Get allocation orders from RegisterClassInfo when possible.

Only target-dependent hints require callbacks. The RCI allocation order
has CSR aliases last according to their order of appearance in the
getCalleeSavedRegs list. This can depend on the calling convention.

This way, AllocationOrder::next doesn't have to check for reserved
registers, and CSRs are always allocated last, even with weird calling
conventions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132690 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 34 insertions, 22 deletions

diff --git a/lib/CodeGen/AllocationOrder.cpp b/lib/CodeGen/AllocationOrder.cpp
index 0b7cd4950e..a8ee2b6357 100644
--- a/lib/CodeGen/AllocationOrder.cpp
+++ b/lib/CodeGen/AllocationOrder.cpp
@@ -25,7 +25,7 @@ using namespace llvm;
 AllocationOrder::AllocationOrder(unsigned VirtReg,
                                  const VirtRegMap &VRM,
                                  const RegisterClassInfo &RegClassInfo)
-  : Pos(0), RCI(RegClassInfo) {
+  : Begin(0), End(0), Pos(0), RCI(RegClassInfo), OwnedBegin(false) {
   const TargetRegisterClass *RC = VRM.getRegInfo().getRegClass(VirtReg);
   std::pair<unsigned, unsigned> HintPair =
     VRM.getRegInfo().getRegAllocationHint(VirtReg);
@@ -37,14 +37,37 @@ AllocationOrder::AllocationOrder(unsigned VirtReg,
   if (TargetRegisterInfo::isVirtualRegister(Hint))
     Hint = VRM.getPhys(Hint);
 
-  // The remaining allocation order may depend on the hint.
-  tie(Begin, End) = VRM.getTargetRegInfo()
-        .getAllocationOrder(RC, HintPair.first, Hint, VRM.getMachineFunction());
+  // The first hint pair component indicates a target-specific hint.
+  if (HintPair.first) {
+    const TargetRegisterInfo &TRI = VRM.getTargetRegInfo();
+    // The remaining allocation order may depend on the hint.
+    const unsigned *B, *E;
+    tie(B, E) = TRI.getAllocationOrder(RC, HintPair.first, Hint,
+                                       VRM.getMachineFunction());
 
-  // Target-dependent hints require resolution.
-  if (HintPair.first)
-    Hint = VRM.getTargetRegInfo().ResolveRegAllocHint(HintPair.first, Hint,
-                                                      VRM.getMachineFunction());
+    // Empty allocation order?
+    if (B == E)
+      return;
+
+    // Copy the allocation order with reserved registers removed.
+    OwnedBegin = true;
+    unsigned *P = new unsigned[E - B];
+    Begin = P;
+    for (; B != E; ++B)
+      if (!RCI.isReserved(*B))
+        *P++ = *B;
+    End = P;
+
+    // Target-dependent hints require resolution.
+    Hint = TRI.ResolveRegAllocHint(HintPair.first, Hint,
+                                   VRM.getMachineFunction());
+  } else {
+    // If there is no hint or just a normal hint, use the cached allocation
+    // order from RegisterClassInfo.
+    ArrayRef<unsigned> O = RCI.getOrder(RC);
+    Begin = O.begin();
+    End = O.end();
+  }
 
   // The hint must be a valid physreg for allocation.
   if (Hint && (!TargetRegisterInfo::isPhysicalRegister(Hint) ||
@@ -52,18 +75,7 @@ AllocationOrder::AllocationOrder(unsigned VirtReg,
     Hint = 0;
 }
 
-unsigned AllocationOrder::next() {
-  // First take the hint.
-  if (!Pos) {
-    Pos = Begin;
-    if (Hint)
-      return Hint;
-  }
-  // Then look at the order from TRI.
-  while(Pos != End) {
-    unsigned Reg = *Pos++;
-    if (Reg != Hint && !RCI.isReserved(Reg))
-      return Reg;
-  }
-  return 0;
+AllocationOrder::~AllocationOrder() {
+  if (OwnedBegin)
+    delete [] Begin;
 }