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clang-p2996/llvm/test/Transforms/LoopInterchange/loop-interchange-optimization-remarks.ll
Congzhe Cao b941857b40 [LoopInterchange] New cost model for loop interchange 
This is another attempt to land this patch.

The patch proposed to use a new cost model for loop interchange,
which is obtained from loop cache analysis.

Given a loopnest, what loop cache analysis returns is a vector of
loops [loop0, loop1, loop2, ...] where loop0 should be replaced as
the outermost loop, loop1 should be placed one more level inside, and
loop2 one more level inside, etc. What loop cache analysis does is not
only more comprehensive than the current cost model, it is also a "one-shot"
query which means that we only need to query it once during the entire
loop interchange pass, which is better than the current cost model where
we query it every time we check whether it is profitable to interchange
two loops. Thus complexity is reduced, especially after D120386 where we
do more interchanges to get the globally optimal loop access pattern.

Updates made to test cases are mostly minor changes and some
corrections. One change that applies to all tests is that we added an option
`-cache-line-size=64` to the RUN lines. This is ensure that loop
cache analysis receives a valid number of cache line size for correct
analysis. Test coverage for loop interchange is not reduced.

Currently we did not completely remove the legacy cost model, but
keep it as fall-back in case the new cost model did not run successfully.
This is because currently we have some limitations in delinearization, which
sometimes makes loop cache analysis bail out. The longer term goal is to
enhance delinearization and eventually remove the legacy cost model
compeletely.

Reviewed By: bmahjour, #loopoptwg

Differential Revision: https://reviews.llvm.org/D124926
2022-06-28 00:08:37 -04:00

