On Tue, 6 Aug 2019 at 00:16, Paolo Bonzini <pbonz...@redhat.com> wrote: > > On 05/08/19 23:13, Richard Henderson wrote: > > On 8/5/19 11:03 AM, Peter Maydell wrote: > >> The x86 architecture requires that all conversions from floating > >> point to integer which raise the 'invalid' exception (infinities of > >> both signs, NaN, and all values which don't fit in the destination > >> integer) return what the x86 spec calls the "indefinite integer > >> value", which is 0x8000_0000 for 32-bits or 0x8000_0000_0000_0000 for > >> 64-bits. The softfloat functions return the more usual behaviour of > >> positive overflows returning the maximum value that fits in the > >> destination integer format and negative overflows returning the > >> minimum value that fits. > >> > >> Wrap the softfloat functions in x86-specific versions which > >> detect the 'invalid' condition and return the indefinite integer. > >> > >> Note that we don't use these wrappers for the 3DNow! pf2id and pf2iw > >> instructions, which do return the minimum value that fits in > >> an int32 if the input float is a large negative number. > >> > >> Fixes: https://bugs.launchpad.net/qemu/+bug/1815423 > >> Signed-off-by: Peter Maydell <peter.mayd...@linaro.org> > >> --- > >> I've tested that this fixes the LP:1815423 test case. If anybody > >> has an x86 VM image to hand that has node.js installed it would > >> also be useful to test the operations in > >> https://bugs.launchpad.net/qemu/+bug/1832281 > >> (I don't have such a VM.) > >> > >> The other approach here would be to make the softfloat functions be > >> flexible enough to allow this behaviour -- from my reading of IEEE754 > >> I think the exact returned result for 'invalid' inputs for float to > >> int conversions is not specified. > >> > >> target/i386/ops_sse.h | 88 +++++++++++++++++++++++++++++-------------- > >> 1 file changed, 60 insertions(+), 28 deletions(-) > > > > I guess this is exactly what we already do in fpu_helper.c. > > Reviewed-by: Richard Henderson <richard.hender...@linaro.org> > > > > > > r~ > > > > Queued, thanks.
Would you like me to do a quick respin to fix the overlong lines that checkpatch noticed ? thanks -- PMM
