From d08095299ec328dd139fadad9016b09cce32e3c8 Mon Sep 17 00:00:00 2001 From: Siu Kwan Lam Date: Fri, 1 Nov 2013 16:58:49 -0500 Subject: [PATCH] add example for using vector instructions --- example/vector_instr.py | 151 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 151 insertions(+) create mode 100644 example/vector_instr.py diff --git a/example/vector_instr.py b/example/vector_instr.py new file mode 100644 index 0000000..b326ad3 --- /dev/null +++ b/example/vector_instr.py @@ -0,0 +1,151 @@ +''' +This example shows: +1) how to use vector instructions +2) how to take advantage of LLVM loop vectorization to transform scalar + operations to vector operations +''' + +from __future__ import print_function +import llvm.core as lc +import llvm.ee as le +import llvm.passes as lp +from ctypes import CFUNCTYPE, POINTER, c_int, c_float + +def build_manual_vector(): + mod = lc.Module.new('manual.vector') + intty = lc.Type.int(32) + vecty = lc.Type.vector(lc.Type.float(), 4) + aryty = lc.Type.pointer(lc.Type.float()) + fnty = lc.Type.function(lc.Type.void(), [aryty, aryty, aryty, intty]) + fn = mod.add_function(fnty, name='vector_add') + bbentry = fn.append_basic_block('entry') + bbloopcond = fn.append_basic_block('loop.cond') + bbloopbody = fn.append_basic_block('loop.body') + bbexit = fn.append_basic_block('exit') + builder = lc.Builder.new(bbentry) + + # populate function body + in1, in2, out, size = fn.args + ZERO = lc.Constant.null(intty) + loopi_ptr = builder.alloca(intty) + builder.store(ZERO, loopi_ptr) + + builder.branch(bbloopcond) + builder.position_at_end(bbloopcond) + + loopi = builder.load(loopi_ptr) + loopcond = builder.icmp(lc.ICMP_ULT, loopi, size) + + builder.cbranch(loopcond, bbloopbody, bbexit) + builder.position_at_end(bbloopbody) + + vecaryty = lc.Type.pointer(vecty) + in1asvec = builder.bitcast(builder.gep(in1, [loopi]), vecaryty) + in2asvec = builder.bitcast(builder.gep(in2, [loopi]), vecaryty) + outasvec = builder.bitcast(builder.gep(out, [loopi]), vecaryty) + + vec1 = builder.load(in1asvec) + vec2 = builder.load(in2asvec) + + vecout = builder.fadd(vec1, vec2) + + builder.store(vecout, outasvec) + + next = builder.add(loopi, lc.Constant.int(intty, 4)) + builder.store(next, loopi_ptr) + + builder.branch(bbloopcond) + builder.position_at_end(bbexit) + + builder.ret_void() + + return mod, fn + + +def build_auto_vector(): + mod = lc.Module.new('auto.vector') + intty = lc.Type.int(32) + aryty = lc.Type.pointer(lc.Type.float()) + fnty = lc.Type.function(lc.Type.void(), [aryty, aryty, aryty, intty]) + fn = mod.add_function(fnty, name='vector_add') + bbentry = fn.append_basic_block('entry') + bbloopcond = fn.append_basic_block('loop.cond') + bbloopbody = fn.append_basic_block('loop.body') + bbexit = fn.append_basic_block('exit') + builder = lc.Builder.new(bbentry) + + # populate function body + in1, in2, out, size = fn.args + in1.add_attribute(lc.ATTR_NO_ALIAS) + in2.add_attribute(lc.ATTR_NO_ALIAS) + out.add_attribute(lc.ATTR_NO_ALIAS) + ZERO = lc.Constant.null(intty) + loopi_ptr = builder.alloca(intty) + builder.store(ZERO, loopi_ptr) + + builder.branch(bbloopcond) + builder.position_at_end(bbloopcond) + + loopi = builder.load(loopi_ptr) + loopcond = builder.icmp(lc.ICMP_ULT, loopi, size) + + builder.cbranch(loopcond, bbloopbody, bbexit) + builder.position_at_end(bbloopbody) + + in1elem = builder.load(builder.gep(in1, [loopi])) + in2elem = builder.load(builder.gep(in2, [loopi])) + + outelem = builder.fadd(in1elem, in2elem) + + builder.store(outelem, builder.gep(out, [loopi])) + + next = builder.add(loopi, lc.Constant.int(intty, 1)) + builder.store(next, loopi_ptr) + + builder.branch(bbloopcond) + builder.position_at_end(bbexit) + + builder.ret_void() + + return mod, fn + +def example(title, module_builder, opt): + print(title.center(80, '=')) + mod, fn = module_builder() + + eb = le.EngineBuilder.new(mod).opt(3) + if opt: + print('opt') + tm = eb.select_target() + pms = lp.build_pass_managers(mod=mod, tm=tm, opt=3, loop_vectorize=True, + fpm=False) + pms.pm.run(mod) + + print(mod) + print(mod.to_native_assembly()) + + engine = eb.create() + ptr = engine.get_pointer_to_function(fn) + + callable = CFUNCTYPE(None, POINTER(c_float), POINTER(c_float), + POINTER(c_float), c_int)(ptr) + + N = 20 + in1 = (c_float * N)(*range(N)) + in2 = (c_float * N)(*range(N)) + out = (c_float * N)() + + print('in1: ', list(in1)) + print('in1: ', list(in2)) + + callable(in1, in2, out, N) + + print('out', list(out)) + + +def main(): + example('manual vector function', build_manual_vector, False) + example('auto vector function', build_auto_vector, True) + +if __name__ == '__main__': + main()