def build_soft_fusion_kernel(loops, loop_chain_index):
"""
Build AST and :class:`Kernel` for a sequence of loops suitable to soft fusion.
"""
kernels = [l.kernel for l in loops]
asts = [k._ast for k in kernels]
base_ast, fuse_asts = dcopy(asts[0]), asts[1:]
base_fundecl = Find(ast.FunDecl).visit(base_ast)[ast.FunDecl][0]
base_fundecl.body[:] = [ast.Block(base_fundecl.body, open_scope=True)]
for unique_id, _fuse_ast in enumerate(fuse_asts, 1):
fuse_ast = dcopy(_fuse_ast)
fuse_fundecl = Find(ast.FunDecl).visit(fuse_ast)[ast.FunDecl][0]
# 1) Extend function name
base_fundecl.name = "%s_%s" % (base_fundecl.name, fuse_fundecl.name)
# 2) Concatenate the arguments in the signature
base_fundecl.args.extend(fuse_fundecl.args)
# 3) Uniquify symbols identifiers
fuse_symbols = SymbolReferences().visit(fuse_ast)
for decl in fuse_fundecl.args:
for symbol, _ in fuse_symbols[decl.sym.symbol]:
symbol.symbol = "%s_%d" % (symbol.symbol, unique_id)
# 4) Concatenate bodies
base_fundecl.body.extend([ast.FlatBlock("\n\n// Fused kernel: \n\n")] +
[ast.Block(fuse_fundecl.body, open_scope=True)])
# Eliminate redundancies in the /fused/ kernel signature
Filter().kernel_args(loops, base_fundecl)
return Kernel(kernels, base_ast, loop_chain_index)
