Ryotaro Kasuga e99ca74dc1
[LoopInterchange] Relax the legality check to accept more patterns (#139690)
When proving the legality of exchanging two loops, it doesn't need to
check the elements of the direction vectors associated with the loops
outside of the two target loops. Before this patch, the legality check
looked at all elements of a direction vector to calculate the
lexicographically order of the vector, which may reject some legal
exchanges. For example, if a direction vector is `[* < =]`, it is safe
to swap the last two loops because the corresponding subsequence of the
vector (`[< =]`) is lexicographically positive for both before and after
the exchange. However, the its order is unknown if we don't drop the
prefix since the first element is `*`. This patch improves the logic of
legality check to ignore such unrelated prefixes of direction vectors.
2025-05-13 21:14:14 +09:00

128 lines
5.3 KiB
LLVM

; RUN: opt < %s -passes=loop-interchange -cache-line-size=64 -pass-remarks-missed='loop-interchange' -pass-remarks-output=%t -S \
; RUN: -verify-dom-info -verify-loop-info -verify-loop-lcssa 2>&1 | FileCheck -check-prefix=IR %s
; RUN: FileCheck --input-file=%t %s
; Both tests should be rejected as interchange candidates. For now, they are
; rejected for dependence analysis reasons, but that's because support for 'S'
; scalar dependencies was removed. When that is properly, the inner loop only
; reductions should still not be supported currently, see discussion at D53027
; for more information on the required checks.
@A = common global [500 x [500 x i32]] zeroinitializer
@X = common global i32 0
@B = common global [500 x [500 x i32]] zeroinitializer
@Y = common global i32 0
;; global X
;; for( int i=1;i<N;i++)
;; for( int j=1;j<N;j++)
;; X+=A[j][i];
; CHECK: --- !Missed
; CHECK-NEXT: Pass: loop-interchange
; CHECK-NEXT: Name: Dependence
; CHECK-NEXT: Function: reduction_01
; IR-LABEL: @reduction_01(
; IR-NOT: split
define void @reduction_01(i32 %N) {
entry:
%cmp16 = icmp sgt i32 %N, 1
br i1 %cmp16, label %for.body3.lr.ph, label %for.end8
for.body3.lr.ph: ; preds = %for.cond1.for.inc6_crit_edge, %entry
%indvars.iv18 = phi i64 [ %indvars.iv.next19, %for.cond1.for.inc6_crit_edge ], [ 1, %entry ]
%X.promoted = load i32, ptr @X
br label %for.body3
for.body3: ; preds = %for.body3, %for.body3.lr.ph
%indvars.iv = phi i64 [ 1, %for.body3.lr.ph ], [ %indvars.iv.next, %for.body3 ]
%add15 = phi i32 [ %X.promoted, %for.body3.lr.ph ], [ %add, %for.body3 ]
%arrayidx5 = getelementptr inbounds [500 x [500 x i32]], ptr @A, i64 0, i64 %indvars.iv, i64 %indvars.iv18
%0 = load i32, ptr %arrayidx5
%add = add nsw i32 %add15, %0
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, %N
br i1 %exitcond, label %for.cond1.for.inc6_crit_edge, label %for.body3
for.cond1.for.inc6_crit_edge: ; preds = %for.body3
%add.lcssa = phi i32 [ %add, %for.body3 ]
store i32 %add.lcssa, ptr @X
%indvars.iv.next19 = add nuw nsw i64 %indvars.iv18, 1
%lftr.wideiv20 = trunc i64 %indvars.iv.next19 to i32
%exitcond21 = icmp eq i32 %lftr.wideiv20, %N
br i1 %exitcond21, label %for.end8, label %for.body3.lr.ph
for.end8: ; preds = %for.cond1.for.inc6_crit_edge, %entry
ret void
}
;; Not tightly nested. Do not interchange.
;; for( int i=1;i<N;i++)
;; for( int j=1;j<N;j++) {
;; for( int k=1;k<N;k++) {
;; X+=A[k][j];
;; }
;; Y+=B[j][i];
;; }
;; Not tightly nested. Do not interchange.
;; Not interchanged hence the phi's in the inner loop will not be split.
; CHECK: --- !Missed
; CHECK-NEXT: Pass: loop-interchange
; CHECK-NEXT: Name: UnsupportedPHIOuter
; CHECK-NEXT: Function: reduction_03
; IR-LABEL: @reduction_03(
; IR-NOT: split
define void @reduction_03(i32 %N) {
entry:
%cmp35 = icmp sgt i32 %N, 1
br i1 %cmp35, label %for.cond4.preheader.lr.ph, label %for.end19
for.cond4.preheader.lr.ph: ; preds = %for.cond1.for.inc17_crit_edge, %entry
%indvars.iv41 = phi i64 [ %indvars.iv.next42, %for.cond1.for.inc17_crit_edge ], [ 1, %entry ]
%Y.promoted = load i32, ptr @Y
br label %for.body6.lr.ph
for.body6.lr.ph: ; preds = %for.cond4.for.end_crit_edge, %for.cond4.preheader.lr.ph
%indvars.iv37 = phi i64 [ 1, %for.cond4.preheader.lr.ph ], [ %indvars.iv.next38, %for.cond4.for.end_crit_edge ]
%add1334 = phi i32 [ %Y.promoted, %for.cond4.preheader.lr.ph ], [ %add13, %for.cond4.for.end_crit_edge ]
%X.promoted = load i32, ptr @X
br label %for.body6
for.body6: ; preds = %for.body6, %for.body6.lr.ph
%indvars.iv = phi i64 [ 1, %for.body6.lr.ph ], [ %indvars.iv.next, %for.body6 ]
%arrayidx8 = getelementptr inbounds [500 x [500 x i32]], ptr @A, i64 0, i64 %indvars.iv, i64 %indvars.iv37
%0 = load i32, ptr %arrayidx8
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, %N
br i1 %exitcond, label %for.cond4.for.end_crit_edge, label %for.body6
for.cond4.for.end_crit_edge: ; preds = %for.body6
%arrayidx12 = getelementptr inbounds [500 x [500 x i32]], ptr @B, i64 0, i64 %indvars.iv37, i64 %indvars.iv41
%1 = load i32, ptr %arrayidx12
%add13 = add nsw i32 %add1334, %1
%indvars.iv.next38 = add nuw nsw i64 %indvars.iv37, 1
%lftr.wideiv39 = trunc i64 %indvars.iv.next38 to i32
%exitcond40 = icmp eq i32 %lftr.wideiv39, %N
br i1 %exitcond40, label %for.cond1.for.inc17_crit_edge, label %for.body6.lr.ph
for.cond1.for.inc17_crit_edge: ; preds = %for.cond4.for.end_crit_edge
%add13.lcssa = phi i32 [ %add13, %for.cond4.for.end_crit_edge ]
store i32 %add13.lcssa, ptr @Y
%indvars.iv.next42 = add nuw nsw i64 %indvars.iv41, 1
%lftr.wideiv43 = trunc i64 %indvars.iv.next42 to i32
%exitcond44 = icmp eq i32 %lftr.wideiv43, %N
br i1 %exitcond44, label %for.end19, label %for.cond4.preheader.lr.ph
for.end19: ; preds = %for.cond1.for.inc17_crit_edge, %entry
ret void
}