riscv/rocket-chip
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Reduce critical path for fdiv valid signal

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This commit is contained in:
Andrew Waterman
2015-11-06 23:25:33 -08:00
parent c7235fecb5
commit 2f515b2af6
1 changed files with 4 additions and 3 deletions
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7
rocket/src/main/scala/fpu.scala
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@@ -445,6 +445,7 @@ class FPU(implicit p: Parameters) extends CoreModule()(p) {
val divSqrt_wdata = Wire(Bits()) val divSqrt_wdata = Wire(Bits())
val divSqrt_flags = Wire(Bits()) val divSqrt_flags = Wire(Bits())
val divSqrt_in_flight = Reg(init=Bool(false)) val divSqrt_in_flight = Reg(init=Bool(false))
val divSqrt_killed = Reg(Bool())
// writeback arbitration // writeback arbitration
case class Pipe(p: Module, lat: Int, cond: (FPUCtrlSigs) => Bool, res: FPResult) case class Pipe(p: Module, lat: Int, cond: (FPUCtrlSigs) => Bool, res: FPResult)
@@ -527,8 +528,7 @@ class FPU(implicit p: Parameters) extends CoreModule()(p) {
val divSqrt = Module(new hardfloat.divSqrtRecodedFloat64) val divSqrt = Module(new hardfloat.divSqrtRecodedFloat64)
divSqrt_inReady := Mux(divSqrt.io.sqrtOp, divSqrt.io.inReady_sqrt, divSqrt.io.inReady_div) divSqrt_inReady := Mux(divSqrt.io.sqrtOp, divSqrt.io.inReady_sqrt, divSqrt.io.inReady_div)
val divSqrt_outValid = divSqrt.io.outValid_div || divSqrt.io.outValid_sqrt val divSqrt_outValid = divSqrt.io.outValid_div || divSqrt.io.outValid_sqrt
val divSqrt_wb_hazard = wen.orR divSqrt.io.inValid := mem_reg_valid && (mem_ctrl.div || mem_ctrl.sqrt)
divSqrt.io.inValid := mem_reg_valid && !divSqrt_wb_hazard && !divSqrt_in_flight && !io.killm && (mem_ctrl.div || mem_ctrl.sqrt)
divSqrt.io.sqrtOp := mem_ctrl.sqrt divSqrt.io.sqrtOp := mem_ctrl.sqrt
divSqrt.io.a := fpiu.io.as_double.in1 divSqrt.io.a := fpiu.io.as_double.in1
divSqrt.io.b := fpiu.io.as_double.in2 divSqrt.io.b := fpiu.io.as_double.in2
@@ -536,13 +536,14 @@ class FPU(implicit p: Parameters) extends CoreModule()(p) {
when (divSqrt.io.inValid && divSqrt_inReady) { when (divSqrt.io.inValid && divSqrt_inReady) {
divSqrt_in_flight := true divSqrt_in_flight := true
divSqrt_killed := killm
divSqrt_single := mem_ctrl.single divSqrt_single := mem_ctrl.single
divSqrt_waddr := mem_reg_inst(11,7) divSqrt_waddr := mem_reg_inst(11,7)
divSqrt_rm := divSqrt.io.roundingMode divSqrt_rm := divSqrt.io.roundingMode
} }
when (divSqrt_outValid) { when (divSqrt_outValid) {
divSqrt_wen := true divSqrt_wen := !divSqrt_killed
divSqrt_wdata_double := divSqrt.io.out divSqrt_wdata_double := divSqrt.io.out
divSqrt_in_flight := false divSqrt_in_flight := false
divSqrt_flags_double := divSqrt.io.exceptionFlags divSqrt_flags_double := divSqrt.io.exceptionFlags