[llvm] [BOLT] Avoid reference updates for non-JT symbol operands (PR #88838)
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Mon Apr 15 22:19:56 PDT 2024
https://github.com/linsinan1995 updated https://github.com/llvm/llvm-project/pull/88838
>From 01deba3048bcabf4ea2bfd110afa693a84f9a53e Mon Sep 17 00:00:00 2001
From: Sinan Lin <sinan.lin at linux.alibaba.com>
Date: Tue, 16 Apr 2024 10:35:48 +0800
Subject: [PATCH] [BOLT] Avoid reference updates for non-JT symbol operands
Add a check to skip updating references for operands that do not directly
refer to jump table symbols but fall within a jump table's address
range to prevent unintended modifications.
---
bolt/lib/Passes/ValidateMemRefs.cpp | 5 ++
bolt/test/X86/jt-symbol-disambiguation-4.s | 63 ++++++++++++++++++++++
2 files changed, 68 insertions(+)
create mode 100644 bolt/test/X86/jt-symbol-disambiguation-4.s
diff --git a/bolt/lib/Passes/ValidateMemRefs.cpp b/bolt/lib/Passes/ValidateMemRefs.cpp
index f29a97c43f497c..7e599fc11e600a 100644
--- a/bolt/lib/Passes/ValidateMemRefs.cpp
+++ b/bolt/lib/Passes/ValidateMemRefs.cpp
@@ -34,6 +34,11 @@ bool ValidateMemRefs::checkAndFixJTReference(BinaryFunction &BF, MCInst &Inst,
if (!JT)
return false;
+ // If the operand does not refer to the jump table symbol, then we
+ // don't need to update the reference.
+ if (JT->getFirstLabel() != Sym)
+ return true;
+
const bool IsLegitAccess = llvm::is_contained(JT->Parents, &BF);
if (IsLegitAccess)
return true;
diff --git a/bolt/test/X86/jt-symbol-disambiguation-4.s b/bolt/test/X86/jt-symbol-disambiguation-4.s
new file mode 100644
index 00000000000000..ee87a0231800eb
--- /dev/null
+++ b/bolt/test/X86/jt-symbol-disambiguation-4.s
@@ -0,0 +1,63 @@
+# If the operand references a symbol that differs from the jump table label,
+# no reference updating is required even if its target address resides within
+# the jump table's range.
+# In this test case, consider the second instruction within the main function,
+# where the address resulting from 'c + 17' corresponds to one byte beyond the
+# address of the .LJTI2_0 jump table label. However, this operand represents
+# an offset calculation related to the global variable 'c' and should remain
+# unaffected by the jump table.
+
+# REQUIRES: system-linux
+
+# RUN: llvm-mc -filetype=obj -triple x86_64-unknown-unknown %s -o %t.o
+# RUN: %clang -no-pie %t.o -o %t.exe -Wl,-q
+
+# RUN: %t.exe | FileCheck %s -check-prefix=CHECK
+# RUN: llvm-bolt -funcs=main,foo/1 %t.exe -o %t.exe.bolt -jump-tables=move
+# RUN: %t.exe.bolt | FileCheck %s -check-prefix=CHECK-AFTERBOLT
+
+# CHECK: {{^}}FF{{$}}
+# CHECK-AFTERBOLT: {{^}}FF{{$}}
+ .text
+ .globl main
+ .p2align 4, 0x90
+ .type main, at function
+main:
+ movq $-16, %rax
+ movl c+17(%rax), %edx
+ movl %edx, %esi
+ movl $.L.str, %edi
+ movl $0, %eax
+ callq printf
+ xorl %eax, %eax
+ retq
+ .p2align 4, 0x90
+ .type foo, at function
+foo:
+ movq $0, %rax
+ jmpq *.LJTI2_0(,%rax,8)
+ addl $-36, %eax
+.LBB2_2:
+ addl $-16, %eax
+ retq
+ .section .rodata,"a", at progbits
+ .p2align 3, 0x0
+c:
+ .byte 1
+ .byte 0xff
+ .zero 14
+ .size c, 16
+.LJTI2_0:
+ .quad .LBB2_2
+ .quad .LBB2_2
+ .quad .LBB2_2
+ .quad .LBB2_2
+ .type c, at object
+ .data
+ .globl c
+ .p2align 4, 0x0
+ .type .L.str, at object
+ .section .rodata.str1.1,"aMS", at progbits,1
+.L.str:
+ .asciz "%X\n"
+ .size .L.str, 4
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