[PATCH] D129009: [LTO] Fix LTO for aliased IFuncs

[Schrodinger ZHU Yifan via Phabricator via cfe-commits]

SchrodingerZhu updated this revision to Diff 441846.
SchrodingerZhu added a comment.

- address cr: code brace


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D129009/new/

https://reviews.llvm.org/D129009

Files:
  llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
  llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
  llvm/test/LTO/alias-indirect-function-lto.c


Index: llvm/test/LTO/alias-indirect-function-lto.c
===================================================================
--- /dev/null
+++ llvm/test/LTO/alias-indirect-function-lto.c
@@ -0,0 +1,5 @@
+// RUN: clang -flto %s -c -o %t1 -target x86_64-unknown-linux-gnu
+void f() __attribute__((ifunc("g")));
+static void *g() { return 0; };
+void h() __attribute__((alias("f")));
+// no crash
Index: llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
===================================================================
--- llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -4103,8 +4103,9 @@
 
   for (const GlobalAlias &A : M.aliases()) {
     auto *Aliasee = A.getAliaseeObject();
-    if (!Aliasee->hasName())
-      // Nameless function don't have an entry in the summary, skip it.
+    if (!Aliasee->hasName() || isa<GlobalIFunc>(Aliasee))
+      // IFunc function and Nameless function don't have an entry in the
+      // summary, skip it.
       continue;
     auto AliasId = VE.getValueID(&A);
     auto AliaseeId = VE.getValueID(Aliasee);
Index: llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
===================================================================
--- llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
+++ llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
@@ -646,15 +646,20 @@
   Index.addGlobalValueSummary(V, std::move(GVarSummary));
 }
 
-static void
-computeAliasSummary(ModuleSummaryIndex &Index, const GlobalAlias &A,
-                    DenseSet<GlobalValue::GUID> &CantBePromoted) {
+static void computeAliasSummary(ModuleSummaryIndex &Index, const GlobalAlias &A,
+                                DenseSet<GlobalValue::GUID> &CantBePromoted) {
+  auto *Aliasee = A.getAliaseeObject();
+
+  if (isa<GlobalIFunc>(Aliasee))
+    // Skip summary for indirect function aliases as
+    // summary for aliasee will not be emitted.
+    return;
+
   bool NonRenamableLocal = isNonRenamableLocal(A);
   GlobalValueSummary::GVFlags Flags(
       A.getLinkage(), A.getVisibility(), NonRenamableLocal,
       /* Live = */ false, A.isDSOLocal(), A.canBeOmittedFromSymbolTable());
   auto AS = std::make_unique<AliasSummary>(Flags);
-  auto *Aliasee = A.getAliaseeObject();
   auto AliaseeVI = Index.getValueInfo(Aliasee->getGUID());
   assert(AliaseeVI && "Alias expects aliasee summary to be available");
   assert(AliaseeVI.getSummaryList().size() == 1 &&


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