[SCEV] Add tests for symbolic max BTC requiring predicates.

Add extra tests for llvm#93498.

Author: fhahn

llvm/test/Analysis/ScalarEvolution/predicated-symbolic-max-backedge-taken-count.ll

@@ -0,0 +1,77 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -passes='print<scalar-evolution>' -scalar-evolution-classify-expressions=0 -disable-output %s 2>&1 | FileCheck %s
+
+; %i and %i + 1 can overflow.
+define void @test1(i64 %x, ptr %a, ptr %b) {
+; CHECK-LABEL: 'test1'
+; CHECK-NEXT:  Determining loop execution counts for: @test1
+; CHECK-NEXT:  Loop %header: <multiple exits> Unpredictable backedge-taken count.
+; CHECK-NEXT:    exit count for header: ***COULDNOTCOMPUTE***
+; CHECK-NEXT:    exit count for latch: ***COULDNOTCOMPUTE***
+; CHECK-NEXT:  Loop %header: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT:  Loop %header: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT:    symbolic max exit count for header: ***COULDNOTCOMPUTE***
+; CHECK-NEXT:    symbolic max exit count for latch: ***COULDNOTCOMPUTE***
+;
+entry:
+  br label %header
+
+header:
+  %conv11 = phi i64 [ 0, %entry ], [ %conv, %latch ]
+  %i.010 = phi i32 [ 0, %entry ], [ %add, %latch ]
+  %add = add i32 %i.010, 1
+  %idxprom = zext i32 %add to i64
+  %arrayidx = getelementptr inbounds i32, ptr %a, i64 %idxprom
+  %ld = load i32, ptr %arrayidx, align 4
+  %uncountable.c = icmp eq i32 %ld, 10
+  br i1 %uncountable.c, label %exit, label %latch
+
+latch:
+  %add2 = add nsw i32 %ld, 1
+  %arrayidx4 = getelementptr inbounds i32, ptr %b, i64 %conv11
+  store i32 %add2, ptr %arrayidx4, align 4
+  %conv = zext i32 %add to i64
+  %cmp = icmp ult i64 %conv, %x
+  br i1 %cmp, label %header, label %exit
+
+exit:
+  ret void
+}
+
+; %i can overflow.
+;
+; We need to check that i doesn't wrap, but we don't need a run-time alias
+; check. We also need an extra no-wrap check to get the backedge taken count.
+define void @test2(i64 %x, ptr %a) {
+; CHECK-LABEL: 'test2'
+; CHECK-NEXT:  Determining loop execution counts for: @test2
+; CHECK-NEXT:  Loop %header: <multiple exits> Unpredictable backedge-taken count.
+; CHECK-NEXT:    exit count for header: ***COULDNOTCOMPUTE***
+; CHECK-NEXT:    exit count for latch: ***COULDNOTCOMPUTE***
+; CHECK-NEXT:  Loop %header: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT:  Loop %header: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT:    symbolic max exit count for header: ***COULDNOTCOMPUTE***
+; CHECK-NEXT:    symbolic max exit count for latch: ***COULDNOTCOMPUTE***
+;
+entry:
+  br label %header
+
+header:
+  %conv11 = phi i64 [ 0, %entry ], [ %conv, %latch ]
+  %i.010 = phi i32  [ 0, %entry ], [ %inc, %latch ]
+  %arrayidx = getelementptr inbounds i32, ptr %a, i64 %conv11
+  %ld = load i32, ptr %arrayidx, align 4
+  %uncountable.c = icmp eq i32 %ld, 10
+  br i1 %uncountable.c, label %exit, label %latch
+
+latch:
+  %add = add nsw i32 %ld, 1
+  store i32 %add, ptr %arrayidx, align 4
+  %inc = add i32 %i.010, 1
+  %conv = zext i32 %inc to i64
+  %cmp = icmp ult i64 %conv, %x
+  br i1 %cmp, label %header, label %exit
+
+exit:
+  ret void
+}