[LAA] Revert a small part of r239295
This commit ([LAA] Fix estimation of number of memchecks) regressed the
logic a bit. We shouldn't quit the analysis if we encounter a pointer
without known bounds *unless* we actually need to emit a memcheck for
it.
The original code was using NumComparisons which is now computed
differently. Instead I compute NeedRTCheck from NumReadPtrChecks and
NumWritePtrChecks.
As side note, I find the separation of NeedRTCheck and CanDoRT
confusing, so I will try to merge them in a follow-up patch.
llvm-svn: 241756
diff --git a/llvm/test/Analysis/LoopAccessAnalysis/pointer-with-unknown-bounds.ll b/llvm/test/Analysis/LoopAccessAnalysis/pointer-with-unknown-bounds.ll
new file mode 100644
index 0000000..d05849e
--- /dev/null
+++ b/llvm/test/Analysis/LoopAccessAnalysis/pointer-with-unknown-bounds.ll
@@ -0,0 +1,42 @@
+; RUN: opt -loop-accesses -analyze < %s | FileCheck %s
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+
+; We shouldn't quit the analysis if we encounter a pointer without known
+; bounds *unless* we actually need to emit a memcheck for it. (We only
+; compute bounds for SCEVAddRecs so A[i*I] is deemed not having known bounds.)
+;
+; for (i = 0; i < 20; ++i)
+; A[i*i] *= 2;
+
+; CHECK: for.body:
+; CHECK: Report: unsafe dependent memory operations in loop
+; CHECK-NOT: Report: cannot identify array bounds
+; CHECK: Interesting Dependences:
+; CHECK: Unknown:
+; CHECK: %loadA = load i16, i16* %arrayidxA, align 2 ->
+; CHECK: store i16 %mul, i16* %arrayidxA, align 2
+
+define void @f(i16* %a) {
+entry:
+ br label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %ind = phi i64 [ 0, %entry ], [ %add, %for.body ]
+
+ %access_ind = mul i64 %ind, %ind
+
+ %arrayidxA = getelementptr inbounds i16, i16* %a, i64 %access_ind
+ %loadA = load i16, i16* %arrayidxA, align 2
+
+ %mul = mul i16 %loadA, 2
+
+ store i16 %mul, i16* %arrayidxA, align 2
+
+ %add = add nuw nsw i64 %ind, 1
+ %exitcond = icmp eq i64 %add, 20
+ br i1 %exitcond, label %for.end, label %for.body
+
+for.end: ; preds = %for.body
+ ret void
+}