linux-stable/arch/x86/math-emu/reg_constant.c
Arnd Bergmann 29e7e9664a x86: math-emu: Hide clang warnings for 16-bit overflow
clang warns about a few parts of the math-emu implementation
where a 16-bit integer becomes negative during assignment:

arch/x86/math-emu/poly_tan.c:88:35: error: implicit conversion from 'int' to 'short' changes value from 49216 to -16320 [-Werror,-Wconstant-conversion]
                                      (0x41 + EXTENDED_Ebias) | SIGN_Negative);
                                      ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~
arch/x86/math-emu/fpu_emu.h:180:58: note: expanded from macro 'setexponent16'
 #define setexponent16(x,y)  { (*(short *)&((x)->exp)) = (y); }
                                                      ~  ^
arch/x86/math-emu/reg_constant.c:37:32: error: implicit conversion from 'int' to 'short' changes value from 49085 to -16451 [-Werror,-Wconstant-conversion]
FPU_REG const CONST_PI2extra = MAKE_REG(NEG, -66,
                               ^~~~~~~~~~~~~~~~~~
arch/x86/math-emu/reg_constant.c:21:25: note: expanded from macro 'MAKE_REG'
                ((EXTENDED_Ebias+(e)) | ((SIGN_##s != 0)*0x8000)) }
                 ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
arch/x86/math-emu/reg_constant.c:48:28: error: implicit conversion from 'int' to 'short' changes value from 65535 to -1 [-Werror,-Wconstant-conversion]
FPU_REG const CONST_QNaN = MAKE_REG(NEG, EXP_OVER, 0x00000000, 0xC0000000);
                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/x86/math-emu/reg_constant.c:21:25: note: expanded from macro 'MAKE_REG'
                ((EXTENDED_Ebias+(e)) | ((SIGN_##s != 0)*0x8000)) }
                 ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

The code is correct as is, so add a typecast to shut up the warnings.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190712090816.350668-1-arnd@arndb.de
2019-07-17 00:42:26 +02:00

118 lines
3.8 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*---------------------------------------------------------------------------+
| reg_constant.c |
| |
| All of the constant FPU_REGs |
| |
| Copyright (C) 1992,1993,1994,1997 |
| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
| Australia. E-mail billm@suburbia.net |
| |
| |
+---------------------------------------------------------------------------*/
#include "fpu_system.h"
#include "fpu_emu.h"
#include "status_w.h"
#include "reg_constant.h"
#include "control_w.h"
#define MAKE_REG(s, e, l, h) { l, h, \
(u16)((EXTENDED_Ebias+(e)) | ((SIGN_##s != 0)*0x8000)) }
FPU_REG const CONST_1 = MAKE_REG(POS, 0, 0x00000000, 0x80000000);
#if 0
FPU_REG const CONST_2 = MAKE_REG(POS, 1, 0x00000000, 0x80000000);
FPU_REG const CONST_HALF = MAKE_REG(POS, -1, 0x00000000, 0x80000000);
#endif /* 0 */
static FPU_REG const CONST_L2T = MAKE_REG(POS, 1, 0xcd1b8afe, 0xd49a784b);
static FPU_REG const CONST_L2E = MAKE_REG(POS, 0, 0x5c17f0bc, 0xb8aa3b29);
FPU_REG const CONST_PI = MAKE_REG(POS, 1, 0x2168c235, 0xc90fdaa2);
FPU_REG const CONST_PI2 = MAKE_REG(POS, 0, 0x2168c235, 0xc90fdaa2);
FPU_REG const CONST_PI4 = MAKE_REG(POS, -1, 0x2168c235, 0xc90fdaa2);
static FPU_REG const CONST_LG2 = MAKE_REG(POS, -2, 0xfbcff799, 0x9a209a84);
static FPU_REG const CONST_LN2 = MAKE_REG(POS, -1, 0xd1cf79ac, 0xb17217f7);
/* Extra bits to take pi/2 to more than 128 bits precision. */
FPU_REG const CONST_PI2extra = MAKE_REG(NEG, -66,
0xfc8f8cbb, 0xece675d1);
/* Only the sign (and tag) is used in internal zeroes */
FPU_REG const CONST_Z = MAKE_REG(POS, EXP_UNDER, 0x0, 0x0);
/* Only the sign and significand (and tag) are used in internal NaNs */
/* The 80486 never generates one of these
FPU_REG const CONST_SNAN = MAKE_REG(POS, EXP_OVER, 0x00000001, 0x80000000);
*/
/* This is the real indefinite QNaN */
FPU_REG const CONST_QNaN = MAKE_REG(NEG, EXP_OVER, 0x00000000, 0xC0000000);
/* Only the sign (and tag) is used in internal infinities */
FPU_REG const CONST_INF = MAKE_REG(POS, EXP_OVER, 0x00000000, 0x80000000);
static void fld_const(FPU_REG const * c, int adj, u_char tag)
{
FPU_REG *st_new_ptr;
if (STACK_OVERFLOW) {
FPU_stack_overflow();
return;
}
push();
reg_copy(c, st_new_ptr);
st_new_ptr->sigl += adj; /* For all our fldxxx constants, we don't need to
borrow or carry. */
FPU_settag0(tag);
clear_C1();
}
/* A fast way to find out whether x is one of RC_DOWN or RC_CHOP
(and not one of RC_RND or RC_UP).
*/
#define DOWN_OR_CHOP(x) (x & RC_DOWN)
static void fld1(int rc)
{
fld_const(&CONST_1, 0, TAG_Valid);
}
static void fldl2t(int rc)
{
fld_const(&CONST_L2T, (rc == RC_UP) ? 1 : 0, TAG_Valid);
}
static void fldl2e(int rc)
{
fld_const(&CONST_L2E, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
}
static void fldpi(int rc)
{
fld_const(&CONST_PI, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
}
static void fldlg2(int rc)
{
fld_const(&CONST_LG2, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
}
static void fldln2(int rc)
{
fld_const(&CONST_LN2, DOWN_OR_CHOP(rc) ? -1 : 0, TAG_Valid);
}
static void fldz(int rc)
{
fld_const(&CONST_Z, 0, TAG_Zero);
}
typedef void (*FUNC_RC) (int);
static FUNC_RC constants_table[] = {
fld1, fldl2t, fldl2e, fldpi, fldlg2, fldln2, fldz, (FUNC_RC) FPU_illegal
};
void fconst(void)
{
(constants_table[FPU_rm]) (control_word & CW_RC);
}