[DA] Add test where ExactSIV misses dependency due to overflow (NFC) #157085
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This was referenced Sep 5, 2025
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@llvm/pr-subscribers-llvm-analysis Author: Ryotaro Kasuga (kasuga-fj) ChangesThis patch adds test cases where DA fails to detect dependencies due to overflow during analysis. For now, they are added to Full diff: https://github.com/llvm/llvm-project/pull/157085.diff 1 Files Affected:
diff --git a/llvm/test/Analysis/DependenceAnalysis/ExactSIV.ll b/llvm/test/Analysis/DependenceAnalysis/ExactSIV.ll
index 0fe62991fede9..97b58c06303e6 100644
--- a/llvm/test/Analysis/DependenceAnalysis/ExactSIV.ll
+++ b/llvm/test/Analysis/DependenceAnalysis/ExactSIV.ll
@@ -807,3 +807,116 @@ for.body: ; preds = %entry, %for.body
for.end: ; preds = %for.body
ret void
}
+
+;; FIXME: There is a loop-carried dependency between
+;; `A[-6*i + INT64_MAX]` and `A[3*i - 2]`. For example,
+;;
+;; - 1 = -6*max_i + INT64_MAX = 3*1 - 2
+;; - 4611686018427387901 = -6*768614336404564651 + INT64_MAX = 3*max_i - 2
+;;
+;; max_i = INT64_MAX/6 // 1537228672809129301
+;; for (long long i = 0; i <= max_i; i++) {
+;; A[-6*i + INT64_MAX] = 0;
+;; if (i)
+;; A[3*i - 2] = 1;
+;; }
+
+define void @exact14(ptr %A) {
+; CHECK-LABEL: 'exact14'
+; CHECK-NEXT: Src: store i8 0, ptr %idx.0, align 1 --> Dst: store i8 0, ptr %idx.0, align 1
+; CHECK-NEXT: da analyze - none!
+; CHECK-NEXT: Src: store i8 0, ptr %idx.0, align 1 --> Dst: store i8 1, ptr %idx.1, align 1
+; CHECK-NEXT: da analyze - none!
+; CHECK-NEXT: Src: store i8 1, ptr %idx.1, align 1 --> Dst: store i8 1, ptr %idx.1, align 1
+; CHECK-NEXT: da analyze - none!
+;
+; CHECK-SIV-ONLY-LABEL: 'exact14'
+; CHECK-SIV-ONLY-NEXT: Src: store i8 0, ptr %idx.0, align 1 --> Dst: store i8 0, ptr %idx.0, align 1
+; CHECK-SIV-ONLY-NEXT: da analyze - none!
+; CHECK-SIV-ONLY-NEXT: Src: store i8 0, ptr %idx.0, align 1 --> Dst: store i8 1, ptr %idx.1, align 1
+; CHECK-SIV-ONLY-NEXT: da analyze - none!
+; CHECK-SIV-ONLY-NEXT: Src: store i8 1, ptr %idx.1, align 1 --> Dst: store i8 1, ptr %idx.1, align 1
+; CHECK-SIV-ONLY-NEXT: da analyze - none!
+;
+entry:
+ br label %loop.header
+
+loop.header:
+ %i = phi i64 [ 0, %entry ], [ %i.inc, %loop.latch ]
+ %subscript.0 = phi i64 [ 9223372036854775807, %entry ], [ %subscript.0.next, %loop.latch ]
+ %subscript.1 = phi i64 [ -2, %entry ], [ %subscript.1.next, %loop.latch ]
+ %idx.0 = getelementptr inbounds i8, ptr %A, i64 %subscript.0
+ store i8 0, ptr %idx.0
+ %cond.store = icmp ne i64 %i, 0
+ br i1 %cond.store, label %if.store, label %loop.latch
+
+if.store:
+ %idx.1 = getelementptr inbounds i8, ptr %A, i64 %subscript.1
+ store i8 1, ptr %idx.1
+ br label %loop.latch
+
+loop.latch:
+ %i.inc = add nuw nsw i64 %i, 1
+ %subscript.0.next = add nuw nsw i64 %subscript.0, -6
+ %subscript.1.next = add nuw nsw i64 %subscript.1, 3
+ %exitcond = icmp sgt i64 %i.inc, 1537228672809129301
+ br i1 %exitcond, label %exit, label %loop.header
+
+exit:
+ ret void
+}
+
+;; A generalized version of @exact14.
