From 026d35bc14a4c1a3233df37edd38f5f955fa5b95 Mon Sep 17 00:00:00 2001 From: Ryotaro Kasuga Date: Fri, 17 Oct 2025 13:26:38 +0000 Subject: [PATCH] [DA] Add tests where dependencies are missed due to overflow --- .../DependenceAnalysis/gcd-miv-overflow.ll | 63 +++++++++ .../DependenceAnalysis/strong-siv-overflow.ll | 72 ++++++++++ .../symbolic-rdiv-overflow.ll | 128 ++++++++++++++++++ .../weak-crossing-siv-overflow.ll | 122 +++++++++++++++++ .../weak-zero-siv-overflow.ll | 121 +++++++++++++++++ 5 files changed, 506 insertions(+) create mode 100644 llvm/test/Analysis/DependenceAnalysis/gcd-miv-overflow.ll create mode 100644 llvm/test/Analysis/DependenceAnalysis/strong-siv-overflow.ll create mode 100644 llvm/test/Analysis/DependenceAnalysis/symbolic-rdiv-overflow.ll create mode 100644 llvm/test/Analysis/DependenceAnalysis/weak-crossing-siv-overflow.ll create mode 100644 llvm/test/Analysis/DependenceAnalysis/weak-zero-siv-overflow.ll diff --git a/llvm/test/Analysis/DependenceAnalysis/gcd-miv-overflow.ll b/llvm/test/Analysis/DependenceAnalysis/gcd-miv-overflow.ll new file mode 100644 index 0000000000000..724b347b56f3a --- /dev/null +++ b/llvm/test/Analysis/DependenceAnalysis/gcd-miv-overflow.ll @@ -0,0 +1,63 @@ +; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 6 +; RUN: opt < %s -disable-output "-passes=print" 2>&1 | FileCheck %s +; RUN: opt < %s -disable-output "-passes=print" -da-enable-dependence-test=gcd-miv 2>&1 \ +; RUN: | FileCheck %s --check-prefix=CHECK-GCD-MIV + +; offset0 = 4; +; offset1 = 0; +; for (i = 0; i < 100; i++) { +; A[offset0] = 1; +; A[offset1] = 2; +; offset0 += 3*m; +; offset1 += 3; +; } +; +; FIXME: DependenceAnalysis currently detects no dependency between the two +; stores, but it does exist. E.g., consider `m` is 12297829382473034411, which +; is a modular multiplicative inverse of 3 under modulo 2^64. Then `offset0` is +; effectively `i + 4`, so accesses will be as follows: +; +; - A[offset0] : A[4], A[5], A[6], ... +; - A[offset1] : A[0], A[3], A[6], ... +; +; The root cause is that DA assumes `3*m` begin a multiple of 3 in mathematical +; sense, which isn't necessarily true due to overflow. +; +define void @gcdmiv_coef_ovfl(ptr %A, i64 %m) { +; CHECK-LABEL: 'gcdmiv_coef_ovfl' +; CHECK-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.0, align 1 +; CHECK-NEXT: da analyze - none! +; CHECK-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-NEXT: da analyze - none! +; CHECK-NEXT: Src: store i8 2, ptr %gep.1, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-NEXT: da analyze - none! +; +; CHECK-GCD-MIV-LABEL: 'gcdmiv_coef_ovfl' +; CHECK-GCD-MIV-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.0, align 1 +; CHECK-GCD-MIV-NEXT: da analyze - consistent output [*]! +; CHECK-GCD-MIV-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-GCD-MIV-NEXT: da analyze - none! +; CHECK-GCD-MIV-NEXT: Src: store i8 2, ptr %gep.1, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-GCD-MIV-NEXT: da analyze - consistent output [*]! +; +entry: + %step = mul i64 3, %m + br label %loop + +loop: + %i = phi i64 [ 0, %entry ], [ %i.inc, %loop ] + %offset.0 = phi i64 [ 4, %entry ] , [ %offset.0.next, %loop ] + %offset.1 = phi i64 [ 0, %entry ] , [ %offset.1.next, %loop ] + %gep.0 = getelementptr inbounds i8, ptr %A, i64 %offset.0 + %gep.1 = getelementptr inbounds i8, ptr %A, i64 %offset.1 + store i8 1, ptr %gep.0 + store i8 2, ptr %gep.1 + %i.inc = add nuw nsw i64 %i, 1 + %offset.0.next = add nsw i64 %offset.0, %step + %offset.1.next = add nsw i64 %offset.1, 3 + %ec = icmp eq i64 %i.inc, 100 + br i1 %ec, label %exit, label %loop + +exit: + ret void +} diff --git a/llvm/test/Analysis/DependenceAnalysis/strong-siv-overflow.ll b/llvm/test/Analysis/DependenceAnalysis/strong-siv-overflow.ll new file mode 100644 index 0000000000000..559f4858612e5 --- /dev/null +++ b/llvm/test/Analysis/DependenceAnalysis/strong-siv-overflow.ll @@ -0,0 +1,72 @@ +; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 6 +; RUN: opt < %s -disable-output "-passes=print" 2>&1 | FileCheck %s +; RUN: opt < %s -disable-output "-passes=print" -da-enable-dependence-test=strong-siv 2>&1 \ +; RUN: | FileCheck %s --check-prefix=CHECK-STRONG-SIV + +; offset0 = -2; +; offset1 = -4; +; for (i = 0; i < (1LL << 62); i++, offset0 += 2, offset1 += 2) { +; if (0 <= offset0) +; A[offset0] = 1; +; if (0 <= offset1) +; A[offset1] = 2; +; } +; +; FIXME: DependenceAnalysis currently detects no dependency between the two +; stores, but it does exist. +; The root cause is that the product of the BTC and the coefficient triggers an +; overflow. +define void @strongsiv_const_ovfl(ptr %A) { +; CHECK-LABEL: 'strongsiv_const_ovfl' +; CHECK-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.0, align 1 +; CHECK-NEXT: da analyze - none! +; CHECK-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-NEXT: da analyze - none! +; CHECK-NEXT: Src: store i8 2, ptr %gep.1, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-NEXT: da analyze - none! +; +; CHECK-STRONG-SIV-LABEL: 'strongsiv_const_ovfl' +; CHECK-STRONG-SIV-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.0, align 1 +; CHECK-STRONG-SIV-NEXT: da analyze - none! +; CHECK-STRONG-SIV-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-STRONG-SIV-NEXT: da analyze - none! +; CHECK-STRONG-SIV-NEXT: Src: store i8 2, ptr %gep.1, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-STRONG-SIV-NEXT: da analyze - none! +; +entry: + br label %loop.header + +loop.header: + %i = phi i64 [ 0, %entry ], [ %i.inc, %loop.latch ] + %offset.0 = phi i64 [ -2, %entry ], [ %offset.0.next, %loop.latch ] + %offset.1 = phi i64 [ -4, %entry ], [ %offset.1.next, %loop.latch ] + %ec = icmp eq i64 %i, 4611686018427387904 + br i1 %ec, label %exit, label %loop.body + +loop.body: + %cond.0 = icmp sge i64 %offset.0, 0 + %cond.1 = icmp sge i64 %offset.1, 0 + br i1 %cond.0, label %if.then.0, label %loop.middle + +if.then.0: + %gep.0 = getelementptr inbounds i8, ptr %A, i64 %offset.0 + store i8 1, ptr %gep.0 + br label %loop.middle + +loop.middle: + br i1 %cond.1, label %if.then.1, label %loop.latch + +if.then.1: + %gep.1 = getelementptr inbounds i8, ptr %A, i64 %offset.1 + store i8 2, ptr %gep.1 + br label %loop.latch + +loop.latch: + %i.inc = add nuw nsw i64 %i, 1 + %offset.0.next = add nsw i64 %offset.0, 2 + %offset.1.next = add nsw i64 %offset.1, 2 + br label %loop.header + +exit: + ret void +} diff --git a/llvm/test/Analysis/DependenceAnalysis/symbolic-rdiv-overflow.ll b/llvm/test/Analysis/DependenceAnalysis/symbolic-rdiv-overflow.ll new file mode 100644 index 0000000000000..f22553f9931a2 --- /dev/null +++ b/llvm/test/Analysis/DependenceAnalysis/symbolic-rdiv-overflow.ll @@ -0,0 +1,128 @@ +; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 6 +; RUN: opt < %s -disable-output "-passes=print" 2>&1 | FileCheck %s +; RUN: opt < %s -disable-output "-passes=print" -da-enable-dependence-test=symbolic-rdiv 2>&1 \ +; RUN: | FileCheck %s --check-prefix=CHECK-SYMBOLIC-RDIV + +; offset = -2; +; for (i = 0; i < (1LL << 62); i++, offset += 2) { +; if (0 <= offset0) +; A[offset0] = 1; +; A[i] = 2; +; } +; +; FIXME: DependenceAnalysis currently detects no dependency between the two +; stores, but it does exist. +; The root cause is that the product of the BTC and the coefficient triggers an +; overflow. +define void @symbolicrdiv_prod_ovfl(ptr %A) { +; CHECK-LABEL: 'symbolicrdiv_prod_ovfl' +; CHECK-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.0, align 1 +; CHECK-NEXT: da analyze - none! +; CHECK-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-NEXT: da analyze - none! +; CHECK-NEXT: Src: store i8 2, ptr %gep.1, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-NEXT: da analyze - none! +; +; CHECK-SYMBOLIC-RDIV-LABEL: 'symbolicrdiv_prod_ovfl' +; CHECK-SYMBOLIC-RDIV-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.0, align 1 +; CHECK-SYMBOLIC-RDIV-NEXT: da analyze - none! +; CHECK-SYMBOLIC-RDIV-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-SYMBOLIC-RDIV-NEXT: da analyze - none! +; CHECK-SYMBOLIC-RDIV-NEXT: Src: store i8 2, ptr %gep.1, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-SYMBOLIC-RDIV-NEXT: da analyze - consistent output [*]! +; +entry: + br label %loop.header + +loop.header: + %i = phi i64 [ 0, %entry ], [ %i.inc, %loop.latch ] + %offset = phi i64 [ -2, %entry ], [ %offset.next, %loop.latch ] + %ec = icmp eq i64 %i, 4611686018427387904 + br i1 %ec, label %exit, label %loop.body + +loop.body: + %cond = icmp sge i64 %offset, 0 + br i1 %cond, label %if.then, label %loop.latch + +if.then: + %gep.0 = getelementptr inbounds i8, ptr %A, i64 %offset + store i8 1, ptr %gep.0 + br label %loop.latch + +loop.latch: + %gep.1 = getelementptr inbounds i8, ptr %A, i64 %i + store i8 2, ptr %gep.1 + %i.inc = add nuw nsw i64 %i, 1 + %offset.next = add nsw i64 %offset, 2 + br label %loop.header + +exit: + ret void +} + +; offset0 = -4611686018427387904 // -2^62 +; offset1 = 4611686018427387904 // 2^62 +; for (i = 0; i < (1LL << 62) - 100; i++) { +; if (0 <= offset0) +; A[offset0] = 1; +; if (0 <= offset1) +; A[offset1] = 2; +; offset0 += 2; +; offset1 -= 1; +; } +; +; FIXME: DependenceAnalysis currently detects no dependency between the two +; stores, but it does exist. +; The root cause is that the calculation of the differenct between the two +; constants (-2^62 and 2^62) triggers an overflow. +define void @symbolicrdiv_delta_ovfl(ptr %A) { +; CHECK-LABEL: 'symbolicrdiv_delta_ovfl' +; CHECK-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.0, align 1 +; CHECK-NEXT: da analyze - none! +; CHECK-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-NEXT: da analyze - none! +; CHECK-NEXT: Src: store i8 2, ptr %gep.1, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-NEXT: da analyze - none! +; +; CHECK-SYMBOLIC-RDIV-LABEL: 'symbolicrdiv_delta_ovfl' +; CHECK-SYMBOLIC-RDIV-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.0, align 1 +; CHECK-SYMBOLIC-RDIV-NEXT: da analyze - consistent output [*]! +; CHECK-SYMBOLIC-RDIV-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-SYMBOLIC-RDIV-NEXT: da analyze - none! +; CHECK-SYMBOLIC-RDIV-NEXT: Src: store i8 2, ptr %gep.1, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-SYMBOLIC-RDIV-NEXT: da analyze - consistent output [*]! +; +entry: + br label %loop.header + +loop.header: + %i = phi i64 [ 0, %entry ], [ %i.inc, %loop.latch ] + %offset.0 = phi i64 [ -4611686018427387904, %entry ], [ %offset.0.next, %loop.latch ] + %offset.1 = phi i64 [ 4611686018427387904, %entry ], [ %offset.1.next, %loop.latch ] + %cond.0 = icmp sge i64 %offset.0, 0 + %cond.1 = icmp sge i64 %offset.1, 0 + br i1 %cond.0, label %if.then.0, label %loop.middle + +if.then.0: + %gep.0 = getelementptr inbounds i8, ptr %A, i64 %offset.0 + store i8 1, ptr %gep.0 + br label %loop.middle + +loop.middle: + br i1 %cond.1, label %if.then.1, label %loop.latch + +if.then.1: + %gep.1 = getelementptr inbounds i8, ptr %A, i64 %offset.1 + store i8 2, ptr %gep.1 + br label %loop.latch + +loop.latch: + %i.inc = add nuw nsw i64 %i, 1 + %offset.0.next = add nsw i64 %offset.0, 2 + %offset.1.next = sub nsw i64 %offset.1, 1 + %ec = icmp eq i64 %i.inc, 4611686018427387804 ; 2^62 - 100 + br i1 %ec, label %exit, label %loop.header + +exit: + ret void +} diff --git a/llvm/test/Analysis/DependenceAnalysis/weak-crossing-siv-overflow.ll b/llvm/test/Analysis/DependenceAnalysis/weak-crossing-siv-overflow.ll new file mode 100644 index 0000000000000..59412d8381d68 --- /dev/null +++ b/llvm/test/Analysis/DependenceAnalysis/weak-crossing-siv-overflow.ll @@ -0,0 +1,122 @@ +; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 6 +; RUN: opt < %s -disable-output "-passes=print" 2>&1 | FileCheck %s +; RUN: opt < %s -disable-output "-passes=print" -da-enable-dependence-test=weak-crossing-siv 2>&1 \ +; RUN: | FileCheck %s --check-prefix=CHECK-WEAK-CROSSING-SIV + +; max_i = INT64_MAX/3 // 3074457345618258602 +; for (long long i = 0; i <= max_i; i++) { +; A[-3*i + INT64_MAX] = 0; +; if (i) +; A[3*i - 2] = 1; +; } +; +; FIXME: DependencyAnalsysis currently detects no dependency between +; `A[-3*i + INT64_MAX]` and `A[3*i - 2]`, but it does exist. For example, +; +; memory location | -3*i + INT64_MAX | 3*i - 2 +; ------------------|------------------|----------- +; A[1] | i = max_i | i = 1 +; A[INT64_MAX - 3] | i = 1 | i = max_i +; +; The root cause is that the calculation of the differenct between the two +; constants (INT64_MAX and -2) triggers an overflow. + +define void @weakcorssing_delta_ovfl(ptr %A) { +; CHECK-LABEL: 'weakcorssing_delta_ovfl' +; 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-WEAK-CROSSING-SIV-LABEL: 'weakcorssing_delta_ovfl' +; CHECK-WEAK-CROSSING-SIV-NEXT: Src: store i8 0, ptr %idx.0, align 1 --> Dst: store i8 0, ptr %idx.0, align 1 +; CHECK-WEAK-CROSSING-SIV-NEXT: da analyze - consistent output [*]! +; CHECK-WEAK-CROSSING-SIV-NEXT: Src: store i8 0, ptr %idx.0, align 1 --> Dst: store i8 1, ptr %idx.1, align 1 +; CHECK-WEAK-CROSSING-SIV-NEXT: da analyze - none! +; CHECK-WEAK-CROSSING-SIV-NEXT: Src: store i8 1, ptr %idx.1, align 1 --> Dst: store i8 1, ptr %idx.1, align 1 +; CHECK-WEAK-CROSSING-SIV-NEXT: da analyze - consistent output [*]! +; +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, -3 + %subscript.1.next = add nsw i64 %subscript.1, 3 + %ec = icmp sgt i64 %i.inc, 3074457345618258602 + br i1 %ec, label %exit, label %loop.header + +exit: + ret void +} + +; max_i = INT64_MAX/3 // 3074457345618258602 +; for (long long i = 0; i <= max_i; i++) { +; A[-3*i + INT64_MAX] = 0; +; A[3*i + 1] = 1; +; } +; +; FIXME: DependencyAnalsysis currently detects no dependency between +; `A[-3*i + INT64_MAX]` and `A[3*i - 2]`, but it does exist. For example, +; +; memory location | -3*i + INT64_MAX | 3*i + 1 +; ------------------|------------------|-------------- +; A[1] | i = max_i | i = 0 +; A[INT64_MAX - 3] | i = 1 | i = max_i - 1 +; +; The root cause is that the product of the BTC, the coefficient, and 2 +; triggers an overflow. +; +define void @weakcorssing_prod_ovfl(ptr %A) { +; CHECK-LABEL: 'weakcorssing_prod_ovfl' +; 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-WEAK-CROSSING-SIV-LABEL: 'weakcorssing_prod_ovfl' +; CHECK-WEAK-CROSSING-SIV-NEXT: Src: store i8 0, ptr %idx.0, align 1 --> Dst: store i8 0, ptr %idx.0, align 1 +; CHECK-WEAK-CROSSING-SIV-NEXT: da analyze - consistent output [*]! +; CHECK-WEAK-CROSSING-SIV-NEXT: Src: store i8 0, ptr %idx.0, align 1 --> Dst: store i8 1, ptr %idx.1, align 1 +; CHECK-WEAK-CROSSING-SIV-NEXT: da analyze - none! +; CHECK-WEAK-CROSSING-SIV-NEXT: Src: store i8 1, ptr %idx.1, align 1 --> Dst: store i8 1, ptr %idx.1, align 1 +; CHECK-WEAK-CROSSING-SIV-NEXT: da analyze - consistent output [*]! +; +entry: + br label %loop + +loop: + %i = phi i64 [ 0, %entry ], [ %i.inc, %loop ] + %subscript.0 = phi i64 [ 9223372036854775807, %entry ], [ %subscript.0.next, %loop ] + %subscript.1 = phi i64 [ 1, %entry ], [ %subscript.1.next, %loop ] + %idx.0 = getelementptr inbounds i8, ptr %A, i64 %subscript.0 + %idx.1 = getelementptr inbounds i8, ptr %A, i64 %subscript.1 + store i8 0, ptr %idx.0 + store i8 1, ptr %idx.1 + %i.inc = add nuw nsw i64 %i, 1 + %subscript.0.next = add nsw i64 %subscript.0, -3 + %subscript.1.next = add nsw i64 %subscript.1, 3 + %ec = icmp sgt i64 %i.inc, 3074457345618258602 + br i1 %ec, label %exit, label %loop + +exit: + ret void +} diff --git a/llvm/test/Analysis/DependenceAnalysis/weak-zero-siv-overflow.ll b/llvm/test/Analysis/DependenceAnalysis/weak-zero-siv-overflow.ll new file mode 100644 index 0000000000000..0e5deb610bd61 --- /dev/null +++ b/llvm/test/Analysis/DependenceAnalysis/weak-zero-siv-overflow.ll @@ -0,0 +1,121 @@ +; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 6 +; RUN: opt < %s -disable-output "-passes=print" 2>&1 | FileCheck %s +; RUN: opt < %s -disable-output "-passes=print" -da-enable-dependence-test=weak-zero-siv 2>&1 \ +; RUN: | FileCheck %s --check-prefix=CHECK-WEAK-ZERO-SIV + +; offset = -2; +; for (i = 0; i < (1LL << 62); i++, offset += 2) { +; if (0 <= offset) +; A[offset] = 1; +; A[2] = 2; +; } +; +; FIXME: DependenceAnalysis currently detects no dependency between the two +; stores, but it does exist. The root cause is that the product of the BTC and +; the coefficient triggers an overflow. +; +define void @weakzero_dst_siv_prod_ovfl(ptr %A) { +; CHECK-LABEL: 'weakzero_dst_siv_prod_ovfl' +; CHECK-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.0, align 1 +; CHECK-NEXT: da analyze - none! +; CHECK-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-NEXT: da analyze - none! +; CHECK-NEXT: Src: store i8 2, ptr %gep.1, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-NEXT: da analyze - consistent output [S]! +; +; CHECK-WEAK-ZERO-SIV-LABEL: 'weakzero_dst_siv_prod_ovfl' +; CHECK-WEAK-ZERO-SIV-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.0, align 1 +; CHECK-WEAK-ZERO-SIV-NEXT: da analyze - consistent output [*]! +; CHECK-WEAK-ZERO-SIV-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-WEAK-ZERO-SIV-NEXT: da analyze - none! +; CHECK-WEAK-ZERO-SIV-NEXT: Src: store i8 2, ptr %gep.1, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-WEAK-ZERO-SIV-NEXT: da analyze - consistent output [S]! +; +entry: + br label %loop.header + +loop.header: + %i = phi i64 [ 0, %entry ], [ %i.inc, %loop.latch ] + %offset = phi i64 [ -2, %entry ], [ %offset.next, %loop.latch ] + %ec = icmp eq i64 %i, 4611686018427387904 + br i1 %ec, label %exit, label %loop.body + +loop.body: + %cond = icmp sge i64 %offset, 0 + br i1 %cond, label %if.then, label %loop.latch + +if.then: + %gep.0 = getelementptr inbounds i8, ptr %A, i64 %offset + store i8 1, ptr %gep.0 + br label %loop.latch + +loop.latch: + %gep.1 = getelementptr inbounds i8, ptr %A, i64 2 + store i8 2, ptr %gep.1 + %i.inc = add nuw nsw i64 %i, 1 + %offset.next = add nsw i64 %offset, 2 + br label %loop.header + +exit: + ret void +} + +; offset = -1; +; for (i = 0; i < n; i++, offset += 2) { +; if (0 <= offset) +; A[offset] = 1; +; A[INT64_MAX] = 2; +; } +; +; FIXME: DependenceAnalysis currently detects no dependency between the two +; stores, but it does exist. When `%n` is 2^62, the value of `%offset` will be +; the same as INT64_MAX at the last iteration. +; The root cause is that the calculation of the differenct between the two +; constants (INT64_MAX and -1) triggers an overflow. +; +define void @weakzero_dst_siv_delta_ovfl(ptr %A, i64 %n) { +; CHECK-LABEL: 'weakzero_dst_siv_delta_ovfl' +; CHECK-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.0, align 1 +; CHECK-NEXT: da analyze - none! +; CHECK-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-NEXT: da analyze - none! +; CHECK-NEXT: Src: store i8 2, ptr %gep.1, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-NEXT: da analyze - consistent output [S]! +; +; CHECK-WEAK-ZERO-SIV-LABEL: 'weakzero_dst_siv_delta_ovfl' +; CHECK-WEAK-ZERO-SIV-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.0, align 1 +; CHECK-WEAK-ZERO-SIV-NEXT: da analyze - consistent output [*]! +; CHECK-WEAK-ZERO-SIV-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-WEAK-ZERO-SIV-NEXT: da analyze - none! +; CHECK-WEAK-ZERO-SIV-NEXT: Src: store i8 2, ptr %gep.1, align 1 --> Dst: store i8 2, ptr %gep.1, align 1 +; CHECK-WEAK-ZERO-SIV-NEXT: da analyze - consistent output [S]! +; +entry: + %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 ] + %offset = phi i64 [ -2, %entry ], [ %offset.next, %loop.latch ] + %ec = icmp eq i64 %i, %n + br i1 %ec, label %exit, label %loop.body + +loop.body: + %cond = icmp sge i64 %offset, 0 + br i1 %cond, label %if.then, label %loop.latch + +if.then: + %gep.0 = getelementptr inbounds i8, ptr %A, i64 %offset + store i8 1, ptr %gep.0 + br label %loop.latch + +loop.latch: + %gep.1 = getelementptr inbounds i8, ptr %A, i64 9223372036854775807 + store i8 2, ptr %gep.1 + %i.inc = add nuw nsw i64 %i, 1 + %offset.next = add nsw i64 %offset, 2 + br label %loop.header + +exit: + ret void +}