[llvm] [PowerPC] Spill non-volatile registers required for traceback table (PR #71115)

[Stefan Pintilie via llvm-commits]

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@@ -437,22 +437,22 @@ entry:
 ;
 ; CHECK: {{.*}}[[LOOP_LABEL:BB[0-9_]+]]: # %for.body
 ; Inline asm statement.
-; CHECK: addi 14, 14, 1
+; CHECK: addi 31, 14, 1
 ; CHECK: bdnz {{.*}}[[LOOP_LABEL]]
 ;
 ; Epilogue code.
 ; CHECK: li 3, 0
-; CHECK-64-DAG: ld 14, -[[STACK_OFFSET]](1) # 8-byte Folded Reload
-; CHECK-32-DAG: lwz 14, -[[STACK_OFFSET]](1) # 4-byte Folded Reload
+; CHECK-64-DAG: ld 31, -[[STACK_OFFSET]](1) # 8-byte Folded Reload
+; CHECK-32-DAG: lwz 31, -[[STACK_OFFSET]](1) # 4-byte Folded Reload
 ; CHECK-DAG: nop
 ; CHECK: blr
 ;
 ; CHECK: [[ELSE_LABEL]]
 ; CHECK-NEXT: slwi 3, 4, 1
-; DISABLE-64-NEXT: ld 14, -[[STACK_OFFSET]](1) # 8-byte Folded Reload
-; DISABLE-32-NEXT: lwz 14, -[[STACK_OFFSET]](1) # 4-byte Folded Reload
+; DISABLE-64-NEXT: ld 31, -[[STACK_OFFSET]](1) # 8-byte Folded Reload
+; DISABLE-32-NEXT: lwz 31, -[[STACK_OFFSET]](1) # 4-byte Folded Reload
 ; CHECK-NEXT: blr
-define i32 @inlineAsm(i32 %cond, i32 %N) {
+define i32 @inlineAsm(i32 %cond, i32 %N) #0 {
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stefanp-ibm wrote:

Does the addition of `nounwind` prevent the compiler from being forced to save all of the CSRs down to `r14`? 
If that's the case do we need to replace `r14` with `r31`? 

https://github.com/llvm/llvm-project/pull/71115