From 41c15785a9b620a8c85944649c20cca853f40e84 Mon Sep 17 00:00:00 2001
From: Denis Vlasenko <vda.linux@googlemail.com>
Date: Wed, 17 Dec 2008 01:36:31 +0000
Subject: since gcc -Os hates us and does not inline string ops, implement
 inline versions of some of them. Enable only those which result roughly in
 the same code size as using out-or-line versions.

None of this affects users, installed headers won't have
any trace of it.
---
 include/libc-string_i386.h | 314 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 314 insertions(+)
 create mode 100644 include/libc-string_i386.h

(limited to 'include/libc-string_i386.h')

diff --git a/include/libc-string_i386.h b/include/libc-string_i386.h
new file mode 100644
index 000000000..3ed9c8783
--- /dev/null
+++ b/include/libc-string_i386.h
@@ -0,0 +1,314 @@
+/*
+ * Copyright (C) 2008 Denys Vlasenko <vda.linux@googlemail.com>
+ *
+ * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball
+ */
+
+#if !defined _STRING_H
+#error "Never use <libc-string_i386.h> directly; include <string.h> instead"
+#endif
+
+#ifndef _LIBC_STRING_i386_H
+#define _LIBC_STRING_i386_H 1
+
+static __always_inline
+void *inlined_memset_const_c_count4(void *s, unsigned eax, unsigned count)
+{
+	int ecx, edi;
+
+	if (count == 0)
+		return s;
+
+	/* Very small (2 stores or less) are best done with direct
+	 * mov <const>,<mem> instructions (they do not clobber registers) */
+	if (count == 1) {
+		*(char *)(s + 0) = eax;
+		return s;
+	}
+
+	eax *= 0x01010101; /* done at compile time */
+
+	if (count == 2) {
+		*(short *)(s + 0) = eax;
+		return s;
+	}
+	if (count == 3) {
+		*(short *)(s + 0) = eax;
+		*(char *) (s + 2) = eax;
+		return s;
+	}
+	if (count == 1*4 + 0) {
+		*(int *)(s + 0) = eax;
+		return s;
+	}
+	if (count == 1*4 + 1) {
+		*(int *) (s + 0) = eax;
+		*(char *)(s + 4) = eax;
+		return s;
+	}
+	if (count == 1*4 + 2) {
+		*(int *)  (s + 0) = eax;
+		*(short *)(s + 4) = eax;
+		return s;
+	}
+
+	/* Small string stores: don't clobber ecx
+	 * (clobbers only eax and edi) */
+#define small_store(arg) { \
+	__asm__ __volatile__( \
+		arg \
+		: "=&D" (edi) \
+		: "a" (eax), "0" (s) \
+		: "memory" \
+	); \
+	return s; \
+}
+	if (count == 1*4 + 3) small_store("stosl; stosw; stosb");
+	if (count == 2*4 + 0) {
+		((int *)s)[0] = eax;
+		((int *)s)[1] = eax;
+		return s;
+	}
+	if (count == 2*4 + 1) small_store("stosl; stosl; stosb");
+	if (count == 2*4 + 2) small_store("stosl; stosl; stosw");
+	if (count == 2*4 + 3) small_store("stosl; stosl; stosw; stosb");
+	if (count == 3*4 + 0) small_store("stosl; stosl; stosl");
+	if (count == 3*4 + 1) small_store("stosl; stosl; stosl; stosb");
+	if (count == 3*4 + 2) small_store("stosl; stosl; stosl; stosw");
+	if (count == 3*4 + 3) small_store("stosl; stosl; stosl; stosw; stosb");
+	if (count == 4*4 + 0) small_store("stosl; stosl; stosl; stosl");
+	if (count == 4*4 + 1) small_store("stosl; stosl; stosl; stosl; stosb");
+	/* going over 7 bytes is suboptimal */
+	/* stosw is 2-byte insn, so this one takes 6 bytes: */
+	if (count == 4*4 + 2) small_store("stosl; stosl; stosl; stosl; stosw");
+	/* 7 bytes */
+	if (count == 4*4 + 3) small_store("stosl; stosl; stosl; stosl; stosw; stosb");
+	/* 5 bytes */
+	if (count == 5*4 + 0) small_store("stosl; stosl; stosl; stosl; stosl");
+	/* 6 bytes */
+	if (count == 5*4 + 1) small_store("stosl; stosl; stosl; stosl; stosl; stosb");
+	/* 7 bytes */
+	if (count == 5*4 + 2) small_store("stosl; stosl; stosl; stosl; stosl; stosw");
+	/* 8 bytes, but oh well... */
+	if (count == 5*4 + 3) small_store("stosl; stosl; stosl; stosl; stosl; stosw; stosb");
+	/* 6 bytes */
+	if (count == 6*4 + 0) small_store("stosl; stosl; stosl; stosl; stosl; stosl");
+	/* the rest would be 7+ bytes and is handled below instead */
+#undef small_store
+
+	/* Not small, but multiple-of-4 store.
