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[MachineLICM] Relax overlay conservative PHI check (llvm#67186)
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Skip LICM if PHI belongs to the current loop, e.g. is in the
loop's header. This prevents LICM from bailing for CFGs like

L1:
  R = LoopInvariant // can be LICM'd
  BR L1
L2:
  PHI(R, ..)
  BR L2
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Hendrik Greving authored Oct 9, 2023
1 parent 7b3bbd8 commit 71a8d2e
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Showing 11 changed files with 204 additions and 230 deletions.
2 changes: 1 addition & 1 deletion llvm/lib/CodeGen/MachineLICM.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1050,7 +1050,7 @@ bool MachineLICMBase::HasLoopPHIUse(const MachineInstr *MI,
if (UseMI.isPHI()) {
// A PHI inside the loop causes a copy because the live range of Reg is
// extended across the PHI.
if (CurLoop->contains(&UseMI))
if (CurLoop->getHeader() == UseMI.getParent())
return true;
// A PHI in an exit block can cause a copy to be inserted if the PHI
// has multiple predecessors in the loop with different values.
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19 changes: 8 additions & 11 deletions llvm/test/CodeGen/X86/2008-04-28-CoalescerBug.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@ define void @t(ptr %depth, ptr %bop, i32 %mode) nounwind {
; CHECK-NEXT: je LBB0_3
; CHECK-NEXT: ## %bb.1: ## %entry
; CHECK-NEXT: cmpl $1, %edx
; CHECK-NEXT: jne LBB0_10
; CHECK-NEXT: jne LBB0_9
; CHECK-NEXT: .p2align 4, 0x90
; CHECK-NEXT: LBB0_2: ## %bb2898.us
; CHECK-NEXT: ## =>This Inner Loop Header: Depth=1
Expand All @@ -26,15 +26,12 @@ define void @t(ptr %depth, ptr %bop, i32 %mode) nounwind {
; CHECK-NEXT: LBB0_4: ## %bb13088
; CHECK-NEXT: ## =>This Inner Loop Header: Depth=1
; CHECK-NEXT: testb %al, %al
; CHECK-NEXT: jne LBB0_5
; CHECK-NEXT: ## %bb.6: ## %bb13101
; CHECK-NEXT: movl $65535, %ecx ## imm = 0xFFFF
; CHECK-NEXT: jne LBB0_6
; CHECK-NEXT: ## %bb.5: ## %bb13101
; CHECK-NEXT: ## in Loop: Header=BB0_4 Depth=1
; CHECK-NEXT: xorl %ecx, %ecx
; CHECK-NEXT: jmp LBB0_7
; CHECK-NEXT: .p2align 4, 0x90
; CHECK-NEXT: LBB0_5: ## in Loop: Header=BB0_4 Depth=1
; CHECK-NEXT: movl $65535, %ecx ## imm = 0xFFFF
; CHECK-NEXT: LBB0_7: ## %bb13107
; CHECK-NEXT: LBB0_6: ## %bb13107
; CHECK-NEXT: ## in Loop: Header=BB0_4 Depth=1
; CHECK-NEXT: movl %ecx, %edx
; CHECK-NEXT: shll $16, %edx
Expand All @@ -44,11 +41,11 @@ define void @t(ptr %depth, ptr %bop, i32 %mode) nounwind {
; CHECK-NEXT: subl %edx, %ecx
