Use a smallvector for inactiveCounts and initialize it lazily
instead of init'ing it maximally to zeros on entry. getFreePhysReg
is pretty hot and only a few elements are typically used. This speeds
up linscan by 5% on 176.gcc.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47631 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocLinearScan.cpp b/lib/CodeGen/RegAllocLinearScan.cpp
index dd3ea7d..d43cc19 100644
--- a/lib/CodeGen/RegAllocLinearScan.cpp
+++ b/lib/CodeGen/RegAllocLinearScan.cpp
@@ -839,7 +839,7 @@
/// getFreePhysReg - return a free physical register for this virtual register
/// interval if we have one, otherwise return 0.
unsigned RALinScan::getFreePhysReg(LiveInterval *cur) {
- std::vector<unsigned> inactiveCounts(tri_->getNumRegs(), 0);
+ SmallVector<unsigned, 256> inactiveCounts;
unsigned MaxInactiveCount = 0;
const TargetRegisterClass *RC = reginfo_->getRegClass(cur->reg);
@@ -856,6 +856,8 @@
const TargetRegisterClass *RegRC = reginfo_->getRegClass(reg);
if (RelatedRegClasses.getLeaderValue(RegRC) == RCLeader) {
reg = vrm_->getPhys(reg);
+ if (inactiveCounts.size() <= reg)
+ inactiveCounts.resize(reg+1);
++inactiveCounts[reg];
MaxInactiveCount = std::max(MaxInactiveCount, inactiveCounts[reg]);
}
@@ -882,10 +884,13 @@
for (; I != E; ++I)
if (prt_->isRegAvail(*I)) {
FreeReg = *I;
- FreeRegInactiveCount = inactiveCounts[FreeReg];
+ if (FreeReg < inactiveCounts.size())
+ FreeRegInactiveCount = inactiveCounts[FreeReg];
+ else
+ FreeRegInactiveCount = 0;
break;
}
-
+
// If there are no free regs, or if this reg has the max inactive count,
// return this register.
if (FreeReg == 0 || FreeRegInactiveCount == MaxInactiveCount) return FreeReg;
@@ -896,7 +901,8 @@
// reevaluated now.
for (; I != E; ++I) {
unsigned Reg = *I;
- if (prt_->isRegAvail(Reg) && FreeRegInactiveCount < inactiveCounts[Reg]) {
+ if (prt_->isRegAvail(Reg) && Reg < inactiveCounts.size() &&
+ FreeRegInactiveCount < inactiveCounts[Reg]) {
FreeReg = Reg;
FreeRegInactiveCount = inactiveCounts[Reg];
if (FreeRegInactiveCount == MaxInactiveCount)