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      1 # RUN: llc -march=hexagon -run-pass branch-folder %s -o - -verify-machineinstrs | FileCheck %s
      2 
      3 # Branch folding will perform tail merging of bb.1 and bb.2, and bb.2 will
      4 # become the common tail. The use of R0 in bb.2 is <undef> while the
      5 # corresponding use in bb.1 is not. The common tail will have the <undef>
      6 # flag removed, which will cause R0 to become a live-in to bb.2. The problem
      7 # is that R0 is not live-out from all predecessors of bb.2, namely is not
      8 # live-out from bb.0. To remedy that, the branch folder should add an
      9 # IMPLICIT_DEF to that block.
     10 
     11 # CHECK-LABEL: name: func0
     12 # CHECK-LABEL: bb.0:
     13 # CHECK: $r0 = IMPLICIT_DEF
     14 # CHECK-LABEL: bb.1:
     15 # CHECK-LABEL: bb.2:
     16 # CHECK: liveins: $r0
     17 # CHECK: PS_storerhabs 0, $r0
     18 # CHECK: PS_jmpret
     19 
     20 ---
     21 name: func0
     22 tracksRegLiveness: true
     23 
     24 body: |
     25   bb.0:
     26     liveins: $r31
     27     successors: %bb.1, %bb.2
     28       J2_jumpt undef $p0, %bb.2, implicit-def $pc
     29       J2_jump %bb.1, implicit-def $pc
     30 
     31   bb.1:
     32     liveins: $r31
     33     successors: %bb.3
     34       $r0 = L2_loadruh_io undef $r1, 0
     35       PS_storerhabs 0, killed $r0
     36       J2_jump %bb.3, implicit-def $pc
     37 
     38   bb.2:
     39     liveins: $r31
     40     successors: %bb.3
     41       PS_storerhabs 0, undef $r0
     42       J2_jump %bb.3, implicit-def $pc
     43 
     44   bb.3:
     45     liveins: $r31
     46       PS_jmpret killed $r31, implicit-def $pc
     47 ...
     48 ---
     49 # CHECK-LABEL: name: func1
     50 # CHECK-LABEL: bb.1:
     51 # CHECK: $r0 = IMPLICIT_DEF
     52 # CHECK-LABEL: bb.2:
     53 # CHECK-LABEL: bb.3:
     54 # CHECK: liveins: $r0
     55 # CHECK: PS_storerhabs 0, killed $r0
     56 # CHECK: PS_jmpret
     57 
     58 name: func1
     59 tracksRegLiveness: true
     60 
     61 body: |
     62   bb.0:
     63     liveins: $r31
     64     successors: %bb.1, %bb.2
     65       J2_jumpt undef $p0, %bb.2, implicit-def $pc
     66       J2_jump %bb.1, implicit-def $pc
     67 
     68   bb.1:
     69     liveins: $r31
     70     successors: %bb.3
     71       $r1 = A2_tfrsi 1
     72       PS_storerhabs 0, undef $r0
     73       $r0 = A2_tfrsi 1
     74       J2_jump %bb.3, implicit-def $pc
     75 
     76   bb.2:
     77     liveins: $r31
     78     successors: %bb.3
     79       $r0 = L2_loadruh_io undef $r1, 0
     80       PS_storerhabs 0, killed $r0
     81       $r0 = A2_tfrsi 1
     82       J2_jump %bb.3, implicit-def $pc
     83 
     84   bb.3:
     85     liveins: $r31
     86       PS_jmpret killed $r31, implicit undef $r0, implicit-def $pc
     87 ...
     88