Re: "Mini" tags to reduce the number of op codes

Scott Lurndal wrote:
 

mitchalsup@aol.com (MitchAlsup1) writes: 

BGB wrote:
>
>
In My 66000 case, the constant is the word following the
instruction. Easy to find, easy to access, no register pollution,
no DCache pollution. 

 

It does occupy some icache space, however; have you boosted the
icache size to compensate? 

 
The space occupied in the ICache is freed up from being in the DCache
so the overall hit rate goes up !! At typical sizes, ICache miss rate
is about ¼ the miss rate of DCache.
 
Besides:: if you had to LD the constant from memory, you use a LD
instruction and 1 or 2 words in DCache, while consuming a GPR. So,
overall, it takes fewer cycles, fewer GPRs, and fewer instructions.
 
Alternatively:: if you paste constants together (LUI, AUPIC) you have
no direct route to either 64-bit constants or 64-bit address spaces.
 
It looks to be a win-win !!