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; Test optimization remarks generated by the LoopInterchange pass.
;
; RUN: opt < %s -basic-aa -loop-interchange -cache-line-size=64 -verify-dom-info -verify-loop-info \
; RUN: -pass-remarks-output=%t -pass-remarks-missed='loop-interchange' \
; RUN: -pass-remarks='loop-interchange' -S
; RUN: cat %t | FileCheck %s
; RUN: opt < %s -basic-aa -loop-interchange -cache-line-size=64 -verify-dom-info -verify-loop-info \
; RUN: -pass-remarks-output=%t -pass-remarks-missed='loop-interchange' \
; RUN: -pass-remarks='loop-interchange' -S -da-disable-delinearization-checks
; RUN: cat %t | FileCheck --check-prefix=DELIN %s
@A = common global [100 x [100 x i32]] zeroinitializer
@B = common global [100 x [100 x i32]] zeroinitializer
@C = common global [100 x i32] zeroinitializer
;;---------------------------------------Test case 01---------------------------------
;; Loops interchange is not profitable.
;; for(int i=1;i<N;i++)
;; for(int j=1;j<N;j++)
;; A[i-1][j-1] = A[i - 1][j-1] + B[i][j];
define void @test01(i32 %N){
entry:
%cmp31 = icmp sgt i32 %N, 1
br i1 %cmp31, label %for.cond1.preheader.lr.ph, label %for.end19
for.cond1.preheader.lr.ph:
%0 = add i32 %N, -1
br label %for.body3.lr.ph
for.body3.lr.ph:
%indvars.iv34 = phi i64 [ 1, %for.cond1.preheader.lr.ph ], [ %indvars.iv.next35, %for.inc17 ]
%1 = add nsw i64 %indvars.iv34, -1
br label %for.body3
for.body3:
%indvars.iv = phi i64 [ 1, %for.body3.lr.ph ], [ %indvars.iv.next, %for.body3 ]
%2 = add nsw i64 %indvars.iv, -1
%arrayidx6 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @A, i64 0, i64 %1, i64 %2
%3 = load i32, i32* %arrayidx6
%arrayidx10 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @B, i64 0, i64 %indvars.iv34, i64 %indvars.iv
%4 = load i32, i32* %arrayidx10
%add = add nsw i32 %4, %3
store i32 %add, i32* %arrayidx6
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv to i32
%exitcond = icmp eq i32 %lftr.wideiv, %0
br i1 %exitcond, label %for.inc17, label %for.body3
for.inc17:
%indvars.iv.next35 = add nuw nsw i64 %indvars.iv34, 1
%lftr.wideiv37 = trunc i64 %indvars.iv34 to i32
%exitcond38 = icmp eq i32 %lftr.wideiv37, %0
br i1 %exitcond38, label %for.end19, label %for.body3.lr.ph
for.end19:
ret void
}
; CHECK: --- !Missed
; CHECK-NEXT: Pass: loop-interchange
; CHECK-NEXT: Name: Dependence
; CHECK-NEXT: Function: test01
; CHECK-NEXT: Args:
; CHECK-NEXT: - String: Cannot interchange loops due to dependences.
; CHECK-NEXT: ...
; DELIN: --- !Missed
; DELIN-NEXT: Pass: loop-interchange
; DELIN-NEXT: Name: InterchangeNotProfitable
; DELIN-NEXT: Function: test01
; DELIN-NEXT: Args:
; DELIN-NEXT: - String: Interchanging loops is too costly and it does not improve parallelism.
; DELIN-NEXT: ...
;;--------------------------------------Test case 02------------------------------------
;; [FIXME] This loop though valid is currently not interchanged due to the
;; limitation that we cannot split the inner loop latch due to multiple use of inner induction
;; variable.(used to increment the loop counter and to access A[j+1][i+1]
;; for(int i=0;i<N-1;i++)
;; for(int j=1;j<N-1;j++)
;; A[j+1][i+1] = A[j+1][i+1] + k;
define void @test02(i32 %k, i32 %N) {
entry:
%sub = add nsw i32 %N, -1
%cmp26 = icmp sgt i32 %N, 1
br i1 %cmp26, label %for.cond1.preheader.lr.ph, label %for.end17
for.cond1.preheader.lr.ph:
%cmp324 = icmp sgt i32 %sub, 1
%0 = add i32 %N, -2
%1 = sext i32 %sub to i64
br label %for.cond1.preheader
for.cond.loopexit:
%cmp = icmp slt i64 %indvars.iv.next29, %1
br i1 %cmp, label %for.cond1.preheader, label %for.end17
for.cond1.preheader:
%indvars.iv28 = phi i64 [ 0, %for.cond1.preheader.lr.ph ], [ %indvars.iv.next29, %for.cond.loopexit ]
%indvars.iv.next29 = add nuw nsw i64 %indvars.iv28, 1
br i1 %cmp324, label %for.body4, label %for.cond.loopexit
for.body4:
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body4 ], [ 1, %for.cond1.preheader ]
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%arrayidx7 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @A, i64 0, i64 %indvars.iv.next, i64 %indvars.iv.next29
%2 = load i32, i32* %arrayidx7
%add8 = add nsw i32 %2, %k
store i32 %add8, i32* %arrayidx7
%lftr.wideiv = trunc i64 %indvars.iv to i32
%exitcond = icmp eq i32 %lftr.wideiv, %0
br i1 %exitcond, label %for.cond.loopexit, label %for.body4
for.end17:
ret void
