[MachO] Stop generating *coal* sections.

Recommit r250342: move coal-sections-powerpc.s to subdirectory for powerpc.

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: 250370

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,

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(

llvm/test/CodeGen/PowerPC/coal-sections.ll

@@ -0,0 +1,24 @@
+; RUN: llc < %s -mtriple powerpc-apple-darwin8 -march=ppc32 | FileCheck %s
+
+; Check that *coal* sections are emitted.
+
+; CHECK: .section  __TEXT,__textcoal_nt,coalesced,pure_instructions
+; CHECK: .section  __TEXT,__textcoal_nt,coalesced,pure_instructions
+; CHECK-NEXT: .globl  _foo
+
+; CHECK: .section  __TEXT,__const_coal,coalesced
+; CHECK-NEXT: .globl  _a
+
+; CHECK: .section  __DATA,__datacoal_nt,coalesced
+; CHECK-NEXT: .globl  _b
+
+@a = weak_odr constant [4 x i32] [i32 1, i32 2, i32 3, i32 4], align 16
+@b = weak global i32 5, align 4
+@g = common global i32* null, align 8
+
+; Function Attrs: nounwind ssp uwtable
+define weak i32* @foo() {
+entry:
+  store i32* getelementptr inbounds ([4 x i32], [4 x i32]* @a, i64 0, i64 0), i32** @g, align 8
+  ret i32* @b
+}

llvm/test/CodeGen/X86/coal-sections.ll

@@ -0,0 +1,23 @@
+; RUN: llc < %s -mtriple x86_64-apple-darwin | FileCheck %s
+
+; Check that *coal* sections are not emitted.
+
+; CHECK: .section  __TEXT,__text,regular,pure_instructions{{$}}
+; CHECK-NEXT: .globl  _foo
+
+; CHECK: .section  __TEXT,__const{{$}}
+; CHECK-NEXT: .globl  _a
+
+; CHECK: .section  __DATA,__data{{$}}
+; CHECK-NEXT: .globl  _b
+
+@a = weak_odr constant [4 x i32] [i32 1, i32 2, i32 3, i32 4], align 16
+@b = weak global i32 5, align 4
+@g = common global i32* null, align 8
+
+; Function Attrs: nounwind ssp uwtable
+define weak i32* @foo() {
+entry:
+  store i32* getelementptr inbounds ([4 x i32], [4 x i32]* @a, i64 0, i64 0), i32** @g, align 8
+  ret i32* @b
+}

llvm/test/CodeGen/X86/global-sections.ll

@@ -117,7 +117,7 @@ bb7:
 
 ; TODO: linux drops this into .rodata, we drop it into ".gnu.linkonce.r.G2"
 
-; DARWIN: .section __TEXT,__const_coal,coalesced
+; DARWIN: .section __TEXT,__const{{$}}
 ; DARWIN: _G2:
 ; DARWIN:    .long 42
 
@@ -176,7 +176,6 @@ bb7:
 ; LINUX: .weak  "foo bar"
 ; LINUX: "foo bar":
 
-; DARWIN: .section              __DATA,__datacoal_nt,coalesced
 ; DARWIN: .globl        "_foo bar"
 ; DARWIN:       .weak_definition "_foo bar"
 ; DARWIN: "_foo bar":
@@ -190,7 +189,7 @@ bb7:
 ; LINUX:   .byte        1
 ; LINUX:   .size        G6, 1
 
-; DARWIN:  .section __TEXT,__const_coal,coalesced
+; DARWIN:  .section __TEXT,__const{{$}}
 ; DARWIN:  .globl _G6
 ; DARWIN:  .weak_definition _G6
 ; DARWIN:_G6:
@@ -239,7 +238,7 @@ bb7:
 @G10 = weak global [100 x i32] zeroinitializer, align 32 ; <[100 x i32]*> [#uses=0]
 
