llvm/test/Transforms/LoopFusion/guard_skip_empty_block.ll

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
; RUN: opt -S -passes=loop-fusion -loop-fusion-disable-cost-model -verify-loop-info -verify-dom-info < %s | FileCheck %s

@B = common global [1024 x i32] zeroinitializer, align 16

; The skip edge of the first loop guard goes through an empty block (%skip)
; that passes like JumpThreading can leave behind. Loop fusion must fold the
; block away so that the guard is recognized and the two loops are fused.
define void @guard_skip_empty_block(ptr noalias %A, i64 %N) {
; CHECK-LABEL: define void @guard_skip_empty_block(
; CHECK-SAME: ptr noalias [[A:%.*]], i64 [[N:%.*]]) {
; CHECK-NEXT:  [[ENTRY:.*:]]
; CHECK-NEXT:    [[CMP4:%.*]] = icmp slt i64 0, [[N]]
; CHECK-NEXT:    [[CMP31:%.*]] = icmp slt i64 0, [[N]]
; CHECK-NEXT:    br i1 [[CMP4]], label %[[BB3:.*]], label %[[BB12:.*]]
; CHECK:       [[BB3]]:
; CHECK-NEXT:    br label %[[BB5:.*]]
; CHECK:       [[BB5]]:
; CHECK-NEXT:    [[I_05:%.*]] = phi i64 [ [[INC:%.*]], %[[BB5]] ], [ 0, %[[BB3]] ]
; CHECK-NEXT:    [[I1_02:%.*]] = phi i64 [ [[INC14:%.*]], %[[BB5]] ], [ 0, %[[BB3]] ]
; CHECK-NEXT:    [[SUB:%.*]] = sub nsw i64 [[I_05]], 3
; CHECK-NEXT:    [[ADD:%.*]] = add nsw i64 [[I_05]], 3
; CHECK-NEXT:    [[MUL:%.*]] = mul nsw i64 [[SUB]], [[ADD]]
; CHECK-NEXT:    [[REM:%.*]] = srem i64 [[MUL]], [[I_05]]
; CHECK-NEXT:    [[CONV:%.*]] = trunc i64 [[REM]] to i32
; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 [[I_05]]
; CHECK-NEXT:    store i32 [[CONV]], ptr [[ARRAYIDX]], align 4
; CHECK-NEXT:    [[INC]] = add nsw i64 [[I_05]], 1
; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i64 [[INC]], [[N]]
; CHECK-NEXT:    [[SUB7:%.*]] = sub nsw i64 [[I1_02]], 3
; CHECK-NEXT:    [[ADD8:%.*]] = add nsw i64 [[I1_02]], 3
; CHECK-NEXT:    [[MUL9:%.*]] = mul nsw i64 [[SUB7]], [[ADD8]]
; CHECK-NEXT:    [[REM10:%.*]] = srem i64 [[MUL9]], [[I1_02]]
; CHECK-NEXT:    [[CONV11:%.*]] = trunc i64 [[REM10]] to i32
; CHECK-NEXT:    [[ARRAYIDX12:%.*]] = getelementptr inbounds [1024 x i32], ptr @B, i64 0, i64 [[I1_02]]
; CHECK-NEXT:    store i32 [[CONV11]], ptr [[ARRAYIDX12]], align 4
; CHECK-NEXT:    [[INC14]] = add nsw i64 [[I1_02]], 1
; CHECK-NEXT:    [[CMP3:%.*]] = icmp slt i64 [[INC14]], [[N]]
; CHECK-NEXT:    br i1 [[CMP3]], label %[[BB5]], label %[[BB15:.*]]
; CHECK:       [[BB15]]:
; CHECK-NEXT:    br label %[[BB12]]
; CHECK:       [[BB12]]:
; CHECK-NEXT:    ret void
;
entry:
  %cmp4 = icmp slt i64 0, %N
  br i1 %cmp4, label %blk3, label %skip

skip:
  br label %blk14

blk3:
  br label %blk5

blk5:
  %i.05 = phi i64 [ %inc, %blk5 ], [ 0, %blk3 ]
  %sub = sub nsw i64 %i.05, 3
  %add = add nsw i64 %i.05, 3
  %mul = mul nsw i64 %sub, %add
  %rem = srem i64 %mul, %i.05
  %conv = trunc i64 %rem to i32
  %arrayidx = getelementptr inbounds i32, ptr %A, i64 %i.05
  store i32 %conv, ptr %arrayidx, align 4
  %inc = add nsw i64 %i.05, 1
  %cmp = icmp slt i64 %inc, %N
  br i1 %cmp, label %blk5, label %blk10

