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If availability info is kept when fallthrough into a bb, add the available registers to live-in set.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64372 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2009-02-12 09:43:23 +00:00
parent 8182347d70
commit 6d209c413e
1 changed files with 21 additions and 3 deletions
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24
lib/CodeGen/VirtRegMap.cpp
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@ -407,6 +407,8 @@ public:
/// slot changes. This removes information about which register the previous
/// value for this slot lives in (as the previous value is dead now).
void ModifyStackSlotOrReMat(int SlotOrReMat);
void AddAvailableRegsToLiveIn(MachineBasicBlock &MBB);
};
}
@ -486,6 +488,22 @@ void AvailableSpills::ModifyStackSlotOrReMat(int SlotOrReMat) {
PhysRegsAvailable.erase(I);
}
/// AddAvailableRegsToLiveIn - Availability information is being kept coming
/// into the specified MBB. Add available physical registers as live-in's
/// so register scavenger and post-allocation scheduler are happy.
void AvailableSpills::AddAvailableRegsToLiveIn(MachineBasicBlock &MBB) {
for (std::multimap<unsigned, int>::iterator
I = PhysRegsAvailable.begin(), E = PhysRegsAvailable.end();
I != E; ++I) {
unsigned Reg = (*I).first;
if (!MBB.isLiveIn(Reg))
MBB.addLiveIn(Reg);
}
}
/// findSinglePredSuccessor - Return via reference a vector of machine basic
/// blocks each of which is a successor of the specified BB and has no other
/// predecessor.
static void findSinglePredSuccessor(MachineBasicBlock *MBB,
SmallVectorImpl<MachineBasicBlock *> &Succs) {
for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
@ -497,8 +515,6 @@ static void findSinglePredSuccessor(MachineBasicBlock *MBB,
}
namespace {
class AvailableSpills;
/// LocalSpiller - This spiller does a simple pass over the machine basic
/// block to attempt to keep spills in registers as much as possible for
/// blocks that have low register pressure (the vreg may be spilled due to
@ -551,8 +567,10 @@ namespace {
// FIXME: More than one successors, each of which has MBB has
// the only predecessor.
MBB = SinglePredSuccs[0];
if (!Visited.count(MBB) && EarlyVisited.insert(MBB))
if (!Visited.count(MBB) && EarlyVisited.insert(MBB)) {
Spills.AddAvailableRegsToLiveIn(*MBB);
RewriteMBB(*MBB, VRM, Spills);
}
}
} while (MBB);