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llvm-project/llvm/test/Transforms/LoopFusion/cannot_fuse.ll

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; RUN: opt -S -loop-fusion -debug-only=loop-fusion -disable-output < %s 2>&1 | FileCheck %s
; REQUIRES: asserts
@B = common global [1024 x i32] zeroinitializer, align 16
; CHECK that the two candidates for fusion are placed into separate candidate
; sets because they are not control flow equivalent.
; CHECK: Performing Loop Fusion on function non_cfe
; CHECK: Fusion Candidates:
; CHECK: *** Fusion Candidate Set ***
; CHECK: bb
; CHECK: ****************************
; CHECK: *** Fusion Candidate Set ***
; CHECK: bb20.preheader
; CHECK: ****************************
; CHECK: Loop Fusion complete
define void @non_cfe(i32* noalias %arg) {
bb:
br label %bb5
bb5: ; preds = %bb14, %bb
%indvars.iv2 = phi i64 [ %indvars.iv.next3, %bb14 ], [ 0, %bb ]
%.01 = phi i32 [ 0, %bb ], [ %tmp15, %bb14 ]
%exitcond4 = icmp ne i64 %indvars.iv2, 100
br i1 %exitcond4, label %bb7, label %bb16
bb7: ; preds = %bb5
%tmp = add nsw i32 %.01, -3
%tmp8 = add nuw nsw i64 %indvars.iv2, 3
%tmp9 = trunc i64 %tmp8 to i32
%tmp10 = mul nsw i32 %tmp, %tmp9
%tmp11 = trunc i64 %indvars.iv2 to i32
%tmp12 = srem i32 %tmp10, %tmp11
%tmp13 = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv2
store i32 %tmp12, i32* %tmp13, align 4
br label %bb14
bb14: ; preds = %bb7
%indvars.iv.next3 = add nuw nsw i64 %indvars.iv2, 1
%tmp15 = add nuw nsw i32 %.01, 1
br label %bb5
bb16: ; preds = %bb5
%tmp17 = load i32, i32* %arg, align 4
%tmp18 = icmp slt i32 %tmp17, 0
br i1 %tmp18, label %bb20, label %bb33
bb20: ; preds = %bb30, %bb16
%indvars.iv = phi i64 [ %indvars.iv.next, %bb30 ], [ 0, %bb16 ]
%.0 = phi i32 [ 0, %bb16 ], [ %tmp31, %bb30 ]
%exitcond = icmp ne i64 %indvars.iv, 100
br i1 %exitcond, label %bb22, label %bb33
bb22: ; preds = %bb20
%tmp23 = add nsw i32 %.0, -3
%tmp24 = add nuw nsw i64 %indvars.iv, 3
%tmp25 = trunc i64 %tmp24 to i32
%tmp26 = mul nsw i32 %tmp23, %tmp25
%tmp27 = trunc i64 %indvars.iv to i32
%tmp28 = srem i32 %tmp26, %tmp27
%tmp29 = getelementptr inbounds [1024 x i32], [1024 x i32]* @B, i64 0, i64 %indvars.iv
store i32 %tmp28, i32* %tmp29, align 4
br label %bb30
bb30: ; preds = %bb22
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%tmp31 = add nuw nsw i32 %.0, 1
br label %bb20
bb33: ; preds = %bb20, %bb16
ret void
}
; Check that fusion detects the two canddates are not adjacent (the exit block
; of the first candidate is not the preheader of the second candidate).
; CHECK: Performing Loop Fusion on function non_adjacent
; CHECK: Fusion Candidates:
; CHECK: *** Fusion Candidate Set ***
; CHECK-NEXT: [[LOOP1PREHEADER:bb[0-9]*]]
; CHECK-NEXT: [[LOOP2PREHEADER:bb[0-9]*]]
; CHECK-NEXT: ****************************
; CHECK: Attempting fusion on Candidate Set:
; CHECK-NEXT: [[LOOP1PREHEADER]]
; CHECK-NEXT: [[LOOP2PREHEADER]]
; CHECK: Fusion candidates are not adjacent. Not fusing.
