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authorJohn Högberg <[email protected]>2019-03-28 14:37:18 +0100
committerJohn Högberg <[email protected]>2019-03-28 14:37:18 +0100
commit2367dc1397063f78cc49eafa8e95e7e3493979d1 (patch)
treed9ff148dde49c5192d85818c853bbede45e671ce
parent2f879097241d289e0100c7d1725485e2276a7f70 (diff)
parent0398c6868940af8561d3401c00441071c57d7ac5 (diff)
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Merge branch 'john/erts/remove-destructive-bs_get_binary2/ERL-901'
* john/erts/remove-destructive-bs_get_binary2/ERL-901: erts: Remove unsafe bs_get_binary2 optimization from loader
-rw-r--r--erts/emulator/beam/beam_load.c19
-rw-r--r--erts/emulator/beam/bs_instrs.tab11
-rw-r--r--erts/emulator/beam/ops.tab1
-rw-r--r--erts/emulator/test/bs_match_misc_SUITE.erl21
4 files changed, 25 insertions, 27 deletions
diff --git a/erts/emulator/beam/beam_load.c b/erts/emulator/beam/beam_load.c
index 69e49e97f3..941c3ebbbe 100644
--- a/erts/emulator/beam/beam_load.c
+++ b/erts/emulator/beam/beam_load.c
@@ -3354,19 +3354,12 @@ gen_get_binary2(LoaderState* stp, GenOpArg Fail, GenOpArg Ms, GenOpArg Live,
NATIVE_ENDIAN(Flags);
if (Size.type == TAG_a && Size.val == am_all) {
- if (Ms.type == Dst.type && Ms.val == Dst.val) {
- GENOP_NAME_ARITY(op, i_bs_get_binary_all_reuse, 3);
- op->a[0] = Ms;
- op->a[1] = Fail;
- op->a[2] = Unit;
- } else {
- GENOP_NAME_ARITY(op, i_bs_get_binary_all2, 5);
- op->a[0] = Ms;
- op->a[1] = Fail;
- op->a[2] = Live;
- op->a[3] = Unit;
- op->a[4] = Dst;
- }
+ GENOP_NAME_ARITY(op, i_bs_get_binary_all2, 5);
+ op->a[0] = Ms;
+ op->a[1] = Fail;
+ op->a[2] = Live;
+ op->a[3] = Unit;
+ op->a[4] = Dst;
} else if (Size.type == TAG_i) {
GENOP_NAME_ARITY(op, i_bs_get_binary_imm2, 6);
op->a[0] = Ms;
diff --git a/erts/emulator/beam/bs_instrs.tab b/erts/emulator/beam/bs_instrs.tab
index 652460a66d..9cad2b03c5 100644
--- a/erts/emulator/beam/bs_instrs.tab
+++ b/erts/emulator/beam/bs_instrs.tab
@@ -1136,7 +1136,6 @@ i_bs_get_utf16.execute(Fail, Flags, Dst) {
}
bs_context_to_binary := ctx_to_bin.fetch.execute;
-i_bs_get_binary_all_reuse := ctx_to_bin.fetch_bin.execute;
ctx_to_bin.head() {
Eterm context;
@@ -1159,16 +1158,6 @@ ctx_to_bin.fetch(Src) {
}
}
-ctx_to_bin.fetch_bin(Src, Fail, Unit) {
- context = $Src;
- mb = ms_matchbuffer(context);
- size = mb->size - mb->offset;
- if (size % $Unit != 0) {
- $FAIL($Fail);
- }
- offs = mb->offset;
-}
-
ctx_to_bin.execute() {
Uint hole_size;
Uint orig = mb->orig;
diff --git a/erts/emulator/beam/ops.tab b/erts/emulator/beam/ops.tab
index 3a95b1a37e..7a125b0f67 100644
--- a/erts/emulator/beam/ops.tab
+++ b/erts/emulator/beam/ops.tab
@@ -1262,7 +1262,6 @@ bs_get_binary2 Fail=f Ms=xy Live=u Sz=sq Unit=u Flags=u Dst=d => \
i_bs_get_binary_imm2 xy f? t W t d
i_bs_get_binary2 xy f t? s t d
i_bs_get_binary_all2 xy f? t t d
-i_bs_get_binary_all_reuse xy f? t
# Fetching float from binaries.
bs_get_float2 Fail=f Ms=xy Live=u Sz=s Unit=u Flags=u Dst=d => \
diff --git a/erts/emulator/test/bs_match_misc_SUITE.erl b/erts/emulator/test/bs_match_misc_SUITE.erl
index 17759d78f3..cae4eb54d2 100644
--- a/erts/emulator/test/bs_match_misc_SUITE.erl
+++ b/erts/emulator/test/bs_match_misc_SUITE.erl
@@ -24,7 +24,7 @@
kenneth/1,encode_binary/1,native/1,happi/1,
size_var/1,wiger/1,x0_context/1,huge_float_field/1,
writable_binary_matched/1,otp_7198/1,unordered_bindings/1,
- float_middle_endian/1]).
+ float_middle_endian/1,unsafe_get_binary_reuse/1]).
-include_lib("common_test/include/ct.hrl").
@@ -36,7 +36,8 @@ all() ->
[bound_var, bound_tail, t_float, little_float, sean,
kenneth, encode_binary, native, happi, size_var, wiger,
x0_context, huge_float_field, writable_binary_matched,
- otp_7198, unordered_bindings, float_middle_endian].
+ otp_7198, unordered_bindings, float_middle_endian,
+ unsafe_get_binary_reuse].
%% Test matching of bound variables.
@@ -556,5 +557,21 @@ unordered_bindings(CompressedLength, HashSize, PadLength, T) ->
Padding:PadLength/binary,PadLength>> = T,
{Content,Mac,Padding}.
+%% ERL-901: A load-time optimization assumed that match contexts had no further
+%% uses when a bs_get_binary2 overwrote the match context's register, and
+%% figured it would be safe to reuse the match context's memory for the
+%% resulting binary.
+%%
+%% This is no longer safe as of OTP 22, as a match context may be reused after
+%% being passed to another function.
+unsafe_get_binary_reuse(Config) when is_list(Config) ->
+ <<_First, Rest/binary>> = <<"hello">>,
+ ubgr_1(Rest),
+ <<Second,_/bits>> = Rest,
+ $e = Second,
+ ok.
+
+ubgr_1(<<_CP/utf8, Rest/binary>>) -> id(Rest);
+ubgr_1(_) -> false.
id(I) -> I.