[lld] r262773 - Use IRMover directly.

[Rafael Espindola via llvm-commits]

Author: rafael
Date: Sat Mar  5 08:51:51 2016
New Revision: 262773

URL: http://llvm.org/viewvc/llvm-project?rev=262773&view=rev
Log:
Use IRMover directly.

This has a few advantages:
* If lld selected a non bitcode symbol, be the bitcode GV is not merged
* lib/Linker is not redoing symbol resolution.

Added:
    lld/trunk/test/ELF/lto/Inputs/resolution.s
    lld/trunk/test/ELF/lto/resolution.ll
Modified:
    lld/trunk/ELF/SymbolTable.cpp

Modified: lld/trunk/ELF/SymbolTable.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SymbolTable.cpp?rev=262773&r1=262772&r2=262773&view=diff
==============================================================================
--- lld/trunk/ELF/SymbolTable.cpp (original)
+++ lld/trunk/ELF/SymbolTable.cpp Sat Mar  5 08:51:51 2016
@@ -20,7 +20,7 @@
 #include "Symbols.h"
 #include "llvm/Bitcode/ReaderWriter.h"
 #include "llvm/IR/LegacyPassManager.h"
-#include "llvm/Linker/Linker.h"
+#include "llvm/Linker/IRMover.h"
 #include "llvm/Support/StringSaver.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Target/TargetMachine.h"
@@ -126,21 +126,36 @@ std::unique_ptr<InputFile> SymbolTable<E
   return createObjectFile(*LtoBuffer);
 }
 
+static void addBitcodeFile(IRMover &Mover, BitcodeFile &F,
+                           LLVMContext &Context) {
+  std::unique_ptr<MemoryBuffer> Buffer =
+      MemoryBuffer::getMemBuffer(F.MB, false);
+  std::unique_ptr<Module> M =
+      check(getLazyBitcodeModule(std::move(Buffer), Context,
+                                 /*ShouldLazyLoadMetadata*/ true));
+  std::vector<GlobalValue *> Keep;
+  for (SymbolBody *B : F.getSymbols()) {
+    if (B->repl() != B)
+      continue;
+    auto *DB = dyn_cast<DefinedBitcode>(B);
+    if (!DB)
+      continue;
+    GlobalValue *GV = M->getNamedValue(B->getName());
+    assert(GV);
+    Keep.push_back(GV);
+  }
+  Mover.move(std::move(M), Keep, [](GlobalValue &, IRMover::ValueAdder) {});
+}
+
 // Merge all the bitcode files we have seen, codegen the result and return
 // the resulting ObjectFile.
 template <class ELFT>
 ObjectFile<ELFT> *SymbolTable<ELFT>::createCombinedLtoObject() {
   LLVMContext Context;
   Module Combined("ld-temp.o", Context);
-  Linker L(Combined);
-  for (const std::unique_ptr<BitcodeFile> &F : BitcodeFiles) {
-    std::unique_ptr<MemoryBuffer> Buffer =
-        MemoryBuffer::getMemBuffer(F->MB, false);
-    std::unique_ptr<Module> M =
-        check(getLazyBitcodeModule(std::move(Buffer), Context,
-                                   /*ShouldLazyLoadMetadata*/ true));
-    L.linkInModule(std::move(M));
-  }
+  IRMover Mover(Combined);
+  for (const std::unique_ptr<BitcodeFile> &F : BitcodeFiles)
+    addBitcodeFile(Mover, *F, Context);
   std::unique_ptr<InputFile> F = codegen(Combined);
   ObjectFiles.emplace_back(cast<ObjectFile<ELFT>>(F.release()));
   return &*ObjectFiles.back();

Added: lld/trunk/test/ELF/lto/Inputs/resolution.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/lto/Inputs/resolution.s?rev=262773&view=auto
==============================================================================
--- lld/trunk/test/ELF/lto/Inputs/resolution.s (added)
+++ lld/trunk/test/ELF/lto/Inputs/resolution.s Sat Mar  5 08:51:51 2016
@@ -0,0 +1,4 @@
+        .data
+        .global a
+a:
+        .long 9

Added: lld/trunk/test/ELF/lto/resolution.ll
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/lto/resolution.ll?rev=262773&view=auto
==============================================================================
--- lld/trunk/test/ELF/lto/resolution.ll (added)
+++ lld/trunk/test/ELF/lto/resolution.ll Sat Mar  5 08:51:51 2016
@@ -0,0 +1,27 @@
+; REQUIRES: x86
+; RUN: llvm-as %s -o %t1.o
+; RUN: llvm-mc -triple=x86_64-pc-linux %p/Inputs/resolution.s -o %t2.o -filetype=obj
+; RUN: ld.lld %t1.o %t2.o -o %t.so -shared
+; RUN: llvm-readobj -s --section-data %t.so | FileCheck %s
+
+; CHECK:      Name: .data
+; CHECK-NEXT: Type: SHT_PROGBITS
+; CHECK-NEXT: Flags [
+; CHECK-NEXT:   SHF_ALLOC
+; CHECK-NEXT:   SHF_WRITE
+; CHECK-NEXT: ]
+; CHECK-NEXT: Address:
+; CHECK-NEXT: Offset:
+; CHECK-NEXT: Size: 4
+; CHECK-NEXT: Link: 0
+; CHECK-NEXT: Info: 0
+; CHECK-NEXT: AddressAlignment: 1
+; CHECK-NEXT: EntrySize: 0
+; CHECK-NEXT: SectionData (
+; CHECK-NEXT:   0000: 09000000 |{{.*}}|
+; CHECK-NEXT: )
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+ at a = weak global i32 8