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authorArnd Bergmann <arnd@arndb.de>2017-07-19 14:53:01 +0200
committerIngo Molnar <mingo@kernel.org>2017-07-20 10:46:24 +0200
commit5623452a0eaec1d44cc9f0770444a48847c9953f (patch)
tree83bd8824ec63c868493fc18135032896f2ce98ec /arch
parent75e2f0a6b16141cb347f442033ec907380d4d66e (diff)
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 <arnd@arndb.de> Cc: Bill Metzenthen <billm@melbpc.org.au> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> 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 <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/math-emu/fpu_emu.h2
1 files changed, 1 insertions, 1 deletions
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; }