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-rw-r--r--lib/compiler/src/v3_codegen.erl136
-rw-r--r--lib/compiler/test/match_SUITE.erl22
2 files changed, 23 insertions, 135 deletions
diff --git a/lib/compiler/src/v3_codegen.erl b/lib/compiler/src/v3_codegen.erl
index e9152ba88f..d7a7778740 100644
--- a/lib/compiler/src/v3_codegen.erl
+++ b/lib/compiler/src/v3_codegen.erl
@@ -79,13 +79,9 @@ function(#k_fdef{anno=#k{a=Anno},func=Name,arity=Arity,
try
#k_match{} = Kb, %Assertion.
- %% Try to suppress the stack frame unless it is
- %% really needed.
- Body0 = avoid_stack_frame(Kb),
-
%% Annotate kernel records with variable usage.
Vdb0 = init_vars(As),
- {Body,_,Vdb} = body(Body0, 1, Vdb0),
+ {Body,_,Vdb} = body(Kb, 1, Vdb0),
%% Generate the BEAM assembly code.
{Asm,EntryLabel,St} = cg_fun(Body, As, Vdb, AtomMod,
@@ -98,136 +94,6 @@ function(#k_fdef{anno=#k{a=Anno},func=Name,arity=Arity,
erlang:raise(Class, Error, Stack)
end.
-
-%% avoid_stack_frame(Kernel) -> Kernel'
-%% If possible, avoid setting up a stack frame. Functions
-%% that only do matching, calls to guard BIFs, and tail-recursive
-%% calls don't need a stack frame.
-
-avoid_stack_frame(#k_match{body=Body}=M) ->
- try
- M#k_match{body=avoid_stack_frame_1(Body)}
- catch
- impossible ->
- M
- end.
-
-avoid_stack_frame_1(#k_alt{first=First0,then=Then0}=Alt) ->
- First = avoid_stack_frame_1(First0),
- Then = avoid_stack_frame_1(Then0),
- Alt#k_alt{first=First,then=Then};
-avoid_stack_frame_1(#k_bif{op=Op}=Bif) ->
- case Op of
- #k_internal{} ->
- %% Most internal BIFs clobber the X registers.
- throw(impossible);
- _ ->
- Bif
- end;
-avoid_stack_frame_1(#k_break{anno=Anno,args=Args}) ->
- #k_guard_break{anno=Anno,args=Args};
-avoid_stack_frame_1(#k_guard_break{}=Break) ->
- Break;
-avoid_stack_frame_1(#k_enter{}=Enter) ->
- %% Tail-recursive calls don't need a stack frame.
- Enter;
-avoid_stack_frame_1(#k_guard{clauses=Cs0}=Guard) ->
- Cs = avoid_stack_frame_list(Cs0),
- Guard#k_guard{clauses=Cs};
-avoid_stack_frame_1(#k_guard_clause{guard=G0,body=B0}=C) ->
- G = avoid_stack_frame_1(G0),
- B = avoid_stack_frame_1(B0),
- C#k_guard_clause{guard=G,body=B};
-avoid_stack_frame_1(#k_match{anno=A,vars=Vs,body=B0,ret=Ret}) ->
- %% Use #k_guard_match{} instead to avoid saving the X registers
- %% to the stack before matching.
- B = avoid_stack_frame_1(B0),
- #k_guard_match{anno=A,vars=Vs,body=B,ret=Ret};
-avoid_stack_frame_1(#k_guard_match{body=B0}=M) ->
- B = avoid_stack_frame_1(B0),
- M#k_guard_match{body=B};
-avoid_stack_frame_1(#k_protected{arg=Arg0}=Prot) ->
- Arg = avoid_stack_frame_1(Arg0),
- Prot#k_protected{arg=Arg};
-avoid_stack_frame_1(#k_put{}=Put) ->
- Put;
-avoid_stack_frame_1(#k_return{}=Ret) ->
- Ret;
-avoid_stack_frame_1(#k_select{var=#k_var{anno=Vanno},types=Types0}=Select) ->
- case member(reuse_for_context, Vanno) of
- false ->
- Types = avoid_stack_frame_list(Types0),
- Select#k_select{types=Types};
- true ->
- %% Including binary patterns that overwrite the register containing
- %% the binary with the match context may not be safe. For example,
- %% bs_match_SUITE:bin_tail_e/1 with inlining will be rejected by
- %% beam_validator.
- %%
- %% Essentially the following code is produced:
- %%
- %% bs_match {x,0} => {x,0}
- %% ...
