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Detect illegal compressed immediates, hints

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David Harris 2024-07-18 22:48:32 -07:00
parent 945722cd5b
commit c64c12dc6c
1 changed files with 60 additions and 58 deletions
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18
src/ifu/decompress.sv
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@ -64,10 +64,10 @@ module decompress import cvw::*; #(parameter cvw_t P) (
assign immCJ = {instr16[12], instr16[8], instr16[10:9], instr16[6], instr16[7], instr16[2], instr16[11], instr16[5:3], {9{instr16[12]}}};
assign immCB = {{4{instr16[12]}}, instr16[6:5], instr16[2], instr16[11:10], instr16[4:3], instr16[12]};
assign immCI = {{7{instr16[12]}}, instr16[6:2]};
assign immCILUI = {{15{instr16[12]}}, instr16[6:2]};
assign immCIASP = {{3{instr16[12]}}, instr16[4:3], instr16[5], instr16[2], instr16[6], 4'b0000};
assign immCILUI = {{15{instr16[12]}}, instr16[6:2]}; // c.lui
assign immCIASP = {{3{instr16[12]}}, instr16[4:3], instr16[5], instr16[2], instr16[6], 4'b0000}; // c.addi16sp
assign immCIW = {2'b00, instr16[10:7], instr16[12:11], instr16[5], instr16[6], 2'b00};
assign immSH = {instr16[12], instr16[6:2]};
assign immSH = {instr16[12], instr16[6:2]}; // c. shift instructions: c.srli, c.srai, c.slli
// only for RV128
// assign immCILSPQ = {2{instr16[5]}, instr16[5:2], instr16[12], instr16[6], 4'b0000};
@ -100,19 +100,21 @@ module decompress import cvw::*; #(parameter cvw_t P) (
5'b00110: LInstrD = {1'b1, immCS[11:5], rs2p, rs1p, 3'b010, immCS[4:0], 7'b0100011}; // c.sw
5'b00111: if (P.XLEN==32) begin
if (P.ZCF_SUPPORTED) LInstrD = {1'b1, immCS[11:5], rs2p, rs1p, 3'b010, immCS[4:0], 7'b0100111}; // c.fsw
end else LInstrD = {1'b1, immCSD[11:5], rs2p, rs1p, 3'b011, immCSD[4:0], 7'b0100011}; //c.sd
end else LInstrD = {1'b1, immCSD[11:5], rs2p, rs1p, 3'b011, immCSD[4:0], 7'b0100011}; // c.sd
5'b01000: if (rds1 != 5'b0)
if (immCI[5:0] != 0) LInstrD = {1'b1, immCI, rds1, 3'b000, rds1, 7'b0010011}; // c.addi
else LInstrD = {1'b1, 25'b0, 7'b0010011}; // c.addi with imm = 0 is a HINT, treated as nop
else if (immCI[5:0] == 6'b0) LInstrD = {1'b1, 25'b0, 7'b0010011}; // c.nop
else if (immCI[5:0] == 6'b0) LInstrD = {1'b1, 25'b0, 7'b0010011}; // c.nop = addi x0, x0, 0
else LInstrD = {1'b1, 25'b0, 7'b0010011}; // c.nop with imm != 0 is a HINT, treated as nop
5'b01001: if (P.XLEN==32) LInstrD = {1'b1, immCJ, 5'b00001, 7'b1101111}; // c.jal
else if (rds1 != 5'b0) LInstrD = {1'b1, immCI, rds1, 3'b000, rds1, 7'b0011011}; // c.addiw
5'b01010: if (rds1 != 5'b0) LInstrD = {1'b1, immCI, 5'b00000, 3'b000, rds1, 7'b0010011}; // c.li
else LInstrD = {1'b1, 25'b0, 7'b0010011}; // c.li with rd = 0 is a HINT, treated as nop
5'b01011: if (rds1 == 5'b00010) LInstrD = {1'b1, immCIASP, rds1, 3'b000, rds1, 7'b0010011}; // c.addi16sp
else if (rds1 != 5'b0) LInstrD = {1'b1, immCILUI, rds1, 7'b0110111}; // c.lui
else if (immCILUI[5:0] != 0) LInstrD = {1'b1, 25'b0, 7'b0010011}; // c.lui with rd = 0, imm!=0 is a HINT, treated as nop
5'b01011: if (rds1 == 5'b00010) begin
if (immCIASP[9:4] != 6'b0) LInstrD = {1'b1, immCIASP, rds1, 3'b000, rds1, 7'b0010011}; // c.addi16sp
end else if (immCILUI[5:0] != 0)
if (rds1 != 5'b0) LInstrD = {1'b1, immCILUI, rds1, 7'b0110111}; // c.lui
else LInstrD = {1'b1, 25'b0, 7'b0010011}; // c.lui with rd = 0, imm!=0 is a HINT, treated as nop
5'b01100: if (instr16[11:10] == 2'b00) begin
if (P.XLEN > 32 | ~immSH[5]) LInstrD = {1'b1, 6'b000000, immSH, rds1p, 3'b101, rds1p, 7'b0010011}; // c.srli; shamt[5] must be 0 in RV32C
end else if (instr16[11:10] == 2'b01) begin