Should sh4add exist for non-CHERI

[arichardson]

Sh4add is used sometimes in SPEC, less than the other ones, but still more frequently than e.g. XOR

sh1add,31761
sh1add.uw,2620
sh2add,59792
sh2add.uw,11373
sh3add,80030
sh3add.uw,16346
sh4add,11630
sh4add.uw,5111

Some other counts for reference

sll,1593
slli,32842
slli.uw,8506
slliw,4013
sllw,1067
slt,5869
slti,4907
sltiu,46735
sltu,38754
sra,42
srai,5426
sraiw,2900
sraw,470
srl,1262
srli,22619
srliw,8606
srlw,785
sub,27380
subw,15601
sw,83862
xnor,9
xor,10111
xori,16697
zext.h,7781

[tariqkurd-repo]

IMHO that's something we can look at post ratification

[arichardson]

IMHO that's something we can look at post ratification

That's fine, just need to make sure we didn't use the shadd4 integer encoding.

[tariqkurd-repo]

That's fine, just need to make sure we didn't use the shadd4 integer encoding.

there isn't one - I repurposed the existing encoding for cap only

[arichardson]

That's fine, just need to make sure we didn't use the shadd4 integer encoding.

there isn't one - I repurposed the existing encoding for cap only

I meant the "natural" integer one

[tariqkurd-repo]

localparam [31:0] SH1ADD = 32'b0010000??????????010?????0110011;
localparam [31:0] SH1ADDY = 32'b0010000??????????011?????0110011;
localparam [31:0] SH2ADD = 32'b0010000??????????100?????0110011;
localparam [31:0] SH2ADDY = 32'b0010000??????????101?????0110011;
localparam [31:0] SH3ADD = 32'b0010000??????????110?????0110011;
localparam [31:0] SH3ADDY = 32'b0010000??????????000?????0110011;
localparam [31:0] SH4ADDY = 32'b0010000??????????111?????0110011;

currently 7/8 slots allocated in that group
swapping the encodings of SH3ADDY and SH4ADDY would be more regular (set the top bit to get the Y form)

[arichardson]

localparam [31:0] SH1ADD = 32'b0010000??????????010?????0110011; localparam [31:0] SH1ADDY = 32'b0010000??????????011?????0110011; localparam [31:0] SH2ADD = 32'b0010000??????????100?????0110011; localparam [31:0] SH2ADDY = 32'b0010000??????????101?????0110011; localparam [31:0] SH3ADD = 32'b0010000??????????110?????0110011; localparam [31:0] SH3ADDY = 32'b0010000??????????000?????0110011; localparam [31:0] SH4ADDY = 32'b0010000??????????111?????0110011;

currently 7/8 slots allocated in that group swapping the encodings of SH3ADDY and SH4ADDY would be more regular (set the top bit to get the Y form)

It sounds like using 100001 for sh4addy and reserving 000 for sh4add would make more sense? Then sh3addy can be 111

[jrtc27]

You mean 001 not 100?

[arichardson]

You mean 001 not 100?

Sorry yes that was a typo