[llvm] [BOLT] Add test case for PIC fixed indirect jump (PR #91547)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-bolt

Author: Maksim Panchenko (maksfb)

<details>
<summary>Changes</summary>

A compiler can generate a redundant indirection for a jump via a fixed jump table target. Add a test case that covers such pattern that covers PIC case. We already have non-PIC case detection.

Currently XFAIL.

---
Full diff: https://github.com/llvm/llvm-project/pull/91547.diff


2 Files Affected:

- (added) bolt/test/X86/Inputs/jump-table-fixed-ref-pic.s (+35) 
- (added) bolt/test/X86/jump-table-fixed-ref-pic.test (+9) 


``````````diff
diff --git a/bolt/test/X86/Inputs/jump-table-fixed-ref-pic.s b/bolt/test/X86/Inputs/jump-table-fixed-ref-pic.s
new file mode 100644
index 0000000000000..66629a4880e64
--- /dev/null
+++ b/bolt/test/X86/Inputs/jump-table-fixed-ref-pic.s
@@ -0,0 +1,35 @@
+  .globl main
+  .type main, %function
+main:
+  .cfi_startproc
+  cmpq $0x3, %rdi
+  jae .L4
+  cmpq $0x1, %rdi
+  jne .L4
+  mov .Ljt_pic+8(%rip), %rax
+  lea .Ljt_pic(%rip), %rdx
+  add %rdx, %rax
+  jmpq *%rax
+.L1:
+  movq $0x1, %rax
+  jmp .L5
+.L2:
+  movq $0x0, %rax
+  jmp .L5
+.L3:
+  movq $0x2, %rax
+  jmp .L5
+.L4:
+  mov $0x3, %rax
+.L5:
+  retq
+  .cfi_endproc
+
+  .section .rodata
+  .align 16
+.Ljt_pic:
+  .long .L1 - .Ljt_pic
+  .long .L2 - .Ljt_pic
+  .long .L3 - .Ljt_pic
+  .long .L4 - .Ljt_pic
+
diff --git a/bolt/test/X86/jump-table-fixed-ref-pic.test b/bolt/test/X86/jump-table-fixed-ref-pic.test
new file mode 100644
index 0000000000000..4195b97aac501
--- /dev/null
+++ b/bolt/test/X86/jump-table-fixed-ref-pic.test
@@ -0,0 +1,9 @@
+# Verify that BOLT detects fixed destination of indirect jump for PIC
+# case.
+
+XFAIL: *
+
+RUN: %clang %cflags -no-pie %S/Inputs/jump-table-fixed-ref-pic.s -Wl,-q -o %t
+RUN: llvm-bolt %t --relocs -o %t.null 2>&1 | FileCheck %s
+
+CHECK: BOLT-INFO: fixed indirect branch detected in main

``````````

</details>


https://github.com/llvm/llvm-project/pull/91547