Version 3.22.18
Add tool to visualize machine code/lithium.
Handle misaligned loads and stores in load elimination. Do not track misaligned loads and be conservative about invalidating misaligned stores. (issue 2934)
Performance and stability improvements on all platforms.
git-svn-id: http://v8.googlecode.com/svn/trunk@17310 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
diff --git a/src/hydrogen-load-elimination.cc b/src/hydrogen-load-elimination.cc
index f33ebe2..3337188 100644
--- a/src/hydrogen-load-elimination.cc
+++ b/src/hydrogen-load-elimination.cc
@@ -212,7 +212,7 @@
// instruction is redundant. Otherwise, return {instr}.
HValue* store(HStoreNamedField* instr) {
int field = FieldOf(instr->access());
- if (field < 0) return instr;
+ if (field < 0) return KillIfMisaligned(instr);
HValue* object = instr->object()->ActualValue();
HValue* value = instr->value();
@@ -250,6 +250,38 @@
}
}
+ // Kill all entries aliasing the given store.
+ void KillStore(HStoreNamedField* s) {
+ int field = FieldOf(s->access());
+ if (field >= 0) {
+ KillFieldInternal(s->object()->ActualValue(), field, s->value());
+ } else {
+ KillIfMisaligned(s);
+ }
+ }
+
+ // Kill multiple entries in the case of a misaligned store.
+ HValue* KillIfMisaligned(HStoreNamedField* instr) {
+ HObjectAccess access = instr->access();
+ if (access.IsInobject()) {
+ int offset = access.offset();
+ if ((offset % kPointerSize) != 0) {
+ // Kill the field containing the first word of the access.
+ HValue* object = instr->object()->ActualValue();
+ int field = offset / kPointerSize;
+ KillFieldInternal(object, field, NULL);
+
+ // Kill the next field in case of overlap.
+ int size = kPointerSize;
+ if (access.representation().IsByte()) size = 1;
+ else if (access.representation().IsInteger32()) size = 4;
+ int next_field = (offset + size - 1) / kPointerSize;
+ if (next_field != field) KillFieldInternal(object, next_field, NULL);
+ }
+ }
+ return instr;
+ }
+
// Find an entry for the given object and field pair.
HFieldApproximation* Find(HValue* object, int field) {
// Search for a field approximation for this object.
@@ -347,7 +379,8 @@
// Compute the field index for the given in-object offset; -1 if not tracked.
int FieldOf(int offset) {
if (offset >= kMaxTrackedFields * kPointerSize) return -1;
- ASSERT((offset % kPointerSize) == 0); // Assume aligned accesses.
+ // TODO(titzer): track misaligned loads in a separate list?
+ if ((offset % kPointerSize) != 0) return -1; // Ignore misaligned accesses.
return offset / kPointerSize;
}
@@ -430,11 +463,7 @@
// Kill non-agreeing fields for each store contained in these effects.
for (int i = 0; i < stores_.length(); i++) {
- HStoreNamedField* s = stores_[i];
- int field = table->FieldOf(s->access());
- if (field >= 0) {
- table->KillFieldInternal(s->object()->ActualValue(), field, s->value());
- }
+ table->KillStore(stores_[i]);
}
}