[PowerPC] make LR/LR8 CTR/CTR8 aliased (#76926)

fixes #47156 
fixes #47155

Author: Chen Zheng

llvm/lib/Target/PowerPC/PPCRegisterInfo.td

@@ -270,12 +270,15 @@ def CR7 : CR<7, "cr7", [CR7LT, CR7GT, CR7EQ, CR7UN]>, DwarfRegNum<[75, 75]>;
 
 // Link register
 def LR  : SPR<8, "lr">, DwarfRegNum<[-2, 65]>;
-//let Aliases = [LR] in
-def LR8 : SPR<8, "lr">, DwarfRegNum<[65, -2]>;
+def LR8 : SPR<8, "lr">, DwarfRegNum<[65, -2]> {
+  let Aliases = [LR];
+}
 
 // Count register
 def CTR  : SPR<9, "ctr">, DwarfRegNum<[-2, 66]>;
-def CTR8 : SPR<9, "ctr">, DwarfRegNum<[66, -2]>;
+def CTR8 : SPR<9, "ctr">, DwarfRegNum<[66, -2]> {
+  let Aliases = [CTR];
+}
 
 // VRsave register
 def VRSAVE: SPR<256, "vrsave">, DwarfRegNum<[109]>;

llvm/test/CodeGen/PowerPC/pr47155-47156.ll

@@ -9,9 +9,11 @@ define void @pr47155() {
 ; CHECK-NEXT: pr47155:%bb.0 entry
 ; CHECK:      SU(0):   INLINEASM &"mtlr 31"{{.*}}implicit-def early-clobber $lr
 ; CHECK:      Successors:
+; CHECK-NEXT:   SU(1): Out  Latency=0
 ; CHECK-NEXT:   SU(1): Ord  Latency=0 Barrier
 ; CHECK-NEXT: SU(1):   INLINEASM &"mtlr 31"{{.*}}implicit-def early-clobber $lr8
 ; CHECK:      Predecessors:
+; CHECK-NEXT:   SU(0): Out  Latency=0
 ; CHECK-NEXT:   SU(0): Ord  Latency=0 Barrier
 ; CHECK-NEXT: ExitSU:
 entry:
@@ -25,11 +27,13 @@ define void @pr47156(ptr %fn) {
 ; CHECK: ********** MI Scheduling **********
 ; CHECK-NEXT: pr47156:%bb.0 entry
 ; CHECK:      SU(0):   INLINEASM &"mtctr 31"{{.*}}implicit-def early-clobber $ctr
-; CHECK-NOT:  Successors:
-; CHECK-NOT:  Predecessors:
-; CHECK:      SU(1):   MTCTR8 renamable $x3, implicit-def $ctr8
 ; CHECK:      Successors:
-; CHECK-NEXT: ExitSU:
+; CHECK-NEXT:   SU(1): Out  Latency=0
+; CHECK-NEXT: SU(1):   MTCTR8 renamable $x3, implicit-def $ctr8
+; CHECK:      Predecessors:
+; CHECK-NEXT:   SU(0): Out  Latency=0
+; CHECK-NEXT: Successors:
+; CHECK-NEXT:  ExitSU:
 ; CHECK-NEXT: SU(2):
 entry:
   call void asm sideeffect "mtctr 31", "~{ctr}"()