; CHECK-NEXT: testw %cx, %cx
; CHECK-NEXT: je LBB0_4
; CHECK-NEXT: ## %bb.8: ## %bb13236
; CHECK-NEXT: ## %bb.7: ## %bb13236
; CHECK-NEXT: ## in Loop: Header=BB0_4 Depth=1
; CHECK-NEXT: testb %al, %al
; CHECK-NEXT: jne LBB0_4
; CHECK-NEXT: ## %bb.9: ## %bb13572
; CHECK-NEXT: ## %bb.8: ## %bb13572
; CHECK-NEXT: ## in Loop: Header=BB0_4 Depth=1
; CHECK-NEXT: movzwl %cx, %ecx
; CHECK-NEXT: movl %ecx, %edx
Expand All @@ -58,7 +55,7 @@ define void @t(ptr %depth, ptr %bop, i32 %mode) nounwind {
; CHECK-NEXT: shrl $16, %edx
; CHECK-NEXT: movw %dx, 0
; CHECK-NEXT: jmp LBB0_4
; CHECK-NEXT: LBB0_10: ## %return
; CHECK-NEXT: LBB0_9: ## %return
; CHECK-NEXT: retq
entry:
switch i32 %mode, label %return [
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29 changes: 14 additions & 15 deletions llvm/test/CodeGen/X86/2012-01-10-UndefExceptionEdge.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -33,11 +33,10 @@ define void @f(ptr nocapture %arg, ptr nocapture %arg1, ptr nocapture %arg2, ptr
; CHECK-NEXT: .cfi_offset %esi, -20
; CHECK-NEXT: .cfi_offset %edi, -16
; CHECK-NEXT: .cfi_offset %ebx, -12
; CHECK-NEXT: xorl %eax, %eax
; CHECK-NEXT: xorl %edi, %edi
; CHECK-NEXT: testb %al, %al
; CHECK-NEXT: xorl %ebx, %ebx
; CHECK-NEXT: testb %bl, %bl
; CHECK-NEXT: Ltmp0:
; CHECK-NEXT: ## implicit-def: $ebx
; CHECK-NEXT: ## implicit-def: $edi
; CHECK-NEXT: calll __Znam
; CHECK-NEXT: Ltmp1:
; CHECK-NEXT: ## %bb.1: ## %bb11
Expand Down Expand Up @@ -86,16 +85,16 @@ define void @f(ptr nocapture %arg, ptr nocapture %arg1, ptr nocapture %arg2, ptr
; CHECK-NEXT: jne LBB0_17
; CHECK-NEXT: ## %bb.15: ## %bb49.preheader
; CHECK-NEXT: ## in Loop: Header=BB0_13 Depth=2
; CHECK-NEXT: xorl %ecx, %ecx
; CHECK-NEXT: movl %esi, %edx
; CHECK-NEXT: movl %edi, %ebx
; CHECK-NEXT: movl %esi, %ecx
; CHECK-NEXT: movl %ebx, %edx
; CHECK-NEXT: xorl %edi, %edi
; CHECK-NEXT: LBB0_16: ## %bb49
; CHECK-NEXT: ## Parent Loop BB0_8 Depth=1
; CHECK-NEXT: ## Parent Loop BB0_13 Depth=2
; CHECK-NEXT: ## => This Inner Loop Header: Depth=3
; CHECK-NEXT: incl %ecx
; CHECK-NEXT: addl $4, %edx
; CHECK-NEXT: decl %ebx
; CHECK-NEXT: incl %edi
; CHECK-NEXT: addl $4, %ecx
; CHECK-NEXT: decl %edx
; CHECK-NEXT: jne LBB0_16
; CHECK-NEXT: LBB0_17: ## %bb57
; CHECK-NEXT: ## in Loop: Header=BB0_13 Depth=2
Expand All @@ -113,7 +112,7 @@ define void @f(ptr nocapture %arg, ptr nocapture %arg1, ptr nocapture %arg2, ptr
; CHECK-NEXT: ## %bb.20: ## %bb61.preheader
; CHECK-NEXT: ## in Loop: Header=BB0_8 Depth=1
; CHECK-NEXT: movl %esi, %eax
; CHECK-NEXT: movl %edi, %ecx
