; RUN: opt -passes='print<access-info>' -disable-output < %s 2>&1 | FileCheck %s
; This loop:
;
; int **A;
; for (i)
; for (j) {
; A[i][j] = A[i-1][j] * B[j]
; B[j+1] = 2 // backward dep between this and the previous
; }
;
; is transformed by Load-PRE to stash away A[i] for the next iteration of the
; outer loop:
;
; Curr = A[0]; // Prev_0
; for (i: 1..N) {
; Prev = Curr; // Prev = PHI (Prev_0, Curr)
; Curr = A[i];
; for (j: 0..N) {
; Curr[j] = Prev[j] * B[j]
; B[j+1] = 2 // backward dep between this and the previous
; }
; }
;
; Since A[i] and A[i-1] are likely to be independent, getUnderlyingObjects
; should not assume that Curr and Prev share the same underlying object.
;
; If it did we would try to dependence-analyze Curr and Prev and the analysis
; would fail with non-constant distance.
;
; To illustrate one of the negative consequences of this, if the loop has a
; backward dependence we won't detect this but instead fully fall back on
; memchecks (that is what LAA does after encountering a case of non-constant
; distance).
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.10.0"
; CHECK-LABEL: function 'f'
; CHECK: for_j.body:
; CHECK-NEXT: Report: unsafe dependent memory operations in loop
; CHECK-NEXT: Backward loop carried data dependence.
; CHECK-NEXT: Dependences:
; CHECK-NEXT: Backward:
; CHECK-NEXT: %loadB = load i8, ptr %gepB, align 1 ->
; CHECK-NEXT: store i8 2, ptr %gepB_plus_one, align 1
define void @f(ptr noalias %A, ptr noalias %B, i64 %N) {
for_i.preheader:
%prev_0 = load ptr, ptr %A, align 8
br label %for_i.body
for_i.body:
%i = phi i64 [1, %for_i.preheader], [%i.1, %for_j.end]
%prev = phi ptr [%prev_0, %for_i.preheader], [%curr, %for_j.end]
%gep = getelementptr inbounds ptr, ptr %A, i64 %i
%curr = load ptr, ptr %gep, align 8
br label %for_j.preheader
for_j.preheader:
br label %for_j.body
for_j.body:
%j = phi i64 [0, %for_j.preheader], [%j.1, %for_j.body]
%gepPrev = getelementptr inbounds i8, ptr %prev, i64 %j
%gepCurr = getelementptr inbounds i8, ptr %curr, i64 %j
%gepB = getelementptr inbounds i8, ptr %B, i64 %j
%loadPrev = load i8, ptr %gepPrev, align 1
%loadB = load i8, ptr %gepB, align 1
%mul = mul i8 %loadPrev, %loadB
store i8 %mul, ptr %gepCurr, align 1
%gepB_plus_one = getelementptr inbounds i8, ptr %gepB, i64 1
store i8 2, ptr %gepB_plus_one, align 1
%j.1 = add nuw i64 %j, 1
%exitcondj = icmp eq i64 %j.1, %N
br i1 %exitcondj, label %for_j.end, label %for_j.body
for_j.end:
%i.1 = add nuw i64 %i, 1
%exitcond = icmp eq i64 %i.1, %N
br i1 %exitcond, label %for_i.end, label %for_i.body
for_i.end:
ret void
}
; CHECK-LABEL: function 'f_deep'
; CHECK: for_j.body:
; FIXME: This is incorrect and is going to be fixed with D86669.
; CHECK-NEXT: Memory dependences are safe with run-time checks
; CHECK-NEXT: Dependences:
define void @f_deep(ptr noalias %A, ptr noalias %B, i64 %N) {
for_i.preheader:
%prev_0 = load ptr, ptr %A, align 8
br label %for_i.body
for_i.body:
%i = phi i64 [1, %for_i.preheader], [%i.1, %for_j.end]
%prev = phi ptr [%prev_0, %for_i.preheader], [%curr, %for_j.end]
%gep = getelementptr inbounds ptr, ptr %A, i64 %i
%curr = load ptr, ptr %gep, align 8
br label %for_j.preheader
for_j.preheader:
br label %for_j.body
for_j.body:
%j = phi i64 [0, %for_j.preheader], [%j.1, %for_j.body]
%gepPrev = getelementptr inbounds i8, ptr %prev, i64 %j
%gepCurr = getelementptr inbounds i8, ptr %curr, i64 %j
%gepB = getelementptr inbounds i8, ptr %B, i64 %j
%gepB1 = getelementptr inbounds i8, ptr %gepB, i64 %j
%gepB2 = getelementptr inbounds i8, ptr %gepB1, i64 0
%gepB3 = getelementptr inbounds i8, ptr %gepB2, i64 0
%gepB4 = getelementptr inbounds i8, ptr %gepB3, i64 0
%gepB5 = getelementptr inbounds i8, ptr %gepB4, i64 0
%gepB6 = getelementptr inbounds i8, ptr %gepB5, i64 0
%gepB7 = getelementptr inbounds i8, ptr %gepB6, i64 0
%gepB8 = getelementptr inbounds i8, ptr %gepB7, i64 0
%gepB9 = getelementptr inbounds i8, ptr %gepB8, i64 0
%loadPrev = load i8, ptr %gepPrev, align 1
%loadB = load i8, ptr %gepB9, align 1
%mul = mul i8 %loadPrev, %loadB
store i8 %mul, ptr %gepCurr, align 1
%gepB_plus_one = getelementptr inbounds i8, ptr %gepB, i64 1
store i8 2, ptr %gepB_plus_one, align 1
%j.1 = add nuw i64 %j, 1
%exitcondj = icmp eq i64 %j.1, %N
br i1 %exitcondj, label %for_j.end, label %for_j.body
for_j.end:
%i.1 = add nuw i64 %i, 1
%exitcond = icmp eq i64 %i.1, %N
br i1 %exitcond, label %for_i.end, label %for_i.body
for_i.end:
ret void
}
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