[PATCH] D92335: [ThinLTO] Import symver directives for imported symbols (PR48214)

[Hans Wennborg via Phabricator via llvm-commits]

hans updated this revision to Diff 308657.
hans added a comment.
Herald added a subscriber: mgorny.

I just realized this makes Linker/ depend on Object/
I'm not sure whether that's a problem or not, but we could avoid that by storing the symvers in a metadata node again.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D92335/new/

https://reviews.llvm.org/D92335

Files:
  llvm/lib/Linker/CMakeLists.txt
  llvm/lib/Linker/IRMover.cpp
  llvm/test/ThinLTO/X86/Inputs/import-symver-foo.ll
  llvm/test/ThinLTO/X86/import-symver.ll
  llvm/utils/gn/secondary/llvm/lib/Linker/BUILD.gn


Index: llvm/utils/gn/secondary/llvm/lib/Linker/BUILD.gn
===================================================================
--- llvm/utils/gn/secondary/llvm/lib/Linker/BUILD.gn
+++ llvm/utils/gn/secondary/llvm/lib/Linker/BUILD.gn
@@ -2,6 +2,7 @@
   output_name = "LLVMLinker"
   deps = [
     "//llvm/lib/IR",
+    "//llvm/lib/Object",
     "//llvm/lib/Support",
     "//llvm/lib/Transforms/Utils",
   ]
Index: llvm/test/ThinLTO/X86/import-symver.ll
===================================================================
--- /dev/null
+++ llvm/test/ThinLTO/X86/import-symver.ll
@@ -0,0 +1,21 @@
+; RUN: opt -thinlto-bc %s -o %t1.bc
+; RUN: opt -thinlto-bc %p/Inputs/import-symver-foo.ll -o %t2.bc
+; RUN: llvm-lto -thinlto-action=thinlink %t1.bc %t2.bc -o %t3.index.bc
+
+; RUN: llvm-lto -thinlto-action=import -exported-symbol=main %t1.bc -thinlto-index=%t3.index.bc
+; RUN: llvm-dis %t1.bc.thinlto.imported.bc -o - | FileCheck %s
+
+; When @bar gets imported, the symver must be imported too.
+; CHECK: module asm ".symver bar, bar at BAR_1.2.3"
+; CHECK: declare dso_local i32 @bar()
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+declare dso_local i32 @foo()
+
+define dso_local i32 @main() {
+entry:
+  %call = tail call i32 @foo()
+  ret i32 %call
+}
Index: llvm/test/ThinLTO/X86/Inputs/import-symver-foo.ll
===================================================================
--- /dev/null
+++ llvm/test/ThinLTO/X86/Inputs/import-symver-foo.ll
@@ -0,0 +1,12 @@
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+module asm ".symver bar, bar at BAR_1.2.3"
+
+declare dso_local i32 @bar()
+
+define dso_local i32 @foo() {
+entry:
+  %call = tail call i32 @bar()
+  ret i32 %call
+}
Index: llvm/lib/Linker/IRMover.cpp
===================================================================
--- llvm/lib/Linker/IRMover.cpp
+++ llvm/lib/Linker/IRMover.cpp
@@ -17,6 +17,7 @@
 #include "llvm/IR/GVMaterializer.h"
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/TypeFinder.h"
+#include "llvm/Object/ModuleSymbolTable.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Transforms/Utils/Cloning.h"
 #include <utility>
@@ -1479,6 +1480,20 @@
   // are properly remapped.
   linkNamedMDNodes();
 
+  // Import symver directives.
+  if (IsPerformingImport) {
+    ModuleSymbolTable::CollectAsmSymvers(*SrcM,
+                                         [&](StringRef Name, StringRef Alias) {
+      if (DstM.getNamedValue(Name)) {
+        SmallString<256> S(".symver ");
+        S += Name;
+        S += ", ";
+        S += Alias;
+        DstM.appendModuleInlineAsm(S);
+      }
+    });
+  }
+
   // Merge the module flags into the DstM module.
   return linkModuleFlagsMetadata();
 }
Index: llvm/lib/Linker/CMakeLists.txt
===================================================================
--- llvm/lib/Linker/CMakeLists.txt
+++ llvm/lib/Linker/CMakeLists.txt
@@ -10,6 +10,7 @@
 
   LINK_COMPONENTS
   Core
+  Object
   Support
   TransformUtils
   )


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