Detect illegal compressed immediates, hints

This commit is contained in:
David Harris 2024-07-18 22:48:32 -07:00
parent bd1658754f
commit 12c8449275

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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};
@ -81,97 +81,99 @@ module decompress import cvw::*; #(parameter cvw_t P) (
end else begin // convert compressed instruction into uncompressed
LInstrD = {1'b0, 16'b0, instr16}; // if a legal instruction is not decoded, default to illegal and preserve 16-bit value for mtval
case ({op, instr16[15:13]})
5'b00000: if (immCIW != 0) LInstrD = {1'b1, immCIW, 5'b00010, 3'b000, rdp, 7'b0010011}; // c.addi4spn
5'b00001: if (P.ZCD_SUPPORTED) LInstrD = {1'b1, immCLD, rs1p, 3'b011, rdp, 7'b0000111}; // c.fld
5'b00010: LInstrD = {1'b1, immCL, rs1p, 3'b010, rdp, 7'b0000011}; // c.lw
5'b00000: if (immCIW != 0) LInstrD = {1'b1, immCIW, 5'b00010, 3'b000, rdp, 7'b0010011}; // c.addi4spn
5'b00001: if (P.ZCD_SUPPORTED) LInstrD = {1'b1, immCLD, rs1p, 3'b011, rdp, 7'b0000111}; // c.fld
5'b00010: LInstrD = {1'b1, immCL, rs1p, 3'b010, rdp, 7'b0000011}; // c.lw
5'b00011: if (P.XLEN==32) begin
if (P.ZCF_SUPPORTED) LInstrD = {1'b1, immCL, rs1p, 3'b010, rdp, 7'b0000111}; // c.flw
end else LInstrD = {1'b1, immCLD, rs1p, 3'b011, rdp, 7'b0000011}; // c.ld
if (P.ZCF_SUPPORTED) LInstrD = {1'b1, immCL, rs1p, 3'b010, rdp, 7'b0000111}; // c.flw
end else LInstrD = {1'b1, immCLD, rs1p, 3'b011, rdp, 7'b0000011}; // c.ld
5'b00100: if (P.ZCB_SUPPORTED)
if (instr16[12:10] == 3'b000) LInstrD = {1'b1, 10'b0, instr16[5], instr16[6], rs1p, 3'b100, rdp, 7'b0000011}; // c.lbu
if (instr16[12:10] == 3'b000) LInstrD = {1'b1, 10'b0, instr16[5], instr16[6], rs1p, 3'b100, rdp, 7'b0000011}; // c.lbu
else if (instr16[12:10] == 3'b001) begin
if (instr16[6]) LInstrD = {1'b1, 10'b0, instr16[5], 1'b0, rs1p, 3'b001, rdp, 7'b0000011}; // c.lh
else LInstrD = {1'b1, 10'b0, instr16[5], 1'b0, rs1p, 3'b101, rdp, 7'b0000011}; // c.lhu
if (instr16[6]) LInstrD = {1'b1, 10'b0, instr16[5], 1'b0, rs1p, 3'b001, rdp, 7'b0000011}; // c.lh
else LInstrD = {1'b1, 10'b0, instr16[5], 1'b0, rs1p, 3'b101, rdp, 7'b0000011}; // c.lhu
end else if (instr16[12:10] == 3'b010)
LInstrD = {1'b1, 7'b0, rs2p, rs1p, 3'b000, 3'b000, instr16[5], instr16[6], 7'b0100011}; // c.sb
else if (instr16[12:10] == 3'b011 & instr16[6] == 1'b0)
LInstrD = {1'b1, 7'b0, rs2p, rs1p, 3'b001, 3'b000, instr16[5], 1'b0, 7'b0100011}; // c.sh
5'b00101: if (P.ZCD_SUPPORTED) LInstrD = {1'b1, immCSD[11:5], rs2p, rs1p, 3'b011, immCSD[4:0], 7'b0100111}; // c.fsd
5'b00110: LInstrD = {1'b1, immCS[11:5], rs2p, rs1p, 3'b010, immCS[4:0], 7'b0100011}; // c.sw
5'b00101: if (P.ZCD_SUPPORTED) LInstrD = {1'b1, immCSD[11:5], rs2p, rs1p, 3'b011, immCSD[4:0], 7'b0100111}; // c.fsd
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
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
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 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
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 = 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) 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
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
if (P.XLEN > 32 | ~immSH[5]) LInstrD = {1'b1, 6'b010000, immSH, rds1p, 3'b101, rds1p, 7'b0010011}; // c.srai; shamt[5] must be 0 in RV32C
end else if (instr16[11:10] == 2'b10) LInstrD = {1'b1, immCI, rds1p, 3'b111, rds1p, 7'b0010011}; // c.andi
if (P.XLEN > 32 | ~immSH[5]) LInstrD = {1'b1, 6'b010000, immSH, rds1p, 3'b101, rds1p, 7'b0010011}; // c.srai; shamt[5] must be 0 in RV32C
end else if (instr16[11:10] == 2'b10) LInstrD = {1'b1, immCI, rds1p, 3'b111, rds1p, 7'b0010011}; // c.andi
else if (instr16[12:10] == 3'b011) begin
if (instr16[6:5] == 2'b00) LInstrD = {1'b1, 7'b0100000, rs2p, rds1p, 3'b000, rds1p, 7'b0110011}; // c.sub
else if (instr16[6:5] == 2'b01) LInstrD = {1'b1, 7'b0000000, rs2p, rds1p, 3'b100, rds1p, 7'b0110011}; // c.xor
else if (instr16[6:5] == 2'b10) LInstrD = {1'b1, 7'b0000000, rs2p, rds1p, 3'b110, rds1p, 7'b0110011}; // c.or
else LInstrD = {1'b1, 7'b0000000, rs2p, rds1p, 3'b111, rds1p, 7'b0110011}; // c.and
if (instr16[6:5] == 2'b00) LInstrD = {1'b1, 7'b0100000, rs2p, rds1p, 3'b000, rds1p, 7'b0110011}; // c.sub
else if (instr16[6:5] == 2'b01) LInstrD = {1'b1, 7'b0000000, rs2p, rds1p, 3'b100, rds1p, 7'b0110011}; // c.xor
else if (instr16[6:5] == 2'b10) LInstrD = {1'b1, 7'b0000000, rs2p, rds1p, 3'b110, rds1p, 7'b0110011}; // c.or
else LInstrD = {1'b1, 7'b0000000, rs2p, rds1p, 3'b111, rds1p, 7'b0110011}; // c.and
end else begin // (instr16[12:10] == 3'b111)
if (instr16[6:5] == 2'b00 & P.XLEN > 32)
LInstrD = {1'b1, 7'b0100000, rs2p, rds1p, 3'b000, rds1p, 7'b0111011}; // c.subw
LInstrD = {1'b1, 7'b0100000, rs2p, rds1p, 3'b000, rds1p, 7'b0111011}; // c.subw
else if (instr16[6:5] == 2'b01 & P.XLEN > 32)
LInstrD = {1'b1, 7'b0000000, rs2p, rds1p, 3'b000, rds1p, 7'b0111011}; // c.addw
LInstrD = {1'b1, 7'b0000000, rs2p, rds1p, 3'b000, rds1p, 7'b0111011}; // c.addw
else if (instr16[6:2] == 5'b11000 & P.ZCB_SUPPORTED)
LInstrD = {1'b1, 12'b000011111111, rds1p, 3'b111, rds1p, 7'b0010011}; // c.zext.b = andi rd, rs1, 255
LInstrD = {1'b1, 12'b000011111111, rds1p, 3'b111, rds1p, 7'b0010011}; // c.zext.b = andi rd, rs1, 255
else if (instr16[6:2] == 5'b11001 & P.ZCB_SUPPORTED & P.ZBB_SUPPORTED)
LInstrD = {1'b1, 12'b011000000100, rds1p, 3'b001, rds1p, 7'b0010011}; // c.sext.b
LInstrD = {1'b1, 12'b011000000100, rds1p, 3'b001, rds1p, 7'b0010011}; // c.sext.b
else if (instr16[6:2] == 5'b11010 & P.ZCB_SUPPORTED & P.ZBB_SUPPORTED)
LInstrD = {1'b1, 7'b0000100, 5'b00000, rds1p, 3'b100, rds1p, 3'b011, P.XLEN > 32, 3'b011}; // c.zext.h
else if (instr16[6:2] == 5'b11011 & P.ZCB_SUPPORTED & P.ZBB_SUPPORTED)
LInstrD = {1'b1, 12'b011000000101, rds1p, 3'b001, rds1p, 7'b0010011}; // c.sext.h
LInstrD = {1'b1, 12'b011000000101, rds1p, 3'b001, rds1p, 7'b0010011}; // c.sext.h
else if (instr16[6:2] == 5'b11101 & P.ZCB_SUPPORTED)
LInstrD = {1'b1, 12'b111111111111, rds1p, 3'b100, rds1p, 7'b0010011}; // c.not = xori
LInstrD = {1'b1, 12'b111111111111, rds1p, 3'b100, rds1p, 7'b0010011}; // c.not = xori
else if (instr16[6:2] == 5'b11100 & P.ZCB_SUPPORTED & P.ZBA_SUPPORTED & P.XLEN > 32)
LInstrD = {1'b1, 7'b0000100, 5'b00000, rds1p, 3'b000, rds1p, 7'b0111011}; // c.zext.w = add.uw rd, rs1, 0
LInstrD = {1'b1, 7'b0000100, 5'b00000, rds1p, 3'b000, rds1p, 7'b0111011}; // c.zext.w = add.uw rd, rs1, 0
else if (instr16[6:5] == 2'b10 & P.ZCB_SUPPORTED & P.ZMMUL_SUPPORTED)
LInstrD = {1'b1, 7'b0000001, rs2p, rds1p, 3'b000, rds1p, 7'b0110011}; // c.mul
LInstrD = {1'b1, 7'b0000001, rs2p, rds1p, 3'b000, rds1p, 7'b0110011}; // c.mul
end
5'b01101: LInstrD = {1'b1, immCJ, 5'b00000, 7'b1101111}; // c.j
5'b01110: LInstrD = {1'b1, immCB[11:5], 5'b00000, rs1p, 3'b000, immCB[4:0], 7'b1100011}; // c.beqz
5'b01111: LInstrD = {1'b1, immCB[11:5], 5'b00000, rs1p, 3'b001, immCB[4:0], 7'b1100011}; // c.bnez
5'b01110: LInstrD = {1'b1, immCB[11:5], 5'b00000, rs1p, 3'b000, immCB[4:0], 7'b1100011}; // c.beqz
5'b01111: LInstrD = {1'b1, immCB[11:5], 5'b00000, rs1p, 3'b001, immCB[4:0], 7'b1100011}; // c.bnez
5'b10000: if (rds1 != 5'b0) begin
if (P.XLEN > 32 | ~immSH[5]) LInstrD = {1'b1, 6'b000000, immSH, rds1, 3'b001, rds1, 7'b0010011}; // c.slli; shamt[5] must be 0 in RV32C
end else if (immSH != 0) LInstrD = {1'b1, 25'b0, 7'b0010011}; // c.slli with rd = 0, immm != 0 is a HINT, treated as nop
if (P.XLEN > 32 | ~immSH[5]) LInstrD = {1'b1, 6'b000000, immSH, rds1, 3'b001, rds1, 7'b0010011}; // c.slli; shamt[5] must be 0 in RV32C
end else if (immSH != 0) LInstrD = {1'b1, 25'b0, 7'b0010011}; // c.slli with rd = 0, immm != 0 is a HINT, treated as nop
5'b10001: if (P.ZCD_SUPPORTED)
if (rds1 != 5'b0) LInstrD = {1'b1, immCILSPD, 5'b00010, 3'b011, rds1, 7'b0000111}; // c.fldsp
5'b10010: if (rds1 != 5'b0) LInstrD = {1'b1, immCILSP, 5'b00010, 3'b010, rds1, 7'b0000011}; // c.lwsp
if (rds1 != 5'b0) LInstrD = {1'b1, immCILSPD, 5'b00010, 3'b011, rds1, 7'b0000111}; // c.fldsp
5'b10010: if (rds1 != 5'b0) LInstrD = {1'b1, immCILSP, 5'b00010, 3'b010, rds1, 7'b0000011}; // c.lwsp
