Commit 70156e10 authored by John Zhang's avatar John Zhang

Boolean flag optimisation

remove the redundant ZEXT and EQ instructions
parent a2a343c2
Optimise on the pattern:
%cmp_res = CMPOP %a %b
%res = ZEXT <@i8> %cmp_res
%con = EQ %res @1_i8
BRANCH2 %con %blk1(...) %blk2(...)
by removing the SELECT and EQ instructions.
def _has_pattern(blk):
ops = blk.operations
assert len(ops) >= 4
last4 = ops[-4:]
assert last4[0].opname == 'mu_cmpop'
assert last4[1].opname == 'mu_convop' and last4[1].args[0].value == 'ZEXT'
assert last4[2].opname == 'mu_cmpop' and last4[2].args[0].value == 'EQ'
assert last4[3].opname == 'mu_branch2'
op_cmp, op_zext, op_eq, op_branch2 = last4
assert op_cmp.result is op_zext.args[2]
assert op_zext.result is op_eq.args[1]
assert op_eq.result is op_branch2.args[0]
return True
except AssertionError:
return False
def optimise(graphs):
for g in graphs:
for blk in g.iterblocks():
if _has_pattern(blk):
ops = blk.operations
br2 = ops[-1]
br2.args[0] = ops[-4].result
blk.operations = ops[:-3] + [ops[-1]]
from rpython.translator.interactive import Translation
from import boolflag
from import graph_of
from import print_graph
def test_boolflag():
def f(x):
if x > 1:
return 3
return 0
t = Translation(f, [int], backend='mu')
g = graph_of(f, t)
assert boolflag._has_pattern(g.startblock)
assert not boolflag._has_pattern(g.startblock)
assert [op.opname for op in g.startblock.operations] == ['mu_cmpop', 'mu_branch2']
ops = g.startblock.operations
assert ops[1].args[0] is ops[0].result
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment