bolt/test/X86/shrinkwrapping-and-rsp.s

   1 # This checks that shrink wrapping does attempt at accessing stack elements
   2 # using RSP when the function is aligning RSP and changing offsets.
   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 %t.o -o %t.exe -Wl,-q -nostdlib
  11 # RUN: llvm-bolt %t.exe -o %t.out --data %t.fdata \
  12 # RUN:     --frame-opt=all --simplify-conditional-tail-calls=false \
  13 # RUN:     --eliminate-unreachable=false | FileCheck %s
  14
  15 # Here we have a function that aligns the stack at prologue. Stack pointer
  16 # analysis can't try to infer offset positions after AND because that depends
  17 # on the runtime value of the stack pointer of callee (whether it is misaligned
  18 # or not).
  19   .globl _start
  20   .type _start, %function
  21 _start:
  22   .cfi_startproc
  23 # FDATA: 0 [unknown] 0 1 _start 0 0 1
  24   push  %rbp
  25   mov   %rsp, %rbp
  26   push  %rbx
  27   push  %r14
  28   and    $0xffffffffffffffe0,%rsp
  29   subq  $0x20, %rsp
  30 b:  je  hot_path
  31 # FDATA: 1 _start #b# 1 _start #hot_path# 0 1
  32 cold_path:
  33   mov %r14, %rdi
  34   mov %rbx, %rdi
  35   # Block push-pop mode by using an instruction that requires the
  36   # stack to be aligned to 128B. This will force the pass
  37   # to try to index stack elements by using RSP +offset directly, but
  38   # we do not know how to access individual elements of the stack thanks
  39   # to the alignment.
  40   movdqa        %xmm8, (%rsp)
  41   addq  $0x20, %rsp
  42   pop %r14
  43   pop %rbx
  44   pop %rbp
  45   ret
  46 hot_path:
  47   addq  $0x20, %rsp
  48   pop %r14
  49   pop %rbx
  50   pop %rbp
  51   ret
  52   .cfi_endproc
  53   .size _start, .-_start
  54
  55 # CHECK:   BOLT-INFO: Shrink wrapping moved 0 spills inserting load/stores and 0 spills inserting push/pops