AuroraMiddleware/v8
1
0
Fork 0
Code Issues 2 Pull Requests Releases Wiki Activity

[turbofan] Also utilize the string length protector.

Browse Source 
Utilize the string length protector to deoptimize if the resulting
string length for string addition overflows. This way we generate
less code here and avoid holding on to the lazy frame state, and
thus potentially reduce the number live ranges.

BUG=v8:5267,v8:5404
R=yangguo@chromium.org

Review-Url: https://codereview.chromium.org/2491943004
Cr-Commit-Position: refs/heads/master@{#40909}
This commit is contained in:
bmeurer 2016-11-11 00:21:52 -08:00 committed by Commit bot
parent 4ee6fdf38b
commit ddba89c433
1 changed files with 34 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
src/compiler/js-typed-lowering.cc
View File

@ -626,6 +626,16 @@ Reduction JSTypedLowering::ReduceCreateConsString(Node* node) {
// Check if we would overflow the allowed maximum string length.
Node* check = graph()->NewNode(simplified()->NumberLessThanOrEqual(), length,
jsgraph()->Constant(String::kMaxLength));
if (isolate()->IsStringLengthOverflowIntact()) {
// Add a code dependency on the string length overflow protector.
dependencies()->AssumePropertyCell(factory()->string_length_protector());
// We can just deoptimize if the {check} fails. Besides generating a
// shorter code sequence than the version below, this has the additional
// benefit of not holding on to the lazy {frame_state} and thus potentially
// reduces the number of live ranges and allows for more truncations.
effect = graph()->NewNode(simplified()->CheckIf(), check, effect, control);
} else {
Node* branch =
graph()->NewNode(common()->Branch(BranchHint::kTrue), check, control);
Node* if_false = graph()->NewNode(common()->IfFalse(), branch);
@ -633,8 +643,8 @@ Reduction JSTypedLowering::ReduceCreateConsString(Node* node) {
{
// Throw a RangeError in case of overflow.
Node* vfalse = efalse = graph()->NewNode(
javascript()->CallRuntime(Runtime::kThrowInvalidStringLength), context,
frame_state, efalse, if_false);
javascript()->CallRuntime(Runtime::kThrowInvalidStringLength),
context, frame_state, efalse, if_false);
if_false = graph()->NewNode(common()->IfSuccess(), vfalse);
if_false = graph()->NewNode(common()->Throw(), vfalse, efalse, if_false);
// TODO(bmeurer): This should be on the AdvancedReducer somehow.
@ -653,6 +663,7 @@ Reduction JSTypedLowering::ReduceCreateConsString(Node* node) {
}
}
control = graph()->NewNode(common()->IfTrue(), branch);
}
// Figure out the map for the resulting ConsString.
// TODO(turbofan): We currently just use the cons_string_map here for