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# This checks that shrink wrapping uses the red zone defined in the X86 ABI by
# placing restores that access elements already deallocated by the stack.
# REQUIRES: system-linux
# RUN: llvm-mc -filetype=obj -triple x86_64-unknown-unknown \
# RUN: %s -o %t.o
# RUN: link_fdata %s %t.o %t.fdata
# RUN: llvm-strip --strip-unneeded %t.o
# RUN: %clang %cflags %t.o -o %t.exe -Wl,-q -nostdlib
# RUN: llvm-bolt -relocs %t.exe -o %t.out -data %t.fdata \
# RUN: -frame-opt=all -simplify-conditional-tail-calls=false \
# RUN: -experimental-shrink-wrapping \
# RUN: -eliminate-unreachable=false | FileCheck %s
# RUN: llvm-objdump -d %t.out --print-imm-hex | \
# RUN: FileCheck --check-prefix CHECK-OBJDUMP %s
# Here we create a CFG where the restore position matches the previous (deleted)
# restore position. Shrink wrapping then will put a stack access to an element
# that was deallocated at the previously deleted POP, which falls in the red
# zone and should be safe for X86 Linux ABI.
.globl _start
.type _start, %function
_start:
.cfi_startproc
# FDATA: 0 [unknown] 0 1 _start 0 0 1
push %rbp
mov %rsp, %rbp
push %rbx
push %r14
subq $0x20, %rsp
b: je hot_path
# FDATA: 1 _start #b# 1 _start #hot_path# 0 1
cold_path:
mov %r14, %rdi
mov %rbx, %rdi
movq rel(%rip), %rdi # Add this to create a relocation and run bolt w/ relocs
leaq -0x20(%rbp), %r14
movq -0x20(%rbp), %rdi
leaq -0x10(%rbp), %rsp
pop %r14
pop %rbx
pop %rbp
ret
hot_path:
addq $0x20, %rsp
pop %r14
pop %rbx
pop %rbp
ret
.cfi_endproc
end:
.size _start, .-_start
.data
rel: .quad end
# CHECK: BOLT-INFO: Shrink wrapping moved 2 spills inserting load/stores and 0 spills inserting push/pops
# CHECK-OBJDUMP: <_start>:
# CHECK-OBJDUMP: leaq (%rbp), %rsp
# CHECK-OBJDUMP-NEXT: popq %rbp
# CHECK-OBJDUMP-NEXT: movq -0x10(%rsp), %rbx
# CHECK-OBJDUMP-NEXT: movq -0x18(%rsp), %r14
# CHECK-OBJDUMP-NEXT: retq
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