From: Arnd Bergmann <arnd@arndb.de> To: Bill Metzenthen <billm@melbpc.org.au>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, x86@kernel.org Cc: Arnd Bergmann <arnd@arndb.de>, "H. Peter Anvin" <hpa@zytor.com>, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com Subject: [PATCH] x86: math-emu: hide clang warnings for 16-bit overflow Date: Fri, 12 Jul 2019 11:08:05 +0200 Message-ID: <20190712090816.350668-1-arnd@arndb.de> (raw) 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 seems correct to me, so add a typecast to shut up the warnings. Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- 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 a5a41ec58072..0c122226ca56 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 8dc9095bab22..742619e94bdf 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 -- 2.20.0
next reply index Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-07-12 9:08 Arnd Bergmann [this message] 2019-07-16 21:22 ` [tip:x86/urgent] x86: math-emu: Hide " tip-bot for Arnd Bergmann 2019-07-16 22:46 ` tip-bot for Arnd Bergmann
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