; CHECK-NEXT: movl %ebx, %ecx
; CHECK-NEXT: LBB0_21: ## %bb61
; CHECK-NEXT: ## Parent Loop BB0_8 Depth=1
; CHECK-NEXT: ## => This Inner Loop Header: Depth=2
Expand All @@ -127,23 +126,23 @@ define void @f(ptr nocapture %arg, ptr nocapture %arg1, ptr nocapture %arg2, ptr
; CHECK-NEXT: jmp LBB0_8
; CHECK-NEXT: LBB0_18: ## %bb43
; CHECK-NEXT: Ltmp5:
; CHECK-NEXT: movl %esi, %ebx
; CHECK-NEXT: movl %esi, %edi
; CHECK-NEXT: calll _OnOverFlow
; CHECK-NEXT: Ltmp6:
; CHECK-NEXT: jmp LBB0_3
; CHECK-NEXT: LBB0_2: ## %bb29
; CHECK-NEXT: Ltmp7:
; CHECK-NEXT: movl %esi, %ebx
; CHECK-NEXT: movl %esi, %edi
; CHECK-NEXT: calll _OnOverFlow
; CHECK-NEXT: Ltmp8:
; CHECK-NEXT: LBB0_3: ## %bb30
; CHECK-NEXT: ud2
; CHECK-NEXT: LBB0_4: ## %bb20.loopexit
; CHECK-NEXT: Ltmp4:
; CHECK-NEXT: LBB0_9:
; CHECK-NEXT: movl %esi, %ebx
; CHECK-NEXT: movl %esi, %edi
; CHECK-NEXT: LBB0_6: ## %bb23
; CHECK-NEXT: testl %ebx, %ebx
; CHECK-NEXT: testl %edi, %edi
; CHECK-NEXT: addl $28, %esp
; CHECK-NEXT: popl %esi
; CHECK-NEXT: popl %edi
Expand Down
31 changes: 2 additions & 29 deletions llvm/test/CodeGen/X86/cmpxchg-clobber-flags.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -137,8 +137,8 @@ define i32 @test_control_flow(ptr %p, i32 %i, i32 %j) nounwind {
; 32-ALL-NEXT: # Parent Loop BB1_2 Depth=1
; 32-ALL-NEXT: # => This Inner Loop Header: Depth=2
; 32-ALL-NEXT: movl %edx, %eax
; 32-ALL-NEXT: xorl %edx, %edx
; 32-ALL-NEXT: testl %eax, %eax
; 32-ALL-NEXT: testl %edx, %edx
; 32-ALL-NEXT: movl $0, %edx
; 32-ALL-NEXT: je .LBB1_3
; 32-ALL-NEXT: # %bb.4: # %while.body.i
; 32-ALL-NEXT: # in Loop: Header=BB1_2 Depth=1
Expand All @@ -148,33 +148,6 @@ define i32 @test_control_flow(ptr %p, i32 %i, i32 %j) nounwind {
; 32-ALL-NEXT: xorl %eax, %eax
; 32-ALL-NEXT: .LBB1_6: # %cond.end
; 32-ALL-NEXT: retl
;
; 64-ALL-LABEL: test_control_flow:
; 64-ALL: # %bb.0: # %entry
; 64-ALL-NEXT: movl %esi, %eax
; 64-ALL-NEXT: cmpl %edx, %esi
; 64-ALL-NEXT: jle .LBB1_5
; 64-ALL-NEXT: .p2align 4, 0x90
; 64-ALL-NEXT: .LBB1_1: # %while.condthread-pre-split.i
; 64-ALL-NEXT: # =>This Loop Header: Depth=1
; 64-ALL-NEXT: # Child Loop BB1_2 Depth 2
; 64-ALL-NEXT: movl (%rdi), %ecx
; 64-ALL-NEXT: .p2align 4, 0x90
; 64-ALL-NEXT: .LBB1_2: # %while.cond.i
; 64-ALL-NEXT: # Parent Loop BB1_1 Depth=1
; 64-ALL-NEXT: # => This Inner Loop Header: Depth=2
; 64-ALL-NEXT: movl %ecx, %eax
; 64-ALL-NEXT: xorl %ecx, %ecx
; 64-ALL-NEXT: testl %eax, %eax
; 64-ALL-NEXT: je .LBB1_2
; 64-ALL-NEXT: # %bb.3: # %while.body.i
; 64-ALL-NEXT: # in Loop: Header=BB1_1 Depth=1
; 64-ALL-NEXT: lock cmpxchgl %eax, (%rdi)
