[llvm] [LTO] Add function alias as function instead of data (PR #112599)

[Shimin Cui via llvm-commits]

https://github.com/scui-ibm updated https://github.com/llvm/llvm-project/pull/112599

>From 668284f98229d283c7b8c0eca90ee4b186e87442 Mon Sep 17 00:00:00 2001
From: Shimin Cui <scui at ca.ibm.com>
Date: Wed, 16 Oct 2024 11:27:54 -0400
Subject: [PATCH 1/2] [LTO] Add function alias as function instead of data

---
 llvm/include/llvm/LTO/legacy/LTOModule.h |  2 +-
 llvm/lib/LTO/LTOModule.cpp               | 17 +++++++++++++----
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/llvm/include/llvm/LTO/legacy/LTOModule.h b/llvm/include/llvm/LTO/legacy/LTOModule.h
index 1b2de3b333855c..e861a56bcbac1d 100644
--- a/llvm/include/llvm/LTO/legacy/LTOModule.h
+++ b/llvm/include/llvm/LTO/legacy/LTOModule.h
@@ -195,7 +195,7 @@ struct LTOModule {
 
   /// Add a function symbol as defined to the list.
   void addDefinedFunctionSymbol(ModuleSymbolTable::Symbol Sym);
-  void addDefinedFunctionSymbol(StringRef Name, const Function *F);
+  void addDefinedFunctionSymbol(StringRef Name, const GlobalValue *F);
 
   /// Add a global symbol from module-level ASM to the defined list.
   void addAsmGlobalSymbol(StringRef, lto_symbol_attributes scope);
diff --git a/llvm/lib/LTO/LTOModule.cpp b/llvm/lib/LTO/LTOModule.cpp
index eac78069f4d2bc..00eb8adb4e1035 100644
--- a/llvm/lib/LTO/LTOModule.cpp
+++ b/llvm/lib/LTO/LTOModule.cpp
@@ -406,11 +406,16 @@ void LTOModule::addDefinedFunctionSymbol(ModuleSymbolTable::Symbol Sym) {
     Buffer.c_str();
   }
 
-  const Function *F = cast<Function>(cast<GlobalValue *>(Sym));
-  addDefinedFunctionSymbol(Buffer, F);
+  auto *GV = cast<GlobalValue *>(Sym);
+  assert((isa<Function>(GV) ||
+          (isa<GlobalAlias>(GV) &&
+           isa<Function>(cast<GlobalAlias>(GV)->getAliasee()))) &&
+         "Not function or function alias");
+
+  addDefinedFunctionSymbol(Buffer, GV);
 }
 
-void LTOModule::addDefinedFunctionSymbol(StringRef Name, const Function *F) {
+void LTOModule::addDefinedFunctionSymbol(StringRef Name, const GlobalValue *F) {
   // add to list of defined symbols
   addDefinedSymbol(Name, F, true);
 }
@@ -611,7 +616,11 @@ void LTOModule::parseSymbols() {
     }
 
     assert(isa<GlobalAlias>(GV));
-    addDefinedDataSymbol(Sym);
+
+    if (isa<Function>(cast<GlobalAlias>(GV)->getAliasee()))
+      addDefinedFunctionSymbol(Sym);
+    else
+      addDefinedDataSymbol(Sym);
   }
 
   // make symbols for all undefines

>From b3ad83937fcedfaf693331ab111219bfe5bf674a Mon Sep 17 00:00:00 2001
From: Shimin Cui <scui at ca.ibm.com>
Date: Thu, 17 Oct 2024 09:41:08 -0400
Subject: [PATCH 2/2] Add a test case with extended -list-symbols-only option
 to print lto symbol attributes