+	 * "mov <const>,%ecx; rep; stosl" sequence is 7 bytes */
+	__asm__ __volatile__(
+		"	rep; stosl\n"
+		: "=&c" (ecx), "=&D" (edi)
+		: "a" (eax), "0" (count / 4), "1" (s)
+		: "memory"
+	);
+	return s;
+}
+#if 1 /* -51 bytes on shared i386 build with gcc 4.3.0 */
+#define memset(s, c, count) ( \
+	( !(__builtin_constant_p(c) && __builtin_constant_p(count)) \
+	  || ((count) > (6*4 + 0) && ((count) % 4) != 0) \
+	) \
+	? memset((s), (c), (count)) \
+	: inlined_memset_const_c_count4((s), (c), (count)) \
+	)
+#endif
+
+
+static __always_inline
+void *inlined_mempcpy_const_count4(void *d, const void *s, unsigned count)
+{
+	int ecx;
+	char *esi, *edi;
+
+	if (count == 0)
+		return d;
+
+	if (count == 1) {
+		*(char *)d = *(char *)s;
+		return d + 1;
+	}
+	if (count == 2) {
+		*(short *)d = *(short *)s;
+		return d + 2;
+	}
+	/* Small string moves: don't clobber ecx
+	 * (clobbers only esi and edi) */
+#define small_move(arg) { \
+	__asm__ __volatile__( \
+		arg \
+		: "=&S" (esi), "=&D" (edi) \
+		: "0" (s), "1" (d) \
+		: "memory" \
+	); \
+	return edi; \
+}
+	if (count == 3) small_move("movsw; movsb");
+	if (count == 1*4 + 0) {
+		*(int *)d = *(int *)s;
+		return d + 4;
+	}
+	if (count == 1*4 + 1) small_move("movsl; movsb");
+	if (count == 1*4 + 2) small_move("movsl; movsw");
+	if (count == 1*4 + 3) small_move("movsl; movsw; movsb");
+	if (count == 2*4 + 0) small_move("movsl; movsl");
+	if (count == 2*4 + 1) small_move("movsl; movsl; movsb");
+	if (count == 2*4 + 2) small_move("movsl; movsl; movsw");
+	if (count == 2*4 + 3) small_move("movsl; movsl; movsw; movsb");
+	if (count == 3*4 + 0) small_move("movsl; movsl; movsl");
+	if (count == 3*4 + 1) small_move("movsl; movsl; movsl; movsb");
+	if (count == 3*4 + 2) small_move("movsl; movsl; movsl; movsw");
+	if (count == 3*4 + 3) small_move("movsl; movsl; movsl; movsw; movsb");
+	if (count == 4*4 + 0) small_move("movsl; movsl; movsl; movsl");
+	if (count == 4*4 + 1) small_move("movsl; movsl; movsl; movsl; movsb");
+	/* going over 7 bytes is suboptimal */
+	/* movsw is 2-byte insn, so this one takes 6 bytes: */
+	if (count == 4*4 + 2) small_move("movsl; movsl; movsl; movsl; movsw");
+	/* 7 bytes */
+	if (count == 4*4 + 3) small_move("movsl; movsl; movsl; movsl; movsw; movsb");
+	/* 5 bytes */
+	if (count == 5*4 + 0) small_move("movsl; movsl; movsl; movsl; movsl");
+	/* 6 bytes */
+	if (count == 5*4 + 1) small_move("movsl; movsl; movsl; movsl; movsl; movsb");
+	/* 7 bytes */
+	if (count == 5*4 + 2) small_move("movsl; movsl; movsl; movsl; movsl; movsw");
+	/* 8 bytes, but oh well... */
+	if (count == 5*4 + 3) small_move("movsl; movsl; movsl; movsl; movsl; movsw; movsb");
+	/* 6 bytes */
+	if (count == 6*4 + 0) small_move("movsl; movsl; movsl; movsl; movsl; movsl");
+	/* the rest would be 7+ bytes and is handled below instead */
+#undef small_move
+
+	/* Not small, but multiple-of-4 move.
