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Cleanup floating point hazard logic.

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This commit is contained in:
Ross Thompson 2022-12-23 14:21:47 -06:00
parent c8a0e7685a
commit deee433d07
2 changed files with 18 additions and 16 deletions
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22
pipelined/src/fpu/fctrl.sv
View File

@ -202,19 +202,20 @@ module fctrl (
// X - all except int->fp, store, load, mv int->fp
// Y - all except cvt, mv, load, class, sqrt
// Z - fma ops only
// load/store mv int->fp cvt int->fp
/// *** turn into registers.
assign XEnE = ~(((FResSelE==2'b10)&~FWriteIntE)|((FResSelE==2'b11)&FRegWriteE)|((FResSelE==2'b01)&(PostProcSelE==2'b00)&OpCtrlE[2]));
// load/class mv cvt
assign YEnE = ~(((FResSelE==2'b10)&(FWriteIntE|FRegWriteE))|(FResSelE==2'b11)|((FResSelE==2'b01)&((PostProcSelE==2'b00)|((PostProcSelE==2'b01)&OpCtrlE[0]))));
assign ZEnE = (PostProcSelE==2'b10)&(FResSelE==2'b01)&(~OpCtrlE[2]|OpCtrlE[1]);
assign XEnD = ~(((FResSelD==2'b10)&~FWriteIntD)|((FResSelD==2'b11)&FRegWriteD)|((FResSelD==2'b01)&(PostProcSelD==2'b00)&OpCtrlD[2]));
// load/class mv cvt
assign YEnD = ~(((FResSelD==2'b10)&(FWriteIntD|FRegWriteD))|(FResSelD==2'b11)|((FResSelD==2'b01)&((PostProcSelD==2'b00)|((PostProcSelD==2'b01)&OpCtrlD[0]))));
// Enables indicate that a source register is used and may need forwarding. Also indicate special cases for infinity or NaN.
// When disabled infinity and NaN on source registers are ignored by the unpacker and thus special case logic.
assign XEnD = ~(((FResSelD==2'b10)&~FWriteIntD)| // load/store
((FResSelD==2'b11)&FRegWriteD)| // mv int to float
((FResSelD==2'b01)&(PostProcSelD==2'b00)&OpCtrlD[2])); // cvt int to float
assign ZEnD = (PostProcSelD==2'b10)&(FResSelD==2'b01)&(~OpCtrlD[2]|OpCtrlD[1]);
assign YEnD = ~(((FResSelD==2'b10)&(FWriteIntD|FRegWriteD))| // load or class
(FResSelD==2'b11)| // mv both ways
((FResSelD==2'b01)&((PostProcSelD==2'b00)|((PostProcSelD==2'b01)&OpCtrlD[0])))); // cvt both or sqrt
assign ZEnD = (PostProcSelD==2'b10)&(FResSelD==2'b01)&(~OpCtrlD[2]|OpCtrlD[1]); // fma, add, sub
// Final Res Sel:
@ -277,6 +278,7 @@ module fctrl (
{FRegWriteE, PostProcSelE, FResSelE, FrmE, FmtE, OpCtrlE, FWriteIntE, IllegalFPUInstrE, FCvtIntE});
flopenrc #(15) DEAdrReg(clk, reset, FlushE, ~StallE, {Adr1D, Adr2D, Adr3D}, {Adr1E, Adr2E, Adr3E});
flopenrc #(1) DEFDivStartReg(clk, reset, FlushE, ~StallE|FDivBusyE, FDivStartD, FDivStartE);
flopenrc #(3) DEEnReg(clk, reset, FlushE, ~StallE, {XEnD, YEnD, ZEnD}, {XEnE, YEnE, ZEnE});
if (`M_SUPPORTED) assign IDivStartE = MDUE & Funct3E[2];
else assign IDivStartE = 0;

12
pipelined/src/fpu/fhazard.sv
View File

@ -56,29 +56,29 @@ module fhazard(
// if the needed value is in the memory stage - input 1
if(XEnE)
if ((Adr1E == RdM) & FRegWriteM)
if ((Adr1E == RdM) & FRegWriteM) begin
// if the result will be FResM (can be taken from the memory stage)
if(FResSelM == 2'b00) ForwardXE = 2'b10; // choose FResM
// if the needed value is in the writeback stage
else if ((Adr1E == RdW) & FRegWriteW) ForwardXE = 2'b01; // choose FPUResult64W
end else if ((Adr1E == RdW) & FRegWriteW) ForwardXE = 2'b01; // choose FPUResult64W
// if the needed value is in the memory stage - input 2
if(YEnE)
if ((Adr2E == RdM) & FRegWriteM)
if ((Adr2E == RdM) & FRegWriteM) begin
// if the result will be FResM (can be taken from the memory stage)
if(FResSelM == 2'b00) ForwardYE = 2'b10; // choose FResM
// if the needed value is in the writeback stage
else if ((Adr2E == RdW) & FRegWriteW) ForwardYE = 2'b01; // choose FPUResult64W
end else if ((Adr2E == RdW) & FRegWriteW) ForwardYE = 2'b01; // choose FPUResult64W
// if the needed value is in the memory stage - input 3
if(ZEnE)
if ((Adr3E == RdM) & FRegWriteM)
if ((Adr3E == RdM) & FRegWriteM) begin
// if the result will be FResM (can be taken from the memory stage)
if(FResSelM == 2'b00) ForwardZE = 2'b10; // choose FResM
// if the needed value is in the writeback stage
else if ((Adr3E == RdW) & FRegWriteW) ForwardZE = 2'b01; // choose FPUResult64W
end else if ((Adr3E == RdW) & FRegWriteW) ForwardZE = 2'b01; // choose FPUResult64W
end