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removed comparator flag to ALU

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This commit is contained in:
Kevin Kim 2023-04-02 21:14:31 -07:00
parent f35b287e66
commit 5e7bbeddd1
6 changed files with 19 additions and 23 deletions
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3
src/ieu/alu.sv
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@ -37,7 +37,6 @@ module alu #(parameter WIDTH=32) (
input logic [1:0] BSelect, // Binary encoding of if it's a ZBA_ZBB_ZBC_ZBS instruction
input logic [2:0] ZBBSelect, // ZBB mux select signal
input logic [2:0] Funct3, // For BMU decoding
input logic CompLT, // Less-Than flag from comparator
input logic [2:0] BALUControl, // ALU Control signals for B instructions in Execute Stage
output logic [WIDTH-1:0] ALUResult, // ALU result
output logic [WIDTH-1:0] Sum); // Sum of operands
@ -90,7 +89,7 @@ module alu #(parameter WIDTH=32) (
// Final Result B instruction select mux
if (`ZBC_SUPPORTED | `ZBS_SUPPORTED | `ZBA_SUPPORTED | `ZBB_SUPPORTED) begin : bitmanipalu
bitmanipalu #(WIDTH) balu(.A, .B, .W64, .BSelect, .ZBBSelect,
.Funct3, .CompLT, .BALUControl, .PreALUResult, .FullResult,
.Funct3, .LT,.LTU, .BALUControl, .PreALUResult, .FullResult,
.CondMaskB, .CondShiftA, .ALUResult);
end else begin
assign ALUResult = PreALUResult;

5
src/ieu/bmu/bitmanipalu.sv
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@ -35,7 +35,8 @@ module bitmanipalu #(parameter WIDTH=32) (
input logic [1:0] BSelect, // Binary encoding of if it's a ZBA_ZBB_ZBC_ZBS instruction
input logic [2:0] ZBBSelect, // ZBB mux select signal
input logic [2:0] Funct3, // Funct3 field of opcode indicates operation to perform
input logic CompLT, // Less-Than flag from comparator
input logic LT, // less than flag
input logic LTU, // less than unsigned flag
input logic [2:0] BALUControl, // ALU Control signals for B instructions in Execute Stage
input logic [WIDTH-1:0] PreALUResult, FullResult,// PreALUResult, FullResult signals
output logic [WIDTH-1:0] CondMaskB, // B is conditionally masked for ZBS instructions
@ -84,7 +85,7 @@ module bitmanipalu #(parameter WIDTH=32) (
// ZBB Unit
if (`ZBB_SUPPORTED) begin: zbb
zbb #(WIDTH) ZBB(.A, .RevA, .B, .W64, .lt(CompLT), .ZBBSelect, .ZBBResult);
zbb #(WIDTH) ZBB(.A, .RevA, .B, .W64, .LT, .LTU, .BUnsigned(Funct3[0]), .ZBBSelect, .ZBBResult);
end else assign ZBBResult = 0;
// Result Select Mux