; 64-ALL-NEXT: jne .LBB1_1
; 64-ALL-NEXT: # %bb.4:
; 64-ALL-NEXT: xorl %eax, %eax
; 64-ALL-NEXT: .LBB1_5: # %cond.end
; 64-ALL-NEXT: retq
entry:
%cmp = icmp sgt i32 %i, %j
br i1 %cmp, label %loop_start, label %cond.end
Expand Down
64 changes: 34 additions & 30 deletions llvm/test/CodeGen/X86/conditional-tailcall.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -456,70 +456,74 @@ define zeroext i1 @pr31257(ptr nocapture readonly dereferenceable(8) %s) minsize
; WIN64-NEXT: .LBB3_1: # %for.cond
; WIN64-NEXT: # =>This Inner Loop Header: Depth=1
; WIN64-NEXT: testq %rax, %rax # encoding: [0x48,0x85,0xc0]
; WIN64-NEXT: je .LBB3_11 # encoding: [0x74,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_11-1, kind: FK_PCRel_1
; WIN64-NEXT: je .LBB3_12 # encoding: [0x74,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_12-1, kind: FK_PCRel_1
; WIN64-NEXT: # %bb.2: # %for.body
; WIN64-NEXT: # in Loop: Header=BB3_1 Depth=1
; WIN64-NEXT: cmpl $2, %r8d # encoding: [0x41,0x83,0xf8,0x02]
; WIN64-NEXT: je .LBB3_9 # encoding: [0x74,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_9-1, kind: FK_PCRel_1
; WIN64-NEXT: je .LBB3_10 # encoding: [0x74,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_10-1, kind: FK_PCRel_1
; WIN64-NEXT: # %bb.3: # %for.body
; WIN64-NEXT: # in Loop: Header=BB3_1 Depth=1
; WIN64-NEXT: cmpl $1, %r8d # encoding: [0x41,0x83,0xf8,0x01]
; WIN64-NEXT: je .LBB3_7 # encoding: [0x74,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_7-1, kind: FK_PCRel_1
; WIN64-NEXT: je .LBB3_8 # encoding: [0x74,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_8-1, kind: FK_PCRel_1
; WIN64-NEXT: # %bb.4: # %for.body
; WIN64-NEXT: # in Loop: Header=BB3_1 Depth=1
; WIN64-NEXT: testl %r8d, %r8d # encoding: [0x45,0x85,0xc0]
; WIN64-NEXT: jne .LBB3_10 # encoding: [0x75,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_10-1, kind: FK_PCRel_1
; WIN64-NEXT: jne .LBB3_11 # encoding: [0x75,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_11-1, kind: FK_PCRel_1
; WIN64-NEXT: # %bb.5: # %sw.bb
; WIN64-NEXT: # in Loop: Header=BB3_1 Depth=1
; WIN64-NEXT: movzbl (%rcx), %r9d # encoding: [0x44,0x0f,0xb6,0x09]
; WIN64-NEXT: cmpl $43, %r9d # encoding: [0x41,0x83,0xf9,0x2b]
; WIN64-NEXT: movl $1, %r8d # encoding: [0x41,0xb8,0x01,0x00,0x00,0x00]
; WIN64-NEXT: je .LBB3_10 # encoding: [0x74,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_10-1, kind: FK_PCRel_1
; WIN64-NEXT: je .LBB3_11 # encoding: [0x74,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_11-1, kind: FK_PCRel_1
