https://github.com/kasuga-fj updated
https://github.com/llvm/llvm-project/pull/157085
>From 4e43533b48aa613b05fb0753ac290809da8f28d1 Mon Sep 17 00:00:00 2001
From: Ryotaro Kasuga <kasuga.ryot...@fujitsu.com>
Date: Fri, 5 Sep 2025 11:32:54 +0000
Subject: [PATCH 1/2] [DA] Add test where ExactSIV misses dependency due to
overflow (NFC)
---
.../Analysis/DependenceAnalysis/ExactSIV.ll | 120 ++++++++++++++++++
1 file changed, 120 insertions(+)
diff --git a/llvm/test/Analysis/DependenceAnalysis/ExactSIV.ll
b/llvm/test/Analysis/DependenceAnalysis/ExactSIV.ll
index 0fe62991fede9..a16751397c487 100644
--- a/llvm/test/Analysis/DependenceAnalysis/ExactSIV.ll
+++ b/llvm/test/Analysis/DependenceAnalysis/ExactSIV.ll
@@ -807,3 +807,123 @@ for.body: ; preds
= %entry, %for.body
for.end: ; preds = %for.body
ret void
}
+
+;; 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;
+;; }
+;;
+;; FIXME: There is a loop-carried dependency between
+;; `A[-6*i + INT64_MAX]` and `A[3*i - 2]`. For example,
+;;
+;; | memory location | -6*i + INT64_MAX | 3*i - 2
+;; |------------------------|------------------------|-----------
+;; | A[1] | i = max_i | i = 1
+;; | A[4611686018427387901] | i = 768614336404564651 | i = max_i
+;;
+;; Actually,
+;; * 1 = -6*max_i + INT64_MAX = 3*1 - 2
+;; * 4611686018427387901 = -6*768614336404564651 + INT64_MAX = 3*max_i - 2
+;;
+
+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 nsw i64 %subscript.0, -6
+ %subscript.1.next = add 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 nsw i64 %subscript.0, -6
+ %subscript.1.next = add nsw i64 %subscript.1, 3
+ %exitcond = icmp sgt i64 %i.inc, %bound
+ br i1 %exitcond, label %exit, label %loop.header
+
+exit:
+ ret void
+}
>From 6a3a5fcb1b0d9d99a5de3c47cef9a26e18542919 Mon Sep 17 00:00:00 2001
From: Ryotaro Kasuga <kasuga.ryot...@fujitsu.com>
Date: Tue, 16 Sep 2025 13:08:24 +0000
Subject: [PATCH 2/2] address review comment
---
llvm/test/Analysis/DependenceAnalysis/ExactSIV.ll | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/llvm/test/Analysis/DependenceAnalysis/ExactSIV.ll
b/llvm/test/Analysis/DependenceAnalysis/ExactSIV.ll
index a16751397c487..2a809c32d7d21 100644
--- a/llvm/test/Analysis/DependenceAnalysis/ExactSIV.ll
+++ b/llvm/test/Analysis/DependenceAnalysis/ExactSIV.ll
@@ -815,8 +815,8 @@ for.end: ; preds =
%for.body
;; A[3*i - 2] = 1;
;; }
;;
-;; FIXME: There is a loop-carried dependency between
-;; `A[-6*i + INT64_MAX]` and `A[3*i - 2]`. For example,
+;; FIXME: DependencyAnalsysis currently detects no dependency between
+;; `A[-6*i + INT64_MAX]` and `A[3*i - 2]`, but it does exist. For example,
;;
;; | memory location | -6*i + INT64_MAX | 3*i - 2
;; |------------------------|------------------------|-----------
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