1 files changed, 10 insertions, 2 deletions
diff --git a/lib/Target/PowerPC/PPCRegisterInfo.td b/lib/Target/PowerPC/PPCRegisterInfo.td
index 066a8fb..5ca3876 100644
--- a/lib/Target/PowerPC/PPCRegisterInfo.td
+++ b/lib/Target/PowerPC/PPCRegisterInfo.td
@@ -316,8 +316,16 @@ def CRBITRC : RegisterClass<"PPC", [i32], 32,
 def CRRC : RegisterClass<"PPC", [i32], 32, (add CR0, CR1, CR5, CR6,
                                                 CR7, CR2, CR3, CR4)>;
 
-def CTRRC : RegisterClass<"PPC", [i32], 32, (add CTR)>;
-def CTRRC8 : RegisterClass<"PPC", [i64], 64, (add CTR8)>;
+// The CTR registers are not allocatable because they're used by the
+// decrement-and-branch instructions, and thus need to stay live across
+// multiple basic blocks.
+def CTRRC : RegisterClass<"PPC", [i32], 32, (add CTR)> {
+  let isAllocatable = 0;
+}
+def CTRRC8 : RegisterClass<"PPC", [i64], 64, (add CTR8)> {
+  let isAllocatable = 0;
+}
+
 def VRSAVERC : RegisterClass<"PPC", [i32], 32, (add VRSAVE)>;
 def CARRYRC : RegisterClass<"PPC", [i32], 32, (add CARRY)> {
   let CopyCost = -1;