- %% bs_match {x,0} => {x,1} %% ILLEGAL
- %%
- %% A bs_match instruction will only accept a match context as the
- %% source operand if the source and destination registers are the
- %% the same (as in the first bs_match instruction above).
- %% The second bs_match instruction is therefore illegal.
- %%
- %% This situation is avoided if there is a stack frame:
- %%
- %% move {x,0} => {y,0}
- %% bs_match {x,0} => {x,0}
- %% ...
- %% bs_match {y,0} => {x,1} %% LEGAL
- %%
- throw(impossible)
- end;
-avoid_stack_frame_1(#k_seq{arg=#k_call{anno=Anno,op=Op}=Call,
- body=#k_break{args=BrArgs0}}=Seq) ->
- case Op of
- #k_remote{mod=#k_atom{val=Mod},
- name=#k_atom{val=Name},
- arity=Arity} ->
- case erl_bifs:is_exit_bif(Mod, Name, Arity) of
- false ->
- %% Will clobber X registers. Must have a stack frame.
- throw(impossible);
- true ->
- %% The call to this BIF will never return. It is safe
- %% to suppress the stack frame.
- Bif = #k_bif{anno=Anno,
- op=#k_internal{name=guard_error,arity=1},
- args=[Call],ret=[]},
- BrArgs = lists:duplicate(length(BrArgs0), #k_nil{}),
- GB = #k_guard_break{anno=#k{us=[],ns=[],a=[]},args=BrArgs},
- Seq#k_seq{arg=Bif,body=GB}
- end;
- _ ->
- %% Will clobber X registers. Must have a stack frame.
- throw(impossible)
- end;
-avoid_stack_frame_1(#k_seq{arg=A0,body=B0}=Seq) ->
- A = avoid_stack_frame_1(A0),
- B = avoid_stack_frame_1(B0),
- Seq#k_seq{arg=A,body=B};
-avoid_stack_frame_1(#k_test{}=Test) ->
- Test;
-avoid_stack_frame_1(#k_type_clause{values=Values0}=TC) ->
- Values = avoid_stack_frame_list(Values0),
- TC#k_type_clause{values=Values};
-avoid_stack_frame_1(#k_val_clause{body=B0}=VC) ->
- B = avoid_stack_frame_1(B0),
- VC#k_val_clause{body=B};
-avoid_stack_frame_1(_Body) ->
- throw(impossible).
-
-avoid_stack_frame_list([H|T]) ->
- [avoid_stack_frame_1(H)|avoid_stack_frame_list(T)];
-avoid_stack_frame_list([]) -> [].
-
-
%% This pass creates beam format annotated with variable lifetime
%% information. Each thing is given an index and for each variable we
%% store the first and last index for its occurrence. The variable
diff --git a/lib/compiler/test/match_SUITE.erl b/lib/compiler/test/match_SUITE.erl
index e3f842b668..72e5356a8d 100644
--- a/lib/compiler/test/match_SUITE.erl
+++ b/lib/compiler/test/match_SUITE.erl
@@ -378,6 +378,13 @@ untuplify(Config) when is_list(Config) ->
%% We do this to cover sys_core_fold:unalias_pat/1.
{1,2,3,4,alias,{[1,2],{3,4},alias}} = untuplify_1([1,2], {3,4}, alias),
error = untuplify_1([1,2], {3,4}, 42),
+
+ %% Test that a previous bug in v3_codegen is gone. (The sinking of
+ %% stack frames into only the case arms that needed them was not always
+ %% safe.)
+ [33, -1, -33, 1] = untuplify_2(32, 65),
+ {33, 1, -33, -1} = untuplify_2(65, 32),
+
ok.
untuplify_1(A, B, C) ->
@@ -390,6 +397,21 @@ untuplify_1(A, B, C) ->
error
end.
+untuplify_2(V1, V2) ->
+ {D1,D2,D3,D4} =
+ if V1 > V2 ->
+ %% The 1 value was overwritten by the value of V2-V1.
+ {V1-V2, 1, V2-V1, -1};
+ true ->
+ {V2-V1, -1, V1-V2, 1}
+ end,
+ if
+ D2 > D4 ->
+ {D1, D2, D3, D4};
+ true ->
+ [D1, D2, D3, D4]
+ end.
+
%% Coverage of beam_dead:shortcut_boolean_label/4.
shortcut_boolean(Config) when is_list(Config) ->
false = shortcut_boolean_1([0]),
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-22 15:39:34 +0000