; WIN64-NEXT: # %bb.6: # %sw.bb
; WIN64-NEXT: # in Loop: Header=BB3_1 Depth=1
; WIN64-NEXT: cmpl $45, %r9d # encoding: [0x41,0x83,0xf9,0x2d]
; WIN64-NEXT: je .LBB3_10 # encoding: [0x74,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_10-1, kind: FK_PCRel_1
; WIN64-NEXT: jmp .LBB3_8 # encoding: [0xeb,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_8-1, kind: FK_PCRel_1
; WIN64-NEXT: .LBB3_7: # %sw.bb14
; WIN64-NEXT: # in Loop: Header=BB3_1 Depth=1
; WIN64-NEXT: movzbl (%rcx), %r9d # encoding: [0x44,0x0f,0xb6,0x09]
; WIN64-NEXT: .LBB3_8: # %if.else
; WIN64-NEXT: je .LBB3_11 # encoding: [0x74,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_11-1, kind: FK_PCRel_1
; WIN64-NEXT: # %bb.7: # %if.else
; WIN64-NEXT: # in Loop: Header=BB3_1 Depth=1
; WIN64-NEXT: addl $-48, %r9d # encoding: [0x41,0x83,0xc1,0xd0]
; WIN64-NEXT: movl $2, %r8d # encoding: [0x41,0xb8,0x02,0x00,0x00,0x00]
; WIN64-NEXT: cmpl $10, %r9d # encoding: [0x41,0x83,0xf9,0x0a]
; WIN64-NEXT: jb .LBB3_10 # encoding: [0x72,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_10-1, kind: FK_PCRel_1
; WIN64-NEXT: jmp .LBB3_12 # encoding: [0xeb,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_12-1, kind: FK_PCRel_1
; WIN64-NEXT: .LBB3_9: # %sw.bb22
; WIN64-NEXT: jmp .LBB3_9 # encoding: [0xeb,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_9-1, kind: FK_PCRel_1
; WIN64-NEXT: .LBB3_8: # %sw.bb14
; WIN64-NEXT: # in Loop: Header=BB3_1 Depth=1
; WIN64-NEXT: movzbl (%rcx), %r8d # encoding: [0x44,0x0f,0xb6,0x01]
; WIN64-NEXT: addl $-48, %r8d # encoding: [0x41,0x83,0xc0,0xd0]
; WIN64-NEXT: cmpl $10, %r8d # encoding: [0x41,0x83,0xf8,0x0a]
; WIN64-NEXT: .LBB3_9: # %if.else
; WIN64-NEXT: # in Loop: Header=BB3_1 Depth=1
; WIN64-NEXT: movzbl (%rcx), %r9d # encoding: [0x44,0x0f,0xb6,0x09]
; WIN64-NEXT: addl $-48, %r9d # encoding: [0x41,0x83,0xc1,0xd0]
; WIN64-NEXT: movl $2, %r8d # encoding: [0x41,0xb8,0x02,0x00,0x00,0x00]
; WIN64-NEXT: cmpl $10, %r9d # encoding: [0x41,0x83,0xf9,0x0a]
; WIN64-NEXT: jb .LBB3_11 # encoding: [0x72,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_11-1, kind: FK_PCRel_1
; WIN64-NEXT: jmp .LBB3_13 # encoding: [0xeb,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_13-1, kind: FK_PCRel_1
; WIN64-NEXT: .LBB3_10: # %sw.bb22
; WIN64-NEXT: # in Loop: Header=BB3_1 Depth=1
; WIN64-NEXT: movzbl (%rcx), %r8d # encoding: [0x44,0x0f,0xb6,0x01]
; WIN64-NEXT: addl $-48, %r8d # encoding: [0x41,0x83,0xc0,0xd0]
; WIN64-NEXT: cmpl $10, %r8d # encoding: [0x41,0x83,0xf8,0x0a]
; WIN64-NEXT: movl $2, %r8d # encoding: [0x41,0xb8,0x02,0x00,0x00,0x00]
