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clang-p2996/llvm/test/Transforms/LoopInterchange/lcssa.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

334 lines
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; RUN: opt < %s -basic-aa -loop-interchange -cache-line-size=64 -pass-remarks-missed='loop-interchange' -verify-loop-lcssa -pass-remarks-output=%t -S
; RUN: FileCheck --input-file %t --check-prefix REMARK %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
@A = common global [100 x [100 x i32]] zeroinitializer
@C = common global [100 x [100 x i32]] zeroinitializer
@X = common global i32 0
@Y = common global i64 0
@F = common global float 0.0
; We cannot interchange this loop at the moment, because iv.outer.next is
; produced in the outer loop latch and used in the loop exit block. If the inner
; loop body is not executed, the outer loop latch won't be executed either
; after interchanging.
; REMARK: UnsupportedExitPHI
; REMARK-NEXT: lcssa_01
define void @lcssa_01() {
entry:
%cmp21 = icmp sgt i64 100, 1
br i1 %cmp21, label %outer.ph, label %for.end16
outer.ph: ; preds = %entry
%cmp218 = icmp sgt i64 100, 1
br label %outer.header
outer.header: ; preds = %outer.inc, %outer.ph
%iv.outer = phi i64 [ 1, %outer.ph ], [ %iv.outer.next, %outer.inc ]
br i1 %cmp218, label %for.body3, label %outer.inc
for.body3: ; preds = %for.body3, %outer.header
%iv.inner = phi i64 [ %iv.inner.next, %for.body3 ], [ 1, %outer.header ]
%arrayidx5 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @A, i64 0, i64 %iv.inner, i64 %iv.outer
%vA = load i32, i32* %arrayidx5
%arrayidx9 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @C, i64 0, i64 %iv.inner, i64 %iv.outer
%vC = load i32, i32* %arrayidx9
%add = add nsw i32 %vA, %vC
store i32 %add, i32* %arrayidx5
%iv.inner.next = add nuw nsw i64 %iv.inner, 1
%exitcond = icmp eq i64 %iv.inner.next, 100
br i1 %exitcond, label %outer.inc, label %for.body3
outer.inc: ; preds = %for.body3, %outer.header
%iv.outer.next = add nsw i64 %iv.outer, 1
%cmp = icmp eq i64 %iv.outer.next, 100
br i1 %cmp, label %outer.header, label %for.exit
for.exit: ; preds = %outer.inc
%iv.outer.next.lcssa = phi i64 [ %iv.outer.next, %outer.inc ]
store i64 %iv.outer.next.lcssa, i64* @Y
br label %for.end16
for.end16: ; preds = %for.exit, %entry
ret void
}
; REMARK: UnsupportedExitPHI
; REMARK-NEXT: lcssa_02
define void @lcssa_02() {
entry:
%cmp21 = icmp sgt i64 100, 1
br i1 %cmp21, label %outer.ph, label %for.end16
outer.ph: ; preds = %entry
%cmp218 = icmp sgt i64 100, 1
br label %outer.header
outer.header: ; preds = %outer.inc, %outer.ph
%iv.outer = phi i64 [ 1, %outer.ph ], [ %iv.outer.next, %outer.inc ]
br i1 %cmp218, label %for.body3, label %outer.inc
for.body3: ; preds = %for.body3, %outer.header
%iv.inner = phi i64 [ %iv.inner.next, %for.body3 ], [ 1, %outer.header ]
%arrayidx5 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @A, i64 0, i64 %iv.inner, i64 %iv.outer
%vA = load i32, i32* %arrayidx5
%arrayidx9 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @C, i64 0, i64 %iv.inner, i64 %iv.outer
%vC = load i32, i32* %arrayidx9
%add = add nsw i32 %vA, %vC
store i32 %add, i32* %arrayidx5
%iv.inner.next = add nuw nsw i64 %iv.inner, 1
%exitcond = icmp eq i64 %iv.inner.next, 100
br i1 %exitcond, label %outer.inc, label %for.body3
outer.inc: ; preds = %for.body3, %outer.header
%iv.inner.end = phi i64 [ 0, %outer.header ], [ %iv.inner.next, %for.body3 ]
%iv.outer.next = add nsw i64 %iv.outer, 1
%cmp = icmp eq i64 %iv.outer.next, 100
br i1 %cmp, label %outer.header, label %for.exit
for.exit: ; preds = %outer.inc
%iv.inner.end.lcssa = phi i64 [ %iv.inner.end, %outer.inc ]
store i64 %iv.inner.end.lcssa, i64* @Y
br label %for.end16
for.end16: ; preds = %for.exit, %entry
ret void
}
; REMARK: Interchanged
; REMARK-NEXT: lcssa_03
define void @lcssa_03() {
entry:
br label %outer.header
outer.header: ; preds = %outer.inc, %entry
%iv.outer = phi i64 [ 1, %entry ], [ %iv.outer.next, %outer.inc ]
br label %for.body3
for.body3: ; preds = %for.body3, %outer.header
%iv.inner = phi i64 [ %iv.inner.next, %for.body3 ], [ 1, %outer.header ]
%arrayidx5 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @A, i64 0, i64 %iv.inner, i64 %iv.outer
%vA = load i32, i32* %arrayidx5
%arrayidx9 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @C, i64 0, i64 %iv.inner, i64 %iv.outer
%vC = load i32, i32* %arrayidx9
%add = add nsw i32 %vA, %vC
store i32 %add, i32* %arrayidx5
%iv.inner.next = add nuw nsw i64 %iv.inner, 1
%exitcond = icmp eq i64 %iv.inner.next, 100
br i1 %exitcond, label %outer.inc, label %for.body3
outer.inc: ; preds = %for.body3
%iv.inner.lcssa = phi i64 [ %iv.inner, %for.body3 ]
%iv.outer.next = add nsw i64 %iv.outer, 1
%cmp = icmp eq i64 %iv.outer.next, 100
br i1 %cmp, label %outer.header, label %for.exit
for.exit: ; preds = %outer.inc
%iv.inner.lcssa.lcssa = phi i64 [ %iv.inner.lcssa, %outer.inc ]
store i64 %iv.inner.lcssa.lcssa, i64* @Y
br label %for.end16
for.end16: ; preds = %for.exit
ret void
}
; Loops with floating point reductions are interchanged with fastmath.
; REMARK: Interchanged
; REMARK-NEXT: lcssa_04
define void @lcssa_04() {
entry:
br label %outer.header
outer.header: ; preds = %outer.inc, %entry
%iv.outer = phi i64 [ 1, %entry ], [ %iv.outer.next, %outer.inc ]
%float.outer = phi float [ 1.000000e+00, %entry ], [ %float.outer.next, %outer.inc ]
br label %for.body3
for.body3: ; preds = %for.body3, %outer.header
%iv.inner = phi i64 [ %iv.inner.next, %for.body3 ], [ 1, %outer.header ]
%float.inner = phi float [ %float.inner.next, %for.body3 ], [ %float.outer, %outer.header ]
%arrayidx5 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @A, i64 0, i64 %iv.inner, i64 %iv.outer
%vA = load i32, i32* %arrayidx5
%arrayidx9 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @C, i64 0, i64 %iv.inner, i64 %iv.outer
%vC = load i32, i32* %arrayidx9
%add = add nsw i32 %vA, %vC
%float.inner.next = fadd fast float %float.inner, 1.000000e+00
store i32 %add, i32* %arrayidx5
%iv.inner.next = add nuw nsw i64 %iv.inner, 1
%exitcond = icmp eq i64 %iv.inner.next, 100
br i1 %exitcond, label %outer.inc, label %for.body3
outer.inc: ; preds = %for.body3
%float.outer.next = phi float [ %float.inner.next, %for.body3 ]
%iv.outer.next = add nsw i64 %iv.outer, 1
%cmp = icmp eq i64 %iv.outer.next, 100
br i1 %cmp, label %outer.header, label %for.exit
for.exit: ; preds = %outer.inc
%float.outer.lcssa = phi float [ %float.outer.next, %outer.inc ]
store float %float.outer.lcssa, float* @F
br label %for.end16
for.end16: ; preds = %for.exit
ret void
}
; PHI node in inner latch with multiple predecessors.
; REMARK: Interchanged
; REMARK-NEXT: lcssa_05
define void @lcssa_05(i32* %ptr) {
entry:
br label %outer.header
outer.header: ; preds = %outer.inc, %entry
%iv.outer = phi i64 [ 1, %entry ], [ %iv.outer.next, %outer.inc ]
br label %for.body3
for.body3: ; preds = %bb3, %outer.header
%iv.inner = phi i64 [ %iv.inner.next, %bb3 ], [ 1, %outer.header ]
br i1 undef, label %bb2, label %bb3
bb2: ; preds = %for.body3
%arrayidx5 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @A, i64 0, i64 %iv.inner, i64 %iv.outer
%vA = load i32, i32* %arrayidx5
%arrayidx9 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @C, i64 0, i64 %iv.inner, i64 %iv.outer
%vC = load i32, i32* %arrayidx9
%add = add nsw i32 %vA, %vC
br label %bb3
bb3: ; preds = %bb2, %for.body3
%addp = phi i32 [ %add, %bb2 ], [ 0, %for.body3 ]
store i32 %addp, i32* %ptr
%iv.inner.next = add nuw nsw i64 %iv.inner, 1
%exitcond = icmp eq i64 %iv.inner.next, 100
br i1 %exitcond, label %outer.inc, label %for.body3
outer.inc: ; preds = %bb3
%iv.inner.lcssa = phi i64 [ %iv.inner, %bb3 ]
%iv.outer.next = add nsw i64 %iv.outer, 1
%cmp = icmp eq i64 %iv.outer.next, 100
br i1 %cmp, label %outer.header, label %for.exit
for.exit: ; preds = %outer.inc
%iv.inner.lcssa.lcssa = phi i64 [ %iv.inner.lcssa, %outer.inc ]
store i64 %iv.inner.lcssa.lcssa, i64* @Y
br label %for.end16
for.end16: ; preds = %for.exit
ret void
}
; REMARK: UnsupportedExitPHI
; REMARK-NEXT: lcssa_06
define void @lcssa_06(i64* %ptr, i32* %ptr1) {
entry:
br label %outer.header
outer.header: ; preds = %outer.inc, %entry
%iv.outer = phi i64 [ 1, %entry ], [ %iv.outer.next, %outer.inc ]
br i1 undef, label %for.body3, label %outer.inc
for.body3: ; preds = %for.body3, %outer.header
%iv.inner = phi i64 [ %iv.inner.next, %for.body3 ], [ 1, %outer.header ]
%arrayidx5 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @A, i64 0, i64 %iv.inner, i64 %iv.outer
%vA = load i32, i32* %arrayidx5
%arrayidx9 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @C, i64 0, i64 %iv.inner, i64 %iv.outer
%vC = load i32, i32* %arrayidx9
%add = add nsw i32 %vA, %vC
store i32 %add, i32* %ptr1
%iv.inner.next = add nuw nsw i64 %iv.inner, 1
%exitcond = icmp eq i64 %iv.inner.next, 100
br i1 %exitcond, label %outer.inc, label %for.body3
outer.inc: ; preds = %for.body3, %outer.header
%sv = phi i64 [ 0, %outer.header ], [ 1, %for.body3 ]
%iv.outer.next = add nsw i64 %iv.outer, 1
%cmp = icmp eq i64 %iv.outer.next, 100
br i1 %cmp, label %outer.header, label %for.exit
for.exit: ; preds = %outer.inc
%sv.lcssa = phi i64 [ %sv, %outer.inc ]
store i64 %sv.lcssa, i64* @Y
br label %for.end16
for.end16: ; preds = %for.exit
ret void
}
; REMARK: Interchanged
; REMARK-NEXT: lcssa_07
define void @lcssa_07() {
entry:
br label %outer.header
outer.header: ; preds = %outer.inc, %entry
%iv.outer = phi i64 [ 1, %entry ], [ %iv.outer.next, %outer.inc ]
br label %for.body3
for.body3: ; preds = %for.body3, %outer.header
%iv.inner = phi i64 [ %iv.inner.next, %for.body3 ], [ 1, %outer.header ]
%arrayidx5 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @A, i64 0, i64 %iv.inner, i64 %iv.outer
%vA = load i32, i32* %arrayidx5
%arrayidx9 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @C, i64 0, i64 %iv.inner, i64 %iv.outer
%vC = load i32, i32* %arrayidx9
%add = add nsw i32 %vA, %vC
store i32 %add, i32* %arrayidx5
%iv.inner.next = add nuw nsw i64 %iv.inner, 1
%exitcond = icmp eq i64 %iv.inner.next, 100
br i1 %exitcond, label %outer.bb, label %for.body3
outer.bb: ; preds = %for.body3
%iv.inner.lcssa = phi i64 [ %iv.inner, %for.body3 ]
br label %outer.inc
outer.inc: ; preds = %outer.bb
%iv.outer.next = add nsw i64 %iv.outer, 1
%cmp = icmp eq i64 %iv.outer.next, 100
br i1 %cmp, label %outer.header, label %for.exit
for.exit: ; preds = %outer.inc
%iv.inner.lcssa.lcssa = phi i64 [ %iv.inner.lcssa, %outer.inc ]
store i64 %iv.inner.lcssa.lcssa, i64* @Y
br label %for.end16
for.end16: ; preds = %for.exit
ret void
}
; Should not crash when the outer header branches to
; both the inner loop and the outer latch, and there
; is an lcssa phi node outside the loopnest.
; REMARK: Interchanged
; REMARK-NEXT: lcssa_08
define i64 @lcssa_08([100 x [100 x i64]]* %Arr) {
entry:
br label %for1.header
for1.header: ; preds = %for1.inc, %entry
%indvars.iv23 = phi i64 [ 0, %entry ], [ %indvars.iv.next24, %for1.inc ]
br i1 undef, label %for2, label %for1.inc
for2: ; preds = %for2, %for1.header
%indvars.iv = phi i64 [ 0, %for1.header ], [ %indvars.iv.next.3, %for2 ]
%arrayidx = getelementptr inbounds [100 x [100 x i64]], [100 x [100 x i64]]* %Arr, i64 0, i64 %indvars.iv, i64 %indvars.iv23
%lv = load i64, i64* %arrayidx, align 4
%indvars.iv.next.3 = add nuw nsw i64 %indvars.iv, 1
%exit1 = icmp eq i64 %indvars.iv.next.3, 100
br i1 %exit1, label %for1.inc, label %for2
for1.inc: ; preds = %for2, %for1.header
%indvars.iv.next24 = add nuw nsw i64 %indvars.iv23, 1
%exit2 = icmp eq i64 %indvars.iv.next24, 100
br i1 %exit2, label %for1.loopexit, label %for1.header
for1.loopexit: ; preds = %for1.inc
%sum.outer.lcssa = phi i64 [ %indvars.iv23, %for1.inc ]
ret i64 %sum.outer.lcssa
}
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