diff options
Diffstat (limited to 'lib/compiler/src/beam_ssa_pre_codegen.erl')
| -rw-r--r-- | lib/compiler/src/beam_ssa_pre_codegen.erl | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/lib/compiler/src/beam_ssa_pre_codegen.erl b/lib/compiler/src/beam_ssa_pre_codegen.erl index a5fcb91cc0..ee55d55861 100644 --- a/lib/compiler/src/beam_ssa_pre_codegen.erl +++ b/lib/compiler/src/beam_ssa_pre_codegen.erl @@ -120,6 +120,7 @@ passes(Opts) -> %% Preliminaries. ?PASS(fix_bs), + ?PASS(exception_trampolines), ?PASS(sanitize), ?PASS(match_fail_instructions), case FixTuples of @@ -693,6 +694,44 @@ legacy_bs_is([I|Is], Last, IsYreg, Count, Copies, Acc) -> legacy_bs_is([], _Last, _IsYreg, Count, Copies, Acc) -> {reverse(Acc),Count,Copies}. +%% exception_trampolines(St0) -> St. +%% +%% Removes the "exception trampolines" that were added to prevent exceptions +%% from being optimized away. + +exception_trampolines(#st{ssa=Blocks0}=St) -> + RPO = reverse(beam_ssa:rpo(Blocks0)), + Blocks = et_1(RPO, #{}, Blocks0), + St#st{ssa=Blocks}. + +et_1([L | Ls], Trampolines, Blocks) -> + #{ L := #b_blk{is=Is,last=Last0}=Block0 } = Blocks, + case {Is, Last0} of + {[#b_set{op=exception_trampoline}], #b_br{succ=Succ}} -> + et_1(Ls, Trampolines#{ L => Succ }, maps:remove(L, Blocks)); + {_, #b_br{succ=Same,fail=Same}} when Same =:= ?BADARG_BLOCK -> + %% The "badarg block" is just a marker saying that we should raise + %% an exception (= {f,0}) instead of jumping to a particular fail + %% block. Since it's not a reachable block we can't allow + %% unconditional jumps to it except through a trampoline. + error({illegal_jump_to_badarg_block, L}); + {_, #b_br{succ=Succ0,fail=Fail0}} -> + Succ = maps:get(Succ0, Trampolines, Succ0), + Fail = maps:get(Fail0, Trampolines, Fail0), + if + Succ =/= Succ0; Fail =/= Fail0 -> + Last = Last0#b_br{succ=Succ,fail=Fail}, + Block = Block0#b_blk{last=Last}, + et_1(Ls, Trampolines, Blocks#{ L := Block }); + Succ =:= Succ0, Fail =:= Fail0 -> + et_1(Ls, Trampolines, Blocks) + end; + {_, _} -> + et_1(Ls, Trampolines, Blocks) + end; +et_1([], _Trampolines, Blocks) -> + Blocks. + %% sanitize(St0) -> St. %% Remove constructs that can cause problems later: %% |