[DA] Add tests where dependencies are missed due to overflow (NFC) #164246
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@sjoerdmeijer These are the cases I was able to find where intermediate computations cause overflow, leading to incorrect results being reported. Note that
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| ; 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) { |
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This is a bit special; the coefficient have already wrapped. This should be fixed by #164408 .
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@llvm/pr-subscribers-llvm-analysis Author: Ryotaro Kasuga (kasuga-fj) ChangesThis patch adds test cases that demonstrate missing dependencies in DA caused by the lack of overflow handling. These issues will be addressed by properly inserting overflow checks and bailing out when one is detected. It covers the following dependence test functions:
It does NOT cover:
Patch is 21.41 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/164246.diff 5 Files Affected:
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<da>" 2>&1 | FileCheck %s
+; RUN: opt < %s -disable-output "-passes=print<da>" -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<da>" 2>&1 | FileCheck %s
+; RUN: opt < %s -disable-output "-passes=print<da>" -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<da>" 2>&1 | FileCheck %s
+; RUN: opt < %s -disable-output "-passes=print<da>" -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<da>" 2>&1 | FileCheck %s
+; RUN: opt < %s -disable-output "-passes=print<da>" -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<da>" 2>&1 | FileCheck %s
+; RUN: opt < %s -disable-output "-passes=print<da>" -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...
[truncated]
|
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This patch adds test cases that demonstrate missing dependencies in DA caused by the lack of overflow handling. These issues will be addressed by properly inserting overflow checks and bailing out when one is detected.
It covers the following dependence test functions:
It does NOT cover: