828bf6828b
On i386, the double version of exp10 can miss underflow exceptions if the result is in the subnormal range for double but the last 11 bits of the 64-bit extended-precision mantissa happen to be zero. This patch forces the exception in a similar way to previous fixes. As with the exp2 and exp fixes, the exp10f changes may in fact not be needed to ensure underflow exceptions, but are included for consistency and to fix the exp10 part of bug 18875 by ensuring that excess range and precision is removed from underflowing return values. Tested for x86_64 and x86. [BZ #18875] [BZ #18966] * sysdeps/i386/fpu/e_exp10.S (dbl_min): New object. (MO): New macro. (__ieee754_exp10): For small results, force underflow exception and remove excess range and precision from return value. * sysdeps/i386/fpu/e_exp10f.S (flt_min): New object. (MO): New macro. (__ieee754_exp10f): For small results, force underflow exception and remove excess range and precision from return value. * math/auto-libm-test-in: Add more tests of exp10. * math/auto-libm-test-out: Regenerated.
72 lines
1.4 KiB
ArmAsm
72 lines
1.4 KiB
ArmAsm
/*
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* Written by Ulrich Drepper.
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*/
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#include <machine/asm.h>
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.section .rodata.cst4,"aM",@progbits,4
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.p2align 2
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.type flt_min,@object
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flt_min: .byte 0, 0, 0x80, 0
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ASM_SIZE_DIRECTIVE(flt_min)
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#ifdef PIC
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# define MO(op) op##@GOTOFF(%ecx)
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#else
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# define MO(op) op
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#endif
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.text
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/* 10^x = 2^(x * log2(10)) */
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ENTRY(__ieee754_exp10f)
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#ifdef PIC
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LOAD_PIC_REG (cx)
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#endif
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flds 4(%esp)
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/* I added the following ugly construct because exp(+-Inf) resulted
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in NaN. The ugliness results from the bright minds at Intel.
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For the i686 the code can be written better.
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-- drepper@cygnus.com. */
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fxam /* Is NaN or +-Inf? */
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fstsw %ax
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movb $0x45, %dh
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andb %ah, %dh
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cmpb $0x05, %dh
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je 1f /* Is +-Inf, jump. */
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fldl2t
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fmulp /* x * log2(10) */
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fld %st
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frndint /* int(x * log2(10)) */
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fsubr %st,%st(1) /* fract(x * log2(10)) */
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fxch
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f2xm1 /* 2^(fract(x * log2(10))) - 1 */
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fld1
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faddp /* 2^(fract(x * log2(10))) */
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fscale /* e^x */
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fstp %st(1)
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flds MO(flt_min)
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fld %st(1)
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fucompp
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fnstsw
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sahf
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jnc 3f
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subl $4, %esp
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cfi_adjust_cfa_offset (4)
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fld %st(0)
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fmul %st(0)
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fstps (%esp)
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fstps (%esp)
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flds (%esp)
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addl $4, %esp
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cfi_adjust_cfa_offset (-4)
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3: ret
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1: testl $0x200, %eax /* Test sign. */
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jz 2f /* If positive, jump. */
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fstp %st
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fldz /* Set result to 0. */
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2: ret
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END (__ieee754_exp10f)
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strong_alias (__ieee754_exp10f, __exp10f_finite)
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