: except in release-checking compilers,
redirect 4-argument qsort calls to qsort_chk; keep 1-argument invocations
corresponding to vec::qsort (cmp): they use C qsort internally anyway. */
#if CHECKING_P
void qsort_chk (void *, size_t, size_t, int (*)(const void *, const void *));
void gcc_qsort (void *, size_t, size_t, int (*)(const void *, const void *));
#define PP_5th(a1, a2, a3, a4, a5, ...) a5
#undef qsort
#if CHECKING_P
#define qsort(...) PP_5th (__VA_ARGS__, qsort_chk, 3, 2, qsort, 0) (__VA_ARGS__)
void qsort_chk (void *, size_t, size_t, int (*)(const void *, const void *));
#else
#define qsort(...) PP_5th (__VA_ARGS__, gcc_qsort, 3, 2, qsort, 0) (__VA_ARGS__)
#endif
#endif /* ! GCC_SYSTEM_H */

2
gcc/vec.c
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@ -215,7 +215,7 @@ void
qsort_chk (void *base, size_t n, size_t size,
int (*cmp)(const void *, const void *))
{
(qsort) (base, n, size, cmp);
gcc_qsort (base, n, size, cmp);
#if 0
#define LIM(n) (n)
#else