## This checks that shrink wrapping does attempt at accessing stack elements ## using RSP when the function is aligning RSP and changing offsets. # 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 %t.exe -o %t.out --data %t.fdata \ # RUN: --frame-opt=all --simplify-conditional-tail-calls=false \ # RUN: --eliminate-unreachable=false | FileCheck %s ## Here we have a function that aligns the stack at prologue. Stack pointer ## analysis can't try to infer offset positions after AND because that depends ## on the runtime value of the stack pointer of callee (whether it is misaligned ## or not). .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 and $0xffffffffffffffe0,%rsp 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 # Block push-pop mode by using an instruction that requires the # stack to be aligned to 128B. This will force the pass # to try to index stack elements by using RSP +offset directly, but # we do not know how to access individual elements of the stack thanks # to the alignment. movdqa %xmm8, (%rsp) addq $0x20, %rsp pop %r14 pop %rbx pop %rbp ret hot_path: addq $0x20, %rsp pop %r14 pop %rbx pop %rbp ret .cfi_endproc .size _start, .-_start # CHECK: BOLT-INFO: Shrink wrapping moved 0 spills inserting load/stores and 0 spills inserting push/pops