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clang-p2996/llvm/test/Analysis/DependenceAnalysis/DifferentOffsets.ll
Sebastian Pop 2c6b239cc6 [DA] handle memory accesses with different offsets and strides (#123436) 
This patch corrects the behavior of the Dependence Analysis for memory
accesses that do not start at the same offset or do not have similar
strides. When offsets or strides cannot be disambiguated at compile
time, DA collects a set of runtime assumptions under which the
dependence test becomes valid. The default remains the same as before
the patch: DA rejects the dependence test as undecidable instead of
collecting runtime assumptions.

---------

Co-authored-by: Michael Kruse <github@meinersbur.de>
Co-authored-by: Ryotaro Kasuga <kasuga.ryotaro@fujitsu.com>
2025-05-19 09:08:59 -05:00

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; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 5
; RUN: opt < %s -disable-output "-passes=print<da>" -aa-pipeline=basic-aa 2>&1 \
; RUN: | FileCheck %s
; The dependence test does not handle array accesses with difference between array accesses
; is not a multiple of the array element size.
; In this test, the element size is i32 = 4 bytes and the difference between the
; load and the store is 2 bytes.
define i32 @alias_with_different_offsets(ptr nocapture %A) {
; CHECK-LABEL: 'alias_with_different_offsets'
; CHECK-NEXT: Src: store i32 2, ptr %arrayidx, align 1 --> Dst: store i32 2, ptr %arrayidx, align 1
; CHECK-NEXT: da analyze - none!
; CHECK-NEXT: Src: store i32 2, ptr %arrayidx, align 1 --> Dst: %0 = load i32, ptr %A, align 1
; CHECK-NEXT: da analyze - confused!
; CHECK-NEXT: Src: %0 = load i32, ptr %A, align 1 --> Dst: %0 = load i32, ptr %A, align 1
; CHECK-NEXT: da analyze - none!
;
entry:
%arrayidx = getelementptr inbounds i8, ptr %A, i64 2
store i32 2, ptr %arrayidx, align 1
%0 = load i32, ptr %A, align 1
ret i32 %0
}
define i32 @alias_with_parametric_offset(ptr nocapture %A, i64 %n) {
; CHECK-LABEL: 'alias_with_parametric_offset'
; CHECK-NEXT: Src: store i32 2, ptr %arrayidx, align 1 --> Dst: store i32 2, ptr %arrayidx, align 1
; CHECK-NEXT: da analyze - none!
; CHECK-NEXT: Src: store i32 2, ptr %arrayidx, align 1 --> Dst: %0 = load i32, ptr %A, align 1
; CHECK-NEXT: da analyze - flow [|<]!
; CHECK-NEXT: Runtime Assumptions:
; CHECK-NEXT: Equal predicate: (zext i2 (trunc i64 %n to i2) to i64) == 0
; CHECK-NEXT: Src: %0 = load i32, ptr %A, align 1 --> Dst: %0 = load i32, ptr %A, align 1
; CHECK-NEXT: da analyze - none!
; CHECK-NEXT: Runtime Assumptions:
; CHECK-NEXT: Equal predicate: (zext i2 (trunc i64 %n to i2) to i64) == 0
;
entry:
%arrayidx = getelementptr inbounds i8, ptr %A, i64 %n
store i32 2, ptr %arrayidx, align 1
%0 = load i32, ptr %A, align 1
ret i32 %0
}
define i32 @alias_with_parametric_expr(ptr nocapture %A, i64 %n, i64 %m) {
; CHECK-LABEL: 'alias_with_parametric_expr'
; CHECK-NEXT: Src: store i32 2, ptr %arrayidx, align 1 --> Dst: store i32 2, ptr %arrayidx, align 1
; CHECK-NEXT: da analyze - none!
; CHECK-NEXT: Src: store i32 2, ptr %arrayidx, align 1 --> Dst: %0 = load i32, ptr %arrayidx1, align 1
; CHECK-NEXT: da analyze - flow [|<]!
; CHECK-NEXT: Runtime Assumptions:
; CHECK-NEXT: Equal predicate: (zext i2 ((trunc i64 %m to i2) + (-2 * (trunc i64 %n to i2))) to i64) == 0
; CHECK-NEXT: Equal predicate: (zext i2 (-2 + (trunc i64 %m to i2)) to i64) == 0
; CHECK-NEXT: Src: %0 = load i32, ptr %arrayidx1, align 1 --> Dst: %0 = load i32, ptr %arrayidx1, align 1
; CHECK-NEXT: da analyze - none!
; CHECK-NEXT: Runtime Assumptions:
; CHECK-NEXT: Equal predicate: (zext i2 ((trunc i64 %m to i2) + (-2 * (trunc i64 %n to i2))) to i64) == 0
; CHECK-NEXT: Equal predicate: (zext i2 (-2 + (trunc i64 %m to i2)) to i64) == 0
;
entry:
%mul = mul nsw i64 %n, 10
%add = add nsw i64 %mul, %m
%arrayidx = getelementptr inbounds i8, ptr %A, i64 %add
store i32 2, ptr %arrayidx, align 1
%add1 = add nsw i64 %m, 42
%arrayidx1 = getelementptr inbounds i8, ptr %A, i64 %add1
%0 = load i32, ptr %arrayidx1, align 1
ret i32 %0
}
define i32 @gep_i8_vs_i32(ptr nocapture %A, i64 %n, i64 %m) {
