diff options
Diffstat (limited to 'lib/compiler/src')
| -rw-r--r-- | lib/compiler/src/beam_bsm.erl | 48 |
1 files changed, 36 insertions, 12 deletions
diff --git a/lib/compiler/src/beam_bsm.erl b/lib/compiler/src/beam_bsm.erl index c9c5b59bf2..02794a8e18 100644 --- a/lib/compiler/src/beam_bsm.erl +++ b/lib/compiler/src/beam_bsm.erl @@ -241,21 +241,45 @@ btb_reaches_match_2([{bif,_,{f,F},Ss,Dst}=I|Is], Regs0, D0) -> Regs = btb_kill([Dst], Regs0), D = btb_follow_branch(F, Regs, D0), btb_reaches_match_1(Is, Regs, D); -btb_reaches_match_2([{test,bs_start_match2,_,_,[Ctx,_],Ctx}|Is], Regs, D) -> - case btb_context_regs(Regs) of - [Ctx] -> - D; - CtxRegs -> - case member(Ctx, CtxRegs) of - false -> btb_reaches_match_2(Is, Regs, D); - true -> btb_error(unsuitable_bs_start_match) +btb_reaches_match_2([{test,bs_start_match2,{f,F},Live,[Ctx,_],Ctx}=I|Is], + Regs0, D0) -> + CtxRegs = btb_context_regs(Regs0), + case member(Ctx, CtxRegs) of + false -> + %% This bs_start_match2 instruction does not use "our" + %% match state. Therefore we can continue the search + %% for another bs_start_match2 instruction. + D = btb_follow_branch(F, Regs0, D0), + Regs = btb_kill_not_live(Live, Regs0), + btb_reaches_match_2(Is, Regs, D); + true -> + %% OK. This instruction will use "our" match state, + %% but we must make sure that all other copies of the + %% match state are killed in the code that follows + %% the instruction. (We know that the fail branch cannot + %% be taken in this case.) + OtherCtxRegs = CtxRegs -- [Ctx], + case btb_are_all_unused(OtherCtxRegs, Is, D0) of + false -> btb_error({OtherCtxRegs,not_all_unused_after,I}); + true -> D0 end end; -btb_reaches_match_2([{test,bs_start_match2,_,_,[Bin,_],Ctx}|Is], Regs, D) -> - CtxRegs = btb_context_regs(Regs), +btb_reaches_match_2([{test,bs_start_match2,{f,F},Live,[Bin,_],Ctx}|Is], + Regs0, D0) -> + CtxRegs = btb_context_regs(Regs0), case member(Bin, CtxRegs) orelse member(Ctx, CtxRegs) of - false -> btb_reaches_match_2(Is, Regs, D); - true -> btb_error(unsuitable_bs_start_match) + false -> + %% This bs_start_match2 does not reference any copy of the + %% match state. Therefore it can safely be passed on the + %% way to another (perhaps more suitable) bs_start_match2 + %% instruction. + D = btb_follow_branch(F, Regs0, D0), + Regs = btb_kill_not_live(Live, Regs0), + btb_reaches_match_2(Is, Regs, D); + true -> + %% This variant of the bs_start_match2 instruction does + %% not accept a match state as source. + btb_error(unsuitable_bs_start_match) end; btb_reaches_match_2([{test,_,{f,F},Ss}=I|Is], Regs, D0) -> btb_ensure_not_used(Ss, I, Regs), |