From 08f1ed8e530ff589e6580b8a3731357120eba0c5 Mon Sep 17 00:00:00 2001 From: David Harris Date: Mon, 6 Mar 2023 11:15:48 -0800 Subject: [PATCH 1/3] More detailed decoding of load/store/branch/jump --- src/ieu/controller.sv | 32 ++++++++++++++++++++++++++++---- 1 file changed, 28 insertions(+), 4 deletions(-) diff --git a/src/ieu/controller.sv b/src/ieu/controller.sv index 52b7f640..25a634a2 100644 --- a/src/ieu/controller.sv +++ b/src/ieu/controller.sv @@ -114,6 +114,8 @@ module controller( logic SFenceVmaD; // sfence.vma instruction logic IntDivM; // Integer divide instruction logic IFunctD, RFunctD, MFunctD; // Detect I, R, and M-type RV32IM/Rv64IM instructions + logic LFunctD, SFunctD, BFunctD; // Detect load, store, branch instructions + logic JFunctD; // detect jalr instruction // Extract fields assign OpD = InstrD[6:0]; @@ -135,10 +137,20 @@ module controller( assign IFunctD = IShiftD | INoShiftD; assign RFunctD = ((Funct3D == 3'b000 | Funct3D == 3'b101) & Funct7b5D) | Funct7ZeroD; assign MFunctD = (Funct7D == 7'b0000001) & (`M_SUPPORTED | (`ZMMUL_SUPPORTED & ~Funct3D[2])); // muldiv + assign LFunctD = Funct3D == 3'b000 | Funct3D == 3'b001 | Funct3D == 3'b010 | Funct3D == 3'b100 | Funct3D == 3'b101 | + ((`XLEN == 64) & (Funct3D == 3'b011 | Funct3D == 3'b110)); + assign SFunctD = Funct3D == 3'b000 | Funct3D == 3'b001 | Funct3D == 3'b010 | + ((`XLEN == 64) & (Funct3D == 3'b011)); + assign BFunctD = (Funct3D[2:1] != 2'b01); // legal branches + assign JFunctD = (Funct3D == 3'b000); end else begin assign IFunctD = 1; // Don't bother to separate out shift decoding assign RFunctD = ~Funct7D[0]; // Not a multiply assign MFunctD = Funct7D[0] & (`M_SUPPORTED | (`ZMMUL_SUPPORTED & ~Funct3D[2])); // muldiv + assign LFunctD = 1; // don't bother to check Funct3 for loads + assign SFunctD = 1; // don't bother to check Funct3 for stores + assign BFunctD = 1; // don't bother to check Funct3 for branches + assign JFunctD = 1; // don't bother to check Funct3 for jumps end // Main Instruction Decoder @@ -146,7 +158,10 @@ module controller( case(OpD) // RegWrite_ImmSrc_ALUSrc_MemRW_ResultSrc_Branch_ALUOp_Jump_ALUResultSrc_W64_CSRRead_Privileged_Fence_MDU_Atomic_Illegal 7'b0000000: ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Illegal instruction - 7'b0000011: ControlsD = `CTRLW'b1_000_01_10_001_0_0_0_0_0_0_0_0_0_00_0; // lw + 7'b0000011: if (LFunctD) + ControlsD = `CTRLW'b1_000_01_10_001_0_0_0_0_0_0_0_0_0_00_0; // loads + else + ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction 7'b0000111: ControlsD = `CTRLW'b0_000_01_10_001_0_0_0_0_0_0_0_0_0_00_1; // flw - only legal if FP supported 7'b0001111: if (`ZIFENCEI_SUPPORTED) ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_1_0_00_0; // fence @@ -161,7 +176,10 @@ module controller( ControlsD = `CTRLW'b1_000_01_00_000_0_1_0_0_1_0_0_0_0_00_0; // IW-type ALU for RV64i else ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction - 7'b0100011: ControlsD = `CTRLW'b0_001_01_01_000_0_0_0_0_0_0_0_0_0_00_0; // sw + 7'b0100011: if (SFunctD) + ControlsD = `CTRLW'b0_001_01_01_000_0_0_0_0_0_0_0_0_0_00_0; // stores + else + ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction 7'b0100111: ControlsD = `CTRLW'b0_001_01_01_000_0_0_0_0_0_0_0_0_0_00_1; // fsw - only legal if FP supported 7'b0101111: if (`A_SUPPORTED) begin if (InstrD[31:27] == 5'b00010) @@ -185,8 +203,14 @@ module controller( ControlsD = `CTRLW'b1_000_00_00_011_0_0_0_0_1_0_0_0_1_00_0; // W-type Multiply/Divide else ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction - 7'b1100011: ControlsD = `CTRLW'b0_010_11_00_000_1_0_0_0_0_0_0_0_0_00_0; // branches - 7'b1100111: ControlsD = `CTRLW'b1_000_01_00_000_0_0_1_1_0_0_0_0_0_00_0; // jalr + 7'b1100011: if (BFunctD) + ControlsD = `CTRLW'b0_010_11_00_000_1_0_0_0_0_0_0_0_0_00_0; // branches + else + ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction + 7'b1100111: if (JFunctD) + ControlsD = `CTRLW'b1_000_01_00_000_0_0_1_1_0_0_0_0_0_00_0; // jalr + else + ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction 7'b1101111: ControlsD = `CTRLW'b1_011_11_00_000_0_0_1_1_0_0_0_0_0_00_0; // jal 7'b1110011: if (`ZICSR_SUPPORTED) begin if (Funct3D == 3'b000) From 94dd39795e08afd1269b1677648cddac09c9c1bd Mon Sep 17 00:00:00 2001 From: David Harris Date: Mon, 6 Mar 2023 11:21:11 -0800 Subject: [PATCH 2/3] Simplified decoder default to illegal instruction --- src/ieu/controller.sv | 32 ++++++++------------------------ 1 file changed, 8 insertions(+), 24 deletions(-) diff --git a/src/ieu/controller.sv b/src/ieu/controller.sv index 25a634a2..783e28a9 100644 --- a/src/ieu/controller.sv +++ b/src/ieu/controller.sv @@ -154,14 +154,13 @@ module controller( end // Main Instruction Decoder - always_comb + /* verilator lint_off CASEINCOMPLETE */ + always_comb begin + ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // default: Illegal instruction case(OpD) // RegWrite_ImmSrc_ALUSrc_MemRW_ResultSrc_Branch_ALUOp_Jump_ALUResultSrc_W64_CSRRead_Privileged_Fence_MDU_Atomic_Illegal - 7'b0000000: ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Illegal instruction - 7'b0000011: if (LFunctD) + 7'b0000011: if (LFunctD) ControlsD = `CTRLW'b1_000_01_10_001_0_0_0_0_0_0_0_0_0_00_0; // loads - else - ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction 7'b0000111: ControlsD = `CTRLW'b0_000_01_10_001_0_0_0_0_0_0_0_0_0_00_1; // flw - only legal if FP supported 7'b0001111: if (`ZIFENCEI_SUPPORTED) ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_1_0_00_0; // fence @@ -169,17 +168,11 @@ module controller( ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_0; // fence treated as nop 7'b0010011: if (IFunctD) ControlsD = `CTRLW'b1_000_01_00_000_0_1_0_0_0_0_0_0_0_00_0; // I-type ALU - else - ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction 7'b0010111: ControlsD = `CTRLW'b1_100_11_00_000_0_0_0_0_0_0_0_0_0_00_0; // auipc 7'b0011011: if (IFunctD & `XLEN == 64) ControlsD = `CTRLW'b1_000_01_00_000_0_1_0_0_1_0_0_0_0_00_0; // IW-type ALU for RV64i - else - ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction 7'b0100011: if (SFunctD) ControlsD = `CTRLW'b0_001_01_01_000_0_0_0_0_0_0_0_0_0_00_0; // stores - else - ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction 7'b0100111: ControlsD = `CTRLW'b0_001_01_01_000_0_0_0_0_0_0_0_0_0_00_1; // fsw - only legal if FP supported 7'b0101111: if (`A_SUPPORTED) begin if (InstrD[31:27] == 5'b00010) @@ -188,39 +181,30 @@ module controller( ControlsD = `CTRLW'b1_101_01_01_100_0_0_0_0_0_0_0_0_0_01_0; // sc else ControlsD = `CTRLW'b1_101_01_11_001_0_0_0_0_0_0_0_0_0_10_0; // amo - end else - ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction + end 7'b0110011: if (RFunctD) ControlsD = `CTRLW'b1_000_00_00_000_0_1_0_0_0_0_0_0_0_00_0; // R-type else if (MFunctD) ControlsD = `CTRLW'b1_000_00_00_011_0_0_0_0_0_0_0_0_1_00_0; // Multiply/divide - else - ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction 7'b0110111: ControlsD = `CTRLW'b1_100_01_00_000_0_0_0_1_0_0_0_0_0_00_0; // lui 7'b0111011: if (RFunctD & (`XLEN == 64)) ControlsD = `CTRLW'b1_000_00_00_000_0_1_0_0_1_0_0_0_0_00_0; // R-type