ARM: locate user-defined text sections next to default text.

Make sure functions located in user specified text sections (via the
section attribute) are located together with the default text sections.
Otherwise, for large object files, the relocations for call instructions
are more likely to be out of range. This becomes even more likely in the
presence of LTO.

rdar://12402636

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165254 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 41 insertions, 4 deletions

diff --git a/lib/Target/ARM/ARMAsmPrinter.cpp b/lib/Target/ARM/ARMAsmPrinter.cpp
index e9e2803ad5..d14c10e163 100644
--- a/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -23,6 +23,8 @@
 #include "InstPrinter/ARMInstPrinter.h"
 #include "MCTargetDesc/ARMAddressingModes.h"
 #include "MCTargetDesc/ARMMCExpr.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SmallString.h"
 #include "llvm/Constants.h"
 #include "llvm/DebugInfo.h"
 #include "llvm/Module.h"
@@ -42,7 +44,6 @@
 #include "llvm/Target/Mangler.h"
 #include "llvm/Target/TargetData.h"
 #include "llvm/Target/TargetMachine.h"
-#include "llvm/ADT/SmallString.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -592,9 +593,24 @@ void ARMAsmPrinter::EmitStartOfAsmFile(Module &M) {
       const TargetLoweringObjectFileMachO &TLOFMacho =
         static_cast<const TargetLoweringObjectFileMachO &>(
           getObjFileLowering());
-      OutStreamer.SwitchSection(TLOFMacho.getTextSection());
-      OutStreamer.SwitchSection(TLOFMacho.getTextCoalSection());
-      OutStreamer.SwitchSection(TLOFMacho.getConstTextCoalSection());
+
+      // Collect the set of sections our functions will go into.
+      SetVector<const MCSection *, SmallVector<const MCSection *, 8>,
+        SmallPtrSet<const MCSection *, 8> > TextSections;
+      // Default text section comes first.
+      TextSections.insert(TLOFMacho.getTextSection());
+      // Now any user defined text sections from function attributes.
+      for (Module::iterator F = M.begin(), e = M.end(); F != e; ++F)
+        if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage())
+          TextSections.insert(TLOFMacho.SectionForGlobal(F, Mang, TM));
+      // Now the coalescable sections.
+      TextSections.insert(TLOFMacho.getTextCoalSection());
+      TextSections.insert(TLOFMacho.getConstTextCoalSection());
+
+      // Emit the sections in the .s file header to fix the order.
+      for (unsigned i = 0, e = TextSections.size(); i != e; ++i)
+        OutStreamer.SwitchSection(TextSections[i]);
+
       if (RelocM == Reloc::DynamicNoPIC) {
         const MCSection *sect =
           OutContext.getMachOSection("__TEXT", "__symbol_stub4",
diff --git a/test/CodeGen/ARM/darwin-section-order.ll b/test/CodeGen/ARM/darwin-section-order.ll
new file mode 100644
index 0000000000..701028c0a5
--- /dev/null
+++ b/test/CodeGen/ARM/darwin-section-order.ll
@@ -0,0 +1,21 @@
+; RUN: llc < %s -mtriple=armv7-apple-darwin | FileCheck %s
+
+; CHECK: .section	__TEXT,__text,regular,pure_instructions
+; CHECK: .section	__TEXT,myprecious
+; CHECK: .section	__TEXT,__textcoal_nt,coalesced,pure_instructions
+; CHECK: .section	__TEXT,__const_coal,coalesced
+; CHECK: .section	__TEXT,__picsymbolstub4,symbol_stubs,none,16
+; CHECK: .section	__TEXT,__StaticInit,regular,pure_instructions
+
+
+define void @normal() nounwind readnone {
+; CHECK: .section	__TEXT,__text,regular,pure_instructions
+; CHECK: _normal:
+  ret void
+}
+
+define void @special() nounwind readnone section "__TEXT,myprecious" {
+; CHECK: .section	__TEXT,myprecious
+; CHECK: _special:
+  ret void
+}