bolt/test/X86/unreachable-jmp.s

   1 # This checks that we don't create an invalid CFG when there is an
   2 # unreachable direct jump right after an indirect one.
   3
   4 # REQUIRES: system-linux
   5
   6 # RUN: llvm-mc -filetype=obj -triple x86_64-unknown-unknown \
   7 # RUN:   %s -o %t.o
   8 # RUN: link_fdata %s %t.o %t.fdata
   9 # RUN: llvm-strip --strip-unneeded %t.o
  10 # RUN: %clang %cflags -no-pie %t.o -o %t.exe -Wl,-q -nostdlib
  11 # RUN: llvm-bolt %t.exe -o %t.out --data %t.fdata \
  12 # RUN:     --eliminate-unreachable --print-cfg | FileCheck %s
  13
  14   .globl _start
  15   .type _start, %function
  16 _start:
  17   .cfi_startproc
  18 # FDATA: 0 [unknown] 0 1 _start 0 0 1
  19   push  %rbp
  20   mov   %rsp, %rbp
  21   push  %rbx
  22   push  %r14
  23   subq  $0x20, %rsp
  24   movq  %rdi, %rcx
  25 b:
  26   jmpq  *JUMP_TABLE(,%rcx,8)
  27 # FDATA: 1 _start #b# 1 _start #hotpath# 0 20
  28 # Unreachable direct jump here. Our CFG should still make sense and properly
  29 # place this instruction in a new basic block.
  30   jmp  .lbb2
  31 .lbb1:  je  .lexit
  32 .lbb2:
  33   xorq  %rax, %rax
  34   addq  $0x20, %rsp
  35   pop %r14
  36   pop %rbx
  37   pop %rbp
  38   ret
  39 hotpath:
  40   movq  $2, %rax
  41   addq  $0x20, %rsp
  42   pop %r14
  43   pop %rbx
  44   pop %rbp
  45   ret
  46 .lexit:
  47   movq  $1, %rax
  48   addq  $0x20, %rsp
  49   pop %r14
  50   pop %rbx
  51   pop %rbp
  52   ret
  53   .cfi_endproc
  54   .size _start, .-_start
  55
  56   .rodata
  57   .globl JUMP_TABLE
  58 JUMP_TABLE:
  59   .quad .lbb1
  60   .quad .lbb2
  61   .quad hotpath
  62
  63 # No basic blocks above should have 4 successors! That is a bug.
  64 # CHECK-NOT:   Successors: {{.*}} (mispreds: 0, count: 20), {{.*}} (mispreds: 0, count: 0), {{.*}} (mispreds: 0, count: 0), {{.*}} (mispreds: 0, count: 0)
  65 # Check successful removal of stray direct jmp
  66 #  CHECK:  UCE removed 1 block