W instructions for RV64i else if (MFunctD & (`XLEN == 64)) ControlsD = `CTRLW'b1_000_00_00_011_0_0_0_0_1_0_0_0_1_00_0; // W-type Multiply/Divide - else - ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction 7'b1100011: if (BFunctD) ControlsD = `CTRLW'b0_010_11_00_000_1_0_0_0_0_0_0_0_0_00_0; // branches - else - ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction 7'b1100111: if (JFunctD) ControlsD = `CTRLW'b1_000_01_00_000_0_0_1_1_0_0_0_0_0_00_0; // jalr - else - ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction 7'b1101111: ControlsD = `CTRLW'b1_011_11_00_000_0_0_1_1_0_0_0_0_0_00_0; // jal 7'b1110011: if (`ZICSR_SUPPORTED) begin if (Funct3D == 3'b000) ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_1_0_0_00_0; // privileged; decoded further in priveleged modules else ControlsD = `CTRLW'b1_000_00_00_010_0_0_0_0_0_1_0_0_0_00_0; // csrs - end else - ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // non-implemented instruction - default: ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // non-implemented instruction + end endcase + end + /* verilator lint_on CASEINCOMPLETE */ // Unswizzle control bits // Squash control signals if coming from an illegal compressed instruction From 4fd461e520f05e2ed8f7cc2ce09e3e097e6a1b4b Mon Sep 17 00:00:00 2001 From: David Harris Date: Mon, 6 Mar 2023 13:10:51 -0800 Subject: [PATCH 3/3] Fixed bug about rv64 shifts only using 6 bits of funct7 --- src/ieu/controller.sv | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/src/ieu/controller.sv b/src/ieu/controller.sv index 783e28a9..876fdaa1 100644 --- a/src/ieu/controller.sv +++ b/src/ieu/controller.sv @@ -127,13 +127,16 @@ module controller( // Be rigorous about detecting illegal instructions if CSRs or bit manipulation is supported // otherwise be cheap - if (`ZICSR_SUPPORTED | `ZBA_SUPPORTED | `ZBB_SUPPORTED | `ZBC_SUPPORTED | `ZBS_SUPPORTED) begin // Exact integer decoding + if (`ZICSR_SUPPORTED | `ZBA_SUPPORTED | `ZBB_SUPPORTED | `ZBC_SUPPORTED | `ZBS_SUPPORTED) begin:legalcheck // Exact integer decoding logic Funct7ZeroD, Funct7b5D, IShiftD, INoShiftD; + logic Funct7ShiftZeroD, Funct7Shiftb5D; assign Funct7ZeroD = (Funct7D == 7'b0000000); // most R-type instructions assign Funct7b5D = (Funct7D == 7'b0100000); // srai, sub - assign IShiftD = (Funct3D == 3'b001 & Funct7ZeroD) | (Funct3D == 3'b101 & (Funct7ZeroD | Funct7b5D)); // slli, srli, srai, or w forms - assign INoShiftD = (Funct3D != 3'b001 & Funct3D != 3'b101); + assign Funct7ShiftZeroD = (`XLEN==64) ? (Funct7D[6:1] == 6'b000000) : Funct7ZeroD; + assign Funct7Shiftb5D = (`XLEN==64) ? (Funct7D[6:1] == 6'b010000) : Funct7b5D; + assign IShiftD = (Funct3D == 3'b001 & Funct7ShiftZeroD) | (Funct3D == 3'b101 & (Funct7ShiftZeroD | Funct7Shiftb5D)); // slli, srli, srai, or w forms + assign INoShiftD = ((Funct3D != 3'b001) & (Funct3D != 3'b101)); assign IFunctD = IShiftD | INoShiftD; assign RFunctD = ((Funct3D == 3'b000 | Funct3D == 3'b101) & Funct7b5D) | Funct7ZeroD; assign MFunctD = (Funct7D == 7'b0000001) & (`M_SUPPORTED | (`ZMMUL_SUPPORTED & ~Funct3D[2])); // muldiv @@ -143,7 +146,7 @@ module controller( ((`XLEN == 64) & (Funct3D == 3'b011)); assign BFunctD = (Funct3D[2:1] != 2'b01); // legal branches assign JFunctD = (Funct3D == 3'b000); - end else begin + end else begin:legalcheck2 assign IFunctD = 1; // Don't bother to separate out shift decoding assign RFunctD = ~Funct7D[0]; // Not a multiply assign MFunctD = Funct7D[0] & (`M_SUPPORTED | (`ZMMUL_SUPPORTED & ~Funct3D[2])); // muldiv