Honour relocation behaviour stuff for ro objects

llvm-svn: 68005

llvm/include/llvm/Constant.h

@@ -20,6 +20,7 @@ namespace llvm {
   template<typename T> class SmallVectorImpl;
 
   namespace Reloc {
+    const unsigned None   = 0;
     const unsigned Local  = 1 << 0; ///< Local relocations are required
     const unsigned Global = 1 << 1; ///< Global relocations are required
     const unsigned LocalOrGlobal = Local | Global;

llvm/include/llvm/Target/TargetAsmInfo.h

@@ -577,6 +577,12 @@ namespace llvm {
     virtual SectionKind::Kind
     SectionKindForGlobal(const GlobalValue *GV) const;
 
+    /// RelocBehaviour - Describes how relocations should be treated when
+    /// selecting sections. Reloc::Global bit should be set if global
+    /// relocations should force object to be placed in read-write
+    /// sections. Reloc::Local bit should be set if local relocations should
+    /// force object to be placed in read-write sections.
+    virtual unsigned RelocBehaviour() const;
 
     /// SectionFlagsForGlobal - This hook allows the target to select proper
     /// section flags either for given global or for section.

llvm/lib/Target/TargetAsmInfo.cpp

@@ -19,6 +19,7 @@
 #include "llvm/Module.h"
 #include "llvm/Type.h"
 #include "llvm/Target/TargetAsmInfo.h"
+#include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/Dwarf.h"
 #include <cctype>
@@ -189,6 +190,12 @@ static bool isConstantString(const Constant *C) {
   return false;
 }
 
+unsigned TargetAsmInfo::RelocBehaviour() const {
+  // By default - all relocations in PIC mode would force symbol to be
+  // placed in r/w section.
+  return (TM.getRelocationModel() != Reloc::Static ?
+          Reloc::LocalOrGlobal : Reloc::None);
+}
 
 SectionKind::Kind
 TargetAsmInfo::SectionKindForGlobal(const GlobalValue *GV) const {
@@ -208,9 +215,21 @@ TargetAsmInfo::SectionKindForGlobal(const GlobalValue *GV) const {
     // check its initializer to decide, which section to output it into. Also
     // note, there is no thread-local r/o section.
     Constant *C = GVar->getInitializer();
-    if (C->ContainsRelocations())
-      return SectionKind::ROData;
-    else {
+    if (C->ContainsRelocations(Reloc::LocalOrGlobal)) {
+      // Decide, whether it is still possible to put symbol into r/o section.
+      unsigned Reloc = RelocBehaviour();
+
+      // We already did a query for 'all' relocs, thus - early exits.
+      if (Reloc == Reloc::LocalOrGlobal)
+        return SectionKind::Data;
+      else if (Reloc == Reloc::None)
+        return SectionKind::ROData;
+      else {
+        // Ok, target wants something funny. Honour it.
+        return (C->ContainsRelocations(Reloc) ?
+                SectionKind::Data : SectionKind::ROData);
+      }
+    } else {
       // Check, if initializer is a null-terminated string
       if (isConstantString(C))
         return SectionKind::RODataMergeStr;