; CHECK-LABEL: 'gep_i8_vs_i32'
; CHECK-NEXT: Src: store i32 42, ptr %arrayidx0, align 1 --> Dst: store i32 42, ptr %arrayidx0, align 1
; CHECK-NEXT: da analyze - none!
; CHECK-NEXT: Src: store i32 42, ptr %arrayidx0, align 1 --> Dst: store i32 42, ptr %arrayidx1, align 4
; CHECK-NEXT: da analyze - output [|<]!
; CHECK-NEXT: Runtime Assumptions:
; CHECK-NEXT: Equal predicate: (zext i2 (trunc i64 %n to i2) to i64) == 0
; CHECK-NEXT: Src: store i32 42, ptr %arrayidx1, align 4 --> Dst: store i32 42, ptr %arrayidx1, align 4
; CHECK-NEXT: da analyze - none!
; CHECK-NEXT: Runtime Assumptions:
; CHECK-NEXT: Equal predicate: (zext i2 (trunc i64 %n to i2) to i64) == 0
;
entry:
%arrayidx0 = getelementptr inbounds i8, ptr %A, i64 %n
store i32 42, ptr %arrayidx0, align 1
%arrayidx1 = getelementptr inbounds i32, ptr %A, i64 %m
store i32 42, ptr %arrayidx1, align 4
ret i32 0
}
define void @linearized_accesses(i64 %n, i64 %m, i64 %o, ptr %A) {
; CHECK-LABEL: 'linearized_accesses'
; CHECK-NEXT: Src: store i32 1, ptr %idx0, align 4 --> Dst: store i32 1, ptr %idx0, align 4
; CHECK-NEXT: da analyze - output [* * *]!
; CHECK-NEXT: Src: store i32 1, ptr %idx0, align 4 --> Dst: store i32 1, ptr %idx1, align 4
; CHECK-NEXT: da analyze - output [* * *|<]!
; CHECK-NEXT: Src: store i32 1, ptr %idx1, align 4 --> Dst: store i32 1, ptr %idx1, align 4
; CHECK-NEXT: da analyze - none!
;
entry:
br label %for.i
for.i:
%i = phi i64 [ 0, %entry ], [ %i.inc, %for.i.inc ]
br label %for.j
for.j:
%j = phi i64 [ 0, %for.i ], [ %j.inc, %for.j.inc ]
br label %for.k
for.k:
%k = phi i64 [ 0, %for.j ], [ %k.inc, %for.k.inc ]
%subscript0 = mul i64 %i, %m
%subscript1 = add i64 %j, %subscript0
%subscript2 = mul i64 %subscript1, %o
%subscript3 = add i64 %subscript2, %k
%idx0 = getelementptr inbounds i64, ptr %A, i64 %subscript3 ; (i64*)(A) + i*m*o + j*o + k
store i32 1, ptr %idx0
%idx1 = getelementptr inbounds i32, ptr %A, i64 %subscript3 ; (i32*)(A) + i*m*o + j*o + k
store i32 1, ptr %idx1
br label %for.k.inc
for.k.inc:
%k.inc = add nsw i64 %k, 1
%k.exitcond = icmp eq i64 %k.inc, %o
br i1 %k.exitcond, label %for.j.inc, label %for.k
for.j.inc:
%j.inc = add nsw i64 %j, 1
%j.exitcond = icmp eq i64 %j.inc, %m
br i1 %j.exitcond, label %for.i.inc, label %for.j
for.i.inc:
%i.inc = add nsw i64 %i, 1
%i.exitcond = icmp eq i64 %i.inc, %n
br i1 %i.exitcond, label %end, label %for.i
end:
ret void
}
define void @multidim_accesses(ptr %A) {
; CHECK-LABEL: 'multidim_accesses'
; CHECK-NEXT: Src: store i32 1, ptr %idx0, align 4 --> Dst: store i32 1, ptr %idx0, align 4
; CHECK-NEXT: da analyze - none!
; CHECK-NEXT: Src: store i32 1, ptr %idx0, align 4 --> Dst: store i32 1, ptr %idx1, align 4
; FIXME: the dependence distance is not constant. Distance vector should be [* * *|<]!
; CHECK-NEXT: da analyze - consistent output [0 0 0|<]!
; CHECK-NEXT: Src: store i32 1, ptr %idx1, align 4 --> Dst: store i32 1, ptr %idx1, align 4
; CHECK-NEXT: da analyze - none!
;
; for (i = 0; i < 256; i++)
; for (j = 0; j < 256; j++)
; for (k = 0; k < 256; k++) {
; int *idx0 = (int *)((long long *)(A) + 256*256*i + 256*j + k);
; *idx0 = 1;
; int *idx1 = (int *)((int *)(A) + 256*256*i + 256*j + k);
; *idx1 = 1;
; }
entry:
br label %for.i
for.i:
%i = phi i64 [ 0, %entry ], [ %i.inc, %for.i.inc ]
br label %for.j
for.j:
%j = phi i64 [ 0, %for.i ], [ %j.inc, %for.j.inc ]
br label %for.k
for.k:
%k = phi i64 [ 0, %for.j ], [ %k.inc, %for.k.inc ]
%idx0 = getelementptr inbounds [256 x [256 x [256 x i64]]], ptr %A, i64 %i, i64 %j, i64 %k
store i32 1, ptr %idx0
%idx1 = getelementptr inbounds [256 x [256 x [256 x i32]]], ptr %A, i64 %i, i64 %j, i64 %k
store i32 1, ptr %idx1
br label %for.k.inc
for.k.inc:
%k.inc = add nsw i64 %k, 1
%k.exitcond = icmp eq i64 %k.inc, 256
br i1 %k.exitcond, label %for.j.inc, label %for.k
for.j.inc:
%j.inc = add nsw i64 %j, 1
%j.exitcond = icmp eq i64 %j.inc, 256
br i1 %j.exitcond, label %for.i.inc, label %for.j
for.i.inc:
%i.inc = add nsw i64 %i, 1
%i.exitcond = icmp eq i64 %i.inc, 256
br i1 %i.exitcond, label %end, label %for.i
end:
ret void
}
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