[BOLT] Tail Duplication: skip unreachable blocks

Summary:
TailDuplication::isInCacheLine makes the assumption that the block
has a valid layout index, which is not the case for unreachable blocks.
Add a check for a valid layout index.

(cherry picked from FBD32659755)
This commit is contained in:
Amir Ayupov 2021-11-24 16:13:42 -08:00 committed by Maksim Panchenko
parent 4e4ef2f3e7
commit 7261655d2c
2 changed files with 35 additions and 0 deletions

View File

@ -387,6 +387,10 @@ void TailDuplication::runOnFunction(BinaryFunction &Function) {
if (BB->hasJumpTable())
continue;
// Skip not-in-layout, i.e. unreachable, blocks.
if (BB->getLayoutIndex() >= BlockLayout.size())
continue;
// and we are estimating that this sucessor is not already in the same cache
// line
BinaryBasicBlock *Succ = BB->getSuccessor();

View File

@ -0,0 +1,31 @@
# This reproduces a bug in TailDuplication::isInCacheLine
# with accessing BlockLayout past bounds (unreachable blocks).
# 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 -relocs \
# RUN: -tail-duplication=1 -tail-duplication-aggressive=1
.globl _start
_start:
jmp d
je _start
movl %esi, %edi
d:
jmpq *JT0(,%rcx,8)
# FDATA: 1 _start #d# 1 _start #e# 1 3
f:
movl 0, %esi
g:
movl 0, %esi
e:
jmp f
.rodata
JT0:
.quad g
.quad e