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llvm-mirror/test/CodeGen/ARM/code-placement.ll
Evan Cheng 0163d059e4 PHI elimination should not break back edge. It can cause some significant code placement issues. rdar://8263994
good:
LBB0_2:
  mov     r2, r0
  . . .
  mov     r1, r2
  bne     LBB0_2

bad:
LBB0_2:
  mov     r2, r0
  . . .
@ BB#3:
  mov     r1, r2
  b       LBB0_2

llvm-svn: 111221
2010-08-17 01:20:36 +00:00

30 lines
1020 B
LLVM

; RUN: llc < %s -mtriple=armv7-apple-darwin | FileCheck %s
; PHI elimination shouldn't break backedge.
; rdar://8263994
%struct.list_data_s = type { i16, i16 }
%struct.list_head = type { %struct.list_head*, %struct.list_data_s* }
define arm_apcscc %struct.list_head* @t(%struct.list_head* %list) nounwind {
entry:
%0 = icmp eq %struct.list_head* %list, null
br i1 %0, label %bb2, label %bb
bb:
; CHECK: LBB0_2:
; CHECK: bne LBB0_2
; CHECK-NOT: b LBB0_2
; CHECK: bx lr
%list_addr.05 = phi %struct.list_head* [ %2, %bb ], [ %list, %entry ]
%next.04 = phi %struct.list_head* [ %list_addr.05, %bb ], [ null, %entry ]
%1 = getelementptr inbounds %struct.list_head* %list_addr.05, i32 0, i32 0
%2 = load %struct.list_head** %1, align 4
store %struct.list_head* %next.04, %struct.list_head** %1, align 4
%3 = icmp eq %struct.list_head* %2, null
br i1 %3, label %bb2, label %bb
bb2:
%next.0.lcssa = phi %struct.list_head* [ null, %entry ], [ %list_addr.05, %bb ]
ret %struct.list_head* %next.0.lcssa
}