[PATCH] D142352: [CodeGen] Filter out available_externally aliases

[Jonas Hahnfeld via Phabricator via llvm-commits]

Hahnfeld created this revision.
Hahnfeld added reviewers: MaskRay, rahmanl, gchatelet.
Herald added subscribers: jeroen.dobbelaere, hiraditya.
Herald added a project: All.
Hahnfeld requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

The Language Reference says that aliases can have `available_externally` linkage if their aliasee is an `available_externally` global value. Using this kind of aliases resulted in crashes during code generation, filter them out (the same that the `AsmPrinter` also filters out `GlobalVariable`s in `emitSpecialLLVMGlobal()`; `Function`s are discarded in the machine pass infrastructure).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D142352

Files:
  llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
  llvm/test/CodeGen/Generic/available_externally_alias.ll


Index: llvm/test/CodeGen/Generic/available_externally_alias.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/Generic/available_externally_alias.ll
@@ -0,0 +1,11 @@
+; RUN: llc < %s
+
+ at v = available_externally global i32 42, align 4
+ at va = available_externally alias i32, ptr @v
+
+define available_externally i32 @f() {
+entry:
+  ret i32 0
+}
+
+ at fa = available_externally alias i32, ptr @f
Index: llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -2235,6 +2235,8 @@
   SmallVector<const GlobalAlias *, 16> AliasStack;
   SmallPtrSet<const GlobalAlias *, 16> AliasVisited;
   for (const auto &Alias : M.aliases()) {
+    if (Alias.hasAvailableExternallyLinkage())
+      continue;
     for (const GlobalAlias *Cur = &Alias; Cur;
          Cur = dyn_cast<GlobalAlias>(Cur->getAliasee())) {
       if (!AliasVisited.insert(Cur).second)


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