Re: [Mesa-dev] [PATCH 2/2] llvmpipe: avoid most 64 bit math in rasterization

2016-01-06 Thread Jose Fonseca
On 06/01/16 18:18, Roland Scheidegger wrote: Am 06.01.2016 um 17:31 schrieb Jose Fonseca: On 06/01/16 16:26, Jose Fonseca wrote: On 06/01/16 00:06, srol...@vmware.com wrote: From: Roland Scheidegger The trick here is to recognize that in the c + n * dcdx calculations, not only can the lower

Re: [Mesa-dev] [PATCH 2/2] llvmpipe: avoid most 64 bit math in rasterization

2016-01-06 Thread Roland Scheidegger
Am 06.01.2016 um 17:31 schrieb Jose Fonseca: > On 06/01/16 16:26, Jose Fonseca wrote: >> On 06/01/16 00:06, srol...@vmware.com wrote: >>> From: Roland Scheidegger >>> >>> The trick here is to recognize that in the c + n * dcdx calculations, >>> not only can the lower FIXED_ORDER bits not change (a

Re: [Mesa-dev] [PATCH 2/2] llvmpipe: avoid most 64 bit math in rasterization

2016-01-06 Thread Jose Fonseca
On 06/01/16 16:26, Jose Fonseca wrote: On 06/01/16 00:06, srol...@vmware.com wrote: From: Roland Scheidegger The trick here is to recognize that in the c + n * dcdx calculations, not only can the lower FIXED_ORDER bits not change (as the dcdx values have those all zero) but that this means the

Re: [Mesa-dev] [PATCH 2/2] llvmpipe: avoid most 64 bit math in rasterization

2016-01-06 Thread Jose Fonseca
On 06/01/16 00:06, srol...@vmware.com wrote: From: Roland Scheidegger The trick here is to recognize that in the c + n * dcdx calculations, not only can the lower FIXED_ORDER bits not change (as the dcdx values have those all zero) but that this means the sign bit of the calculations cannot be

[Mesa-dev] [PATCH 2/2] llvmpipe: avoid most 64 bit math in rasterization

2016-01-05 Thread sroland
From: Roland Scheidegger The trick here is to recognize that in the c + n * dcdx calculations, not only can the lower FIXED_ORDER bits not change (as the dcdx values have those all zero) but that this means the sign bit of the calculations cannot be different as well, that is sign(c + n*dcdx) ==