[llvm] [DA] Fix the check between Subscript and Size after delinearization (PR #151326)

[Ryotaro Kasuga via llvm-commits]

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@@ -630,3 +631,78 @@ for.latch:
 exit:
   ret void
 }
+
+; i = 0;
+; do {
+;   a[k * i] = 42;
+;   a[k * (i + 1)] = 42;
+;   i++;
+; } while (i < k);
+;
+; The dependency direction between the two stores depends on the sign of k.
+; FIXME: Each store has loop-carried dependencies on itself if k is zero.
+;
+define void @coeff_may_negative(ptr %a, i32 %k) {
+; CHECK-LABEL: 'coeff_may_negative'
+; CHECK-NEXT:  Src: store i8 42, ptr %idx.0, align 1 --> Dst: store i8 42, ptr %idx.0, align 1
+; CHECK-NEXT:    da analyze - none!
+; CHECK-NEXT:  Src: store i8 42, ptr %idx.0, align 1 --> Dst: store i8 42, ptr %idx.1, align 1
+; CHECK-NEXT:    da analyze - consistent output [-1]!
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kasuga-fj wrote:

I thought I had fixed it, but wait a second, found it's still incorrect! Probably I must fix the process after the special handling in `isKnownLessThan` (or I misunderstand something)

https://github.com/llvm/llvm-project/pull/151326