riscv/rocket-chip
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Avoid pipeline replays when fetch queue is full

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This commit is contained in:
Andrew Waterman
2017-08-04 14:59:32 -07:00
parent a45997d03f
commit 4bfbe75d74
1 changed files with 2 additions and 1 deletions
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3
src/main/scala/rocket/Frontend.scala
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@@ -86,6 +86,7 @@ class FrontendModule(outer: Frontend) extends LazyModuleImp(outer)
val fq = withReset(reset || io.cpu.req.valid) { Module(new ShiftQueue(new FrontendResp, 5, flow = true)) } val fq = withReset(reset || io.cpu.req.valid) { Module(new ShiftQueue(new FrontendResp, 5, flow = true)) }
val s0_valid = io.cpu.req.valid || !fq.io.mask(fq.io.mask.getWidth-3) val s0_valid = io.cpu.req.valid || !fq.io.mask(fq.io.mask.getWidth-3)
val s1_valid = RegNext(s0_valid)
val s1_pc = Reg(UInt(width=vaddrBitsExtended)) val s1_pc = Reg(UInt(width=vaddrBitsExtended))
val s1_speculative = Reg(Bool()) val s1_speculative = Reg(Bool())
val s2_valid = RegInit(false.B) val s2_valid = RegInit(false.B)
@@ -143,7 +144,7 @@ class FrontendModule(outer: Frontend) extends LazyModuleImp(outer)
icache.io.s2_kill := s2_speculative && !s2_tlb_resp.cacheable || s2_xcpt icache.io.s2_kill := s2_speculative && !s2_tlb_resp.cacheable || s2_xcpt
icache.io.s2_prefetch := s2_tlb_resp.prefetchable icache.io.s2_prefetch := s2_tlb_resp.prefetchable
fq.io.enq.valid := s2_valid && (icache.io.resp.valid || !s2_tlb_resp.miss && icache.io.s2_kill) fq.io.enq.valid := RegNext(s1_valid) && s2_valid && (icache.io.resp.valid || !s2_tlb_resp.miss && icache.io.s2_kill)
fq.io.enq.bits.pc := s2_pc fq.io.enq.bits.pc := s2_pc
io.cpu.npc := alignPC(Mux(io.cpu.req.valid, io.cpu.req.bits.pc, npc)) io.cpu.npc := alignPC(Mux(io.cpu.req.valid, io.cpu.req.bits.pc, npc))