; WIN64-NEXT: jae _Z20isValidIntegerSuffixN9__gnu_cxx17__normal_iteratorIPKcSsEES3_ # TAILCALL
; WIN64-NEXT: # encoding: [0x73,A]
; WIN64-NEXT: # fixup A - offset: 1, value: _Z20isValidIntegerSuffixN9__gnu_cxx17__normal_iteratorIPKcSsEES3_-1, kind: FK_PCRel_1
; WIN64-NEXT: .LBB3_10: # %for.inc
; WIN64-NEXT: .LBB3_11: # %for.inc
; WIN64-NEXT: # in Loop: Header=BB3_1 Depth=1
; WIN64-NEXT: incq %rcx # encoding: [0x48,0xff,0xc1]
; WIN64-NEXT: decq %rax # encoding: [0x48,0xff,0xc8]
; WIN64-NEXT: jmp .LBB3_1 # encoding: [0xeb,A]
; WIN64-NEXT: # fixup A - offset: 1, value: .LBB3_1-1, kind: FK_PCRel_1
; WIN64-NEXT: .LBB3_11:
; WIN64-NEXT: .LBB3_12:
; WIN64-NEXT: cmpl $2, %r8d # encoding: [0x41,0x83,0xf8,0x02]
; WIN64-NEXT: sete %al # encoding: [0x0f,0x94,0xc0]
; WIN64-NEXT: # kill: def $al killed $al killed $eax
; WIN64-NEXT: retq # encoding: [0xc3]
; WIN64-NEXT: .LBB3_12:
; WIN64-NEXT: .LBB3_13:
; WIN64-NEXT: xorl %eax, %eax # encoding: [0x31,0xc0]
; WIN64-NEXT: # kill: def $al killed $al killed $eax
; WIN64-NEXT: retq # encoding: [0xc3]
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/CodeGen/X86/licm-nested.ll
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
; REQUIRES: asserts
; RUN: llc -mtriple=x86_64-apple-darwin < %s -o /dev/null -stats -info-output-file - | grep "hoisted out of loops" | grep 3
; RUN: llc -mtriple=x86_64-apple-darwin < %s -o /dev/null -stats -info-output-file - | grep "hoisted out of loops" | grep 7

; MachineLICM should be able to hoist the symbolic addresses out of
; the inner loops.
Expand Down
10 changes: 5 additions & 5 deletions llvm/test/CodeGen/X86/loop-strength-reduce7.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -17,15 +17,15 @@ define fastcc void @outer_loop(ptr nocapture %gfp, ptr nocapture %xr, i32 %targ_
; CHECK-NEXT: LBB0_2: ## %bb28.i37
; CHECK-NEXT: ## =>This Loop Header: Depth=1
; CHECK-NEXT: ## Child Loop BB0_3 Depth 2
; CHECK-NEXT: xorl %edx, %edx
; CHECK-NEXT: movl %eax, %esi
; CHECK-NEXT: movl %eax, %edx
; CHECK-NEXT: xorl %esi, %esi
; CHECK-NEXT: .p2align 4, 0x90
; CHECK-NEXT: LBB0_3: ## %bb29.i38
; CHECK-NEXT: ## Parent Loop BB0_2 Depth=1
; CHECK-NEXT: ## => This Inner Loop Header: Depth=2
; CHECK-NEXT: incl %edx
; CHECK-NEXT: addl $12, %esi
; CHECK-NEXT: cmpl $11, %edx
; CHECK-NEXT: incl %esi
; CHECK-NEXT: addl $12, %edx
; CHECK-NEXT: cmpl $11, %esi
; CHECK-NEXT: jbe LBB0_3
; CHECK-NEXT: ## %bb.1: ## %bb28.i37.loopexit
; CHECK-NEXT: ## in Loop: Header=BB0_2 Depth=1
Expand Down
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