Change the way we choose a free register: instead of picking the first
free allocatable register, we prefer the a free one with the most uses
of inactive intervals.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16148 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocIterativeScan.cpp b/lib/CodeGen/RegAllocIterativeScan.cpp
index 26fa7b7..4cdcc1d 100644
--- a/lib/CodeGen/RegAllocIterativeScan.cpp
+++ b/lib/CodeGen/RegAllocIterativeScan.cpp
@@ -463,17 +463,28 @@
}
-unsigned RA::getFreePhysReg(IntervalPtrs::value_type cur)
+unsigned RA::getFreePhysReg(LiveInterval* cur)
{
+ std::vector<unsigned> inactiveCounts(mri_->getNumRegs(), 0);
+ for (IntervalPtrs::iterator i = inactive_.begin(), e = inactive_.end();
+ i != e; ++i) {
+ unsigned reg = (*i)->reg;
+ if (MRegisterInfo::isVirtualRegister(reg))
+ reg = vrm_->getPhys(reg);
+ ++inactiveCounts[reg];
+ }
+
const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(cur->reg);
+ unsigned freeReg = 0;
for (TargetRegisterClass::iterator i = rc->allocation_order_begin(*mf_);
i != rc->allocation_order_end(*mf_); ++i) {
unsigned reg = *i;
- if (prt_->isRegAvail(reg))
- return reg;
+ if (prt_->isRegAvail(reg) &&
+ (!freeReg || inactiveCounts[freeReg] < inactiveCounts[reg]))
+ freeReg = reg;
}
- return 0;
+ return freeReg;
}
FunctionPass* llvm::createIterativeScanRegisterAllocator() {