[MachO] Stop generating *coal* sections.

Recommit r250342: add -arch=ppc32 to the RUN lines of powerpc tests.

Some background on why we don't have to use *coal* sections anymore:
Long ago when C++ was new and "weak" had not been standardized, an attempt was
made in cctools to support C++ inlines that can be coalesced by putting them
into their own section (TEXT/textcoal_nt instead of TEXT/text).

The current macho linker supports the weak-def bit on any symbol to allow it to
be coalesced, but the compiler still puts weak-def functions/data into alternate
section names, which the linker must map back to the base section name.

This patch makes changes that are necessary to prevent the compiler from using
the "coal" sections and have it use the non-coal sections instead when the
target architecture is not powerpc:

TEXT/textcoal_nt instead use TEXT/text
TEXT/const_coal instead use TEXT/const
DATA/datacoal_nt instead use DATA/data

If the target is powerpc, we continue to use the *coal* sections since anyone
targeting powerpc is probably using an old linker that doesn't have support for
the weak-def bits.

Also, have the assembler issue a warning if it encounters a *coal* section in
the assembly file and inform the users to use the non-coal sections instead.

rdar://problem/14265330

Differential Revision: http://reviews.llvm.org/D13188

llvm-svn: 250349

2 files changed, 53 insertions, 13 deletions

diff --git a/llvm/lib/MC/MCObjectFileInfo.cpp b/llvm/lib/MC/MCObjectFileInfo.cpp
index 31091ef284a..666a1c306c5 100644
--- a/llvm/lib/MC/MCObjectFileInfo.cpp
+++ b/llvm/lib/MC/MCObjectFileInfo.cpp
@@ -114,22 +114,37 @@ void MCObjectFileInfo::initMachOMCObjectFileInfo(Triple T) {
     = Ctx->getMachOSection("__TEXT", "__const", 0,
                            SectionKind::getReadOnly());
 
-  TextCoalSection
-    = Ctx->getMachOSection("__TEXT", "__textcoal_nt",
-                           MachO::S_COALESCED |
-                           MachO::S_ATTR_PURE_INSTRUCTIONS,
-                           SectionKind::getText());
-  ConstTextCoalSection
-    = Ctx->getMachOSection("__TEXT", "__const_coal",
-                           MachO::S_COALESCED,
-                           SectionKind::getReadOnly());
+  // If the target is not powerpc, map the coal sections to the non-coal
+  // sections.
+  //
+  // "__TEXT/__textcoal_nt" => section "__TEXT/__text"
+  // "__TEXT/__const_coal"  => section "__TEXT/__const"
+  // "__DATA/__datacoal_nt" => section "__DATA/__data"
+  Triple::ArchType ArchTy = T.getArch();
+
+  if (ArchTy == Triple::ppc || ArchTy == Triple::ppc64) {
+    TextCoalSection
+      = Ctx->getMachOSection("__TEXT", "__textcoal_nt",
+                             MachO::S_COALESCED |
+                             MachO::S_ATTR_PURE_INSTRUCTIONS,
+                             SectionKind::getText());
+    ConstTextCoalSection
+      = Ctx->getMachOSection("__TEXT", "__const_coal",
+                             MachO::S_COALESCED,
+                             SectionKind::getReadOnly());
+    DataCoalSection
+      = Ctx->getMachOSection("__DATA","__datacoal_nt",
+                             MachO::S_COALESCED,
+                             SectionKind::getDataRel());
+  } else {
+    TextCoalSection = TextSection;
+    ConstTextCoalSection = ReadOnlySection;
+    DataCoalSection = DataSection;
+  }
+
   ConstDataSection  // .const_data
     = Ctx->getMachOSection("__DATA", "__const", 0,
                            SectionKind::getReadOnlyWithRel());
-  DataCoalSection
-    = Ctx->getMachOSection("__DATA","__datacoal_nt",
-                           MachO::S_COALESCED,
-                           SectionKind::getDataRel());
   DataCommonSection
     = Ctx->getMachOSection("__DATA","__common",
                            MachO::S_ZEROFILL,
diff --git a/llvm/lib/MC/MCParser/DarwinAsmParser.cpp b/llvm/lib/MC/MCParser/DarwinAsmParser.cpp
index dc664e8a8f6..5e99ad092f7 100644
--- a/llvm/lib/MC/MCParser/DarwinAsmParser.cpp
+++ b/llvm/lib/MC/MCParser/DarwinAsmParser.cpp
@@ -10,8 +10,10 @@
 #include "llvm/MC/MCParser/MCAsmParserExtension.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/ADT/Triple.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCObjectFileInfo.h"
 #include "llvm/MC/MCParser/MCAsmLexer.h"
 #include "llvm/MC/MCParser/MCAsmParser.h"
 #include "llvm/MC/MCSectionMachO.h"
@@ -579,6 +581,29 @@ bool DarwinAsmParser::parseDirectiveSection(StringRef, SMLoc) {
   if (!ErrorStr.empty())
     return Error(Loc, ErrorStr.c_str());
 
+  // Issue a warning if the target is not powerpc and Section is a *coal* section.
+  Triple TT = getParser().getContext().getObjectFileInfo()->getTargetTriple();
+  Triple::ArchType ArchTy = TT.getArch();
+
+  if (ArchTy != Triple::ppc && ArchTy != Triple::ppc64) {
+    StringRef NonCoalSection = StringSwitch<StringRef>(Section)
+                                   .Case("__textcoal_nt", "__text")
+                                   .Case("__const_coal", "__const")
+                                   .Case("__datacoal_nt", "__data")
+                                   .Default(Section);
+
+    if (!Section.equals(NonCoalSection)) {
+      StringRef SectionVal(Loc.getPointer());
+      size_t B = SectionVal.find(',') + 1, E = SectionVal.find(',', B);
+      SMLoc BLoc = SMLoc::getFromPointer(SectionVal.data() + B);
+      SMLoc ELoc = SMLoc::getFromPointer(SectionVal.data() + E);
+      getParser().Warning(Loc, "section \"" + Section + "\" is deprecated",
+                          SMRange(BLoc, ELoc));
+      getParser().Note(Loc, "change section name to \"" + NonCoalSection +
+                       "\"", SMRange(BLoc, ELoc));
+    }
+  }
+
   // FIXME: Arch specific.
   bool isText = Segment == "__TEXT";  // FIXME: Hack.
   getStreamer().SwitchSection(getContext().getMachOSection(