On Mon, Oct 12, 2015 at 07:37:46PM +0200, Christophe Gisquet wrote: > When the input of a pass has 15 or 16 bits of precision (in particular > the column pass), the addition of a bias to W4 may lead to overflows > in the input to pmaddwd. > > This requires postponing the adding of the bias to after the first > butterfly. To do so, the fact that m15, unused although zeroed, is > exploited. In case the pass is safe, an address can be directly used, > and the number of xmm regs can be decreased. Otherwise, the 32bits bias > is loaded into it. > --- > libavcodec/x86/proresdsp.asm | 8 ++++---- > libavcodec/x86/simple_idct10_template.asm | 13 ++++++++++++- > 2 files changed, 16 insertions(+), 5 deletions(-)
how can i reproduce these overflows ? [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Opposition brings concord. Out of discord comes the fairest harmony. -- Heraclitus
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