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| author | Andrew Waterman <andrew@sifive.com> | 2018-02-21 13:25:44 -0800 |
|---|---|---|
| committer | Andrew Waterman <andrew@sifive.com> | 2018-02-21 15:35:19 -0800 |
| commit | 0329b0741a698f102d64be4f0538427978bacb83 (patch) | |
| tree | 5270e8966e36c6d76c280d22ec78014eb4b75a04 /riscv/execute.cc | |
| parent | c746388b542eacd2586acfbc0a742b08a5c0bd6f (diff) | |
| download | spike-0329b0741a698f102d64be4f0538427978bacb83.zip spike-0329b0741a698f102d64be4f0538427978bacb83.tar.gz spike-0329b0741a698f102d64be4f0538427978bacb83.tar.bz2 | |
Don't allow 32-bit instructions to take up multiple slots in I$
I$ indices now maintain a 1:N relationship with PCs. This is somewhat
faster and also simpler.
Diffstat (limited to 'riscv/execute.cc')
| -rw-r--r-- | riscv/execute.cc | 18 |
1 files changed, 2 insertions, 16 deletions
diff --git a/riscv/execute.cc b/riscv/execute.cc index 878893c..e60ffd1 100644 --- a/riscv/execute.cc +++ b/riscv/execute.cc @@ -171,13 +171,6 @@ void processor_t::step(size_t n) // // According to Andrew Waterman's recollection, this optimization // resulted in approximately a 2x performance increase. - // - // If there is support for compressed instructions, the mmu and the - // switch statement get more complicated. Each branch target is stored - // in the index corresponding to mmu->icache_index(), but consecutive - // non-branching instructions are stored in consecutive indices even if - // mmu->icache_index() specifies a different index (which is the case - // for 32-bit instructions in the presence of compressed instructions). // This figures out where to jump to in the switch statement size_t idx = _mmu->icache_index(pc); @@ -193,10 +186,10 @@ void processor_t::step(size_t n) // is located within the execute_insn() function call. #define ICACHE_ACCESS(i) { \ insn_fetch_t fetch = ic_entry->data; \ - ic_entry++; \ pc = execute_insn(this, pc, fetch); \ + ic_entry = ic_entry->next; \ if (i == mmu_t::ICACHE_ENTRIES-1) break; \ - if (unlikely(ic_entry->tag != pc)) goto miss; \ + if (unlikely(ic_entry->tag != pc)) break; \ if (unlikely(instret+1 == n)) break; \ instret++; \ state.pc = pc; \ @@ -210,13 +203,6 @@ void processor_t::step(size_t n) } advance_pc(); - continue; - -miss: - advance_pc(); - // refill I$ if it looks like there wasn't a taken branch - if (pc > (ic_entry-1)->tag && pc <= (ic_entry-1)->tag + MAX_INSN_LENGTH) - _mmu->refill_icache(pc, ic_entry); } } catch(trap_t& t) |