; CHECK: Loop Fusion complete
define void @non_adjacent(i32* noalias %arg) {
bb:
br label %bb3
bb3: ; preds = %bb11, %bb
%.01 = phi i64 [ 0, %bb ], [ %tmp12, %bb11 ]
%exitcond2 = icmp ne i64 %.01, 100
br i1 %exitcond2, label %bb5, label %bb4
bb4: ; preds = %bb3
br label %bb13
bb5: ; preds = %bb3
%tmp = add nsw i64 %.01, -3
%tmp6 = add nuw nsw i64 %.01, 3
%tmp7 = mul nsw i64 %tmp, %tmp6
%tmp8 = srem i64 %tmp7, %.01
%tmp9 = trunc i64 %tmp8 to i32
%tmp10 = getelementptr inbounds i32, i32* %arg, i64 %.01
store i32 %tmp9, i32* %tmp10, align 4
br label %bb11
bb11: ; preds = %bb5
%tmp12 = add nuw nsw i64 %.01, 1
br label %bb3
bb13: ; preds = %bb4
br label %bb14
bb14: ; preds = %bb23, %bb13
%.0 = phi i64 [ 0, %bb13 ], [ %tmp24, %bb23 ]
%exitcond = icmp ne i64 %.0, 100
br i1 %exitcond, label %bb16, label %bb15
bb15: ; preds = %bb14
br label %bb25
bb16: ; preds = %bb14
%tmp17 = add nsw i64 %.0, -3
%tmp18 = add nuw nsw i64 %.0, 3
%tmp19 = mul nsw i64 %tmp17, %tmp18
%tmp20 = srem i64 %tmp19, %.0
%tmp21 = trunc i64 %tmp20 to i32
%tmp22 = getelementptr inbounds [1024 x i32], [1024 x i32]* @B, i64 0, i64 %.0
store i32 %tmp21, i32* %tmp22, align 4
br label %bb23
bb23: ; preds = %bb16
%tmp24 = add nuw nsw i64 %.0, 1
br label %bb14
bb25: ; preds = %bb15
ret void
}
; Check that the different bounds are detected and prevent fusion.
; CHECK: Performing Loop Fusion on function different_bounds
; CHECK: Fusion Candidates:
; CHECK: *** Fusion Candidate Set ***
; CHECK-NEXT: [[LOOP1PREHEADER:bb[0-9]*]]
; CHECK-NEXT: [[LOOP2PREHEADER:bb[0-9]*]]
; CHECK-NEXT: ****************************
; CHECK: Attempting fusion on Candidate Set:
; CHECK-NEXT: [[LOOP1PREHEADER]]
; CHECK-NEXT: [[LOOP2PREHEADER]]
; CHECK: Fusion candidates do not have identical trip counts. Not fusing.
; CHECK: Loop Fusion complete
define void @different_bounds(i32* noalias %arg) {
bb:
br label %bb3
bb3: ; preds = %bb11, %bb
%.01 = phi i64 [ 0, %bb ], [ %tmp12, %bb11 ]
%exitcond2 = icmp ne i64 %.01, 100
br i1 %exitcond2, label %bb5, label %bb4
bb4: ; preds = %bb3
br label %bb13
bb5: ; preds = %bb3
%tmp = add nsw i64 %.01, -3
%tmp6 = add nuw nsw i64 %.01, 3
%tmp7 = mul nsw i64 %tmp, %tmp6
%tmp8 = srem i64 %tmp7, %.01
%tmp9 = trunc i64 %tmp8 to i32
%tmp10 = getelementptr inbounds i32, i32* %arg, i64 %.01
store i32 %tmp9, i32* %tmp10, align 4
br label %bb11
bb11: ; preds = %bb5
%tmp12 = add nuw nsw i64 %.01, 1
br label %bb3
bb13: ; preds = %bb4
br label %bb14
bb14: ; preds = %bb23, %bb13
%.0 = phi i64 [ 0, %bb13 ], [ %tmp24, %bb23 ]
%exitcond = icmp ne i64 %.0, 200
br i1 %exitcond, label %bb16, label %bb15
bb15: ; preds = %bb14
br label %bb25
bb16: ; preds = %bb14
%tmp17 = add nsw i64 %.0, -3
%tmp18 = add nuw nsw i64 %.0, 3
%tmp19 = mul nsw i64 %tmp17, %tmp18
%tmp20 = srem i64 %tmp19, %.0
%tmp21 = trunc i64 %tmp20 to i32
%tmp22 = getelementptr inbounds [1024 x i32], [1024 x i32]* @B, i64 0, i64 %.0
store i32 %tmp21, i32* %tmp22, align 4
br label %bb23
bb23: ; preds = %bb16
%tmp24 = add nuw nsw i64 %.0, 1
br label %bb14
bb25: ; preds = %bb15
ret void
}
; Check that the negative dependence between the two candidates is identified
; and prevents fusion.
