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Reapply r135121 with a fixed copy constructor.

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Original commit message:

Count references to interference cache entries.

Each InterferenceCache::Cursor instance references a cache entry. A
non-zero reference count guarantees that the entry won't be reused for a
new register.

This makes it possible to have multiple live cursors examining
interference for different physregs.

The total number of live cursors into a cache must be kept below
InterferenceCache::getMaxCursors().

Code generation should be unaffected by this change, and it doesn't seem
to affect the cache replacement strategy either.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135130 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen
2011-07-14 05:35:11 +00:00
parent 49c19f778b
commit f1c709837b
3 changed files with 70 additions and 11 deletions
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17
lib/CodeGen/InterferenceCache.cpp
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@ -14,6 +14,7 @@
#define DEBUG_TYPE "regalloc"
#include "InterferenceCache.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Support/ErrorHandling.h"
using namespace llvm;
@ -40,9 +41,18 @@ InterferenceCache::Entry *InterferenceCache::get(unsigned PhysReg) {
E = RoundRobin;
if (++RoundRobin == CacheEntries)
RoundRobin = 0;
Entries[E].reset(PhysReg, LIUArray, TRI, MF);
PhysRegEntries[PhysReg] = E;
return &Entries[E];
for (unsigned i = 0; i != CacheEntries; ++i) {
// Skip entries that are in use.
if (Entries[E].hasRefs()) {
if (++E == CacheEntries)
E = 0;
continue;
}
Entries[E].reset(PhysReg, LIUArray, TRI, MF);
PhysRegEntries[PhysReg] = E;
return &Entries[E];
}
llvm_unreachable("Ran out of interference cache entries.");
}
/// revalidate - LIU contents have changed, update tags.
@ -59,6 +69,7 @@ void InterferenceCache::Entry::reset(unsigned physReg,
LiveIntervalUnion *LIUArray,
const TargetRegisterInfo *TRI,
const MachineFunction *MF) {
assert(!hasRefs() && "Cannot reset cache entry with references");
// LIU's changed, invalidate cache.
++Tag;
PhysReg = physReg;