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    Subject[PATCH 4.19 27/74] x86: math-emu: Hide clang warnings for 16-bit overflow
    Date
    [ Upstream commit 29e7e9664aec17b94a9c8c5a75f8d216a206aa3a ]

    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
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/x86/math-emu/fpu_emu.h | 2 +-
    arch/x86/math-emu/reg_constant.c | 2 +-
    2 files changed, 2 insertions(+), 2 deletions(-)

    diff --git a/arch/x86/math-emu/fpu_emu.h b/arch/x86/math-emu/fpu_emu.h
    index a5a41ec580721..0c122226ca56f 100644
    --- a/arch/x86/math-emu/fpu_emu.h
    +++ b/arch/x86/math-emu/fpu_emu.h
    @@ -177,7 +177,7 @@ static inline void reg_copy(FPU_REG const *x, FPU_REG *y)
    #define setexponentpos(x,y) { (*(short *)&((x)->exp)) = \
    ((y) + EXTENDED_Ebias) & 0x7fff; }
    #define exponent16(x) (*(short *)&((x)->exp))
    -#define setexponent16(x,y) { (*(short *)&((x)->exp)) = (y); }
    +#define setexponent16(x,y) { (*(short *)&((x)->exp)) = (u16)(y); }
    #define addexponent(x,y) { (*(short *)&((x)->exp)) += (y); }
    #define stdexp(x) { (*(short *)&((x)->exp)) += EXTENDED_Ebias; }

    diff --git a/arch/x86/math-emu/reg_constant.c b/arch/x86/math-emu/reg_constant.c
    index 8dc9095bab224..742619e94bdf2 100644
    --- a/arch/x86/math-emu/reg_constant.c
    +++ b/arch/x86/math-emu/reg_constant.c
    @@ -18,7 +18,7 @@
    #include "control_w.h"

    #define MAKE_REG(s, e, l, h) { l, h, \
    - ((EXTENDED_Ebias+(e)) | ((SIGN_##s != 0)*0x8000)) }
    + (u16)((EXTENDED_Ebias+(e)) | ((SIGN_##s != 0)*0x8000)) }

    FPU_REG const CONST_1 = MAKE_REG(POS, 0, 0x00000000, 0x80000000);
    #if 0
    --
    2.20.1


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