[Delinearization] Add test for inferred array size exceeds integer range (NFC) (#169048)

Add test cases where the delinearized arrays may not satisfy the
following "common" property:

`&A[I_1][I_2]...[I_n] == &A[J_1][J_2]...[J_n]` iff
`(I_1, I_2, ..., I_n) == (J_1, J_2, ..., J_n)`

The root cause of this issue is that the inferred array size is too
large and the offset calculation overflows.
Such results should be discarded during validation. This will be fixed
by #169902 .

Author: kasuga-fj

llvm/test/Analysis/Delinearization/validation_large_size.ll

@@ -0,0 +1,140 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 6
+; RUN: opt < %s -passes='print<delinearization>' --delinearize-use-fixed-size-array-heuristic -disable-output 2>&1 | FileCheck %s
+
+; FIXME: As for array accesses, the following property should hold (without
+; out-of-bound accesses):
+;
+;   &A[I_1][I_2]...[I_n] == &A[J_1][J_2]...[J_n] iff
+;   (I_1, I_2, ..., I_n) == (J_1, J_2, ..., J_n)
+;
+; Currently, delinearization doesn't guarantee this property, especially when
+; the inferred array size is very large so that the product of dimensions may
+; overflow. The delinearization validation should consider such cases as
+; invalid.
+
+; for (i = 0; i < (1ULL << 60); i++)
+;   for (j = 0; j < 256; j++)
+;     A[i*256 + j] = 0;
+;
+; The store will be delinearized to `A[i][j]` with its size `[][256]`. Since
+; `i` can be very large, the mapping from subscripts to addresses is not
+; injective. E.g., `&A[0][j] = &A[2^56][j] = ...`.
+;
+define void @large_size_fixed(ptr %A) {
+; CHECK-LABEL: 'large_size_fixed'
+; CHECK-NEXT:  Inst: store i8 0, ptr %gep, align 1
+; CHECK-NEXT:  AccessFunction: {{\{\{}}0,+,256}<%for.i.header>,+,1}<nsw><%for.j>
+; CHECK-NEXT:  Base offset: %A
+; CHECK-NEXT:  ArrayDecl[UnknownSize][256] with elements of 1 bytes.
+; CHECK-NEXT:  ArrayRef[{0,+,1}<nuw><nsw><%for.i.header>][{0,+,1}<nuw><nsw><%for.j>]
+; CHECK-NEXT:  Delinearization validation: Succeeded
+;
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i64 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %i.mul = mul i64 %i, 256
+  br label %for.j
+
+for.j:
+  %j = phi i64 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %offset = add nsw i64 %i.mul, %j
+  %gep = getelementptr i8, ptr %A, i64 %offset
+  store i8 0, ptr %gep
+  %j.inc = add i64 %j, 1
+  %ec.j = icmp eq i64 %j.inc, 256
+  br i1 %ec.j, label %for.i.latch, label %for.j
+
+for.i.latch:
+  %i.inc = add i64 %i, 1
+  %ec.i = icmp eq i64 %i.inc, 1152921504606846976
+  br i1 %ec.i, label %exit, label %for.i.header
+
+exit:
+  ret void
+}
+
+; for (i = 0; i < n; i++)
+;   for (j = 0; j < m; j++)
+;     for (k = 0; k < o; k++)
+;       if (i < 5 && j < 5 && k < 5)
+;         A[i*m*o + j*o + k] = 0;
+;
+; The product (%m * %o) can overflow, e.g., (%m, %o) = (2^32 - 1, 2^32). In
+; this case, the delinearization `A[%i][%j][%k]` with its size `[][%m][%o]`
+; should be considered invalid, because the address calculation will be:
+;
+; A[%i][%j][%k] = %A + %i*%m*%o + %j*%o + %k
+;               = %A - 2^32*%i + %j*2^32 + %k
+;               = %A + 2^32*(%j - %i) + %k
+;
+; It means `&A[0][0][%k]` = `&A[1][1][%k]` = ..., which implies that the
+; mapping from subscripts to addresses is not injective.
+;
+define void @large_size_parametric(i64 %n, i64 %m, i64 %o, ptr %A) {
+; CHECK-LABEL: 'large_size_parametric'
+; CHECK-NEXT:  Inst: store i8 0, ptr %gep, align 1
+; CHECK-NEXT:  AccessFunction: {{\{\{\{}}0,+,(%m * %o)}<%for.i.header>,+,%o}<%for.j.header>,+,1}<nw><%for.k.header>
+; CHECK-NEXT:  Base offset: %A
+; CHECK-NEXT:  ArrayDecl[UnknownSize][%m][%o] with elements of 1 bytes.
+; CHECK-NEXT:  ArrayRef[{0,+,1}<nuw><nsw><%for.i.header>][{0,+,1}<nuw><nsw><%for.j.header>][{0,+,1}<nuw><nsw><%for.k.header>]
+; CHECK-NEXT:  Delinearization validation: Succeeded
+;
+entry:
+  %guard.i = icmp sgt i64 %n, 0
+  %m_o = mul i64 %m, %o
+  br i1 %guard.i, label %for.i.header, label %exit
+
+for.i.header:
+  %i = phi i64 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %i_m_o = mul i64 %i, %m_o
+  br label %for.j.preheader
+
+for.j.preheader:
+  %guard.j = icmp sgt i64 %m, 0
+  br i1 %guard.j, label %for.j.header, label %for.i.latch
+
+for.j.header:
+  %j = phi i64 [ 0, %for.j.preheader ], [ %j.inc, %for.j.latch ]
+  %j_o = mul i64 %j, %o
+  br label %for.k.preheader
+
+for.k.preheader:
+  %guard.k = icmp sgt i64 %o, 0
+  br i1 %guard.k, label %for.k.header, label %for.j.latch
+
+for.k.header:
+  %k = phi i64 [ 0, %for.k.preheader ], [ %k.inc, %for.k.latch ]
+  %cond.i = icmp slt i64 %i, 5
+  %cond.j = icmp slt i64 %j, 5
+  %cond.k = icmp slt i64 %k, 5
+  %cond.ij = and i1 %cond.i, %cond.j
+  %cond = and i1 %cond.ij, %cond.k
+  br i1 %cond, label %if.then, label %for.k.latch
+
+if.then:
+  %offset.tmp = add i64 %i_m_o, %j_o
+  %offset = add i64 %offset.tmp, %k
+  %gep = getelementptr i8, ptr %A, i64 %offset
+  store i8 0, ptr %gep, align 1
+  br label %for.k.latch
+
+for.k.latch:
+  %k.inc = add nsw i64 %k, 1
+  %ec.k = icmp eq i64 %k.inc, %o
+  br i1 %ec.k, label %for.j.latch, label %for.k.header
+
+for.j.latch:
+  %j.inc = add nsw i64 %j, 1
+  %ec.j = icmp eq i64 %j.inc, %m
+  br i1 %ec.j, label %for.i.latch, label %for.j.header
+
+for.i.latch:
+  %i.inc = add nsw i64 %i, 1
+  %ec.i = icmp eq i64 %i.inc, %n
+  br i1 %ec.i, label %exit, label %for.i.header
+
+exit:
+  ret void
+}