[llvm] [DA] Add a test where the Exact RDIV test misses a dependency (NFC) (PR #189577)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-analysis

Author: Ryotaro Kasuga (kasuga-fj)

<details>
<summary>Changes</summary>

Add a test to demonstrate the case where the Exact RDIV test misses a dependency because the calculation of `Delta` overflows.

---
Full diff: https://github.com/llvm/llvm-project/pull/189577.diff


1 Files Affected:

- (added) llvm/test/Analysis/DependenceAnalysis/exact-rdiv-delta-overflow.ll (+76) 


``````````diff
diff --git a/llvm/test/Analysis/DependenceAnalysis/exact-rdiv-delta-overflow.ll b/llvm/test/Analysis/DependenceAnalysis/exact-rdiv-delta-overflow.ll
new file mode 100644
index 0000000000000..25b7ccb837709
--- /dev/null
+++ b/llvm/test/Analysis/DependenceAnalysis/exact-rdiv-delta-overflow.ll
@@ -0,0 +1,76 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 6
+; RUN: opt < %s -disable-output "-passes=print<da>" 2>&1 \
+; RUN:     | FileCheck %s --check-prefixes=CHECK,CHECK-ALL
+; RUN: opt < %s -disable-output "-passes=print<da>" -da-enable-dependence-test=exact-rdiv 2>&1 \
+; RUN:     | FileCheck %s --check-prefixes=CHECK,CHECK-EXACT-RDIV
+
+
+; max_i = INT64_MAX/6  // 1537228672809129301
+; for (i = 0; i <= max_i; i++) {
+;   A[-6*i + INT64_MAX] = 0;
+; }
+;
+; for (i = 0; i <= max_i + 1; i++) {
+;   if (i)
+;     A[3*i - 2] = 1;
+; }
+;
+;  memory access           | i = 1 | i = 768614336404564651 | i = max_i
+; -------------------------|-------|------------------------|----------------
+;  A[-6*i + INT64_MAX]     |       | A[3*max_i - 2]         | A[1]
+;  A[3*i - 2]              | A[1]  |                        | A[3*max_i - 2]
+;
+; FIXME: There is a dependency between the two stores.
+;
+define void @exact_rdiv_delta_ovfl(ptr %A) {
+; CHECK-ALL-LABEL: 'exact_rdiv_delta_ovfl'
+; CHECK-ALL-NEXT:  Src: store i8 0, ptr %gep.0, align 1 --> Dst: store i8 0, ptr %gep.0, align 1
+; CHECK-ALL-NEXT:    da analyze - none!
+; CHECK-ALL-NEXT:  Src: store i8 0, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.1, align 1
+; CHECK-ALL-NEXT:    da analyze - none!
+; CHECK-ALL-NEXT:  Src: store i8 1, ptr %gep.1, align 1 --> Dst: store i8 1, ptr %gep.1, align 1
+; CHECK-ALL-NEXT:    da analyze - none!
+;
+; CHECK-EXACT-RDIV-LABEL: 'exact_rdiv_delta_ovfl'
+; CHECK-EXACT-RDIV-NEXT:  Src: store i8 0, ptr %gep.0, align 1 --> Dst: store i8 0, ptr %gep.0, align 1
+; CHECK-EXACT-RDIV-NEXT:    da analyze - output [*]!
+; CHECK-EXACT-RDIV-NEXT:  Src: store i8 0, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.1, align 1
+; CHECK-EXACT-RDIV-NEXT:    da analyze - none!
+; CHECK-EXACT-RDIV-NEXT:  Src: store i8 1, ptr %gep.1, align 1 --> Dst: store i8 1, ptr %gep.1, align 1
+; CHECK-EXACT-RDIV-NEXT:    da analyze - output [*]!
+;
+entry:
+  br label %loop.0
+
+loop.0:
+  %i.0 = phi i64 [ 0, %entry ], [ %i.0.inc, %loop.0 ]
+  %offset.0 = phi i64 [ 9223372036854775807, %entry ], [ %offset.0.next, %loop.0 ]
+  %gep.0 = getelementptr i8, ptr %A, i64 %offset.0
+  store i8 0, ptr %gep.0
+  %i.0.inc = add i64 %i.0, 1
+  %offset.0.next = add i64 %offset.0, -6
+  %ec.0 = icmp eq i64 %i.0, 1537228672809129301
+  br i1 %ec.0, label %loop.1.header, label %loop.0
+
+loop.1.header:
+  %i.1 = phi i64 [ 0, %loop.0 ], [ %i.1.inc, %loop.1.latch ]
+  %offset.1 = phi i64 [ -2, %loop.0 ], [ %offset.1.next, %loop.1.latch ]
+  %cond.store = icmp ne i64 %i.1, 0
+  br i1 %cond.store, label %if.store, label %loop.1.latch
+
+if.store:
+  %gep.1 = getelementptr i8, ptr %A, i64 %offset.1
+  store i8 1, ptr %gep.1
+  br label %loop.1.latch
+
+loop.1.latch:
+  %i.1.inc = add i64 %i.1, 1
+  %offset.1.next = add i64 %offset.1, 3
+  %ec.1 = icmp eq i64 %i.1, 1537228672809129302
+  br i1 %ec.1, label %exit, label %loop.1.header
+
+exit:
+  ret void
+}
+;; NOTE: These prefixes are unused and the list is autogenerated. Do not add tests below this line:
+; CHECK: {{.*}}

``````````

</details>


https://github.com/llvm/llvm-project/pull/189577