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authorErlang/OTP <[email protected]>2010-01-19 07:02:42 +0000
committerErlang/OTP <[email protected]>2010-01-19 07:02:42 +0000
commit257fce5ee076fa0aabce47279d1d1112fad6abbb (patch)
treec0f92e813239c4f8c91058ed290c70a62d488631
parent141b8f28bc2180c0fb17479562cc59dce51218d4 (diff)
parent31e231d813d8a15a937ebd5fbb71299ce1faf9c1 (diff)
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Merge branch 'bg/compiler-beam_validator' into ccase/r13b04_dev
* bg/compiler-beam_validator: beam_validator: fix incorrect assumptions about GC guard BIFs OTP-8378 In rare circumstances when using garbaging collecting guard BIFs, the validation pass (beam_validator) would signal that the code was unsafe, when it in fact was correct. (Thanks to Kiran Khaladkar.)
-rw-r--r--erts/emulator/beam/erl_bif_guard.c14
-rw-r--r--lib/compiler/src/beam_validator.erl16
-rw-r--r--lib/compiler/test/beam_validator_SUITE.erl46
3 files changed, 55 insertions, 21 deletions
diff --git a/erts/emulator/beam/erl_bif_guard.c b/erts/emulator/beam/erl_bif_guard.c
index 8b47db10dd..440b0b4f14 100644
--- a/erts/emulator/beam/erl_bif_guard.c
+++ b/erts/emulator/beam/erl_bif_guard.c
@@ -1,19 +1,19 @@
/*
* %CopyrightBegin%
- *
- * Copyright Ericsson AB 2006-2009. All Rights Reserved.
- *
+ *
+ * Copyright Ericsson AB 2006-2010. All Rights Reserved.
+ *
* The contents of this file are subject to the Erlang Public License,
* Version 1.1, (the "License"); you may not use this file except in
* compliance with the License. You should have received a copy of the
* Erlang Public License along with this software. If not, it can be
* retrieved online at http://www.erlang.org/.
- *
+ *
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
- *
+ *
* %CopyrightEnd%
*/
@@ -318,6 +318,10 @@ double_to_integer(Process* p, double x)
* The following code is used when a guard that may build on the
* heap is called directly. They must not use HAlloc(), but must
* do a garbage collection if there is insufficient heap space.
+ *
+ * Important note: All error checking MUST be done before doing
+ * a garbage collection. The compiler assumes that all registers
+ * are still valid if a guard BIF generates an exception.
*/
#define ERTS_NEED_GC(p, need) ((HEAP_LIMIT((p)) - HEAP_TOP((p))) <= (need))
diff --git a/lib/compiler/src/beam_validator.erl b/lib/compiler/src/beam_validator.erl
index 08ba9c3ee4..1fd61831e0 100644
--- a/lib/compiler/src/beam_validator.erl
+++ b/lib/compiler/src/beam_validator.erl
@@ -1,19 +1,19 @@
%%
%% %CopyrightBegin%
-%%
-%% Copyright Ericsson AB 2004-2009. All Rights Reserved.
-%%
+%%
+%% Copyright Ericsson AB 2004-2010. All Rights Reserved.
+%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
-%%
+%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
-%%
+%%
%% %CopyrightEnd%
-module(beam_validator).
@@ -604,9 +604,9 @@ valfun_4({gc_bif,Op,{f,Fail},Live,Src,Dst}, #vst{current=St0}=Vst0) ->
St = kill_heap_allocation(St0),
Vst1 = Vst0#vst{current=St},
verify_live(Live, Vst1),
- Vst2 = prune_x_regs(Live, Vst1),
- validate_src(Src, Vst2),
- Vst = branch_state(Fail, Vst2),
+ Vst2 = branch_state(Fail, Vst1),
+ Vst = prune_x_regs(Live, Vst2),
+ validate_src(Src, Vst),
Type = bif_type(Op, Src, Vst),
set_type_reg(Type, Dst, Vst);
valfun_4(return, #vst{current=#st{numy=none}}=Vst) ->
diff --git a/lib/compiler/test/beam_validator_SUITE.erl b/lib/compiler/test/beam_validator_SUITE.erl
index ef8feb8a27..74b5d7c7eb 100644
--- a/lib/compiler/test/beam_validator_SUITE.erl
+++ b/lib/compiler/test/beam_validator_SUITE.erl
@@ -1,19 +1,19 @@
%%
%% %CopyrightBegin%
-%%
-%% Copyright Ericsson AB 2004-2009. All Rights Reserved.
-%%
+%%
+%% Copyright Ericsson AB 2004-2010. All Rights Reserved.
+%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
-%%
+%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
-%%
+%%
%% %CopyrightEnd%
%%
-module(beam_validator_SUITE).
@@ -28,7 +28,7 @@
freg_range/1,freg_uninit/1,freg_state/1,
bin_match/1,bin_aligned/1,bad_dsetel/1,
state_after_fault_in_catch/1,no_exception_in_catch/1,
- undef_label/1,illegal_instruction/1]).
+ undef_label/1,illegal_instruction/1,failing_gc_guard_bif/1]).
-include("test_server.hrl").
@@ -52,13 +52,13 @@ all(suite) ->
freg_range,freg_uninit,freg_state,
bin_match,bin_aligned,
bad_dsetel,state_after_fault_in_catch,no_exception_in_catch,
- undef_label,illegal_instruction].
+ undef_label,illegal_instruction,failing_gc_guard_bif].
beam_files(Config) when is_list(Config) ->
?line {ok,Cwd} = file:get_cwd(),
?line Parent = filename:dirname(Cwd),
?line Wc = filename:join([Parent,"*","*.beam"]),
- %% Must have at least two files here, or there will could be
+ %% Must have at least two files here, or there will be
%% a grammatical error in the output of the io:format/2 call below. ;-)
?line [_,_|_] = Fs = filelib:wildcard(Wc),
?line io:format("~p files\n", [length(Fs)]),
@@ -356,6 +356,36 @@ illegal_instruction(Config) when is_list(Config) ->
{{'_',y,0},{[],0,illegal_instruction}}] = Errors,
ok.
+%% The beam_validator used to assume that a GC guard BIF could
+%% do a garbage collection even if it failed. That assumption
+%% is not correct, and will cause the beam_validator to reject
+%% valid programs such as this test case.
+%%
+%% (Thanks to Kiran Khaladkar.)
+%%
+failing_gc_guard_bif(Config) when is_list(Config) ->
+ ?line ok = process_request(lists:seq(1, 36)),
+ ?line error = process_request([]),
+ ?line error = process_request(not_a_list),
+ ok.
+
+process_request(ConfId) ->
+ case process_request_foo(ConfId) of
+ false ->
+ if
+ length(ConfId) == 36 ->
+ Response = ok;
+ true ->
+ Response = error
+ end
+ end,
+ process_request_bar(self(), [Response]).
+
+process_request_foo(_) ->
+ false.
+
+process_request_bar(Pid, [Response]) when is_pid(Pid) ->
+ Response.
%%%-------------------------------------------------------------------------