[LAA] Add test cases where BTC can be used to rule out dependences.

Test cases for using the backedge-taken-count to rule out dependencies between
an invariant and strided accesses.

diff --git a/llvm/test/Analysis/LoopAccessAnalysis/loop-invariant-dep-with-backedge-taken-count.ll b/llvm/test/Analysis/LoopAccessAnalysis/loop-invariant-dep-with-backedge-taken-count.ll
new file mode 100644 (file)
index 0000000..a45753e
--- /dev/null
+++ b/llvm/test/Analysis/LoopAccessAnalysis/loop-invariant-dep-with-backedge-taken-count.ll
@@ -0,0 +1,189 @@
+; RUN: opt -passes=print-access-info -disable-output %s 2>&1 | FileCheck %s
+
+; Test cases for using the backedge-taken-count to rule out dependencies between
+; an invariant and strided accesses.
+
+define void @test_distance_greater_than_BTC_100(ptr %a) {
+; CHECK-LABEL: Loop access info in function 'test_distance_greater_than_BTC_100':
+; CHECK-NEXT:   loop:
+; CHECK-NEXT:     Report: unsafe dependent memory operations in loop.
+; CHECK-NEXT: Unknown data dependence.
+; CHECK-NEXT:     Dependences:
+; CHECK-NEXT:       Unknown:
+; CHECK-NEXT:           %l = load i32, ptr %gep.x, align 4 ->
+; CHECK-NEXT:           store i32 %l, ptr %gep, align 4
+; CHECK-EMPTY:
+; CHECK-NEXT:     Run-time memory checks:
+; CHECK-NEXT:     Grouped accesses:
+; CHECK-EMPTY:
+;
+entry:
+  %gep.x = getelementptr i32, ptr %a, i32 100
+  br label %loop
+
+loop:
+  %iv = phi i32 [ 0, %entry ], [ %iv.next, %loop ]
+  %gep = getelementptr i32, ptr %a, i32 %iv
+  %l = load i32, ptr %gep.x
+  store i32 %l, ptr %gep
+  %iv.next = add i32 %iv, 1
+  %ec = icmp eq i32 %iv.next, 100
+  br i1 %ec, label %exit, label %loop
+
+exit:
+  ret void
+}
+
+define void @test_distance_much_greater_than_BTC_100(ptr %a) {
+; CHECK-LABEL: Loop access info in function 'test_distance_much_greater_than_BTC_100':
+; CHECK-NEXT:   loop:
+; CHECK-NEXT:     Report: unsafe dependent memory operations in loop.
+; CHECK-NEXT: Unknown data dependence.
+; CHECK-NEXT:     Dependences:
+; CHECK-NEXT:       Unknown:
+; CHECK-NEXT:           %l = load i32, ptr %gep.x, align 4 ->
+; CHECK-NEXT:           store i32 %l, ptr %gep, align 4
+; CHECK-EMPTY:
+; CHECK-NEXT:     Run-time memory checks:
+; CHECK-NEXT:     Grouped accesses:
+; CHECK-EMPTY:
+;
+entry:
+  %gep.x = getelementptr i32, ptr %a, i32 200
+  br label %loop
+
+loop:
+  %iv = phi i32 [ 0, %entry ], [ %iv.next, %loop ]
+  %gep = getelementptr i32, ptr %a, i32 %iv
+  %l = load i32, ptr %gep.x
+  store i32 %l, ptr %gep
+  %iv.next = add i32 %iv, 1
+  %ec = icmp eq i32 %iv.next, 100
+  br i1 %ec, label %exit, label %loop
+
+exit:
+  ret void
+}
+
+define void @test_distance_equal_BTC_100(ptr %a) {
+; CHECK-LABEL: Loop access info in function 'test_distance_equal_BTC_100':
+; CHECK-NEXT:   loop:
+; CHECK-NEXT:     Report: unsafe dependent memory operations in loop.
+; CHECK-NEXT: Unknown data dependence.
