[llvm] ad415e3 - LoopVectorize/iv-select-cmp: comment out-of-bound tests (NFC)

[Ramkumar Ramachandra via llvm-commits]

Author: Ramkumar Ramachandra
Date: 2023-09-25T14:02:19+01:00
New Revision: ad415e3095a73be5837f3ea4f9ad1f8d190794e2

URL: https://github.com/llvm/llvm-project/commit/ad415e3095a73be5837f3ea4f9ad1f8d190794e2
DIFF: https://github.com/llvm/llvm-project/commit/ad415e3095a73be5837f3ea4f9ad1f8d190794e2.diff

LOG: LoopVectorize/iv-select-cmp: comment out-of-bound tests (NFC)

To help future contributors understand a couple of mysterious
out-of-bound tests, add a brief comment to each.

Added: 
    

Modified: 
    llvm/test/Transforms/LoopVectorize/iv-select-cmp.ll

Removed: 
    


################################################################################
diff  --git a/llvm/test/Transforms/LoopVectorize/iv-select-cmp.ll b/llvm/test/Transforms/LoopVectorize/iv-select-cmp.ll
index 9f180d97526c853..2d7936c107a10c2 100644
--- a/llvm/test/Transforms/LoopVectorize/iv-select-cmp.ll
+++ b/llvm/test/Transforms/LoopVectorize/iv-select-cmp.ll
@@ -426,6 +426,8 @@ exit:                                             ; preds = %for.body
   ret i64 %cond
 }
 
+; The sentinel value for increasing-IV vectorization is -LONG_MAX, and since
+; the IV hits this value, it is impossible to vectorize this case.
 define i64 @not_vectorized_select_icmp_iv_out_of_bound(ptr nocapture readonly %a, ptr nocapture readonly %b, i64 %rdx.start, i64 %n) {
 ; CHECK-LABEL: @not_vectorized_select_icmp_iv_out_of_bound
 ; CHECK-NOT:   vector.body:
@@ -452,6 +454,8 @@ exit:                                             ; preds = %for.body
   ret i64 %cond
 }
 
+; The sentinel value for decreasing-IV vectorization is LONG_MAX, and since
+; the IV hits this value, it is impossible to vectorize this case.
 define i64 @not_vectorized_select_decreasing_induction_icmp_iv_out_of_bound(ptr nocapture readonly %a) {
 ; CHECK-LABEL: @not_vectorized_select_decreasing_induction_icmp_iv_out_of_bound
 ; CHECK-NOT:   vector.body: