Re: [PATCH] i386: DPPS rounding fix

2022-08-25 Thread Richard Henderson
On 8/25/22 09:48, Paolo Bonzini wrote: The DPPS (Dot Product) instruction is defined to first sum pairs of intermediate results, then sum those values to get the final result. i.e. (A+B)+(C+D) We incrementally sum the results, i.e. ((A+B)+C)+D, which can result in incorrect rouding. For consist

[PATCH] i386: DPPS rounding fix

2022-08-25 Thread Paolo Bonzini
The DPPS (Dot Product) instruction is defined to first sum pairs of intermediate results, then sum those values to get the final result. i.e. (A+B)+(C+D) We incrementally sum the results, i.e. ((A+B)+C)+D, which can result in incorrect rouding. For consistency, also change the variable names to t

[PATCH] i386: DPPS rounding fix

2022-08-25 Thread Paolo Bonzini
The DPPS (Dot Product) instruction is defined to first sum pairs of intermediate results, then sum those values to get the final result. i.e. (A+B)+(C+D) We incrementally sum the results, i.e. ((A+B)+C)+D, which can result in incorrect rouding. For consistency, also change the variable names to t