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Fixed bmu shift decode logic: bad funct7 for variable shifts, commented better, removed unnecessary guard

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David Harris 2024-11-29 05:58:14 -08:00
parent 722dc9bfda
commit cf47dd7e6b
1 changed files with 13 additions and 12 deletions
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25
src/ieu/bmu/bmuctrl.sv
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@ -152,18 +152,19 @@ module bmuctrl import cvw::*; #(parameter cvw_t P) (
endcase
end
if (P.ZBB_SUPPORTED | P.ZBS_SUPPORTED) // rv32i/64i shift instructions need BMU ALUSelect when BMU shifter is used
if (P.XLEN == 64 | !Funct7D[0])
casez({OpD, Funct7D, Funct3D})
// rv32i shifts cannot shift by more than 31. w-type shifts only supported in RV64
17'b0110011_000000?_001: if (P.XLEN == 64 | !Funct7D[0]) BMUControlsD = `BMUCTRLW'b001_0000_0000_1_0_0_0_1_0_0_0_0_0; // sll
17'b0110011_0?0000?_101: if (P.XLEN == 64 | !Funct7D[0]) BMUControlsD = `BMUCTRLW'b001_0000_0000_1_0_0_0_1_0_0_0_0_0; // sra, srl
17'b0010011_000000?_001: if (P.XLEN == 64 | !Funct7D[0]) BMUControlsD = `BMUCTRLW'b001_0000_0000_1_1_0_0_1_0_0_0_0_0; // slli
17'b0010011_0?0000?_101: if (P.XLEN == 64 | !Funct7D[0]) BMUControlsD = `BMUCTRLW'b001_0000_0000_1_1_0_0_1_0_0_0_0_0; // srai, srli
17'b0111011_0000000_001: if (P.XLEN == 64) BMUControlsD = `BMUCTRLW'b001_0000_0000_1_0_1_0_1_0_0_0_0_0; // sllw
17'b0111011_0?00000_101: if (P.XLEN == 64) BMUControlsD = `BMUCTRLW'b001_0000_0000_1_0_1_0_1_0_0_0_0_0; // sraw, srlw
17'b0011011_0000000_001: if (P.XLEN == 64) BMUControlsD = `BMUCTRLW'b001_0000_0000_1_1_1_0_1_0_0_0_0_0; // slliw
17'b0011011_0?00000_101: if (P.XLEN == 64) BMUControlsD = `BMUCTRLW'b001_0000_0000_1_1_1_0_1_0_0_0_0_0; // sraiw, srliw
endcase
casez({OpD, Funct7D, Funct3D})
// variable shifts don't encode shift amount in funct7
17'b0110011_0000000_001: BMUControlsD = `BMUCTRLW'b001_0000_0000_1_0_0_0_1_0_0_0_0_0; // sll
17'b0110011_0?00000_101: BMUControlsD = `BMUCTRLW'b001_0000_0000_1_0_0_0_1_0_0_0_0_0; // sra, srl
// Immediate Shifts by more than 32 (Funct7[0]) are only supported in RV64
17'b0010011_000000?_001: if (P.XLEN == 64 | !Funct7D[0]) BMUControlsD = `BMUCTRLW'b001_0000_0000_1_1_0_0_1_0_0_0_0_0; // slli
17'b0010011_0?0000?_101: if (P.XLEN == 64 | !Funct7D[0]) BMUControlsD = `BMUCTRLW'b001_0000_0000_1_1_0_0_1_0_0_0_0_0; // srai, srli
// w-type shifts only supported in RV64 and must have Funct7[0] = 0 because the shift amount is < 32
17'b0111011_0000000_001: if (P.XLEN == 64) BMUControlsD = `BMUCTRLW'b001_0000_0000_1_0_1_0_1_0_0_0_0_0; // sllw
17'b0111011_0?00000_101: if (P.XLEN == 64) BMUControlsD = `BMUCTRLW'b001_0000_0000_1_0_1_0_1_0_0_0_0_0; // sraw, srlw
17'b0011011_0000000_001: if (P.XLEN == 64) BMUControlsD = `BMUCTRLW'b001_0000_0000_1_1_1_0_1_0_0_0_0_0; // slliw
17'b0011011_0?00000_101: if (P.XLEN == 64) BMUControlsD = `BMUCTRLW'b001_0000_0000_1_1_1_0_1_0_0_0_0_0; // sraiw, srliw
endcase
if (P.ZBKB_SUPPORTED) begin // ZBKB Bitmanip
casez({OpD,Funct7D, Funct3D})