}
; CHECK: --- !Missed
; CHECK-NEXT: Pass: loop-interchange
; CHECK-NEXT: Name: Dependence
; CHECK-NEXT: Function: test02
; CHECK-NEXT: Args:
; CHECK-NEXT: - String: Cannot interchange loops due to dependences.
; CHECK-NEXT: ...
; DELIN: --- !Passed
; DELIN-NEXT: Pass: loop-interchange
; DELIN-NEXT: Name: Interchanged
; DELIN-NEXT: Function: test02
; DELIN-NEXT: Args:
; DELIN-NEXT: - String: Loop interchanged with enclosing loop.
; DELIN-NEXT: ...
;;-----------------------------------Test case 03-------------------------------
;; Test to make sure we can handle output dependencies.
;;
;; for (int i = 0; i < 2; ++i)
;; for(int j = 0; j < 3; ++j) {
;; A[j][i] = i;
;; A[j][i+1] = j;
;; }
@A10 = local_unnamed_addr global [3 x [3 x i32]] zeroinitializer, align 16
define void @test03() {
entry:
br label %for.cond1.preheader
for.cond.loopexit: ; preds = %for.body4
%exitcond28 = icmp ne i64 %indvars.iv.next27, 2
br i1 %exitcond28, label %for.cond1.preheader, label %for.cond.cleanup
for.cond1.preheader: ; preds = %for.cond.loopexit, %entry
%indvars.iv26 = phi i64 [ 0, %entry ], [ %indvars.iv.next27, %for.cond.loopexit ]
%indvars.iv.next27 = add nuw nsw i64 %indvars.iv26, 1
br label %for.body4
for.cond.cleanup: ; preds = %for.cond.loopexit
ret void
for.body4: ; preds = %for.body4, %for.cond1.preheader
%indvars.iv = phi i64 [ 0, %for.cond1.preheader ], [ %indvars.iv.next, %for.body4 ]
%arrayidx6 = getelementptr inbounds [3 x [3 x i32]], [3 x [3 x i32]]* @A10, i64 0, i64 %indvars.iv, i64 %indvars.iv26
%tmp = trunc i64 %indvars.iv26 to i32
store i32 %tmp, i32* %arrayidx6, align 4
%arrayidx10 = getelementptr inbounds [3 x [3 x i32]], [3 x [3 x i32]]* @A10, i64 0, i64 %indvars.iv, i64 %indvars.iv.next27
%tmp1 = trunc i64 %indvars.iv to i32
store i32 %tmp1, i32* %arrayidx10, align 4
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%exitcond = icmp ne i64 %indvars.iv.next, 3
br i1 %exitcond, label %for.body4, label %for.cond.loopexit
}
; CHECK: --- !Passed
; CHECK-NEXT: Pass: loop-interchange
; CHECK-NEXT: Name: Interchanged
; CHECK-NEXT: Function: test03
; CHECK-NEXT: Args:
; CHECK-NEXT: - String: Loop interchanged with enclosing loop.
; CHECK-NEXT: ...
; DELIN: --- !Passed
; DELIN-NEXT: Pass: loop-interchange
; DELIN-NEXT: Name: Interchanged
; DELIN-NEXT: Function: test03
; DELIN-NEXT: Args:
; DELIN-NEXT: - String: Loop interchanged with enclosing loop.
; DELIN-NEXT: ...
;;--------------------------------------Test case 04-------------------------------------
;; Loops not tightly nested are not interchanged
;; for(int j=0;j<N;j++) {
;; B[j] = j+k;
;; for(int i=0;i<N;i++)
;; A[j][i] = A[j][i]+B[j];
;; }
define void @test04(i32 %k, i32 %N){
entry:
%cmp30 = icmp sgt i32 %N, 0
br i1 %cmp30, label %for.body.lr.ph, label %for.end17
for.body.lr.ph:
%0 = add i32 %N, -1
%1 = zext i32 %k to i64
br label %for.body
for.body:
%indvars.iv32 = phi i64 [ 0, %for.body.lr.ph ], [ %indvars.iv.next33, %for.inc15 ]
%2 = add nsw i64 %indvars.iv32, %1
%arrayidx = getelementptr inbounds [100 x i32], [100 x i32]* @C, i64 0, i64 %indvars.iv32
%3 = trunc i64 %2 to i32
store i32 %3, i32* %arrayidx
br label %for.body3
for.body3:
%indvars.iv = phi i64 [ 0, %for.body ], [ %indvars.iv.next, %for.body3 ]
%arrayidx7 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @A, i64 0, i64 %indvars.iv32, i64 %indvars.iv
%4 = load i32, i32* %arrayidx7
%add10 = add nsw i32 %3, %4
store i32 %add10, i32* %arrayidx7
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv to i32
%exitcond = icmp eq i32 %lftr.wideiv, %0
br i1 %exitcond, label %for.inc15, label %for.body3
for.inc15:
%indvars.iv.next33 = add nuw nsw i64 %indvars.iv32, 1
%lftr.wideiv35 = trunc i64 %indvars.iv32 to i32
%exitcond36 = icmp eq i32 %lftr.wideiv35, %0
br i1 %exitcond36, label %for.end17, label %for.body
for.end17:
ret void
}
; CHECK: --- !Missed
; CHECK-NEXT: Pass: loop-interchange
; CHECK-NEXT: Name: Dependence
; CHECK-NEXT: Function: test04
; CHECK-NEXT: Args:
; CHECK-NEXT: - String: Cannot interchange loops due to dependences.
; CHECK-NEXT: ...
; DELIN: --- !Missed
; DELIN-NEXT: Pass: loop-interchange
; DELIN-NEXT: Name: NotTightlyNested
; DELIN-NEXT: Function: test04
; DELIN-NEXT: Args:
; DELIN-NEXT: - String: Cannot interchange loops because they are not tightly nested.
; DELIN-NEXT: ...
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