Stop producing .data.rel sections.

If a section is rw, it is irrelevant if the dynamic linker will write to
it or not.

It looks like llvm implemented this because gcc was doing it. It looks
like gcc implemented this in the hope that it would put all the
relocated items close together and speed up the dynamic linker.

There are two problem with this:
* It doesn't work. Both bfd and gold will map .data.rel to .data and
  concatenate the input sections in the order they are seen.
* If we want a feature like that, it can be implemented directly in the
  linker since it knowns where the dynamic relocations are.

llvm-svn: 253436

1 files changed, 29 insertions, 40 deletions

diff --git a/llvm/lib/MC/MCObjectFileInfo.cpp b/llvm/lib/MC/MCObjectFileInfo.cpp
index 943eaef..8b75457 100644
--- a/llvm/lib/MC/MCObjectFileInfo.cpp
+++ b/llvm/lib/MC/MCObjectFileInfo.cpp
@@ -76,16 +76,15 @@ void MCObjectFileInfo::initMachOMCObjectFileInfo(Triple T) {
                            MachO::S_ATTR_PURE_INSTRUCTIONS,
                            SectionKind::getText());
   DataSection // .data
-    = Ctx->getMachOSection("__DATA", "__data", 0,
-                           SectionKind::getDataRel());
+      = Ctx->getMachOSection("__DATA", "__data", 0, SectionKind::getData());
 
   // BSSSection might not be expected initialized on msvc.
   BSSSection = nullptr;
 
   TLSDataSection // .tdata
-    = Ctx->getMachOSection("__DATA", "__thread_data",
-                           MachO::S_THREAD_LOCAL_REGULAR,
-                           SectionKind::getDataRel());
+      = Ctx->getMachOSection("__DATA", "__thread_data",
+                             MachO::S_THREAD_LOCAL_REGULAR,
+                             SectionKind::getData());
   TLSBSSSection // .tbss
     = Ctx->getMachOSection("__DATA", "__thread_bss",
                            MachO::S_THREAD_LOCAL_ZEROFILL,
@@ -93,14 +92,13 @@ void MCObjectFileInfo::initMachOMCObjectFileInfo(Triple T) {
 
   // TODO: Verify datarel below.
   TLSTLVSection // .tlv
-    = Ctx->getMachOSection("__DATA", "__thread_vars",
-                           MachO::S_THREAD_LOCAL_VARIABLES,
-                           SectionKind::getDataRel());
+      = Ctx->getMachOSection("__DATA", "__thread_vars",
+                             MachO::S_THREAD_LOCAL_VARIABLES,
+                             SectionKind::getData());
 
-  TLSThreadInitSection
-    = Ctx->getMachOSection("__DATA", "__thread_init",
-                          MachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
-                          SectionKind::getDataRel());
+  TLSThreadInitSection = Ctx->getMachOSection(
+      "__DATA", "__thread_init", MachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
+      SectionKind::getData());
 
   CStringSection // .cstring
     = Ctx->getMachOSection("__TEXT", "__cstring",
@@ -145,10 +143,8 @@ void MCObjectFileInfo::initMachOMCObjectFileInfo(Triple T) {
       = Ctx->getMachOSection("__TEXT", "__const_coal",
                              MachO::S_COALESCED,
                              SectionKind::getReadOnly());
-    DataCoalSection
-      = Ctx->getMachOSection("__DATA","__datacoal_nt",
-                             MachO::S_COALESCED,
-                             SectionKind::getDataRel());
+    DataCoalSection = Ctx->getMachOSection(
+        "__DATA", "__datacoal_nt", MachO::S_COALESCED, SectionKind::getData());
   } else {
     TextCoalSection = TextSection;
     ConstTextCoalSection = ReadOnlySection;
@@ -177,21 +173,17 @@ void MCObjectFileInfo::initMachOMCObjectFileInfo(Triple T) {
                            SectionKind::getMetadata());
 
   if (RelocM == Reloc::Static) {
-    StaticCtorSection
-      = Ctx->getMachOSection("__TEXT", "__constructor", 0,
-                             SectionKind::getDataRel());
-    StaticDtorSection
-      = Ctx->getMachOSection("__TEXT", "__destructor", 0,
-                             SectionKind::getDataRel());
+    StaticCtorSection = Ctx->getMachOSection("__TEXT", "__constructor", 0,
+                                             SectionKind::getData());
+    StaticDtorSection = Ctx->getMachOSection("__TEXT", "__destructor", 0,
+                                             SectionKind::getData());
   } else {
-    StaticCtorSection
-      = Ctx->getMachOSection("__DATA", "__mod_init_func",
-                             MachO::S_MOD_INIT_FUNC_POINTERS,
-                             SectionKind::getDataRel());
-    StaticDtorSection
-      = Ctx->getMachOSection("__DATA", "__mod_term_func",
-                             MachO::S_MOD_TERM_FUNC_POINTERS,
-                             SectionKind::getDataRel());
+    StaticCtorSection = Ctx->getMachOSection("__DATA", "__mod_init_func",
+                                             MachO::S_MOD_INIT_FUNC_POINTERS,
+                                             SectionKind::getData());
+    StaticDtorSection = Ctx->getMachOSection("__DATA", "__mod_term_func",
+                                             MachO::S_MOD_TERM_FUNC_POINTERS,
+                                             SectionKind::getData());
   }
 
   // Exception Handling.
@@ -452,9 +444,6 @@ void MCObjectFileInfo::initELFMCObjectFileInfo(Triple T) {
   TLSBSSSection = Ctx->getELFSection(
       ".tbss", ELF::SHT_NOBITS, ELF::SHF_ALLOC | ELF::SHF_TLS | ELF::SHF_WRITE);
 
-  DataRelSection = Ctx->getELFSection(".data.rel", ELF::SHT_PROGBITS,
-                                      ELF::SHF_ALLOC | ELF::SHF_WRITE);
-
   DataRelROSection = Ctx->getELFSection(".data.rel.ro", ELF::SHT_PROGBITS,
                                         ELF::SHF_ALLOC | ELF::SHF_WRITE);
 
@@ -556,7 +545,7 @@ void MCObjectFileInfo::initCOFFMCObjectFileInfo(Triple T) {
   EHFrameSection = Ctx->getCOFFSection(
       ".eh_frame", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
                        COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE,
-      SectionKind::getDataRel());
+      SectionKind::getData());
 
   bool IsWoA = T.getArch() == Triple::arm || T.getArch() == Triple::thumb;
 
@@ -576,7 +565,7 @@ void MCObjectFileInfo::initCOFFMCObjectFileInfo(Triple T) {
   DataSection = Ctx->getCOFFSection(
       ".data", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ |
                    COFF::IMAGE_SCN_MEM_WRITE,
-      SectionKind::getDataRel());
+      SectionKind::getData());
   ReadOnlySection = Ctx->getCOFFSection(
       ".rdata", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
       SectionKind::getReadOnly());
@@ -594,11 +583,11 @@ void MCObjectFileInfo::initCOFFMCObjectFileInfo(Triple T) {
     StaticCtorSection = Ctx->getCOFFSection(
         ".ctors", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
                       COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE,
-        SectionKind::getDataRel());
+        SectionKind::getData());
     StaticDtorSection = Ctx->getCOFFSection(
         ".dtors", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
                       COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE,
-        SectionKind::getDataRel());
+        SectionKind::getData());
   }
 
   // FIXME: We're emitting LSDA info into a readonly section on COFF, even
@@ -751,11 +740,11 @@ void MCObjectFileInfo::initCOFFMCObjectFileInfo(Triple T) {
 
   PDataSection = Ctx->getCOFFSection(
       ".pdata", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
-      SectionKind::getDataRel());
+      SectionKind::getData());
 
   XDataSection = Ctx->getCOFFSection(
       ".xdata", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
-      SectionKind::getDataRel());
+      SectionKind::getData());
 
   SXDataSection = Ctx->getCOFFSection(".sxdata", COFF::IMAGE_SCN_LNK_INFO,
                                       SectionKind::getMetadata());
@@ -763,7 +752,7 @@ void MCObjectFileInfo::initCOFFMCObjectFileInfo(Triple T) {
   TLSDataSection = Ctx->getCOFFSection(
       ".tls$", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ |
                    COFF::IMAGE_SCN_MEM_WRITE,
-      SectionKind::getDataRel());
+      SectionKind::getData());
 
   StackMapSection = Ctx->getCOFFSection(".llvm_stackmaps",
                                         COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |