bolt/test/AArch64/double_jump.cpp

   1 // A contrived example to test the double jump removal peephole.
   2
   3 // RUN: %clang %cflags -O0 %s -o %t.exe
   4 // RUN: llvm-bolt %t.exe -o %t.bolt --peepholes=double-jumps | \
   5 // RUN:   FileCheck %s -check-prefix=CHECKBOLT
   6 // RUN: llvm-objdump --no-print-imm-hex -d %t.bolt | FileCheck %s
   7
   8 // CHECKBOLT: BOLT-INFO: Peephole: 1 double jumps patched.
   9
  10 // CHECK: <_Z3foom>:
  11 // CHECK-NEXT: sub     sp, sp, #16
  12 // CHECK-NEXT: str     x0, [sp, #8]
  13 // CHECK-NEXT: ldr     [[REG:x[0-28]+]], [sp, #8]
  14 // CHECK-NEXT: cmp     [[REG]], #0
  15 // CHECK-NEXT: b.eq    {{.*}} <_Z3foom+0x34>
  16 // CHECK-NEXT: add     [[REG]], [[REG]], #1
  17 // CHECK-NEXT: add     [[REG]], [[REG]], #1
  18 // CHECK-NEXT: cmp     [[REG]], #2
  19 // CHECK-NEXT: b.eq    {{.*}} <_Z3foom+0x28>
  20 // CHECK-NEXT: add     [[REG]], [[REG]], #1
  21 // CHECK-NEXT: mov     [[REG]], x1
  22 // CHECK-NEXT: ldr     x1, [sp]
  23 // CHECK-NEXT: b       {{.*}} <bar>
  24 // CHECK-NEXT: ldr     x1, [sp]
  25 // CHECK-NEXT: add     [[REG]], [[REG]], #1
  26 // CHECK-NEXT: b       {{.*}} <bar>
  27
  28 extern "C" unsigned long bar(unsigned long count) { return count + 1; }
  29
  30 unsigned long foo(unsigned long count) {
  31   asm volatile("     cmp %0,#0\n"
  32                "     b.eq .L7\n"
  33                "     add %0, %0, #1\n"
  34                "     b .L1\n"
  35                ".L1: b .L2\n"
  36                ".L2: add  %0, %0, #1\n"
  37                "     cmp  %0, #2\n"
  38                "     b.ne .L3\n"
  39                "     b .L4\n"
  40                ".L3: b .L5\n"
  41                ".L5: add %0, %0, #1\n"
  42                ".L4: mov %0,x1\n"
  43                "     ldr x1, [sp]\n"
  44                "     b .L6\n"
  45                ".L7: ldr x1, [sp]\n"
  46                "     add %0, %0, #1\n"
  47                "     b .L6\n"
  48                ".L6: b bar\n"
  49                :
  50                : "r"(count)
  51                :);
  52   return count;
  53 }
  54
  55 extern "C" int _start() { return foo(38); }