Re: [PATCH][V2] net: dsa: mv88e6xxx: avoid unintended sign extension on a 16 bit shift

2018-02-19 Thread Richard Cochran
On Mon, Feb 19, 2018 at 12:19:16PM +, David Laight wrote: > This seems to be somewhat excessive 64bit maths on a 32bit system. > It is more than enough to make timelo/timehi 'unsigned int'. Do you see a difference in the generated code? Thanks, Richard

Re: [PATCH][V2] net: dsa: mv88e6xxx: avoid unintended sign extension on a 16 bit shift

2018-02-19 Thread Richard Cochran
On Mon, Feb 19, 2018 at 12:19:16PM +, David Laight wrote: > This seems to be somewhat excessive 64bit maths on a 32bit system. > It is more than enough to make timelo/timehi 'unsigned int'. Do you see a difference in the generated code? Thanks, Richard

RE: [PATCH][V2] net: dsa: mv88e6xxx: avoid unintended sign extension on a 16 bit shift

2018-02-19 Thread David Laight
From: Colin King > Sent: 16 February 2018 16:55 > > From: Colin Ian King > > The shifting of timehi by 16 bits to the left will be promoted to > a 32 bit signed int and then sign-extended to an u64. If the top bit > of timehi is set then all then all the upper bits of

RE: [PATCH][V2] net: dsa: mv88e6xxx: avoid unintended sign extension on a 16 bit shift

2018-02-19 Thread David Laight
From: Colin King > Sent: 16 February 2018 16:55 > > From: Colin Ian King > > The shifting of timehi by 16 bits to the left will be promoted to > a 32 bit signed int and then sign-extended to an u64. If the top bit > of timehi is set then all then all the upper bits of ns end up as also > being

Re: [PATCH][V2] net: dsa: mv88e6xxx: avoid unintended sign extension on a 16 bit shift

2018-02-16 Thread David Miller
From: Colin King Date: Fri, 16 Feb 2018 16:55:05 + > From: Colin Ian King > > The shifting of timehi by 16 bits to the left will be promoted to > a 32 bit signed int and then sign-extended to an u64. If the top bit > of timehi is set then

Re: [PATCH][V2] net: dsa: mv88e6xxx: avoid unintended sign extension on a 16 bit shift

2018-02-16 Thread David Miller
From: Colin King Date: Fri, 16 Feb 2018 16:55:05 + > From: Colin Ian King > > The shifting of timehi by 16 bits to the left will be promoted to > a 32 bit signed int and then sign-extended to an u64. If the top bit > of timehi is set then all then all the upper bits of ns end up as also >