When the register allocator runs out of registers, spill a physical register around the def's and use's of the interval being allocated to make it possible for the interval to target a register and spill it right away and restore a register for uses. This likely generates terrible code but is before than aborting.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48218 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/VirtRegMap.h b/lib/CodeGen/VirtRegMap.h
index d1c14f6..7ebf31e 100644
--- a/lib/CodeGen/VirtRegMap.h
+++ b/lib/CodeGen/VirtRegMap.h
@@ -93,6 +93,17 @@
/// splitting.
std::map<MachineInstr*, std::vector<unsigned> > RestorePt2VirtMap;
+ /// EmergencySpillMap - This records the physical registers that should
+ /// be spilled / restored around the MachineInstr since the register
+ /// allocator has run out of registers.
+ std::map<MachineInstr*, std::vector<unsigned> > EmergencySpillMap;
+
+ /// EmergencySpillSlots - This records emergency spill slots used to
+ /// spill physical registers when the register allocator runs out of
+ /// registers. Ideally only one stack slot is used per function per
+ /// register class.
+ std::map<const TargetRegisterClass*, int> EmergencySpillSlots;
+
/// ReMatId - Instead of assigning a stack slot to a to be rematerialized
/// virtual register, an unique id is being assigned. This keeps track of
/// the highest id used so far. Note, this starts at (1<<18) to avoid
@@ -293,6 +304,8 @@
}
}
+ /// @brief - transfer restore point information from one instruction to
+ /// another.
void transferRestorePts(MachineInstr *Old, MachineInstr *New) {
std::map<MachineInstr*,std::vector<unsigned> >::iterator I =
RestorePt2VirtMap.find(Old);
@@ -306,6 +319,33 @@
RestorePt2VirtMap.erase(I);
}
+ /// @brief records that the specified physical register must be spilled
+ /// around the specified machine instr.
+ void addEmergencySpill(unsigned PhysReg, MachineInstr *MI) {
+ if (EmergencySpillMap.find(MI) != EmergencySpillMap.end())
+ EmergencySpillMap[MI].push_back(PhysReg);
+ else {
+ std::vector<unsigned> PhysRegs;
+ PhysRegs.push_back(PhysReg);
+ EmergencySpillMap.insert(std::make_pair(MI, PhysRegs));
+ }
+ }
+
+ /// @brief returns true if one or more physical registers must be spilled
+ /// around the specified instruction.
+ bool hasEmergencySpills(MachineInstr *MI) const {
+ return EmergencySpillMap.find(MI) != EmergencySpillMap.end();
+ }
+
+ /// @brief returns the physical registers to be spilled and restored around
+ /// the instruction.
+ std::vector<unsigned> &getEmergencySpills(MachineInstr *MI) {
+ return EmergencySpillMap[MI];
+ }
+
+ /// @brief return or get a emergency spill slot for the register class.
+ int getEmergencySpillSlot(const TargetRegisterClass *RC);
+
/// @brief Return lowest spill slot index.
int getLowSpillSlot() const {
return LowSpillSlot;