From 6a9feaac935c9345f825b272cf3225248e282f3f Mon Sep 17 00:00:00 2001 From: Jakob Stoklund Olesen Date: Thu, 14 Jul 2011 00:31:14 +0000 Subject: 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@135121 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/InterferenceCache.cpp | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) (limited to 'lib/CodeGen/InterferenceCache.cpp') diff --git a/lib/CodeGen/InterferenceCache.cpp b/lib/CodeGen/InterferenceCache.cpp index b1014a97fa..a09bb39f83 100644 --- a/lib/CodeGen/InterferenceCache.cpp +++ b/lib/CodeGen/InterferenceCache.cpp @@ -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; -- cgit v1.2.3-18-g5258