RISC-V Design · All levels

Decode Pipeline Stages and Timing Partitioning: Software and Programmer View

Software and Programmer View for Decode Pipeline Stages and Timing Partitioning.

Software and programmer view

Software and Programmer View for Decode Pipeline Stages and Timing Partitioning is anchored on Decode-stage slack at target frequency and bubbles per kilo-instruction caused by front-end backpressure.. Convert observations into mechanism-backed decisions with explicit ownership.

  • Keep ISA profile, ABI, and extension assumptions explicit.

  • Validate runtime feature detection against hardware contract.

  • Correlate compiler output with microarchitectural counters.

  • Preserve deterministic trap and privilege behavior in all modes.

Decode contract

diagram
DECODE CONTROL MAP - Decode Pipeline Stages and Timing Partitioning

opcode/funct3/funct7      controls asserted
-----------------------   ---------------------------------------
LUI / AUIPC               rd_write, imm_select(U), alu_add_pc
JAL / JALR                rd_write, pc_redirect, link_write
BRANCH                    cmp_enable, branch_type, pc_redirect
LOAD                      mem_read, rd_write, wb_sel(memory)
STORE                     mem_write, store_size, addr_calc
OP-IMM                    alu_enable, imm_select(I), rd_write
OP                        alu_enable, src2_reg, rd_write
SYSTEM / CSR              csr_readwrite, trap_check, privilege_gate
VECTOR (V extension)      vdecode, lane_mask, vtype_update