 
-; DARWIN:       .section        __DATA,__datacoal_nt,coalesced
+; DARWIN:       .section        __DATA,__data{{$}}
 ; DARWIN: .globl _G10
 ; DARWIN:       .weak_definition _G10
 ; DARWIN:       .align  5

llvm/test/MC/MachO/PowerPC/coal-sections-powerpc.s

@@ -0,0 +1,46 @@
+// RUN: llvm-mc -triple powerpc-apple-darwin8 -arch=ppc32 -filetype=obj %s -o - | llvm-readobj -sections | FileCheck %s
+
+// CHECK: Section {
+// CHECK-NEXT: Index: 0
+
+// CHECK: Section {
+// CHECK-NEXT: Index: 1
+// CHECK-NEXT: Name: __textcoal_nt (
+
+// CHECK: Section {
+// CHECK-NEXT: Index: 2
+
+// CHECK: Section {
+// CHECK-NEXT: Index: 3
+// CHECK-NEXT: Name: __const_coal (
+
+// CHECK: Section {
+// CHECK-NEXT: Index: 4
+// CHECK-NEXT: Name: __datacoal_nt (
+
+  .section  __TEXT,__text,regular,pure_instructions
+  .machine ppc
+  .section  __TEXT,__textcoal_nt,coalesced,pure_instructions
+  .section  __TEXT,__symbol_stub1,symbol_stubs,pure_instructions,16
+  .section  __TEXT,__text,regular,pure_instructions
+  .section  __TEXT,__textcoal_nt,coalesced,pure_instructions
+  .globl  _foo
+  .weak_definition  _foo
+  .align  4
+_foo:
+	blr
+
+.subsections_via_symbols
+	.section	__TEXT,__const_coal,coalesced
+	.globl	_a                      ; @a
+	.weak_definition	_a
+	.align	4
+_a:
+	.long	1                       ; 0x1
+
+	.section	__DATA,__datacoal_nt,coalesced
+	.globl	_b                      ; @b
+	.weak_definition	_b
+	.align	2
+_b:
+	.long	5                       ; 0x5

llvm/test/MC/MachO/PowerPC/lit.local.cfg

@@ -0,0 +1,2 @@
+if not 'PowerPC' in config.root.targets:
+    config.unsupported = True

llvm/test/MC/MachO/coal-sections-x86_64.s

@@ -0,0 +1,48 @@
+// RUN: llvm-mc -triple x86_64-apple-darwin -filetype=obj %s -o - 2>%t.err | llvm-readobj -sections | FileCheck %s
+// RUN: FileCheck --check-prefix=WARNING < %t.err %s
+
+// CHECK: Section {
+// CHECK-NEXT: Index: 0
+// CHECK-NEXT: Name: __text (
+
+// CHECK: Section {
+// CHECK-NEXT: Index: 1
+// CHECK-NEXT: Name: __textcoal_nt (
+
+// CHECK: Section {
+// CHECK-NEXT: Index: 2
+// CHECK-NEXT: Name: __const_coal (
+
+// CHECK: Section {
+// CHECK-NEXT: Index: 3
+// CHECK-NEXT: Name: __datacoal_nt (
+
+// WARNING: warning: section "__textcoal_nt" is deprecated
+// WARNING: note: change section name to "__text"
+// WARNING: warning: section "__const_coal" is deprecated
+// WARNING: note: change section name to "__const"
+// WARNING: warning: section "__datacoal_nt" is deprecated
+// WARNING: note: change section name to "__data"
+
+	.section	__TEXT,__textcoal_nt,coalesced,pure_instructions
+	.globl	_foo
+	.weak_definition	_foo
+	.align	4, 0x90
+_foo:
+	retq
+
+	.section	__TEXT,__const_coal,coalesced
+	.globl	_a                      ## @a
+	.weak_definition	_a
+	.align	4
+_a:
+	.long	1                       ## 0x1
+
+	.section	__DATA,__datacoal_nt,coalesced
+	.globl	_b                      ## @b
+	.weak_definition	_b
+	.align	2
+_b:
+	.long	5                       ## 0x5
+
+.subsections_via_symbols