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Added WFI support to IFU to keep it in the pipeline

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David Harris 2022-04-14 17:26:17 +00:00
parent c3bca40e05
commit 0932d4df46
1 changed files with 10 additions and 1 deletions
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11
pipelined/src/ifu/ifu.sv
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@ -115,6 +115,8 @@ module ifu (
(* mark_debug = "true" *) logic [31:0] PostSpillInstrRawF;
// branch predictor signal
logic [`XLEN-1:0] PCNext1F, PCNext2F, PCNext0F;
logic [31:0] InstrNextF;
logic wfiD;
assign PCFExt = {2'b00, PCFSpill};
@ -134,6 +136,13 @@ module ifu (
assign {SelNextSpillF, CompressedF} = 0;
end
/////////////////////////////////////////////////////////////////////////////////////////////
// WFI
/////////////////////////////////////////////////////////////////////////////////////////////
assign wfiD = (InstrD[6:0] == 7'b111011 && InstrD[31:20] == 12'b000100000101); // WFI in decode stage
assign InstrNextF = wfiD ? InstrD : PostSpillInstrRawF; // on WFI, keep replaying WFI
////////////////////////////////////////////////////////////////////////////////////////////////
// Memory management
////////////////////////////////////////////////////////////////////////////////////////////////
@ -239,7 +248,7 @@ module ifu (
assign IFUStallF = IFUCacheBusStallF | SelNextSpillF;
assign CPUBusy = StallF & ~SelNextSpillF;
flopenl #(32) AlignedInstrRawDFlop(clk, reset, ~StallD, FlushD ? nop : PostSpillInstrRawF, nop, InstrRawD);
flopenl #(32) AlignedInstrRawDFlop(clk, reset, ~StallD, FlushD ? nop : InstrNextF /*PostSpillInstrRawF*/, nop, InstrRawD);
////////////////////////////////////////////////////////////////////////////////////////////////
// PCNextF logic