[llvm] [MachinePipeliner] Remove UB from tests (NFC) (PR #123169)

[Ryotaro Kasuga via llvm-commits]

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@@ -10,18 +10,19 @@
 ; CHECK: endloop0
 
 ; Function Attrs: nounwind
-define ptr @f0(ptr nocapture readonly %a0, i32 %a1, i32 %a2, i32 %a3,  ptr %b) #0 {
+define ptr @f0(ptr nocapture readonly %a0, i32 %a1, i32 %a2, i32 %a3, ptr %b, ptr %c) #0 {
 b0:
-  br i1 undef, label %b1, label %b3
+  %cond = freeze i1 poison
+  br i1 %cond, label %b1, label %b3
 
 b1:                                               ; preds = %b0
   br label %b2
 
 b2:                                               ; preds = %b2, %b1
   %v1 = phi ptr [ %a0, %b1 ], [ %v2, %b2 ]
   %v2 = phi ptr [ undef, %b1 ], [ %v15, %b2 ]
-  %v3 = phi ptr [ null, %b1 ], [ %v4, %b2 ]
-  %v4 = phi ptr [ null, %b1 ], [ %v14, %b2 ]
+  %v3 = phi ptr [ %c, %b1 ], [ %v4, %b2 ]
+  %v4 = phi ptr [ %c, %b1 ], [ %v14, %b2 ]
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kasuga-fj wrote:

`%v2` does not appear to be used as a pointer operand of a load/store, so it has been left in place.

https://github.com/llvm/llvm-project/pull/123169