[llvm-branch-commits] [lld] ELF: Add branch-to-branch optimization. (PR #138366)

[Fangrui Song via llvm-branch-commits]

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@@ -0,0 +1,98 @@
+# REQUIRES: x86
+
+## Test that the branch-to-branch optimization follows the links
+## from f1 -> f2 -> f3 and updates all references to point to f3.
+ 
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+# RUN: ld.lld %t.o -o %t --branch-to-branch
+# RUN: llvm-objdump -d -s %t | FileCheck --check-prefixes=CHECK,B2B %s
+# RUN: ld.lld %t.o -o %t -O2
+# RUN: llvm-objdump -d -s %t | FileCheck --check-prefixes=CHECK,B2B %s
+
+## Test that branch-to-branch is disabled by default.
+
+# RUN: ld.lld %t.o -o %t
+# RUN: llvm-objdump -d -s %t | FileCheck --check-prefixes=CHECK,NOB2B %s
+# RUN: ld.lld %t.o -o %t -O2 --no-branch-to-branch
+# RUN: llvm-objdump -d -s %t | FileCheck --check-prefixes=CHECK,NOB2B %s
+
+## Test that branch-to-branch is disabled for preemptible symbols.
+
+# RUN: ld.lld %t.o -o %t --branch-to-branch -shared
+# RUN: llvm-objdump -d -s %t | FileCheck --check-prefixes=CHECK,NOB2B %s
+
+.section .rodata.vtable,"a"
+.globl vtable
+vtable:
+# B2B: Contents of section .rodata:
+# B2B-NEXT: [[VF:[0-9a-f]{8}]]
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MaskRay wrote:

We need to check the exact value, otherwise the PLT32 with an addend not -4 is not tested.

https://github.com/llvm/llvm-project/pull/138366