Re-apply r278065 (Weak symbol support in RuntimeDyld) with a fix for ELF.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278149 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 93 insertions, 2 deletions

diff --git a/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h b/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h
index 805852b4887..db9c519b826 100644
--- a/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h
+++ b/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h
@@ -116,11 +116,13 @@ class OrcMCJITReplacement : public ExecutionEngine {
     LinkingResolver(OrcMCJITReplacement &M) : M(M) {}
 
     JITSymbol findSymbol(const std::string &Name) override {
-      return M.findMangledSymbol(Name);
+      return M.ClientResolver->findSymbol(Name);
     }
 
     JITSymbol findSymbolInLogicalDylib(const std::string &Name) override {
-      return M.ClientResolver->findSymbol(Name);
+      if (auto Sym = M.findMangledSymbol(Name))
+        return Sym;
+      return M.ClientResolver->findSymbolInLogicalDylib(Name);
     }
 
   private:
diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
index 1770525879e..0c69b1a5160 100644
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
@@ -226,6 +226,24 @@ RuntimeDyldImpl::loadObjectImpl(const object::ObjectFile &Obj) {
       // Compute JIT symbol flags.
       JITSymbolFlags JITSymFlags = JITSymbolFlags::fromObjectSymbol(*I);
 
+      // If this is a weak definition, check to see if there's a strong one.
+      // If there is, skip this symbol (we won't be providing it: the strong
+      // definition will). If there's no strong definition, make this definition
+      // strong.
+      if (JITSymFlags.isWeak()) {
+        // First check whether there's already a definition in this instance.
+        // FIXME: Override existing weak definitions with strong ones.
+        if (GlobalSymbolTable.count(Name))
+          continue;
+        // Then check the symbol resolver to see if there's a definition
+        // elsewhere in this logical dylib.
+        if (auto Sym = Resolver.findSymbolInLogicalDylib(Name))
+          if (Sym.getFlags().isStrongDefinition())
+            continue;
+        // else
+        JITSymFlags &= ~JITSymbolFlags::Weak;
+      }
+
       if (Flags & SymbolRef::SF_Absolute &&
           SymType != object::SymbolRef::ST_File) {
         uint64_t Addr = 0;
diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
index 0f0ef993bc4..6929732cb29 100644
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
@@ -1258,6 +1258,7 @@ RuntimeDyldELF::processRelocationRef(
       break;
     }
     case SymbolRef::ST_Data:
+    case SymbolRef::ST_Function:
     case SymbolRef::ST_Unknown: {
       Value.SymbolName = TargetName.data();
       Value.Addend = Addend;
diff --git a/test/ExecutionEngine/MCJIT/Inputs/weak-function-2.ll b/test/ExecutionEngine/MCJIT/Inputs/weak-function-2.ll
new file mode 100644
index 00000000000..a7ff83df039
--- /dev/null
+++ b/test/ExecutionEngine/MCJIT/Inputs/weak-function-2.ll
@@ -0,0 +1,9 @@
+define linkonce_odr i32 @baz() #0 {
+entry:
+  ret i32 0
+}
+
+define i8* @bar() {
+entry:
+  ret i8* bitcast (i32 ()* @baz to i8*)
+}
diff --git a/test/ExecutionEngine/MCJIT/weak-function.ll b/test/ExecutionEngine/MCJIT/weak-function.ll
new file mode 100644
index 00000000000..562d6ade33b
--- /dev/null
+++ b/test/ExecutionEngine/MCJIT/weak-function.ll
@@ -0,0 +1,26 @@
+; RUN: lli -jit-kind=mcjit -extra-module %p/Inputs/weak-function-2.ll %s
+;
+; Check that functions in two different modules agree on the address of weak
+; function 'baz'
+
+define linkonce_odr i32 @baz() {
+entry:
+  ret i32 0
+}
+
+define i8* @foo() {
+entry:
+  ret i8* bitcast (i32 ()* @baz to i8*)
+}
+
+declare i8* @bar()
+
+define i32 @main(i32 %argc, i8** %argv) {
+entry:
+  %call = tail call i8* @foo()
+  %call1 = tail call i8* @bar()
+  %cmp = icmp ne i8* %call, %call1
+  %conv = zext i1 %cmp to i32
+  ret i32 %conv
+}
+
diff --git a/test/ExecutionEngine/OrcMCJIT/Inputs/weak-function-2.ll b/test/ExecutionEngine/OrcMCJIT/Inputs/weak-function-2.ll
new file mode 100644
index 00000000000..a7ff83df039
--- /dev/null
+++ b/test/ExecutionEngine/OrcMCJIT/Inputs/weak-function-2.ll
@@ -0,0 +1,9 @@
+define linkonce_odr i32 @baz() #0 {
+entry:
+  ret i32 0
+}
+
+define i8* @bar() {
+entry:
+  ret i8* bitcast (i32 ()* @baz to i8*)
+}
diff --git a/test/ExecutionEngine/OrcMCJIT/weak-function.ll b/test/ExecutionEngine/OrcMCJIT/weak-function.ll
new file mode 100644
index 00000000000..db255cdbb2c
--- /dev/null
+++ b/test/ExecutionEngine/OrcMCJIT/weak-function.ll
@@ -0,0 +1,26 @@
+; RUN: lli -jit-kind=orc-mcjit -extra-module %p/Inputs/weak-function-2.ll %s
+;
+; Check that functions in two different modules agree on the address of weak
+; function 'baz'
+
+define linkonce_odr i32 @baz() {
+entry:
+  ret i32 0
+}
+
+define i8* @foo() {
+entry:
+  ret i8* bitcast (i32 ()* @baz to i8*)
+}
+
+declare i8* @bar()
+
+define i32 @main(i32 %argc, i8** %argv) {
+entry:
+  %call = tail call i8* @foo()
+  %call1 = tail call i8* @bar()
+  %cmp = icmp ne i8* %call, %call1
+  %conv = zext i1 %cmp to i32
+  ret i32 %conv
+}
+