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Cleanup and optimization of Zicclsm.

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This commit is contained in:
Rose Thompson 2023-11-13 14:28:22 -06:00
parent da59cb71a9
commit 707b0c557c
1 changed files with 22 additions and 24 deletions
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46
src/lsu/align.sv
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@ -58,6 +58,8 @@ module align import cvw::*; #(parameter cvw_t P) (
output logic [P.LLEN-1:0] DCacheReadDataWordSpillM, // The final 32 bit instruction after merging the two spilled fetches into 1 instruction
output logic SpillStallM);
localparam LLENINBYTES = P.LLEN/8;
localparam OFFSET_BIT_POS = $clog2(P.DCACHE_LINELENINBITS/8);
// Spill threshold occurs when all the cache offset PC bits are 1 (except [0]). Without a cache this is just PCF[1]
typedef enum logic [1:0] {STATE_READY, STATE_SPILL, STATE_STORE_DELAY} statetype;
@ -71,12 +73,16 @@ module align import cvw::*; #(parameter cvw_t P) (
logic [P.LLEN*2-1:0] ReadDataWordSpillAllM;
logic [P.LLEN*2-1:0] ReadDataWordSpillShiftedM;
localparam LLENINBYTES = P.LLEN/8;
logic [P.XLEN-1:0] IEUAdrIncrementM;
logic [(P.LLEN-1)*2/8:0] ByteMaskSaveM;
logic [(P.LLEN-1)*2/8:0] ByteMaskMuxM;
logic SaveByteMask;
logic HalfMisalignedM, WordMisalignedM;
logic [OFFSET_BIT_POS-1:$clog2(LLENINBYTES)] WordOffsetM;
logic [$clog2(LLENINBYTES)-1:0] ByteOffsetM;
logic HalfSpillM, WordSpillM;
logic [$clog2(LLENINBYTES)-1:0] AccessByteOffsetM;
/* verilator lint_off WIDTHEXPAND */
assign IEUAdrIncrementM = IEUAdrM + LLENINBYTES;
@ -92,11 +98,6 @@ module align import cvw::*; #(parameter cvw_t P) (
// 1) operation size
// 2) offset
// 3) access location within the cacheline
localparam OFFSET_BIT_POS = $clog2(P.DCACHE_LINELENINBITS/8);
logic [OFFSET_BIT_POS-1:$clog2(LLENINBYTES)] WordOffsetM;
logic [$clog2(LLENINBYTES)-1:0] ByteOffsetM;
logic HalfSpillM, WordSpillM;
logic [$clog2(LLENINBYTES)-1:0] AccessByteOffsetM;
assign {WordOffsetM, ByteOffsetM} = IEUAdrM[OFFSET_BIT_POS-1:0];
@ -109,17 +110,26 @@ module align import cvw::*; #(parameter cvw_t P) (
default: AccessByteOffsetM = ByteOffsetM;
endcase
end
assign HalfSpillM = (IEUAdrM[OFFSET_BIT_POS-1:1] == '1) & (ByteOffsetM[0] != '0) & Funct3M[1:0] == 2'b01;
assign WordSpillM = (IEUAdrM[OFFSET_BIT_POS-1:2] == '1) & (ByteOffsetM[1:0] != '0) & Funct3M[1:0] == 2'b10;
// compute misalignement
assign HalfMisalignedM = (ByteOffsetM[0] != '0) & Funct3M[1:0] == 2'b01;
assign WordMisalignedM = (ByteOffsetM[1:0] != '0) & Funct3M[1:0] == 2'b10;
assign HalfSpillM = (IEUAdrM[OFFSET_BIT_POS-1:1] == '1) & HalfMisalignedM;
assign WordSpillM = (IEUAdrM[OFFSET_BIT_POS-1:2] == '1) & WordMisalignedM;
if(P.LLEN == 64) begin
logic DoubleSpillM;
assign DoubleSpillM = (IEUAdrM[OFFSET_BIT_POS-1:3] == '1) & (ByteOffsetM[2:0] != '0) & Funct3M[1:0] == 2'b11;
logic DoubleMisalignedM;
assign DoubleMisalignedM = (ByteOffsetM[2:0] != '0) & Funct3M[1:0] == 2'b11;
assign DoubleSpillM = (IEUAdrM[OFFSET_BIT_POS-1:3] == '1) & DoubleMisalignedM;
assign MisalignedM = HalfMisalignedM | WordMisalignedM | DoubleMisalignedM;
assign SpillM = (|MemRWM) & CacheableM & (HalfSpillM | WordSpillM | DoubleSpillM);
end else begin
assign SpillM = (|MemRWM) & CacheableM & (HalfSpillM | WordSpillM);
assign MisalignedM = HalfMisalignedM | WordMisalignedM;
end
// align by shifting
// Don't take the spill if there is a stall, TLB miss, or hardware update to the D/A bits
assign TakeSpillM = SpillM & ~CacheBusHPWTStall & ~(DTLBMissM | (P.SVADU_SUPPORTED & DataUpdateDAM));
@ -151,24 +161,12 @@ module align import cvw::*; #(parameter cvw_t P) (
// Merge spilled data
////////////////////////////////////////////////////////////////////////////////////////////////////
// save the first 2 bytes
// save the first native word
flopenr #(P.LLEN) SpillDataReg(clk, reset, SpillSaveM, DCacheReadDataWordM[P.LLEN-1:0], ReadDataWordFirstHalfM);
// merge together
mux2 #(2*P.LLEN) postspillmux(DCacheReadDataWordM, {DCacheReadDataWordM[P.LLEN-1:0], ReadDataWordFirstHalfM}, SpillM, ReadDataWordSpillAllM);
mux2 #(2*P.LLEN) postspillmux(DCacheReadDataWordM, {DCacheReadDataWordM[P.LLEN-1:0], ReadDataWordFirstHalfM}, SelSpillM, ReadDataWordSpillAllM);
// align by shifting
// *** optimize by merging with halfSpill, WordSpill, etc
logic HalfMisalignedM, WordMisalignedM;
assign HalfMisalignedM = Funct3M[1:0] == 2'b01 & ByteOffsetM[0] != 1'b0;
assign WordMisalignedM = Funct3M[1:0] == 2'b10 & ByteOffsetM[1:0] != 2'b00;
if(P.LLEN == 64) begin
logic DoubleMisalignedM;
assign DoubleMisalignedM = Funct3M[1:0] == 2'b11 & ByteOffsetM[2:0] != 3'b00;
assign MisalignedM = HalfMisalignedM | WordMisalignedM | DoubleMisalignedM;
end else begin
assign MisalignedM = HalfMisalignedM | WordMisalignedM;
end
// shifter (4:1 mux for 32 bit, 8:1 mux for 64 bit)
// 8 * is for shifting by bytes not bits