; CHECK: Performing Loop Fusion on function negative_dependence
; CHECK: Fusion Candidates:
; CHECK: *** Fusion Candidate Set ***
; CHECK-NEXT: [[LOOP1PREHEADER:bb[0-9]*]]
; CHECK-NEXT: [[LOOP2PREHEADER:bb[0-9]*]]
; CHECK-NEXT: ****************************
; CHECK: Attempting fusion on Candidate Set:
; CHECK-NEXT: [[LOOP1PREHEADER]]
; CHECK-NEXT: [[LOOP2PREHEADER]]
; CHECK: Memory dependencies do not allow fusion!
; CHECK: Loop Fusion complete
define void @negative_dependence(i32* noalias %arg) {
bb:
br label %bb5
bb5: ; preds = %bb9, %bb
%indvars.iv2 = phi i64 [ %indvars.iv.next3, %bb9 ], [ 0, %bb ]
%exitcond4 = icmp ne i64 %indvars.iv2, 100
br i1 %exitcond4, label %bb7, label %bb11
bb7: ; preds = %bb5
%tmp = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv2
%tmp8 = trunc i64 %indvars.iv2 to i32
store i32 %tmp8, i32* %tmp, align 4
br label %bb9
bb9: ; preds = %bb7
%indvars.iv.next3 = add nuw nsw i64 %indvars.iv2, 1
br label %bb5
bb11: ; preds = %bb18, %bb5
%indvars.iv = phi i64 [ %indvars.iv.next, %bb18 ], [ 0, %bb5 ]
%exitcond = icmp ne i64 %indvars.iv, 100
br i1 %exitcond, label %bb13, label %bb19
bb13: ; preds = %bb11
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%tmp14 = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv.next
%tmp15 = load i32, i32* %tmp14, align 4
%tmp16 = shl nsw i32 %tmp15, 1
%tmp17 = getelementptr inbounds [1024 x i32], [1024 x i32]* @B, i64 0, i64 %indvars.iv
store i32 %tmp16, i32* %tmp17, align 4
br label %bb18
bb18: ; preds = %bb13
br label %bb11
bb19: ; preds = %bb11
ret void
}
; Check for values defined in Loop 0 and used in Loop 1.
; It is not safe to fuse in this case, because the second loop has
; a use of %.01.lcssa which is defined in the body of loop 0. The
; first loop must execute completely in order to compute the correct
; value of %.01.lcssa to be used in the second loop.
; CHECK: Performing Loop Fusion on function sumTest
; CHECK: Fusion Candidates:
; CHECK: *** Fusion Candidate Set ***
; CHECK-NEXT: [[LOOP1PREHEADER:bb[0-9]*]]
; CHECK-NEXT: [[LOOP2PREHEADER:bb[0-9]*]]
; CHECK-NEXT: ****************************
; CHECK: Attempting fusion on Candidate Set:
; CHECK-NEXT: [[LOOP1PREHEADER]]
; CHECK-NEXT: [[LOOP2PREHEADER]]
; CHECK: Memory dependencies do not allow fusion!
