runtime: Minor cleanup and extra comments around interpreter
Change-Id: I24c0b261de8cf737babd9d01bf679482d48c8bc9
diff --git a/runtime/stack.h b/runtime/stack.h
index 79d2f40..d60714f 100644
--- a/runtime/stack.h
+++ b/runtime/stack.h
@@ -95,6 +95,8 @@
}
~ShadowFrame() {}
+ // TODO(iam): Clean references array up since they're always there,
+ // we don't need to do conditionals.
bool HasReferenceArray() const {
return true;
}
@@ -149,6 +151,9 @@
return *reinterpret_cast<unaligned_double*>(vreg);
}
+ // Look up the reference given its virtual register number.
+ // If this returns non-null then this does not mean the vreg is currently a reference
+ // on non-moving collectors. Check that the raw reg with GetVReg is equal to this if not certain.
template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
mirror::Object* GetVRegReference(size_t i) const SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
DCHECK_LT(i, NumberOfVRegs());
@@ -283,6 +288,8 @@
ShadowFrame(uint32_t num_vregs, ShadowFrame* link, ArtMethod* method,
uint32_t dex_pc, bool has_reference_array)
: number_of_vregs_(num_vregs), link_(link), method_(method), dex_pc_(dex_pc) {
+ // TODO(iam): Remove this parameter, it's an an artifact of portable removal
+ DCHECK(has_reference_array);
if (has_reference_array) {
memset(vregs_, 0, num_vregs * (sizeof(uint32_t) + sizeof(StackReference<mirror::Object>)));
} else {
@@ -306,6 +313,15 @@
ShadowFrame* link_;
ArtMethod* method_;
uint32_t dex_pc_;
+
+ // This is a two-part array:
+ // - [0..number_of_vregs) holds the raw virtual registers, and each element here is always 4
+ // bytes.
+ // - [number_of_vregs..number_of_vregs*2) holds only reference registers. Each element here is
+ // ptr-sized.
+ // In other words when a primitive is stored in vX, the second (reference) part of the array will
+ // be null. When a reference is stored in vX, the second (reference) part of the array will be a
+ // copy of vX.
uint32_t vregs_[0];
DISALLOW_IMPLICIT_CONSTRUCTORS(ShadowFrame);