[lld] [LLD] [COFF] [test] Readd lto-late-arm.ll (PR #143494)

[Martin Storsjö via llvm-commits]

https://github.com/mstorsjo created https://github.com/llvm/llvm-project/pull/143494

This testcase was removed in 4cafd28b7dd92080103d11cccc78d9a2f01e1242, as a082f665f85b1002ab22af263eeafceca5288657 had made it no longer trigger the error that it was supposed to do. (Because the latter of those two commits makes the symbol "__rt_sdiv" be included among the potential libcalls listed by lto::LTO::getRuntimeLibcallSymbols().)

Readd the test as a positive test, making sure that such libcalls can get linked.

We do have preexisting test coverage for LTO libcalls overall in libcall-archive.ll, but readd this test to cover specifically the ARM division helper functions as well.

>From 75b104c4418f98b897d6b7416d6f32a1bf1880b3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Storsj=C3=B6?= <martin at martin.st>
Date: Tue, 10 Jun 2025 11:55:02 +0300
Subject: [PATCH] [LLD] [COFF] [test] Readd lto-late-arm.ll

This testcase was removed in 4cafd28b7dd92080103d11cccc78d9a2f01e1242,
as a082f665f85b1002ab22af263eeafceca5288657 had made it no longer
trigger the error that it was supposed to do. (Because the latter
of those two commits makes the symbol "__rt_sdiv" be included among
the potential libcalls listed by lto::LTO::getRuntimeLibcallSymbols().)

Readd the test as a positive test, making sure that such libcalls
can get linked.

We do have preexisting test coverage for LTO libcalls overall in
libcall-archive.ll, but readd this test to cover specifically the
ARM division helper functions as well.
---
 lld/test/COFF/lto-late-arm.ll | 38 +++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 lld/test/COFF/lto-late-arm.ll

diff --git a/lld/test/COFF/lto-late-arm.ll b/lld/test/COFF/lto-late-arm.ll
new file mode 100644
index 0000000000000..1070fc52a0136
--- /dev/null
+++ b/lld/test/COFF/lto-late-arm.ll
@@ -0,0 +1,38 @@
+; REQUIRES: arm
+
+;; A bitcode file can generate undefined references to symbols that weren't
+;; listed as undefined on the bitcode file itself, when lowering produces
+;; calls to e.g. builtin helper functions. Ideally all those functions are
+;; listed by lto::LTO::getRuntimeLibcallSymbols(), then we successfully
+;; can link cases when the helper functions are provided as bitcode too.
+;; (In practice, compiler-rt builtins are always compiled with -fno-lto, so
+;; this shouldn't really happen anyway.)
+
+; RUN: rm -rf %t.dir
+; RUN: split-file %s %t.dir
+; RUN: llvm-as %t.dir/main.ll -o %t.main.obj
+; RUN: llvm-as %t.dir/sdiv.ll -o %t.sdiv.obj
+; RUN: llvm-ar rcs %t.sdiv.lib %t.sdiv.obj
+
+; RUN: lld-link /entry:entry %t.main.obj %t.sdiv.lib /out:%t.exe /subsystem:console
+
+;--- main.ll
+target datalayout = "e-m:w-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "thumbv7-w64-windows-gnu"
+
+ at num = dso_local global i32 100
+
+define dso_local arm_aapcs_vfpcc i32 @entry(i32 %param) {
+entry:
+  %0 = load i32, ptr @num
+  %div = sdiv i32 %0, %param
+  ret i32 %div
+}
+;--- sdiv.ll
+target datalayout = "e-m:w-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "thumbv7-w64-windows-gnu"
+
+define dso_local arm_aapcs_vfpcc void @__rt_sdiv() {
+entry:
+  ret void
+}