[GlobalOpt] Fix unreachable ifunc globalopt crash (#157332)

[Arghnews]

Also fixes (#131488)

Unreachable case is triggering Callees.empty() assert. Since this was originally a continue anyway, have applied that as a fix and added a test case. Please let me know if there's a better way.

Not sure who/how to get folks to review, tagging a few people (apologies if you're not the right person/this is the wrong way to do it, please let me know what to do in future if so)

@labrinea @dtcxzyw @nikic @fhahn

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Justin Riddell (Arghnews)

Changes

Also fixes (#131488)

Unreachable case is triggering Callees.empty() assert. Since this was originally a continue anyway, have applied that as a fix and added a test case

---

Full diff: https://github.com/llvm/llvm-project/pull/157593.diff

2 Files Affected:

• (modified) llvm/lib/Transforms/IPO/GlobalOpt.cpp (+2-1)
• (added) llvm/test/Transforms/GlobalOpt/resolve-indirect-ifunc.ll (+11)

diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index d7edd1288309b..f88d51f443bcf 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -2551,7 +2551,8 @@ static bool OptimizeNonTrivialIFuncs(
         }))
       continue;
 
-    assert(!Callees.empty() && "Expecting successful collection of versions");
+    if (Callees.empty())
+      continue;
 
     LLVM_DEBUG(dbgs() << "Statically resolving calls to function "
                       << Resolver->getName() << "\n");
diff --git a/llvm/test/Transforms/GlobalOpt/resolve-indirect-ifunc.ll b/llvm/test/Transforms/GlobalOpt/resolve-indirect-ifunc.ll
new file mode 100644
index 0000000000000..1f944a7bde19b
--- /dev/null
+++ b/llvm/test/Transforms/GlobalOpt/resolve-indirect-ifunc.ll
@@ -0,0 +1,11 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt --passes=globalopt -o - -S < %s | FileCheck %s
+
+define ptr @f1() partition "part1" {
+; CHECK-LABEL: define ptr @f1() partition "part1" {
+; CHECK-NEXT:    unreachable
+;
+  unreachable
+}
+
+@i1 = ifunc void(), ptr @f1, partition "part2"

[nikic]

LGTM

[Arghnews]

Fyi @nikic I don't have write access, will need someone to commit for me, thanks

[nikic]

@hstk30-hw Please ensure that you drop any mentions from the commit description when merging changes. We'll be getting these notifications forever now.

[hstk30-hw]

Okay, thanks for your reminder. I'll be more mindful next time