; CHECK: Loop Fusion complete
define i32 @sumTest(i32* noalias %arg) {
bb:
br label %bb6
bb6: ; preds = %bb9, %bb
%indvars.iv3 = phi i64 [ %indvars.iv.next4, %bb9 ], [ 0, %bb ]
%.01 = phi i32 [ 0, %bb ], [ %tmp11, %bb9 ]
%exitcond5 = icmp ne i64 %indvars.iv3, 100
br i1 %exitcond5, label %bb9, label %bb13
bb9: ; preds = %bb6
%tmp = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv3
%tmp10 = load i32, i32* %tmp, align 4
%tmp11 = add nsw i32 %.01, %tmp10
%indvars.iv.next4 = add nuw nsw i64 %indvars.iv3, 1
br label %bb6
bb13: ; preds = %bb20, %bb6
%.01.lcssa = phi i32 [ %.01, %bb6 ], [ %.01.lcssa, %bb20 ]
%indvars.iv = phi i64 [ %indvars.iv.next, %bb20 ], [ 0, %bb6 ]
%exitcond = icmp ne i64 %indvars.iv, 100
br i1 %exitcond, label %bb15, label %bb14
bb14: ; preds = %bb13
br label %bb21
bb15: ; preds = %bb13
%tmp16 = getelementptr inbounds i32, i32* %arg, i64 %indvars.iv
%tmp17 = load i32, i32* %tmp16, align 4
%tmp18 = sdiv i32 %tmp17, %.01.lcssa
%tmp19 = getelementptr inbounds [1024 x i32], [1024 x i32]* @B, i64 0, i64 %indvars.iv
store i32 %tmp18, i32* %tmp19, align 4
br label %bb20
bb20: ; preds = %bb15
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
br label %bb13
bb21: ; preds = %bb14
ret i32 %.01.lcssa
}
; Similar to sumTest above. The first loop computes %add and must
; complete before it is used in the second loop. Thus, these two loops
; also cannot be fused.
; CHECK: Performing Loop Fusion on function test
; CHECK: Fusion Candidates:
; CHECK: *** Fusion Candidate Set ***
; CHECK-NEXT: [[LOOP1PREHEADER:for.body[0-9]*.preheader]]
; CHECK-NEXT: [[LOOP2PREHEADER:for.body[0-9]*.preheader]]
; CHECK-NEXT: ****************************
; CHECK: Attempting fusion on Candidate Set:
; CHECK-NEXT: [[LOOP1PREHEADER]]
; CHECK-NEXT: [[LOOP2PREHEADER]]
; CHECK: Memory dependencies do not allow fusion!
; CHECK: Loop Fusion complete
define float @test(float* nocapture %a, i32 %n) {
entry:
%conv = zext i32 %n to i64
%cmp32 = icmp eq i32 %n, 0
br i1 %cmp32, label %for.cond.cleanup7, label %for.body
for.body: ; preds = %for.body, %entry
%i.034 = phi i64 [ %inc, %for.body ], [ 0, %entry ]
%sum1.033 = phi float [ %add, %for.body ], [ 0.000000e+00, %entry ]
%idxprom = trunc i64 %i.034 to i32
%arrayidx = getelementptr inbounds float, float* %a, i32 %idxprom
%0 = load float, float* %arrayidx, align 4
%add = fadd float %sum1.033, %0
%inc = add nuw nsw i64 %i.034, 1
%cmp = icmp ult i64 %inc, %conv
br i1 %cmp, label %for.body, label %for.body8
for.body8: ; preds = %for.body, %for.body8
%i2.031 = phi i64 [ %inc14, %for.body8 ], [ 0, %for.body ]
%idxprom9 = trunc i64 %i2.031 to i32
%arrayidx10 = getelementptr inbounds float, float* %a, i32 %idxprom9
%1 = load float, float* %arrayidx10, align 4
%div = fdiv float %1, %add
store float %div, float* %arrayidx10, align 4
%inc14 = add nuw nsw i64 %i2.031, 1
%cmp5 = icmp ult i64 %inc14, %conv
br i1 %cmp5, label %for.body8, label %for.cond.cleanup7
for.cond.cleanup7: ; preds = %for.body8, %entry
%sum1.0.lcssa36 = phi float [ 0.000000e+00, %entry ], [ %add, %for.body8 ]
ret float %sum1.0.lcssa36
}
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