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9438b237ab
Various x86 / x86_64 versions of scalb / scalbf / scalbl produce spurious "invalid" exceptions for (qNaN, -Inf) arguments, because this is wrongly handled like (+/-Inf, -Inf) which *should* raise such an exception. (In fact the NaN case of the code determining whether to quietly return a zero or a NaN for second argument -Inf was accidentally dead since the code had been made to return a NaN with exception.) This patch fixes the code to do the proper test for an infinity as distinct from a NaN. (Since the existing code does nothing to distinguish qNaNs and sNaNs here, this patch doesn't either. If in future we systematically implement proper sNaN semantics following TS 18661-1:2014, there will be lots of bugs to address - Thomas found lots of issues with his patch <https://sourceware.org/ml/libc-ports/2013-04/msg00008.html> to add SNaN tests (which never went in and would now require significant reworking).) Tested for x86_64 and x86. Committed. [BZ #16783] * sysdeps/i386/fpu/e_scalb.S (__ieee754_scalb): Do not handle arguments (NaN, -Inf) the same as (+/-Inf, -Inf). * sysdeps/i386/fpu/e_scalbf.S (__ieee754_scalbf): Likewise. * sysdeps/i386/fpu/e_scalbl.S (__ieee754_scalbl): Likewise. * sysdeps/x86_64/fpu/e_scalbl.S (__ieee754_scalbl): Likewise. * math/libm-test.inc (scalb_test_data): Add more tests.
99 lines
1.5 KiB
ArmAsm
99 lines
1.5 KiB
ArmAsm
/*
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* Written by J.T. Conklin <jtc@netbsd.org>.
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* Public domain.
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*
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* Correct handling of y==-inf <drepper@gnu>
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*/
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#include <machine/asm.h>
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.section .rodata
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.align ALIGNARG(4)
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.type zero_nan,@object
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zero_nan:
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.double 0.0
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nan: .byte 0, 0, 0, 0, 0, 0, 0xff, 0x7f
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.byte 0, 0, 0, 0, 0, 0, 0, 0x80
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.byte 0, 0, 0, 0, 0, 0, 0xff, 0x7f
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ASM_SIZE_DIRECTIVE(zero_nan)
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#ifdef PIC
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# define MO(op) op##@GOTOFF(%ecx)
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# define MOX(op,x,f) op##@GOTOFF(%ecx,x,f)
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#else
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# define MO(op) op
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# define MOX(op,x,f) op(,x,f)
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#endif
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.text
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ENTRY(__ieee754_scalb)
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fldl 12(%esp)
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fxam
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fnstsw
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fldl 4(%esp)
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andl $0x4700, %eax
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cmpl $0x0700, %eax
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je 1f
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andl $0x4500, %eax
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cmpl $0x0100, %eax
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je 2f
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fxam
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fnstsw
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andl $0x4500, %eax
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cmpl $0x0100, %eax
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je 3f
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fld %st(1)
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frndint
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fcomp %st(2)
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fnstsw
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sahf
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jne 4f
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fscale
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fstp %st(1)
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ret
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/* y is -inf */
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1: fxam
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#ifdef PIC
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LOAD_PIC_REG (cx)
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#endif
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fnstsw
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movl 8(%esp), %edx
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shrl $5, %eax
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fstp %st
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fstp %st
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andl $0x80000000, %edx
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andl $0x0228, %eax
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cmpl $0x0028, %eax
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je 4f
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andl $8, %eax
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shrl $27, %edx
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addl %edx, %eax
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fldl MOX(zero_nan, %eax, 1)
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ret
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/* The result is NaN, but we must not raise an exception.
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So use a variable. */
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2: fstp %st
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fstp %st
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#ifdef PIC
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LOAD_PIC_REG (cx)
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#endif
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fldl MO(nan)
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ret
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/* The first parameter is a NaN. Return it. */
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3: fstp %st(1)
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ret
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/* Return NaN and raise the invalid exception. */
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4: fstp %st
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fstp %st
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fldz
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fdiv %st
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ret
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END(__ieee754_scalb)
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strong_alias (__ieee754_scalb, __scalb_finite)
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