diff options
| -rw-r--r-- | lib/compiler/src/beam_ssa_codegen.erl | 39 |
1 files changed, 35 insertions, 4 deletions
diff --git a/lib/compiler/src/beam_ssa_codegen.erl b/lib/compiler/src/beam_ssa_codegen.erl index 3c14062d0b..d3facc5911 100644 --- a/lib/compiler/src/beam_ssa_codegen.erl +++ b/lib/compiler/src/beam_ssa_codegen.erl @@ -747,7 +747,16 @@ need_live_anno(Op) -> end. %%% -%%% Add annotations for defined Y registers. +%%% Add the following annotations for Y registers: +%%% +%%% def_yregs An ordset with variables that refer to live Y registers. +%%% That is, Y registers that that have been killed +%%% are not included. This annotation is added to all +%%% instructions that require Y registers to be initialized. +%%% +%%% kill_yregs This annotation is added to call instructions. It is +%%% an ordset containing variables referring to Y registers +%%% that will no longer be used after the call instruction. %%% defined(Linear, #cg{regs=Regs}) -> @@ -863,13 +872,35 @@ opt_allocate(Linear, #cg{regs=Regs}) -> opt_allocate_1([{L,#cg_blk{is=[#cg_alloc{stack=Stk}=I0|Is]}=Blk0}|Bs]=Bs0, Regs) when is_integer(Stk) -> - Yregs = opt_alloc_def(Bs0, gb_sets:singleton(L), []), - I = I0#cg_alloc{def_yregs=Yregs}, - [{L,Blk0#cg_blk{is=[I|Is]}}|opt_allocate_1(Bs, Regs)]; + %% Collect the variables that are initialized by copy + %% instruction in this block. + case ordsets:from_list(opt_allocate_defs(Is, Regs)) of + Yregs when length(Yregs) =:= Stk -> + %% Those copy instructions are sufficient to fully + %% initialize the stack frame. + I = I0#cg_alloc{def_yregs=Yregs}, + [{L,Blk0#cg_blk{is=[I|Is]}}|opt_allocate_1(Bs, Regs)]; + Yregs0 -> + %% Determine a conservative approximation of the Y + %% registers that are guaranteed to be initialized by all + %% successors of this block, and to it add the variables + %% initialized by copy instructions in this block. + Yregs1 = opt_alloc_def(Bs0, gb_sets:singleton(L), []), + Yregs = ordsets:union(Yregs0, Yregs1), + I = I0#cg_alloc{def_yregs=Yregs}, + [{L,Blk0#cg_blk{is=[I|Is]}}|opt_allocate_1(Bs, Regs)] + end; opt_allocate_1([B|Bs], Regs) -> [B|opt_allocate_1(Bs, Regs)]; opt_allocate_1([], _) -> []. +opt_allocate_defs([#cg_set{op=copy,dst=Dst}|Is], Regs) -> + case is_yreg(Dst, Regs) of + true -> [Dst|opt_allocate_defs(Is, Regs)]; + false -> [] + end; +opt_allocate_defs(_, _Regs) -> []. + opt_alloc_def([{L,#cg_blk{is=Is,last=Last}}|Bs], Ws0, Def0) -> case gb_sets:is_member(L, Ws0) of false -> |