blk10:
  br label %blk14

blk14:
  %cmp31 = icmp slt i64 0, %N
  br i1 %cmp31, label %blk8, label %blk12

blk8:
  br label %blk9

blk9:
  %i1.02 = phi i64 [ %inc14, %blk9 ], [ 0, %blk8 ]
  %sub7 = sub nsw i64 %i1.02, 3
  %add8 = add nsw i64 %i1.02, 3
  %mul9 = mul nsw i64 %sub7, %add8
  %rem10 = srem i64 %mul9, %i1.02
  %conv11 = trunc i64 %rem10 to i32
  %arrayidx12 = getelementptr inbounds [1024 x i32], ptr @B, i64 0, i64 %i1.02
  store i32 %conv11, ptr %arrayidx12, align 4
  %inc14 = add nsw i64 %i1.02, 1
  %cmp3 = icmp slt i64 %inc14, %N
  br i1 %cmp3, label %blk9, label %blk15

blk15:
  br label %blk12

blk12:
  ret void
}

; Same shape inside an outer loop: the skip block belongs to the outer loop
; and must be removed from LoopInfo as well.
define void @guard_skip_empty_block_nested(ptr noalias %A, i64 %N, i64 %M) {
; CHECK-LABEL: define void @guard_skip_empty_block_nested(
; CHECK-SAME: ptr noalias [[A:%.*]], i64 [[N:%.*]], i64 [[M:%.*]]) {
; CHECK-NEXT:  [[ENTRY:.*:]]
; CHECK-NEXT:    [[CMPM:%.*]] = icmp slt i64 0, [[M]]
; CHECK-NEXT:    br i1 [[CMPM]], label %[[OUTER_PH:.*]], label %[[EXIT:.*]]
; CHECK:       [[OUTER_PH]]:
; CHECK-NEXT:    br label %[[OUTER:.*]]
; CHECK:       [[OUTER]]:
; CHECK-NEXT:    [[J:%.*]] = phi i64 [ 0, %[[OUTER_PH]] ], [ [[J_INC:%.*]], %[[OUTER_LATCH:.*]] ]
; CHECK-NEXT:    [[CMP4:%.*]] = icmp slt i64 0, [[N]]
; CHECK-NEXT:    [[CMP31:%.*]] = icmp slt i64 0, [[N]]
; CHECK-NEXT:    br i1 [[CMP4]], label %[[BB3:.*]], label %[[OUTER_LATCH]]
; CHECK:       [[BB3]]:
; CHECK-NEXT:    br label %[[BB5:.*]]
; CHECK:       [[BB5]]:
; CHECK-NEXT:    [[I_05:%.*]] = phi i64 [ [[INC:%.*]], %[[BB5]] ], [ 0, %[[BB3]] ]
; CHECK-NEXT:    [[I1_02:%.*]] = phi i64 [ [[INC14:%.*]], %[[BB5]] ], [ 0, %[[BB3]] ]
; CHECK-NEXT:    [[SUB:%.*]] = sub nsw i64 [[I_05]], 3
; CHECK-NEXT:    [[ADD:%.*]] = add nsw i64 [[I_05]], 3
; CHECK-NEXT:    [[MUL:%.*]] = mul nsw i64 [[SUB]], [[ADD]]
; CHECK-NEXT:    [[REM:%.*]] = srem i64 [[MUL]], [[I_05]]
; CHECK-NEXT:    [[CONV:%.*]] = trunc i64 [[REM]] to i32
; CHECK-NEXT:    [[IDX:%.*]] = add nsw i64 [[I_05]], [[J]]
; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 [[IDX]]
; CHECK-NEXT:    store i32 [[CONV]], ptr [[ARRAYIDX]], align 4
; CHECK-NEXT:    [[INC]] = add nsw i64 [[I_05]], 1
; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i64 [[INC]], [[N]]
; CHECK-NEXT:    [[SUB7:%.*]] = sub nsw i64 [[I1_02]], 3
; CHECK-NEXT:    [[ADD8:%.*]] = add nsw i64 [[I1_02]], 3
; CHECK-NEXT:    [[MUL9:%.*]] = mul nsw i64 [[SUB7]], [[ADD8]]
; CHECK-NEXT:    [[REM10:%.*]] = srem i64 [[MUL9]], [[I1_02]]
; CHECK-NEXT:    [[CONV11:%.*]] = trunc i64 [[REM10]] to i32
; CHECK-NEXT:    [[ARRAYIDX12:%.*]] = getelementptr inbounds [1024 x i32], ptr @B, i64 0, i64 [[I1_02]]
; CHECK-NEXT:    store i32 [[CONV11]], ptr [[ARRAYIDX12]], align 4
; CHECK-NEXT:    [[INC14]] = add nsw i64 [[I1_02]], 1
; CHECK-NEXT:    [[CMP3:%.*]] = icmp slt i64 [[INC14]], [[N]]
; CHECK-NEXT:    br i1 [[CMP3]], label %[[BB5]], label %[[BB15:.*]]
; CHECK:       [[BB15]]:
; CHECK-NEXT:    br label %[[OUTER_LATCH]]
; CHECK:       [[OUTER_LATCH]]:
; CHECK-NEXT:    [[J_INC]] = add nsw i64 [[J]], 1
; CHECK-NEXT:    [[CMPJ:%.*]] = icmp slt i64 [[J_INC]], [[M]]
; CHECK-NEXT:    br i1 [[CMPJ]], label %[[OUTER]], label %[[EXIT_LOOPEXIT:.*]]
; CHECK:       [[EXIT_LOOPEXIT]]:
; CHECK-NEXT:    br label %[[EXIT]]
; CHECK:       [[EXIT]]:
; CHECK-NEXT:    ret void
;
entry:
  %cmpM = icmp slt i64 0, %M
  br i1 %cmpM, label %outer.ph, label %exit

