riscv/rocket-chip
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Mitigate D$ hit -> branch -> NPC critical path

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This commit is contained in:
Andrew Waterman
2013-11-24 14:19:46 -08:00
parent 53f726008b
commit 65b8340cea
3 changed files with 6 additions and 8 deletions
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8
rocket/src/main/scala/ctrl.scala
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@@ -459,7 +459,7 @@ class Control(implicit conf: RocketConfiguration) extends Module
.otherwise {
ex_reg_br_type := id_br_type;
ex_reg_jalr := id_jalr
ex_reg_btb_hit := io.imem.resp.bits.taken
ex_reg_btb_hit := io.imem.resp.bits.taken && !id_jalr
ex_reg_div_mul_val := id_mul_val || id_div_val
ex_reg_mem_val := id_mem_val.toBool;
ex_reg_valid := Bool(true)
@@ -484,9 +484,7 @@ class Control(implicit conf: RocketConfiguration) extends Module
val replay_ex_other = wb_dcache_miss && ex_reg_load_use || mem_reg_replay_next
val replay_ex = replay_ex_structural || replay_ex_other
ctrl_killx := take_pc_wb || replay_ex
val take_pc_ex = Mux(ex_reg_jalr,
!(ex_reg_btb_hit && io.dpath.jalr_eq) && !replay_ex_other,
ex_reg_btb_hit != io.dpath.ex_br_taken)
val take_pc_ex = ex_reg_jalr && !io.dpath.jalr_eq || io.dpath.ex_br_taken
// detect 2-cycle load-use delay for LB/LH/SC
val ex_slow_bypass = ex_reg_mem_cmd === M_XSC || AVec(MT_B, MT_BU, MT_H, MT_HU).contains(ex_reg_mem_type)
@@ -714,7 +712,7 @@ class Control(implicit conf: RocketConfiguration) extends Module
io.dpath.pcr := wb_reg_pcr.toUInt
io.dpath.eret := wb_reg_eret
io.dpath.ex_mem_type := ex_reg_mem_type
io.dpath.ex_br_type := ex_reg_br_type
io.dpath.ex_br_type := ex_reg_br_type ^ ex_reg_btb_hit
io.dpath.ex_rs2_val := ex_reg_mem_val && isWrite(ex_reg_mem_cmd) || ex_reg_rocc_val
io.dpath.ex_rocc_val := ex_reg_rocc_val
io.dpath.mem_rocc_val := mem_reg_rocc_val