bolt/test/X86/split-func-jump-table-fragment-reverse.s

   1 # This reproduces a bug with jump table identification where jump table has
   2 # entries pointing to code in function and its cold fragment.
   3 # The fragment is only reachable through jump table.
   4
   5 # REQUIRES: system-linux
   6
   7 # RUN: llvm-mc -filetype=obj -triple x86_64-unknown-unknown %s -o %t.o
   8 # RUN: llvm-strip --strip-unneeded %t.o
   9 # RUN: %clang %cflags %t.o -o %t.exe -Wl,-q
  10 # RUN: llvm-bolt %t.exe -o %t.out --lite=0 -v=1 2>&1 | FileCheck %s
  11
  12 # CHECK-NOT: unclaimed PC-relative relocations left in data
  13 # CHECK: BOLT-INFO: marking main.cold as a fragment of main
  14   .text
  15   .globl _start
  16   .type _start, %function
  17 _start:
  18   callq main.cold
  19   call exit
  20 .size _start, .-_start
  21
  22   .globl main.cold
  23   .type main.cold, %function
  24   .p2align 2
  25 main.cold:
  26 LBB0:
  27   andl $0xf, %ecx
  28   cmpb $0x4, %cl
  29   # exit through ret
  30   ja LBB3
  31
  32 # jump table dispatch, jumping to label indexed by val in %ecx
  33 LBB1:
  34   leaq JUMP_TABLE(%rip), %r8
  35   movzbl %cl, %ecx
  36   movslq (%r8,%rcx,4), %rax
  37   addq %rax, %r8
  38   jmpq *%r8
  39
  40 LBB2:
  41   xorq %rax, %rax
  42 LBB3:
  43   addq $0x8, %rsp
  44   ret
  45 .size main.cold, .-main.cold
  46
  47 # main function, referenced from jump table in cold fragment
  48   .globl main
  49   .type main, %function
  50   .p2align 2
  51 main:
  52   # load bearing nop: pad LBB4 so that it can't be treated
  53   # as __builtin_unreachable by analyzeJumpTable
  54   nop
  55 LBB4:
  56   callq abort
  57 .size main, .-main
  58
  59   .rodata
  60 # jmp table, entries must be R_X86_64_PC32 relocs
  61   .globl JUMP_TABLE
  62 JUMP_TABLE:
  63   .long LBB2-JUMP_TABLE
  64   .long LBB3-JUMP_TABLE
  65   .long LBB4-JUMP_TABLE
  66   .long LBB3-JUMP_TABLE