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Hello! According to C99, reminder function returns: If x or y is a NaN, a NaN is returned. If x is an infinity, and y is not a NaN, a domain error occurs, and a NaN is returned. If y is zero, and x is not a NaN, a domain error occurs, and a NaN is returned. and fmod returns: If x or y is a NaN, a NaN is returned. If x is an infinity, a domain error occurs, and a NaN is returned. If y is zero, a domain error occurs, and a NaN is returned. If x is +0 (-0), and y is not zero, +0 (-0) is returned. However, x87 fprem and fprem1 instructions that are used to implement these builtin functions do not return NaN for infinities, but generate invalid-arithmetic-operand exception. Attached patch enables these builtins for finite math only, consistent with gcc documentation: '-ffinite-math-only': Allow optimizations for floating-point arithmetic that assume that arguments and results are not NaNs or +-Infs. This option is not turned on by any '-O' option since it can result in incorrect output for programs that depend on an exact implementation of IEEE or ISO rules/specifications for math functions. It may, however, yield faster code for programs that do not require the guarantees of these specifications. 2014-09-30 Uros Bizjak <ubizjak@gmail.com> * config/i386/i386.md (fmodxf3): Enable for flag_finite_math_only only. (fmod<mode>3): Ditto. (fpremxf4_i387): Ditto. (reminderxf3): Ditto. (reminder<mode>3): Ditto. (fprem1xf4_i387): Ditto. Patch was bootstrapped and regression tested on x86_64-linux-gnu {,-m32}. The patch also fixes ieee_2.f90 testsuite failure with FX's pending IEEE support improvement patch. 2014-09-30 Uros Bizjak <ubizjak@gmail.com> * config/i386/i386.md (fmodxf3): Enable for flag_finite_math_only only. (fmod<mode>3): Ditto. (fpremxf4_i387): Ditto. (reminderxf3): Ditto. (reminder<mode>3): Ditto. (fprem1xf4_i387): Ditto. The patch will be committed to mainline and other release branches. Uros.
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