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authorBjörn Gustavsson <[email protected]>2016-05-24 10:52:22 +0200
committerBjörn Gustavsson <[email protected]>2016-05-25 16:41:26 +0200
commit2a4281cf29a1fc7cc8408d7c42b60f930888133a (patch)
tree432e23361920cbe63da4fe22080138173c35b7e0 /lib/compiler/src
parentca368c8503712dce0044201bf25323ace3372a62 (diff)
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v3_codegen: Don't confuse beam_validator
Generate code that not only is safe, but can easily be seen by beam_validator to be safe.
Diffstat (limited to 'lib/compiler/src')
-rw-r--r--lib/compiler/src/v3_codegen.erl38
1 files changed, 32 insertions, 6 deletions
diff --git a/lib/compiler/src/v3_codegen.erl b/lib/compiler/src/v3_codegen.erl
index 45403338b4..f5f3c73793 100644
--- a/lib/compiler/src/v3_codegen.erl
+++ b/lib/compiler/src/v3_codegen.erl
@@ -1089,6 +1089,23 @@ protected_cg(Ts, Rs, _Fail, I, Vdb, Bef, St0) ->
%% test_cg(TestName, Args, Fail, I, Vdb, Bef, St) -> {[Ainstr],Aft,St}.
%% Generate test instruction. Use explicit fail label here.
+test_cg(is_map, [A], Fail, I, Vdb, Bef, St) ->
+ %% We must avoid creating code like this:
+ %%
+ %% move x(0) y(0)
+ %% is_map Fail [x(0)]
+ %% make_fun => x(0) %% Overwrite x(0)
+ %% put_map_assoc y(0) ...
+ %%
+ %% The code is safe, but beam_validator does not understand that.
+ %% Extending beam_validator to handle such (rare) code as the
+ %% above would make it slower for all programs. Instead, change
+ %% the code generator to always prefer the Y register for is_map()
+ %% and put_map_assoc() instructions, ensuring that they use the
+ %% same register.
+ Arg = cg_reg_arg_prefer_y(A, Bef),
+ Aft = clear_dead(Bef, I, Vdb),
+ {[{test,is_map,{f,Fail},[Arg]}],Aft,St};
test_cg(Test, As, Fail, I, Vdb, Bef, St) ->
Args = cg_reg_args(As, Bef),
Aft = clear_dead(Bef, I, Vdb),
@@ -1541,7 +1558,7 @@ set_cg([{var,R}], {map,Op,Map,[{map_pair,{var,_}=K,V}]}, Le, Vdb, Bef,
Fail = {f,Bfail},
{Sis,Int0} = maybe_adjust_stack(Bef, Le#l.i, Le#l.i+1, Vdb, St),
- SrcReg = cg_reg_arg(Map,Int0),
+ SrcReg = cg_reg_arg_prefer_y(Map, Int0),
Line = line(Le#l.a),
List = [cg_reg_arg(K,Int0),cg_reg_arg(V,Int0)],
@@ -1568,7 +1585,7 @@ set_cg([{var,R}], {map,Op,Map,Es}, Le, Vdb, Bef,
Fail = {f,Bfail},
{Sis,Int0} = maybe_adjust_stack(Bef, Le#l.i, Le#l.i+1, Vdb, St),
- SrcReg = cg_reg_arg(Map,Int0),
+ SrcReg = cg_reg_arg_prefer_y(Map, Int0),
Line = line(Le#l.a),
%% fetch registers for values to be put into the map
@@ -1841,6 +1858,9 @@ cg_reg_args(As, Bef) -> [cg_reg_arg(A, Bef) || A <- As].
cg_reg_arg({var,V}, Bef) -> fetch_var(V, Bef);
cg_reg_arg(Literal, _) -> Literal.
+cg_reg_arg_prefer_y({var,V}, Bef) -> fetch_var_prefer_y(V, Bef);
+cg_reg_arg_prefer_y(Literal, _) -> Literal.
+
%% cg_setup_call([Arg], Bef, Cur, Vdb) -> {[Instr],Aft}.
%% Do the complete setup for a call/enter.
@@ -2082,6 +2102,12 @@ fetch_var(V, Sr) ->
error -> fetch_stack(V, Sr#sr.stk)
end.
+fetch_var_prefer_y(V, #sr{reg=Reg,stk=Stk}) ->
+ case find_stack(V, Stk) of
+ {ok,R} -> R;
+ error -> fetch_reg(V, Reg)
+ end.
+
load_vars(Vs, Regs) ->
foldl(fun ({var,V}, Rs) -> put_reg(V, Rs) end, Regs, Vs).
@@ -2155,11 +2181,11 @@ fetch_stack(Var, Stk) -> fetch_stack(Var, Stk, 0).
fetch_stack(V, [{V}|_], I) -> {yy,I};
fetch_stack(V, [_|Stk], I) -> fetch_stack(V, Stk, I+1).
-% find_stack(Var, Stk) -> find_stack(Var, Stk, 0).
+find_stack(Var, Stk) -> find_stack(Var, Stk, 0).
-% find_stack(V, [{V}|Stk], I) -> {ok,{yy,I}};
-% find_stack(V, [O|Stk], I) -> find_stack(V, Stk, I+1);
-% find_stack(V, [], I) -> error.
+find_stack(V, [{V}|_], I) -> {ok,{yy,I}};
+find_stack(V, [_|Stk], I) -> find_stack(V, Stk, I+1);
+find_stack(_, [], _) -> error.
on_stack(V, Stk) -> keymember(V, 1, Stk).