5'b10011: if (P.XLEN == 32) begin
if (P.ZCF_SUPPORTED) LInstrD = {1'b1, immCILSP, 5'b00010, 3'b010, rds1, 7'b0000111}; // c.flwsp
end else if (rds1 != 5'b0) LInstrD = {1'b1, immCILSPD, 5'b00010, 3'b011, rds1, 7'b0000011}; // c.ldsp
if (P.ZCF_SUPPORTED) LInstrD = {1'b1, immCILSP, 5'b00010, 3'b010, rds1, 7'b0000111}; // c.flwsp
end else if (rds1 != 5'b0) LInstrD = {1'b1, immCILSPD, 5'b00010, 3'b011, rds1, 7'b0000011}; // c.ldsp
5'b10100: if (instr16[12] == 0)
if (rs2 == 5'b00000) begin
if (rds1 != 5'b0) LInstrD = {1'b1, 7'b0000000, 5'b00000, rds1, 3'b000, 5'b00000, 7'b1100111}; // c.jr
if (rds1 != 5'b0) LInstrD = {1'b1, 7'b0000000, 5'b00000, rds1, 3'b000, 5'b00000, 7'b1100111}; // c.jr
end else
if (rds1 != 5'b0) LInstrD = {1'b1, 7'b0000000, rs2, 5'b00000, 3'b000, rds1, 7'b0110011}; // c.mv
else LInstrD = {1'b1, 25'b0, 7'b0010011}; // c.mv with rd = 0 is a HINT, treated as nop
if (rds1 != 5'b0) LInstrD = {1'b1, 7'b0000000, rs2, 5'b00000, 3'b000, rds1, 7'b0110011}; // c.mv
else LInstrD = {1'b1, 25'b0, 7'b0010011}; // c.mv with rd = 0 is a HINT, treated as nop
else
if (rs2 == 5'b00000) begin
if (rds1 == 5'b00000) LInstrD = {1'b1, 12'b1, 5'b00000, 3'b000, 5'b00000, 7'b1110011}; // c.ebreak
else if (rds1 != 5'b0) LInstrD = {1'b1, 12'b0, rds1, 3'b000, 5'b00001, 7'b1100111}; // c.jalr
if (rds1 == 5'b00000) LInstrD = {1'b1, 12'b1, 5'b00000, 3'b000, 5'b00000, 7'b1110011}; // c.ebreak
else if (rds1 != 5'b0) LInstrD = {1'b1, 12'b0, rds1, 3'b000, 5'b00001, 7'b1100111}; // c.jalr
end else
if (rds1 != 0) LInstrD = {1'b1, 7'b0000000, rs2, rds1, 3'b000, rds1, 7'b0110011}; // c.add
else LInstrD = {1'b1, 25'b0, 7'b0010011}; // c.add with rd = 0 is a HINT, treated as nop, even if it is a C.NTL
if (rds1 != 0) LInstrD = {1'b1, 7'b0000000, rs2, rds1, 3'b000, rds1, 7'b0110011}; // c.add
else LInstrD = {1'b1, 25'b0, 7'b0010011}; // c.add with rd = 0 is a HINT, treated as nop, even if it is a C.NTL
5'b10101: if (P.ZCD_SUPPORTED) LInstrD = {1'b1, immCSSD[11:5], rs2, 5'b00010, 3'b011, immCSSD[4:0], 7'b0100111}; // c.fsdsp
5'b10110: LInstrD = {1'b1, immCSS[11:5], rs2, 5'b00010, 3'b010, immCSS[4:0], 7'b0100011}; // c.swsp
5'b10110: LInstrD = {1'b1, immCSS[11:5], rs2, 5'b00010, 3'b010, immCSS[4:0], 7'b0100011}; // c.swsp
5'b10111: if (P.XLEN==32) begin
if (P.ZCF_SUPPORTED) LInstrD = {1'b1, immCSS[11:5], rs2, 5'b00010, 3'b010, immCSS[4:0], 7'b0100111}; // c.fswsp
if (P.ZCF_SUPPORTED) LInstrD = {1'b1, immCSS[11:5], rs2, 5'b00010, 3'b010, immCSS[4:0], 7'b0100111}; // c.fswsp
end else LInstrD = {1'b1, immCSSD[11:5], rs2, 5'b00010, 3'b011, immCSSD[4:0], 7'b0100011}; // c.sdsp
default: ; // illegal instruction
endcase