+	 * "mov <const>,%ecx; rep; movsl" sequence is 7 bytes */
+	__asm__ __volatile__(
+		"	rep; movsl\n"
+		: "=&c" (ecx), "=&S" (esi), "=&D" (edi)
+		: "0" (count / 4), "1" (s), "2" (d)
+		: "memory"
+	);
+	return edi;
+}
+static __always_inline
+void *inlined_memcpy_const_count4(void *d, const void *s, unsigned count)
+{
+	inlined_mempcpy_const_count4(d, s, count);
+	return d;
+}
+#if 1 /* +34 bytes on shared i386 build with gcc 4.3.0 */
+#define mempcpy(d, s, count) ( \
+	( !(__builtin_constant_p(count)) \
+	  || ((count) > (6*4 + 0) && ((count) % 4) != 0) \
+	) \
+	? mempcpy((d), (s), (count)) \
+	: inlined_mempcpy_const_count4((d), (s), (count)) \
+	)
+#define memcpy(d, s, count) ( \
+	( !(__builtin_constant_p(count)) \
+	  || ((count) > (6*4 + 0) && ((count) % 4) != 0) \
+	) \
+	? memcpy((d), (s), (count)) \
+	: inlined_memcpy_const_count4((d), (s), (count)) \
+	)
+#endif
+
+
+static __always_inline
+size_t inlined_strlen(const char *s)
+{
+	int edi;
+	int ecx;
+	__asm__ __volatile__(
+		"	repne; scasb\n"
+	/*	"	notl	%0\n" */
+	/*	"	decl	%0\n" */
+		: "=c" (ecx), "=&D" (edi)
+		: "1" (s), "a" (0), "0" (0xffffffffu)
+		/* : no clobbers */
+	);
+	return -ecx - 1;
+}
+#if 0 /* +1108 bytes on shared i386 build with gcc 4.3.0 */
+#define strlen(s) inlined_strlen(s)
+#endif
+
+
+static __always_inline
+char *inlined_stpcpy(char *dest, const char *src)
+{
+	char *esi, *edi;
+	int eax;
+	__asm__ __volatile__(
+		"1:	lodsb\n"
+		"	stosb\n"
+		"	testb	%%al, %%al\n"
+		"	jnz	1b\n"
+		: "=&S" (esi), "=&D" (edi), "=&a" (eax)
+		: "0" (src), "1" (dest)
+		: "memory"
+	);
+	return edi - 1;
+}
+static __always_inline
+char *inlined_strcpy(char *dest, const char *src)
+{
+	inlined_stpcpy(dest, src);
+	return dest;
+}
+#if 0 /* +562 bytes on shared i386 build with gcc 4.3.0 */
+#define stpcpy(dest, src) inlined_stpcpy(dest, src)
+#define strcpy(dest, src) inlined_strcpy(dest, src)
+#endif
+
+
+static __always_inline
+void *inlined_memchr(const void *s, int c, size_t count)
+{
+	void *edi;
+	int ecx;
+	/* Unfortunately, c gets loaded to %eax (wide insn), not %al */
+	__asm__ __volatile__(
+		"	jecxz	1f\n"
+		"	repne; scasb\n"
+		"	leal	-1(%%edi), %%edi\n"
+		"	je	2f\n"
+		"1:\n"
+		"	xorl	%%edi, %%edi\n"
+		"2:\n"
+		: "=&D" (edi), "=&c" (ecx)
+		: "a" (c), "0" (s), "1" (count)
+		/* : no clobbers */
+	);
+	return edi;
+}
+static __always_inline
+void *inlined_memchr_const_c(const void *s, int c, size_t count)
+{
+	void *edi;
+	int ecx, eax;
+	__asm__ __volatile__(
+		"	jecxz	1f\n"
+		"	movb	%4, %%al\n" /* const c to %%al */
+		"	repne; scasb\n"
+		"	leal	-1(%%edi), %%edi\n"
+		"	je	2f\n"
+		"1:\n"
+		"	xorl	%%edi, %%edi\n"
+		"2:\n"
+		: "=&D" (edi), "=&c" (ecx), "=&a" (eax)
+		: "0" (s), "i" (c), "1" (count)
+		/* : no clobbers */
+	);
+	return edi;
+}
+#if 1 /* +2 bytes on shared i386 build with gcc 4.3.0 */
+#define memchr(s, c, count) ( \
+	__builtin_constant_p(c) \
+	? inlined_memchr_const_c(s, (c) & 0xff, count) \
+	: inlined_memchr(s, c, count) \
+	)
+#endif
+
+#endif /* _LIBC_STRING_i386_H  */
-- 
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