outer.ph:
  br label %outer

outer:
  %j = phi i64 [ 0, %outer.ph ], [ %j.inc, %outer.latch ]
  %cmp4 = icmp slt i64 0, %N
  br i1 %cmp4, label %blk3, label %skip

skip:
  br label %blk14

blk3:
  br label %blk5

blk5:
  %i.05 = phi i64 [ %inc, %blk5 ], [ 0, %blk3 ]
  %sub = sub nsw i64 %i.05, 3
  %add = add nsw i64 %i.05, 3
  %mul = mul nsw i64 %sub, %add
  %rem = srem i64 %mul, %i.05
  %conv = trunc i64 %rem to i32
  %idx = add nsw i64 %i.05, %j
  %arrayidx = getelementptr inbounds i32, ptr %A, i64 %idx
  store i32 %conv, ptr %arrayidx, align 4
  %inc = add nsw i64 %i.05, 1
  %cmp = icmp slt i64 %inc, %N
  br i1 %cmp, label %blk5, label %blk10

blk10:
  br label %blk14

blk14:
  %cmp31 = icmp slt i64 0, %N
  br i1 %cmp31, label %blk8, label %outer.latch

blk8:
  br label %blk9

blk9:
  %i1.02 = phi i64 [ %inc14, %blk9 ], [ 0, %blk8 ]
  %sub7 = sub nsw i64 %i1.02, 3
  %add8 = add nsw i64 %i1.02, 3
  %mul9 = mul nsw i64 %sub7, %add8
  %rem10 = srem i64 %mul9, %i1.02
  %conv11 = trunc i64 %rem10 to i32
  %arrayidx12 = getelementptr inbounds [1024 x i32], ptr @B, i64 0, i64 %i1.02
  store i32 %conv11, ptr %arrayidx12, align 4
  %inc14 = add nsw i64 %i1.02, 1
  %cmp3 = icmp slt i64 %inc14, %N
  br i1 %cmp3, label %blk9, label %blk15

blk15:
  br label %outer.latch

outer.latch:
  %j.inc = add nsw i64 %j, 1
  %cmpj = icmp slt i64 %j.inc, %M
  br i1 %cmpj, label %outer, label %exit.loopexit

exit.loopexit:
  br label %exit

exit:
  ret void
}

; The loops have different trip counts and are not fused, but the empty skip
; block is still folded and the PHI in the merge block is updated.
define i32 @guard_skip_empty_block_phi(ptr noalias %A, i64 %N, i64 %M) {
; CHECK-LABEL: define i32 @guard_skip_empty_block_phi(
; CHECK-SAME: ptr noalias [[A:%.*]], i64 [[N:%.*]], i64 [[M:%.*]]) {
; CHECK-NEXT:  [[ENTRY:.*]]:
; CHECK-NEXT:    [[CMP4:%.*]] = icmp slt i64 0, [[N]]
; CHECK-NEXT:    br i1 [[CMP4]], label %[[BB3:.*]], label %[[BB14:.*]]
; CHECK:       [[BB3]]:
; CHECK-NEXT:    br label %[[BB5:.*]]
; CHECK:       [[BB5]]:
; CHECK-NEXT:    [[I_05:%.*]] = phi i64 [ [[INC:%.*]], %[[BB5]] ], [ 0, %[[BB3]] ]
; CHECK-NEXT:    [[CONV:%.*]] = trunc i64 [[I_05]] to i32
; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 [[I_05]]
; CHECK-NEXT:    store i32 [[CONV]], ptr [[ARRAYIDX]], align 4
; CHECK-NEXT:    [[INC]] = add nsw i64 [[I_05]], 1
; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i64 [[INC]], [[N]]
; CHECK-NEXT:    br i1 [[CMP]], label %[[BB5]], label %[[BB10:.*]]
; CHECK:       [[BB10]]:
; CHECK-NEXT:    br label %[[BB14]]
; CHECK:       [[BB14]]:
; CHECK-NEXT:    [[P:%.*]] = phi i32 [ 0, %[[ENTRY]] ], [ 1, %[[BB10]] ]
; CHECK-NEXT:    [[CMP31:%.*]] = icmp slt i64 0, [[M]]
; CHECK-NEXT:    br i1 [[CMP31]], label %[[BB8:.*]], label %[[BB12:.*]]
; CHECK:       [[BB8]]:
; CHECK-NEXT:    br label %[[BB9:.*]]
; CHECK:       [[BB9]]:
; CHECK-NEXT:    [[I1_02:%.*]] = phi i64 [ [[INC14:%.*]], %[[BB9]] ], [ 0, %[[BB8]] ]
; CHECK-NEXT:    [[CONV11:%.*]] = trunc i64 [[I1_02]] to i32
; CHECK-NEXT:    [[ARRAYIDX12:%.*]] = getelementptr inbounds [1024 x i32], ptr @B, i64 0, i64 [[I1_02]]
; CHECK-NEXT:    store i32 [[CONV11]], ptr [[ARRAYIDX12]], align 4
; CHECK-NEXT:    [[INC14]] = add nsw i64 [[I1_02]], 1
; CHECK-NEXT:    [[CMP3:%.*]] = icmp slt i64 [[INC14]], [[M]]
; CHECK-NEXT:    br i1 [[CMP3]], label %[[BB9]], label %[[BB15:.*]]
; CHECK:       [[BB15]]:
; CHECK-NEXT:    br label %[[BB12]]
; CHECK:       [[BB12]]:
; CHECK-NEXT:    ret i32 [[P]]
;
entry:
  %cmp4 = icmp slt i64 0, %N
  br i1 %cmp4, label %blk3, label %skip

skip:
  br label %blk14

blk3:
  br label %blk5

blk5:
  %i.05 = phi i64 [ %inc, %blk5 ], [ 0, %blk3 ]
  %conv = trunc i64 %i.05 to i32
  %arrayidx = getelementptr inbounds i32, ptr %A, i64 %i.05
  store i32 %conv, ptr %arrayidx, align 4
  %inc = add nsw i64 %i.05, 1
  %cmp = icmp slt i64 %inc, %N
  br i1 %cmp, label %blk5, label %blk10

blk10:
  br label %blk14

blk14:
  %p = phi i32 [ 0, %skip ], [ 1, %blk10 ]
  %cmp31 = icmp slt i64 0, %M
  br i1 %cmp31, label %blk8, label %blk12

blk8:
  br label %blk9

blk9:
  %i1.02 = phi i64 [ %inc14, %blk9 ], [ 0, %blk8 ]
  %conv11 = trunc i64 %i1.02 to i32
  %arrayidx12 = getelementptr inbounds [1024 x i32], ptr @B, i64 0, i64 %i1.02
  store i32 %conv11, ptr %arrayidx12, align 4
  %inc14 = add nsw i64 %i1.02, 1
  %cmp3 = icmp slt i64 %inc14, %M
  br i1 %cmp3, label %blk9, label %blk15

