Imported Upstream version 6.0.0.172

Former-commit-id: f3cc9b82f3e5bd8f0fd3ebc098f789556b44e9cd

external/llvm/test/Analysis/ScalarEvolution/trip-count-unknown-stride.ll

@@ -0,0 +1,62 @@
+; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
+
+; ScalarEvolution should be able to compute trip count of the loop by proving
+; that this is not an infinite loop with side effects.
+
+; CHECK: Determining loop execution counts for: @foo1
+; CHECK: backedge-taken count is ((-1 + %n) /u %s)
+
+; We should have a conservative estimate for the max backedge taken count for
+; loops with unknown stride.
+; CHECK: max backedge-taken count is -1
+
+target datalayout = "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128"
+
+; Function Attrs: norecurse nounwind
+define void @foo1(i32* nocapture %A, i32 %n, i32 %s) #0 {
+entry:
+  %cmp4 = icmp sgt i32 %n, 0
+  br i1 %cmp4, label %for.body, label %for.end
+
+for.body:                                         ; preds = %entry, %for.body
+  %i.05 = phi i32 [ %add, %for.body ], [ 0, %entry ]
+  %arrayidx = getelementptr inbounds i32, i32* %A, i32 %i.05
+  %0 = load i32, i32* %arrayidx, align 4
+  %inc = add nsw i32 %0, 1
+  store i32 %inc, i32* %arrayidx, align 4
+  %add = add nsw i32 %i.05, %s
+  %cmp = icmp slt i32 %add, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+
+; Check that we are able to compute trip count of a loop without an entry guard.
+; CHECK: Determining loop execution counts for: @foo2
+; CHECK: backedge-taken count is ((-1 + (%n smax %s)) /u %s)
+
+; We should have a conservative estimate for the max backedge taken count for
+; loops with unknown stride.
+; CHECK: max backedge-taken count is -1
+
+; Function Attrs: norecurse nounwind
+define void @foo2(i32* nocapture %A, i32 %n, i32 %s) #0 {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %i.05 = phi i32 [ %add, %for.body ], [ 0, %entry ]
+  %arrayidx = getelementptr inbounds i32, i32* %A, i32 %i.05
+  %0 = load i32, i32* %arrayidx, align 4
+  %inc = add nsw i32 %0, 1
+  store i32 %inc, i32* %arrayidx, align 4
+  %add = add nsw i32 %i.05, %s
+  %cmp = icmp slt i32 %add, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+