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Make IRQ vectors right-sized. CXXRTL was spending > 1/3rd of its time in the CSR update.

This commit is contained in:
Luke Wren 2022-10-05 22:11:53 +01:00
parent 0915cc2834
commit 6f8b75c041
1 changed files with 35 additions and 32 deletions
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67
hdl/hazard3_csr.v
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@ -331,45 +331,48 @@ localparam MAX_IRQS = 512;
localparam [3:0] IRQ_PRIORITY_MASK = ~(4'hf >> IRQ_PRIORITY_BITS);
// Assigned later:
wire [MAX_IRQS-1:0] meipa;
wire [NUM_IRQS-1:0] meipa;
wire [8:0] meinext_irq;
wire meinext_noirq;
reg [3:0] eirq_highest_priority;
reg [MAX_IRQS-1:0] meiea;
reg [MAX_IRQS-1:0] meifa;
reg [4*MAX_IRQS-1:0] meipra;
// Interrupt array registers:
reg [NUM_IRQS-1:0] meiea;
reg [NUM_IRQS-1:0] meifa;
reg [4*NUM_IRQS-1:0] meipra;
// Padded vectors for CSR readout
wire [MAX_IRQS-1:0] meiea_rdata = {{MAX_IRQS{1'b0}}, meiea};
wire [MAX_IRQS-1:0] meifa_rdata = {{MAX_IRQS{1'b0}}, meifa};
wire [4*MAX_IRQS-1:0] meipra_rdata = {{4*MAX_IRQS{1'b0}}, meipra};
always @ (posedge clk or negedge rst_n) begin: update_irq_reg_arrays
integer i;
if (!rst_n) begin
meiea <= {MAX_IRQS{1'b0}};
meifa <= {MAX_IRQS{1'b0}};
meipra <= {4*MAX_IRQS{1'b0}};
meiea <= {NUM_IRQS{1'b0}};
meifa <= {NUM_IRQS{1'b0}};
meipra <= {4*NUM_IRQS{1'b0}};
end else begin
// Assign as though all 512 IRQs existed.
if (wen_m_mode && addr == MEIEA) begin
meiea[16 * wdata[4:0] +: 16] <= wdata_update[31:16];
end else if (wen_m_mode && addr == MEIFA) begin
meifa[16 * wdata[4:0] +: 16] <= wdata_update[31:16];
end else if (wen_m_mode && addr == MEIPRA) begin
meipra[16 * wdata[6:0] +: 16] <= wdata_update[31:16];
end
// Clear IRQ force when the corresponding IRQ is sample from meinext
// (so that an IRQ can be posted *once* without modifying the ISR source)
if (ren_m_mode && addr == MEINEXT && !meinext_noirq) begin
meifa[meinext_irq] <= 1'b0;
end
// Finally, force all nonimplemented register fields to 0 so they are
// trimmed. Some tools have trouble propagating constants through the
// indexed assignments used above -- a final assignment makes the
// propagation simpler as this is the head of the decision tree.
for (i = 0; i < MAX_IRQS; i = i + 1) begin
if (i >= NUM_IRQS) begin
meiea[i] <= 1'b0;
meifa[i] <= 1'b0;
meipra[4 * i +: 4] <= 4'h0;
for (i = 0; i < NUM_IRQS; i = i + 1) begin
// CSR write update
if (wen_m_mode && addr == MEIEA && wdata[4:0] == i / 16) begin
meiea[i] <= wdata_update[16 + (i % 16)];
end
if (wen_m_mode && addr == MEIFA && wdata[4:0] == i / 16) begin
meifa[i] <= wdata_update[16 + (i % 16)];
end
if (wen_m_mode && addr == MEIPRA && wdata[6:0] == i / 4) begin
meipra[4 * i +: 4] <= wdata_update[16 + 4 * (i % 4) +: 4];
end
// Clear IRQ force when the corresponding IRQ is sampled from meinext
// (so that an IRQ can be posted *once* without modifying the ISR source)
if (meinext_irq == i && ren_m_mode && addr == MEINEXT && !meinext_noirq) begin
meifa[meinext_irq] <= 1'b0;
end
// Finally, force nonimplemented priority fields to 0 so they are
// trimmed. Some tools have trouble propagating constants through
// the indexed assignments used above -- a final assignment makes
// the propagation simpler as this is the head of the decision tree.
if (IRQ_PRIORITY_BITS < 4) begin
meipra[4 * i + 0] <= 1'b0;
end
@ -1221,7 +1224,7 @@ always @ (*) begin
MEIEA: if (CSR_M_TRAP) begin
decode_match = match_mrw;
rdata = {
meiea[wdata[4:0] * 16 +: 16],
meiea_rdata[wdata[4:0] * 16 +: 16],
16'h0
};
end
@ -1237,7 +1240,7 @@ always @ (*) begin
MEIFA: if (CSR_M_TRAP) begin
decode_match = match_mrw;
rdata = {
meifa[wdata[4:0] * 16 +: 16],
meifa_rdata[wdata[4:0] * 16 +: 16],
16'h0
};
end
@ -1245,7 +1248,7 @@ always @ (*) begin
MEIPRA: if (CSR_M_TRAP) begin
decode_match = match_mrw;
rdata = {
meipra[wdata[6:0] * 16 +: 16],
meipra_rdata[wdata[6:0] * 16 +: 16],
16'h0
};
end