---
 llvm/test/LTO/PowerPC/list-symbol.ll | 16 +++++++
 llvm/tools/llvm-lto/llvm-lto.cpp     | 65 +++++++++++++++++++++++++++-
 2 files changed, 79 insertions(+), 2 deletions(-)
 create mode 100644 llvm/test/LTO/PowerPC/list-symbol.ll

diff --git a/llvm/test/LTO/PowerPC/list-symbol.ll b/llvm/test/LTO/PowerPC/list-symbol.ll
new file mode 100644
index 00000000000000..75300b11f7f188
--- /dev/null
+++ b/llvm/test/LTO/PowerPC/list-symbol.ll
@@ -0,0 +1,16 @@
+; RUN: llvm-as < %s > %t
+; RUN: llvm-lto -list-symbols-only %t | FileCheck %s
+; REQUIRES: default_triple
+
+; CHECK-DAG: v    { data defined default }
+; CHECK-DAG: va    { data defined default alias }
+; CHECK-DAG: f    { function defined default }
+; CHECK-DAG: fa    { function defined default alias }
+
+ at v = global i32 0
+ at va = alias i32, ptr @v
+ at fa = alias void (ptr), ptr @f
+
+define void @f() {
+  ret void
+}
diff --git a/llvm/tools/llvm-lto/llvm-lto.cpp b/llvm/tools/llvm-lto/llvm-lto.cpp
index f5076f0b975178..4090faf4e3fd95 100644
--- a/llvm/tools/llvm-lto/llvm-lto.cpp
+++ b/llvm/tools/llvm-lto/llvm-lto.cpp
@@ -407,6 +407,64 @@ static void printIndexStats() {
   }
 }
 
+/// Print the lto symbol attributes.
+static void printLTOSymbolAttributes(lto_symbol_attributes Attrs) {
+  outs() << "{ ";
+  unsigned Permission = Attrs & LTO_SYMBOL_PERMISSIONS_MASK;
+  switch (Permission) {
+  case LTO_SYMBOL_PERMISSIONS_CODE:
+    outs() << "function ";
+    break;
+  case LTO_SYMBOL_PERMISSIONS_DATA:
+    outs() << "data ";
+    break;
+  case LTO_SYMBOL_PERMISSIONS_RODATA:
+    outs() << "constant ";
+    break;
+  }
+  unsigned Definition = Attrs & LTO_SYMBOL_DEFINITION_MASK;
+  switch (Definition) {
+  case LTO_SYMBOL_DEFINITION_REGULAR:
+    outs() << "defined ";
+    break;
+  case LTO_SYMBOL_DEFINITION_TENTATIVE:
+    outs() << "common ";
+    break;
+  case LTO_SYMBOL_DEFINITION_WEAK:
+    outs() << "weak ";
+    break;
+  case LTO_SYMBOL_DEFINITION_UNDEFINED:
+    outs() << "extern ";
+    break;
+  case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
+    outs() << "extern-weak ";
+    break;
+  }
+  unsigned Scope = Attrs & LTO_SYMBOL_SCOPE_MASK;
+  switch (Scope) {
+  case LTO_SYMBOL_SCOPE_INTERNAL:
+    outs() << "internal ";
+    break;
+  case LTO_SYMBOL_SCOPE_HIDDEN:
+    outs() << "hidden ";
+    break;
+  case LTO_SYMBOL_SCOPE_PROTECTED:
+    outs() << "protected ";
+    break;
+  case LTO_SYMBOL_SCOPE_DEFAULT:
+    outs() << "default ";
+    break;
+  case LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN:
+    outs() << "omitted ";
+    break;
+  }
+  if (Attrs & LTO_SYMBOL_COMDAT)
+    outs() << "comdat ";
+  if (Attrs & LTO_SYMBOL_ALIAS)
+    outs() << "alias ";
+  outs() << "}";
+}
+
 /// Load each IR file and dump certain information based on active flags.
 ///
 /// The main point here is to provide lit-testable coverage for the LTOModule
@@ -421,8 +479,11 @@ static void testLTOModule(const TargetOptions &Options) {
     if (ListSymbolsOnly) {
       // List the symbols.
       outs() << Filename << ":\n";
-      for (int I = 0, E = Module->getSymbolCount(); I != E; ++I)
-        outs() << Module->getSymbolName(I) << "\n";
+      for (int I = 0, E = Module->getSymbolCount(); I != E; ++I) {
+        outs() << Module->getSymbolName(I) << "    ";
+        printLTOSymbolAttributes(Module->getSymbolAttributes(I));
+        outs() << "\n";
+      }
     }
     if (QueryHasCtorDtor)
       outs() << Filename