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authorBjörn Gustavsson <[email protected]>2018-12-05 14:01:38 +0100
committerBjörn Gustavsson <[email protected]>2018-12-05 14:07:04 +0100
commitb3bd35ccd0004d59e478308df3bc85c351557f3c (patch)
treedd3c7bab42456c42404e9429c6c85b83a7c52aac /lib
parent8caf018e460ca1efbe0df41aa042cf1d25c62dd3 (diff)
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Fix unsafe optimization of stack trace building
The `sys_core_fold` pass of the compiler would optimize away the building of the stacktrace in code such as: try ... catch C:R:Stk -> erlang:raise(C, {R,Stk}, Stk) end That optimization is unsafe and would cause a crash in a later compiler pass.
Diffstat (limited to 'lib')
-rw-r--r--lib/compiler/src/sys_core_fold.erl20
-rw-r--r--lib/compiler/test/trycatch_SUITE.erl26
2 files changed, 39 insertions, 7 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index 3a65b40fa5..1681d97efb 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -2635,12 +2635,20 @@ opt_build_stacktrace(#c_let{vars=[#c_var{name=Cooked}],
#c_call{module=#c_literal{val=erlang},
name=#c_literal{val=raise},
args=[Class,Exp,#c_var{name=Cooked}]} ->
- %% The stacktrace is only used in a call to erlang:raise/3.
- %% There is no need to build the stacktrace. Replace the
- %% call to erlang:raise/3 with the the raw_raise/3 instruction,
- %% which will use a raw stacktrace.
- #c_primop{name=#c_literal{val=raw_raise},
- args=[Class,Exp,RawStk]};
+ case core_lib:is_var_used(Cooked, #c_cons{hd=Class,tl=Exp}) of
+ true ->
+ %% Not safe. The stacktrace is used in the class or
+ %% reason.
+ Let;
+ false ->
+ %% The stacktrace is only used in the last
+ %% argument for erlang:raise/3. There is no need
+ %% to build the stacktrace. Replace the call to
+ %% erlang:raise/3 with the the raw_raise/3
+ %% instruction, which will use a raw stacktrace.
+ #c_primop{name=#c_literal{val=raw_raise},
+ args=[Class,Exp,RawStk]}
+ end;
#c_let{vars=[#c_var{name=V}],arg=Arg,body=B0} when V =/= Cooked ->
case core_lib:is_var_used(Cooked, Arg) of
false ->
diff --git a/lib/compiler/test/trycatch_SUITE.erl b/lib/compiler/test/trycatch_SUITE.erl
index 1b7ef4ddb0..8f9cd9ab1e 100644
--- a/lib/compiler/test/trycatch_SUITE.erl
+++ b/lib/compiler/test/trycatch_SUITE.erl
@@ -1189,7 +1189,8 @@ bad_raise(Expr) ->
test_raise(Expr) ->
test_raise_1(Expr),
test_raise_2(Expr),
- test_raise_3(Expr).
+ test_raise_3(Expr),
+ test_raise_4(Expr).
test_raise_1(Expr) ->
erase(exception),
@@ -1263,5 +1264,28 @@ do_test_raise_3(Expr) ->
erlang:raise(exit, {exception,C,E}, Stk)
end.
+test_raise_4(Expr) ->
+ try
+ do_test_raise_4(Expr)
+ catch
+ exit:{exception,C,E,Stk}:Stk ->
+ try
+ Expr()
+ catch
+ C:E:S ->
+ [StkTop|_] = S,
+ [StkTop|_] = Stk
+ end
+ end.
+
+do_test_raise_4(Expr) ->
+ try
+ Expr()
+ catch
+ C:E:Stk ->
+ %% Here the stacktrace must be built.
+ erlang:raise(exit, {exception,C,E,Stk}, Stk)
+ end.
+
id(I) -> I.