ad284e38a3
and as long as we're not compiling with IPA, gcc(1) won't optimize the call away. The whole purpose of using memcpy(3) is to avoid misaligned loads and stores when we need to read or write the value in the unaligned memory location. But if gcc(1) optimizes the call to memcpy(3) away, it will typically introduce misaligned loads and stores. In this context that's not a good idea.
205 lines
5.1 KiB
C
205 lines
5.1 KiB
C
/*
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* Copyright (c) 2005 Marcel Moolenaar
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <machine/float.h>
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#include <string.h>
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/* Memory accesses. */
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#define Load 0x01
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#define Store 0x02
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/* Data type. */
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#define Integer 0x11
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#define FloatingPoint 0x12
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/* Data size. */
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#define Small 0x21
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#define Medium 0x22
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#define Large 0x23
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/* Post increment. */
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#define NoPostInc 0x31
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#define MinConstPostInc 0x32
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#define PlusConstPostInc 0x33
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#define ScratchRegPostInc 0x34
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#define PreservedRegPostInc 0x35
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#if ACCESS == 0 || TYPE == 0 || SIZE == 0 || POSTINC == 0
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#error define ACCESS, TYPE, SIZE and/or POSTINC
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#endif
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#if TYPE == Integer
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# define REG "r8"
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# if SIZE == Small
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# define DATA_TYPE short
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# define DATA_VALUE 0x1234
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# define LD "ld2"
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# define ST "st2"
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# elif SIZE == Medium
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# define DATA_TYPE int
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# define DATA_VALUE 0x12345678
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# define LD "ld4"
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# define ST "st4"
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# elif SIZE == Large
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# define DATA_TYPE long
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# define DATA_VALUE 0x1234567890ABCDEF
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# define LD "ld8"
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# define ST "st8"
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# endif
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#elif TYPE == FloatingPoint
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# define REG "f6"
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# if SIZE == Small
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# define DATA_TYPE float
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# define DATA_VALUE FLT_MIN
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# define LD "ldfs"
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# define ST "stfs"
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# elif SIZE == Medium
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# define DATA_TYPE double
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# define DATA_VALUE DBL_MIN
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# define LD "ldfd"
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# define ST "stfd"
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# elif SIZE == Large
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# define DATA_TYPE long double
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# define DATA_VALUE LDBL_MIN
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# define LD "ldfe"
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# define ST "stfe"
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# endif
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#endif
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struct {
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DATA_TYPE aligned;
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char _;
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char misaligned[sizeof(DATA_TYPE)];
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} data;
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DATA_TYPE *aligned = &data.aligned;
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DATA_TYPE *misaligned = (DATA_TYPE *)data.misaligned;
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DATA_TYPE value = DATA_VALUE;
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void
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block_copy(void *dst, void *src, size_t sz)
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{
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memcpy(dst, src, sz);
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}
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int
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main()
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{
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/* Set PSR.ac. */
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asm volatile("sum 8");
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#if ACCESS == Load
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/*
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* LOAD
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*/
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block_copy(misaligned, &value, sizeof(DATA_TYPE));
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# if POSTINC == NoPostInc
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/* Misaligned load. */
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*aligned = *misaligned;
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# elif POSTINC == MinConstPostInc
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asm volatile(
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"ld8 r2=%0;;"
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LD " " REG "=[r2],%2;;"
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"st8 %0=r2;" ST " %1=" REG ";;"
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: "=m"(misaligned), "=m"(*aligned)
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: "i"(-sizeof(DATA_TYPE))
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: REG, "r2", "memory");
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# elif POSTINC == PlusConstPostInc
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asm volatile(
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"ld8 r2=%0;;"
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LD " " REG "=[r2],%2;;"
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"st8 %0=r2;" ST " %1=" REG ";;"
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: "=m"(misaligned), "=m"(*aligned)
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: "i"(sizeof(DATA_TYPE))
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: REG, "r2", "memory");
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# elif POSTINC == ScratchRegPostInc
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asm volatile(
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"ld8 r2=%0; mov r3=%2;;"
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LD " " REG "=[r2],r3;;"
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"st8 %0=r2;" ST " %1=" REG ";;"
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: "=m"(misaligned), "=m"(*aligned)
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: "i"(sizeof(DATA_TYPE))
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: REG, "r2", "r3", "memory");
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# elif POSTINC == PreservedRegPostInc
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asm volatile(
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"ld8 r2=%0; mov r4=%2;;"
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LD " " REG "=[r2],r4;;"
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"st8 %0=r2;" ST " %1=" REG ";;"
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: "=m"(misaligned), "=m"(*aligned)
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: "i"(sizeof(DATA_TYPE))
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: REG, "r2", "r4", "memory");
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# endif
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#elif ACCESS == Store
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/*
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* STORE
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*/
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# if POSTINC == NoPostInc
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/* Misaligned store. */
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*misaligned = value;
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# elif POSTINC == MinConstPostInc
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asm volatile(
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"ld8 r2=%0;" LD " " REG "=%1;;"
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ST " [r2]=" REG ",%2;;"
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"st8 %0=r2;;"
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: "=m"(misaligned)
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: "m"(value), "i"(-sizeof(DATA_TYPE))
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: REG, "r2", "memory");
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# elif POSTINC == PlusConstPostInc
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asm volatile(
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"ld8 r2=%0;" LD " " REG "=%1;;"
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ST " [r2]=" REG ",%2;;"
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"st8 %0=r2;;"
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: "=m"(misaligned)
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: "m"(value), "i"(sizeof(DATA_TYPE))
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: REG, "r2", "memory");
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# elif POSTINC == ScratchRegPostInc || POSTINC == PreservedRegPostInc
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return (1);
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# endif
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block_copy(aligned, data.misaligned, sizeof(DATA_TYPE));
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#endif
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if (*aligned != value)
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return (2);
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#if POSTINC == NoPostInc
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return (0);
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#elif POSTINC == MinConstPostInc
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return (((char *)misaligned == data.misaligned - sizeof(DATA_TYPE))
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? 0 : 4);
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#else
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return (((char *)misaligned == data.misaligned + sizeof(DATA_TYPE))
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? 0 : 4);
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#endif
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}
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