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Fix representation of HLoadRoot.

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HLoadRoot doesn't participate in representation inference, and its
represenation is not Tagged at code generation, which leads to incorrect
pointer map assignment and eventual stale pointer access after GC.

BUG=chromium:419036
LOG=Y
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/626383003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24410 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
ulan@chromium.org 2014-10-06 11:42:13 +00:00
parent 33da50f2ea
commit de51833695
2 changed files with 17 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
src/hydrogen-instructions.h
View File

@ -2716,6 +2716,7 @@ class HLoadRoot FINAL : public HTemplateInstruction<0> {
// TODO(bmeurer): We'll need kDependsOnRoots once we add the
// corresponding HStoreRoot instruction.
SetDependsOnFlag(kCalls);
set_representation(Representation::Tagged());
}
virtual bool IsDeletable() const OVERRIDE { return true; }
@ -6373,11 +6374,13 @@ class HLoadNamedField FINAL : public HTemplateInstruction<2> {
return !access().IsInobject() || access().offset() >= size;
}
virtual Representation RequiredInputRepresentation(int index) OVERRIDE {
if (index == 0 && access().IsExternalMemory()) {
if (index == 0) {
// object must be external in case of external memory access
return Representation::External();
return access().IsExternalMemory() ? Representation::External()
: Representation::Tagged();
}
return Representation::Tagged();
DCHECK(index == 1);
return Representation::None();
}
virtual Range* InferRange(Zone* zone) OVERRIDE;
virtual std::ostream& PrintDataTo(std::ostream& os) const OVERRIDE; // NOLINT

12
src/hydrogen-representation-changes.cc
View File

@ -63,7 +63,17 @@ static bool IsNonDeoptingIntToSmiChange(HChange* change) {
void HRepresentationChangesPhase::InsertRepresentationChangesForValue(
HValue* value) {
Representation r = value->representation();
if (r.IsNone()) return;
if (r.IsNone()) {
#ifdef DEBUG
for (HUseIterator it(value->uses()); !it.Done(); it.Advance()) {
HValue* use_value = it.value();
int use_index = it.index();
Representation req = use_value->RequiredInputRepresentation(use_index);
DCHECK(req.IsNone());
}
#endif
return;
}
if (value->HasNoUses()) {
if (value->IsForceRepresentation()) value->DeleteAndReplaceWith(NULL);
return;