+; CHECK-NEXT:     Dependences:
+; CHECK-NEXT:       Unknown:
+; CHECK-NEXT:           %l = load i32, ptr %gep.x, align 4 ->
+; CHECK-NEXT:           store i32 %l, ptr %gep, align 4
+; CHECK-EMPTY:
+; CHECK-NEXT:     Run-time memory checks:
+; CHECK-NEXT:     Grouped accesses:
+; CHECK-EMPTY:
+;
+entry:
+  %gep.x = getelementptr i32, ptr %a, i32 99
+  br label %loop
+
+loop:
+  %iv = phi i32 [ 0, %entry ], [ %iv.next, %loop ]
+  %gep = getelementptr i32, ptr %a, i32 %iv
+  %l = load i32, ptr %gep.x
+  store i32 %l, ptr %gep
+  %iv.next = add i32 %iv, 1
+  %ec = icmp eq i32 %iv.next, 100
+  br i1 %ec, label %exit, label %loop
+
+exit:
+  ret void
+}
+
+define void @test_distance_greater_than_BTC_10000(ptr %a) {
+; CHECK-LABEL: Loop access info in function 'test_distance_greater_than_BTC_10000':
+; CHECK-NEXT:   loop:
+; CHECK-NEXT:     Report: unsafe dependent memory operations in loop.
+; CHECK-NEXT: Unknown data dependence.
+; CHECK-NEXT:     Dependences:
+; CHECK-NEXT:       Unknown:
+; CHECK-NEXT:           %l = load i32, ptr %gep.x, align 4 ->
+; CHECK-NEXT:           store i32 %l, ptr %gep, align 4
+; CHECK-EMPTY:
+; CHECK-NEXT:     Run-time memory checks:
+; CHECK-NEXT:     Grouped accesses:
+; CHECK-EMPTY:
+;
+entry:
+  %gep.x = getelementptr i32, ptr %a, i32 10000
+  br label %loop
+
+loop:
+  %iv = phi i32 [ 0, %entry ], [ %iv.next, %loop ]
+  %gep = getelementptr i32, ptr %a, i32 %iv
+  %l = load i32, ptr %gep.x
+  store i32 %l, ptr %gep
+  %iv.next = add i32 %iv, 1
+  %ec = icmp eq i32 %iv.next, 10000
+  br i1 %ec, label %exit, label %loop
+
+exit:
+  ret void
+}
+
+define void @test_distance_equal_to_BTC_10000(ptr %a) {
+; CHECK-LABEL: Loop access info in function 'test_distance_equal_to_BTC_10000':
+; CHECK-NEXT:   loop:
+; CHECK-NEXT:     Report: unsafe dependent memory operations in loop.
+; CHECK-NEXT: Unknown data dependence.
+; CHECK-NEXT:     Dependences:
+; CHECK-NEXT:       Unknown:
+; CHECK-NEXT:           %l = load i32, ptr %gep.x, align 4 ->
+; CHECK-NEXT:           store i32 %l, ptr %gep, align 4
+; CHECK-EMPTY:
+; CHECK-NEXT:     Run-time memory checks:
+; CHECK-NEXT:     Grouped accesses:
+; CHECK-EMPTY:
+;
+entry:
+  %gep.x = getelementptr i32, ptr %a, i32 9999
+  br label %loop
+
+loop:
+  %iv = phi i32 [ 0, %entry ], [ %iv.next, %loop ]
+  %gep = getelementptr i32, ptr %a, i32 %iv
+  %l = load i32, ptr %gep.x
+  store i32 %l, ptr %gep
+  %iv.next = add i32 %iv, 1
+  %ec = icmp eq i32 %iv.next, 100000
+  br i1 %ec, label %exit, label %loop
+
+exit:
+  ret void
+}
+
+define void @test_btc_is_unknown_value(ptr %a, i32 %N) {
+; CHECK-LABEL: Loop access info in function 'test_btc_is_unknown_value':
+; CHECK-NEXT:   loop:
+; CHECK-NEXT:     Report: unsafe dependent memory operations in loop.
+; CHECK-NEXT: Unknown data dependence.
+; CHECK-NEXT:     Dependences:
+; CHECK-NEXT:       Unknown:
+; CHECK-NEXT:           %l = load i32, ptr %gep.x, align 4 ->
+; CHECK-NEXT:           store i32 %l, ptr %gep, align 4
+; CHECK-EMPTY:
+; CHECK-NEXT:     Run-time memory checks:
+; CHECK-NEXT:     Grouped accesses:
+;
+entry:
+  %gep.x = getelementptr i32, ptr %a, i32 100
+  br label %loop
+
+loop:
+  %iv = phi i32 [ 0, %entry ], [ %iv.next, %loop ]
+  %gep = getelementptr i32, ptr %a, i32 %iv
+  %l = load i32, ptr %gep.x
+  store i32 %l, ptr %gep
+  %iv.next = add i32 %iv, 1
+  %ec = icmp eq i32 %iv.next, %N
+  br i1 %ec, label %exit, label %loop
+
+exit:
+  ret void
+}