From 5623452a0eaec1d44cc9f0770444a48847c9953f Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Wed, 19 Jul 2017 14:53:01 +0200 Subject: [PATCH] x86/fpu/math-emu: Avoid bogus -Wint-in-bool-context warning gcc-7.1.1 produces this warning: arch/x86/math-emu/reg_add_sub.c: In function 'FPU_add': arch/x86/math-emu/reg_add_sub.c:80:48: error: ?: using integer constants in boolean context [-Werror=int-in-bool-context] This appears to be a bug in gcc-7.1.1, and I have reported it as PR81484. The compiler suggests that code written as if (a & b ? c : d) is usually incorrect and should have been if (a & (b ? c : d)) However, in this case, we correctly write if ((a & b) ? c : d) and should not get a warning for it. This adds a dirty workaround for the problem, adding a comparison with zero inside of the macro. The warning is currently disabled in the kernel, so we may decide not to apply the patch, and instead wait for future gcc releases to fix the problem. On the other hand, it seems to be the only instance of this particular problem. Signed-off-by: Arnd Bergmann Cc: Bill Metzenthen Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20170719125310.2487451-4-arnd@arndb.de Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81484 Signed-off-by: Ingo Molnar --- arch/x86/math-emu/fpu_emu.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/math-emu/fpu_emu.h b/arch/x86/math-emu/fpu_emu.h index afbc4d805d66..c9c320dccca1 100644 --- a/arch/x86/math-emu/fpu_emu.h +++ b/arch/x86/math-emu/fpu_emu.h @@ -157,7 +157,7 @@ extern u_char const data_sizes_16[32]; #define signbyte(a) (((u_char *)(a))[9]) #define getsign(a) (signbyte(a) & 0x80) -#define setsign(a,b) { if (b) signbyte(a) |= 0x80; else signbyte(a) &= 0x7f; } +#define setsign(a,b) { if ((b) != 0) signbyte(a) |= 0x80; else signbyte(a) &= 0x7f; } #define copysign(a,b) { if (getsign(a)) signbyte(b) |= 0x80; \ else signbyte(b) &= 0x7f; } #define changesign(a) { signbyte(a) ^= 0x80; } -- GitLab