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Add tags to live interval unions to avoid using stale queries.

Browse Source 
The tag is updated whenever the live interval union is changed, and it is tested
before using cached information.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125224 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2011-02-09 21:52:03 +00:00
parent 80fd30563c
commit 4f6364fd3f
2 changed files with 15 additions and 2 deletions
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2
lib/CodeGen/LiveIntervalUnion.cpp
View File

@ -28,6 +28,7 @@ using namespace llvm;
void LiveIntervalUnion::unify(LiveInterval &VirtReg) {
if (VirtReg.empty())
return;
++Tag;
// Insert each of the virtual register's live segments into the map.
LiveInterval::iterator RegPos = VirtReg.begin();
@ -46,6 +47,7 @@ void LiveIntervalUnion::unify(LiveInterval &VirtReg) {
void LiveIntervalUnion::extract(LiveInterval &VirtReg) {
if (VirtReg.empty())
return;
++Tag;
// Remove each of the virtual register's live segments from the map.
LiveInterval::iterator RegPos = VirtReg.begin();

15
lib/CodeGen/LiveIntervalUnion.h
View File

@ -64,10 +64,12 @@ public:
private:
const unsigned RepReg; // representative register number
unsigned Tag; // unique tag for current contents.
LiveSegments Segments; // union of virtual reg segments
public:
LiveIntervalUnion(unsigned r, Allocator &a) : RepReg(r), Segments(a) {}
LiveIntervalUnion(unsigned r, Allocator &a) : RepReg(r), Tag(0), Segments(a)
{}
// Iterate over all segments in the union of live virtual registers ordered
// by their starting position.
@ -81,6 +83,12 @@ public:
typedef LiveSegments Map;
const Map &getMap() { return Segments; }
/// getTag - Return an opaque tag representing the current state of the union.
unsigned getTag() const { return Tag; }
/// changedSince - Return true if the union change since getTag returned tag.
bool changedSince(unsigned tag) const { return tag != Tag; }
// Add a live virtual register to this union and merge its segments.
void unify(LiveInterval &VirtReg);
@ -155,6 +163,7 @@ public:
bool CheckedFirstInterference;
bool SeenAllInterferences;
bool SeenUnspillableVReg;
unsigned Tag;
public:
Query(): LiveUnion(), VirtReg() {}
@ -171,17 +180,19 @@ public:
CheckedFirstInterference = false;
SeenAllInterferences = false;
SeenUnspillableVReg = false;
Tag = 0;
}
void init(LiveInterval *VReg, LiveIntervalUnion *LIU) {
assert(VReg && LIU && "Invalid arguments");
if (VirtReg == VReg && LiveUnion == LIU) {
if (VirtReg == VReg && LiveUnion == LIU && !LIU->changedSince(Tag)) {
// Retain cached results, e.g. firstInterference.
return;
}
clear();
LiveUnion = LIU;
VirtReg = VReg;
Tag = LIU->getTag();
}
LiveInterval &virtReg() const {