[PATCH] D129297: [LSR] Fix bug - check if loop has preheader before calling isInductionPHI

[Nick Desaulniers via Phabricator via llvm-commits]

nickdesaulniers added inline comments.


================
Comment at: llvm/test/Transforms/LoopStrengthReduce/remove_scev_indvars.ll:97-123
+%struct.kernfs_node = type { %struct.kernfs_node* }
+
+ at kernfs_path_from_node_locked_kn_to = dso_local local_unnamed_addr global %struct.kernfs_node zeroinitializer, align 8
+ at kernfs_path_from_node_locked___trans_tmp_1 = dso_local local_unnamed_addr global i32 0, align 4
+
+define dso_local void @kernfs_path_from_node() {
+entry:
----------------
via llvm-reduce, I was able to reduce this test case to:

```
define void @kernfs_path_from_node() {
entry:
  callbr void asm sideeffect "", "i"(i8* blockaddress(@kernfs_path_from_node, %while.body))
          to label %asm.fallthrough [label %while.body]

asm.fallthrough:                                  ; preds = %entry
  br label %while.body

while.body:                                       ; preds = %while.body, %asm.fallthrough, %entry
  %depth.04 = phi i32 [ %inc, %while.body ], [ 0, %asm.fallthrough ], [ 0, %entry ]
  %inc = add i32 %depth.04, 1
  br i1 false, label %while.end, label %while.body

while.end:                                        ; preds = %while.body
  %inc.lcssa = phi i32 [ %depth.04, %while.body ]
  store i32 %inc.lcssa, i32* null, align 4
  ret void
}
```


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D129297/new/

https://reviews.llvm.org/D129297