blk15:
  br label %blk12

blk12:
  ret i32 %p
}

; The skip block is not empty: it must be left alone, so the first loop stays
; unguarded and the loops are not fused.
define void @guard_skip_block_not_empty(ptr noalias %A, i64 %N) {
; CHECK-LABEL: define void @guard_skip_block_not_empty(
; CHECK-SAME: ptr noalias [[A:%.*]], i64 [[N:%.*]]) {
; CHECK-NEXT:  [[ENTRY:.*:]]
; CHECK-NEXT:    [[CMP4:%.*]] = icmp slt i64 0, [[N]]
; CHECK-NEXT:    br i1 [[CMP4]], label %[[BB3:.*]], label %[[SKIP:.*]]
; CHECK:       [[SKIP]]:
; CHECK-NEXT:    store i32 0, ptr [[A]], align 4
; CHECK-NEXT:    br label %[[BB14:.*]]
; CHECK:       [[BB3]]:
; CHECK-NEXT:    br label %[[BB5:.*]]
; CHECK:       [[BB5]]:
; CHECK-NEXT:    [[I_05:%.*]] = phi i64 [ [[INC:%.*]], %[[BB5]] ], [ 0, %[[BB3]] ]
; CHECK-NEXT:    [[CONV:%.*]] = trunc i64 [[I_05]] to i32
; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 [[I_05]]
; CHECK-NEXT:    store i32 [[CONV]], ptr [[ARRAYIDX]], align 4
; CHECK-NEXT:    [[INC]] = add nsw i64 [[I_05]], 1
; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i64 [[INC]], [[N]]
; CHECK-NEXT:    br i1 [[CMP]], label %[[BB5]], label %[[BB10:.*]]
; CHECK:       [[BB10]]:
; CHECK-NEXT:    br label %[[BB14]]
; CHECK:       [[BB14]]:
; CHECK-NEXT:    [[CMP31:%.*]] = icmp slt i64 0, [[N]]
; CHECK-NEXT:    br i1 [[CMP31]], label %[[BB8:.*]], label %[[BB12:.*]]
; CHECK:       [[BB8]]:
; CHECK-NEXT:    br label %[[BB9:.*]]
; CHECK:       [[BB9]]:
; CHECK-NEXT:    [[I1_02:%.*]] = phi i64 [ [[INC14:%.*]], %[[BB9]] ], [ 0, %[[BB8]] ]
; CHECK-NEXT:    [[CONV11:%.*]] = trunc i64 [[I1_02]] to i32
; CHECK-NEXT:    [[ARRAYIDX12:%.*]] = getelementptr inbounds [1024 x i32], ptr @B, i64 0, i64 [[I1_02]]
; CHECK-NEXT:    store i32 [[CONV11]], ptr [[ARRAYIDX12]], align 4
; CHECK-NEXT:    [[INC14]] = add nsw i64 [[I1_02]], 1
; CHECK-NEXT:    [[CMP3:%.*]] = icmp slt i64 [[INC14]], [[N]]
; CHECK-NEXT:    br i1 [[CMP3]], label %[[BB9]], label %[[BB15:.*]]
; CHECK:       [[BB15]]:
; CHECK-NEXT:    br label %[[BB12]]
; CHECK:       [[BB12]]:
; CHECK-NEXT:    ret void
;
entry:
  %cmp4 = icmp slt i64 0, %N
  br i1 %cmp4, label %blk3, label %skip

skip:
  store i32 0, ptr %A, align 4
  br label %blk14

blk3:
  br label %blk5

blk5:
  %i.05 = phi i64 [ %inc, %blk5 ], [ 0, %blk3 ]
  %conv = trunc i64 %i.05 to i32
  %arrayidx = getelementptr inbounds i32, ptr %A, i64 %i.05
  store i32 %conv, ptr %arrayidx, align 4
  %inc = add nsw i64 %i.05, 1
  %cmp = icmp slt i64 %inc, %N
  br i1 %cmp, label %blk5, label %blk10

blk10:
  br label %blk14

blk14:
  %cmp31 = icmp slt i64 0, %N
  br i1 %cmp31, label %blk8, label %blk12

blk8:
  br label %blk9

blk9:
  %i1.02 = phi i64 [ %inc14, %blk9 ], [ 0, %blk8 ]
  %conv11 = trunc i64 %i1.02 to i32
  %arrayidx12 = getelementptr inbounds [1024 x i32], ptr @B, i64 0, i64 %i1.02
  store i32 %conv11, ptr %arrayidx12, align 4
  %inc14 = add nsw i64 %i1.02, 1
  %cmp3 = icmp slt i64 %inc14, %N
  br i1 %cmp3, label %blk9, label %blk15

blk15:
  br label %blk12

blk12:
  ret void
}