bolt/test/runtime/X86/instrumentation-dup-jts.s

   1 # This reproduces a bug with instrumentation when trying to instrument
   2 # functions that share a jump table with multiple indirect jumps. Usually,
   3 # each indirect jump that uses a JT will have its own copy of it. When
   4 # this does not happen, we need to duplicate the jump table safely, so
   5 # we can split the edges correctly (each copy of the jump table may have
   6 # different split edges). For this to happen, we need to correctly match
   7 # the sequence of instructions that perform the indirect jump to identify
   8 # the base address of the jump table and patch it to point to the new
   9 # cloned JT.
  10 #
  11 # Here we test this variant:
  12 #         movq  jt.2397(,%rax,8), %rax
  13 #   jmp *%rax
  14 #
  15 # Which is suboptimal since the compiler could've avoided using an intermediary
  16 # register, but GCC does generate this code and it triggered a bug in our
  17 # matcher. Usual jumps in non-PIC code have this format:
  18 #
  19 #   jmp *jt.2397(,%rax,8)
  20 #
  21 # This is the C code fed to GCC:
  22 #  #include <stdio.h>
  23 #int interp(char* code) {
  24 #    static void* jt[] = { &&op_end, &&op_inc, &&do_dec };
  25 #    int pc = 0;
  26 #    int res = 0;
  27 #    goto *jt[code[pc++] - '0'];
  28 #
  29 #op_inc:
  30 #    res += 1;
  31 #    printf("%d\n", res);
  32 #    goto *jt[code[pc++] - '0'];
  33 #do_dec:
  34 #    res -= 1;
  35 #    printf("%d\n", res);
  36 #    goto *jt[code[pc++] - '0'];
  37 #op_end:
  38 #    return res;
  39 #}
  40 #int main(int argc, char** argv) {
  41 #    return interp(argv[1]);
  42 #}
  43
  44
  45 # REQUIRES: system-linux,bolt-runtime
  46
  47 # RUN: llvm-mc -filetype=obj -triple x86_64-unknown-unknown \
  48 # RUN:   %s -o %t.o
  49 # RUN: %clang %cflags -no-pie %t.o -o %t.exe -Wl,-q
  50
  51 # RUN: llvm-bolt %t.exe --instrument --instrumentation-file=%t.fdata \
  52 # RUN:   -o %t.instrumented
  53
  54 # Instrumented program needs to finish returning zero
  55 # RUN: %t.instrumented 120
  56
  57 # Test that the instrumented data makes sense
  58 # RUN:  llvm-bolt %t.exe -o %t.bolted --data %t.fdata \
  59 # RUN:    --reorder-blocks=ext-tsp --reorder-functions=hfsort+ \
  60 # RUN:    --print-only=interp --print-finalized | FileCheck %s
  61
  62 # RUN: %t.bolted 120
  63
  64 # Check that our two indirect jumps are recorded in the fdata file and that
  65 # each has its own independent profile
  66 # CHECK:  Successors: .Ltmp1 (mispreds: 0, count: 1), .Ltmp0 (mispreds: 0, count: 0), .Ltmp2 (mispreds: 0, count: 0)
  67 # CHECK:  Successors: .Ltmp0 (mispreds: 0, count: 1), .Ltmp2 (mispreds: 0, count: 1), .Ltmp1 (mispreds: 0, count: 0)
  68
  69         .file   "test.c"
  70         .text
  71         .section        .rodata.str1.1,"aMS",@progbits,1
  72 .LC0:
  73         .string "%d\n"
  74         .text
  75         .p2align 4,,15
  76         .globl  interp
  77         .type   interp, @function
  78 interp:
  79 .LFB11:
  80         .cfi_startproc
  81         pushq   %rbp
  82         .cfi_def_cfa_offset 16
  83         .cfi_offset 6, -16
  84         xorl    %ebp, %ebp
  85         pushq   %rbx
  86         .cfi_def_cfa_offset 24
  87         .cfi_offset 3, -24
  88         leaq    1(%rdi), %rbx
  89         subq    $8, %rsp
  90         .cfi_def_cfa_offset 32
  91         movsbl  (%rdi), %eax
  92         subl    $48, %eax
  93         cltq
  94         movq    jt.2397(,%rax,8), %rax
  95         jmp     *%rax
  96         .p2align 4,,10
  97         .p2align 3
  98 .L3:
  99         addl    $1, %ebp
 100 .L8:
 101         movl    %ebp, %esi
 102         movl    $.LC0, %edi
 103         xorl    %eax, %eax
 104         addq    $1, %rbx
 105         call    printf
 106         movsbl  -1(%rbx), %eax
 107         subl    $48, %eax
 108         cltq
 109         movq    jt.2397(,%rax,8), %rax
 110         jmp     *%rax
 111         .p2align 4,,10
 112         .p2align 3
 113 .L6:
 114         addq    $8, %rsp
 115         .cfi_remember_state
 116         .cfi_def_cfa_offset 24
 117         movl    %ebp, %eax
 118         popq    %rbx
 119         .cfi_def_cfa_offset 16
 120         popq    %rbp
 121         .cfi_def_cfa_offset 8
 122         ret
 123         .p2align 4,,10
 124         .p2align 3
 125 .L4:
 126         .cfi_restore_state
 127         subl    $1, %ebp
 128         jmp     .L8
 129         .cfi_endproc
 130 .LFE11:
 131         .size   interp, .-interp
 132         .section        .text.startup,"ax",@progbits
 133         .p2align 4,,15
 134         .globl  main
 135         .type   main, @function
 136 main:
 137 .LFB12:
 138         .cfi_startproc
 139         movq    8(%rsi), %rdi
 140         jmp     interp
 141         .cfi_endproc
 142 .LFE12:
 143         .size   main, .-main
 144         .section        .rodata
 145         .align 16
 146         .type   jt.2397, @object
 147         .size   jt.2397, 24
 148 jt.2397:
 149         .quad   .L6
 150         .quad   .L3
 151         .quad   .L4
 152         .ident  "GCC: (GNU) 8"
 153         .section        .note.GNU-stack,"",@progbits