Freeze reserved registers before starting register allocation.

The register allocators don't currently support adding reserved
registers while they are running.  Extend the MRI API to keep track of
the set of reserved registers when register allocation started.

Target hooks like hasFP() and needsStackRealignment() can look at this
set to avoid reserving more registers during register allocation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147577 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/CodeGen/MachineRegisterInfo.cpp b/lib/CodeGen/MachineRegisterInfo.cpp
index c35b154aa1..67291a0eb8 100644
--- a/lib/CodeGen/MachineRegisterInfo.cpp
+++ b/lib/CodeGen/MachineRegisterInfo.cpp
@@ -259,3 +259,7 @@ void MachineRegisterInfo::dumpUses(unsigned Reg) const {
     I.getOperand().getParent()->dump();
 }
 #endif
+
+void MachineRegisterInfo::freezeReservedRegs(const MachineFunction &MF) {
+  ReservedRegs = TRI->getReservedRegs(MF);
+}