15
src/ieu/bmu/bmuctrl.sv
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@ -48,7 +48,6 @@ module bmuctrl(
output logic [1:0] BSelectE, // Indicates if ZBA_ZBB_ZBC_ZBS instruction in one-hot encoding
output logic [2:0] ZBBSelectE, // ZBB mux select signal
output logic BRegWriteE, // Indicates if it is a R type B instruction in Execute
output logic BComparatorSignedE, // Indicates if comparator signed in Execute Stage
output logic [2:0] BALUControlE // ALU Control signals for B instructions in Execute Stage
);
@ -56,7 +55,6 @@ module bmuctrl(
logic [2:0] Funct3D; // Funct3 field in Decode stage
logic [6:0] Funct7D; // Funct7 field in Decode stage
logic [4:0] Rs2D; // Rs2 source register in Decode stage
logic BComparatorSignedD; // Indicates if comparator signed (max, min instruction) in Decode Stage
logic RotateD; // Indicates if rotate instruction in Decode Stage
logic MaskD; // Indicates if zbs instruction in Decode Stage
logic PreShiftD; // Indicates if sh1add, sh2add, sh3add instruction in Decode Stage
@ -110,10 +108,10 @@ module bmuctrl(
BMUControlsD = `BMUCTRLW'b000_10_010_1_1_0_1_0_0_0_0_0; // rev8
17'b0010011_0010100_101: if (Rs2D[4:0] == 5'b00111)
BMUControlsD = `BMUCTRLW'b000_10_010_1_1_0_1_0_0_0_0_0; // orc.b
17'b0110011_0000101_110: BMUControlsD = `BMUCTRLW'b000_10_111_1_0_0_1_0_0_0_0_0; // max
17'b0110011_0000101_111: BMUControlsD = `BMUCTRLW'b000_10_111_1_0_0_1_0_0_0_0_0; // maxu
17'b0110011_0000101_100: BMUControlsD = `BMUCTRLW'b000_10_011_1_0_0_1_0_0_0_0_0; // min
17'b0110011_0000101_101: BMUControlsD = `BMUCTRLW'b000_10_011_1_0_0_1_0_0_0_0_0; // minu
17'b0110011_0000101_110: BMUControlsD = `BMUCTRLW'b000_10_111_1_0_0_1_1_0_0_0_0; // max
17'b0110011_0000101_111: BMUControlsD = `BMUCTRLW'b000_10_111_1_0_0_1_1_0_0_0_0; // maxu
17'b0110011_0000101_100: BMUControlsD = `BMUCTRLW'b000_10_011_1_0_0_1_1_0_0_0_0; // min
17'b0110011_0000101_101: BMUControlsD = `BMUCTRLW'b000_10_011_1_0_0_1_1_0_0_0_0; // minu
endcase
if (`XLEN==32)
casez({OpD, Funct7D, Funct3D})
@ -172,12 +170,9 @@ module bmuctrl(
// Pack BALUControl Signals
assign BALUControlD = {RotateD, MaskD, PreShiftD};
// Comparator should perform signed comparison when min/max instruction. We have overlap in funct3 with some branch instructions so we use opcode to differentiate betwen min/max and branches
assign BComparatorSignedD = (Funct3D[2]^Funct3D[0]) & ~OpD[6];
// Choose ALUSelect brom BMU for BMU operations, Funct3 for IEU operations, or 0 for addition
assign ALUSelectD = BALUOpD ? BALUSelectD : (ALUOpD ? Funct3D : 3'b000);
// BMU Execute stage pipieline control register
flopenrc#(10) controlregBMU(clk, reset, FlushE, ~StallE, {BSelectD, ZBBSelectD, BRegWriteD, BComparatorSignedD, BALUControlD}, {BSelectE, ZBBSelectE, BRegWriteE, BComparatorSignedE, BALUControlE});
flopenrc#(9) controlregBMU(clk, reset, FlushE, ~StallE, {BSelectD, ZBBSelectD, BRegWriteD, BALUControlD}, {BSelectE, ZBBSelectE, BRegWriteE, BALUControlE});
endmodule

10
src/ieu/bmu/zbb.sv
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@ -33,21 +33,25 @@
module zbb #(parameter WIDTH=32) (
input logic [WIDTH-1:0] A, RevA, B, // Operands
input logic W64, // Indicates word operation
input logic lt, // lt flag
input logic LT, // lt flag
input logic LTU, // ltu flag
input logic BUnsigned, // max/min (signed) flag
input logic [2:0] ZBBSelect, // ZBB Result select signal
output logic [WIDTH-1:0] ZBBResult); // ZBB result
logic lt; // lt given signed/unsigned
logic [WIDTH-1:0] CntResult; // count result
logic [WIDTH-1:0] MinMaxResult; // min, max result
logic [WIDTH-1:0] ByteResult; // byte results
logic [WIDTH-1:0] ExtResult; // sign/zero extend results
mux2 #(1) ltmux(LT, LTU, BUnsigned , lt);
cnt #(WIDTH) cnt(.A, .RevA, .B(B[1:0]), .W64, .CntResult);
byteUnit #(WIDTH) bu(.A, .ByteSelect(B[0]), .ByteResult);
ext #(WIDTH) ext(.A, .ExtSelect({~B[2], {B[2] & B[0]}}), .ExtResult);
// ZBBSelect[2] differentiates between min(u) vs max(u) instruction
mux2 #(WIDTH) minmaxmux(B, A, lt^ZBBSelect[2], MinMaxResult);
mux2 #(WIDTH) minmaxmux(B, A, ZBBSelect[2]^lt, MinMaxResult);
// ZBB Result select mux
mux4 #(WIDTH) zbbresultmux(CntResult, ExtResult, ByteResult, MinMaxResult, ZBBSelect[1:0], ZBBResult);

7
src/ieu/controller.sv
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@ -125,7 +125,6 @@ module controller(
logic IntDivM; // Integer divide instruction
logic [1:0] BSelectD; // One-Hot encoding if it's ZBA_ZBB_ZBC_ZBS instruction in decode stage
logic [2:0] ZBBSelectD; // ZBB Mux Select Signal
logic BComparatorSignedE; // Indicates if max, min (signed comarison) instruction in Execute Stage
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
@ -257,7 +256,7 @@ module controller(
bmuctrl bmuctrl(.clk, .reset, .StallD, .FlushD, .InstrD, .ALUOpD, .BSelectD, .ZBBSelectD,
.BRegWriteD, .BALUSrcBD, .BW64D, .BSubArithD, .IllegalBitmanipInstrD, .StallE, .FlushE,
.ALUSelectD, .BSelectE, .ZBBSelectE, .BRegWriteE, .BComparatorSignedE, .BALUControlE);
.ALUSelectD, .BSelectE, .ZBBSelectE, .BRegWriteE, .BALUControlE);
if (`ZBA_SUPPORTED) begin
// ALU Decoding is more comprehensive when ZBA is supported. slt and slti conflicts with sh1add, sh1add.uw
assign sltD = (Funct3D == 3'b010 & (~(Funct7D[4]) | ~OpD[5])) ;
@ -283,7 +282,6 @@ module controller(
assign BSelectE = 2'b00;
assign BSelectD = 2'b00;
assign ZBBSelectE = 3'b000;
assign BComparatorSignedE = 1'b0;
assign BALUControlE = 3'b0;
end
@ -311,8 +309,7 @@ module controller(
// Branch Logic
// The comparator handles both signed and unsigned branches using BranchSignedE
// Hence, only eq and lt flags are needed
// We also want comparator to handle signed comparison on a max/min bitmanip instruction
assign BranchSignedE = (~(Funct3E[2:1] == 2'b11) & BranchE) | BComparatorSignedE;
assign BranchSignedE = (~(Funct3E[2:1] == 2'b11) & BranchE);
assign {eqE, ltE} = FlagsE;
mux2 #(1) branchflagmux(eqE, ltE, Funct3E[2], BranchFlagE);
assign BranchTakenE = BranchFlagE ^ Funct3E[0];

2
src/ieu/datapath.sv
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@ -114,7 +114,7 @@ module datapath (
comparator #(`XLEN) comp(ForwardedSrcAE, ForwardedSrcBE, BranchSignedE, FlagsE);
mux2 #(`XLEN) srcamux(ForwardedSrcAE, PCE, ALUSrcAE, SrcAE);
mux2 #(`XLEN) srcbmux(ForwardedSrcBE, ImmExtE, ALUSrcBE, SrcBE);
alu #(`XLEN) alu(SrcAE, SrcBE, W64E, SubArithE, ALUSelectE, BSelectE, ZBBSelectE, Funct3E, FlagsE[0], BALUControlE, ALUResultE, IEUAdrE);
alu #(`XLEN) alu(SrcAE, SrcBE, W64E, SubArithE, ALUSelectE, BSelectE, ZBBSelectE, Funct3E, BALUControlE, ALUResultE, IEUAdrE);
mux2 #(`XLEN) altresultmux(ImmExtE, PCLinkE, JumpE, AltResultE);
mux2 #(`XLEN) ieuresultmux(ALUResultE, AltResultE, ALUResultSrcE, IEUResultE);