+;;
+;; for (long long i = 0; i <= n / 6; i++) {
+;; A[-6*i + n] = 0;
+;; if (i)
+;; A[3*i - 2] = 1;
+;; }
+
+define void @exact15(ptr %A, i64 %n) {
+; CHECK-LABEL: 'exact15'
+; CHECK-NEXT: Src: store i8 0, ptr %idx.0, align 1 --> Dst: store i8 0, ptr %idx.0, align 1
+; CHECK-NEXT: da analyze - none!
+; CHECK-NEXT: Src: store i8 0, ptr %idx.0, align 1 --> Dst: store i8 1, ptr %idx.1, align 1
+; CHECK-NEXT: da analyze - output [*|<]!
+; CHECK-NEXT: Src: store i8 1, ptr %idx.1, align 1 --> Dst: store i8 1, ptr %idx.1, align 1
+; CHECK-NEXT: da analyze - none!
+;
+; CHECK-SIV-ONLY-LABEL: 'exact15'
+; CHECK-SIV-ONLY-NEXT: Src: store i8 0, ptr %idx.0, align 1 --> Dst: store i8 0, ptr %idx.0, align 1
+; CHECK-SIV-ONLY-NEXT: da analyze - none!
+; CHECK-SIV-ONLY-NEXT: Src: store i8 0, ptr %idx.0, align 1 --> Dst: store i8 1, ptr %idx.1, align 1
+; CHECK-SIV-ONLY-NEXT: da analyze - output [*|<]!
+; CHECK-SIV-ONLY-NEXT: Src: store i8 1, ptr %idx.1, align 1 --> Dst: store i8 1, ptr %idx.1, align 1
+; CHECK-SIV-ONLY-NEXT: da analyze - none!
+;
+entry:
+ %bound = sdiv i64 %n, 6
+ %guard = icmp sgt i64 %n, 0
+ br i1 %guard, label %loop.header, label %exit
+
+loop.header:
+ %i = phi i64 [ 0, %entry ], [ %i.inc, %loop.latch ]
+ %subscript.0 = phi i64 [ %n, %entry ], [ %subscript.0.next, %loop.latch ]
+ %subscript.1 = phi i64 [ -2, %entry ], [ %subscript.1.next, %loop.latch ]
+ %idx.0 = getelementptr inbounds i8, ptr %A, i64 %subscript.0
+ store i8 0, ptr %idx.0
+ %cond.store = icmp ne i64 %i, 0
+ br i1 %cond.store, label %if.store, label %loop.latch
+
+if.store:
+ %idx.1 = getelementptr inbounds i8, ptr %A, i64 %subscript.1
+ store i8 1, ptr %idx.1
+ br label %loop.latch
+
+loop.latch:
+ %i.inc = add nuw nsw i64 %i, 1
+ %subscript.0.next = add nuw nsw i64 %subscript.0, -6
+ %subscript.1.next = add nuw nsw i64 %subscript.1, 3
+ %exitcond = icmp sgt i64 %i.inc, %bound
+ br i1 %exitcond, label %exit, label %loop.header
+
+exit:
+ ret void
+}
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Meinersbur
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Sep 16, 2025
kasuga-fj
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Sep 16, 2025
This patch introduces a new option, `da-run-siv-routines-only`, which runs only the SIV family routines in the DA. This is useful for testing (regression tests, not dependence tests) as it helps detect behavioral changes in the SIV routines. Actually, regarding the test cases added in #157085, fixing the incorrect result requires changes across multiple functions (at a minimum, `exactSIVtest`, `gcdMIVtest` and `symbolicRDIVtest`). It is difficult to address all of them at once. This patch also generates the CHECK directives using the new option for `ExactSIV.ll` as it is necessary for subsequent patches. However, I believe it will also be useful for other `xxSIV.ll` tests. Notably, the SIV family routines tend to be affected by other routines, as they are typically invoked at the beginning of the overall analysis.
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September 16, 2025 18:48
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Thanks for the review! |
kasuga-fj
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Sep 19, 2025
This patch adds an overflow check to the `exactSIVtest` function to fix the issue demonstrated in the test case added in #157085. This patch only fixes one of the routines. To fully resolve the test case, the other functions need to be addressed as well.
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This patch adds test cases where DA fails to detect dependencies due to overflow during analysis. For now, they are added to
ExactSIV.ll, butsymbolicRDIVtestandgcdMIVtestalso exhibit similar issues and will need to be fixed as well.