Mark jump tables in code sections with DataRegion directives.

Even out-of-line jump tables can be in the code section, so mark them
as data-regions for those targets which support the directives.

rdar://12362871&12362974

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164571 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -1082,6 +1082,11 @@ void AsmPrinter::EmitJumpTableInfo() {
 
   EmitAlignment(Log2_32(MJTI->getEntryAlignment(*TM.getTargetData())));
 
+  // Jump tables in code sections are marked with a data_region directive
+  // where that's supported.
+  if (!JTInDiffSection)
+    OutStreamer.EmitDataRegion(MCDR_DataRegionJT32);
+
   for (unsigned JTI = 0, e = JT.size(); JTI != e; ++JTI) {
     const std::vector<MachineBasicBlock*> &JTBBs = JT[JTI].MBBs;
 
@@ -1122,6 +1127,8 @@ void AsmPrinter::EmitJumpTableInfo() {
     for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii)
       EmitJumpTableEntry(MJTI, JTBBs[ii], JTI);
   }
+  if (!JTInDiffSection)
+    OutStreamer.EmitDataRegion(MCDR_DataRegionEnd);
 }
 
 /// EmitJumpTableEntry - Emit a jump table entry for the specified MBB to the

lib/Target/X86/MCTargetDesc/X86MCAsmInfo.cpp

@@ -34,6 +34,10 @@ AsmWriterFlavor("x86-asm-syntax", cl::init(ATT),
              clEnumValN(Intel, "intel", "Emit Intel-style assembly"),
              clEnumValEnd));
 
+static cl::opt<bool>
+MarkedJTDataRegions("mark-data-regions", cl::init(false),
+  cl::desc("Mark code section jump table data regions."),
+  cl::Hidden);
 
 void X86MCAsmInfoDarwin::anchor() { }
 
@@ -59,6 +63,7 @@ X86MCAsmInfoDarwin::X86MCAsmInfoDarwin(const Triple &T) {
 
   SupportsDebugInformation = true;
   DwarfUsesInlineInfoSection = true;
+  UseDataRegionDirectives = MarkedJTDataRegions;
 
   // Exceptions handling
   ExceptionsType = ExceptionHandling::DwarfCFI;

test/CodeGen/X86/pic_jumptable.ll

@@ -1,5 +1,7 @@
 ; RUN: llc < %s -relocation-model=pic -mtriple=i386-linux-gnu -asm-verbose=false \
 ; RUN:   | FileCheck %s --check-prefix=CHECK-LINUX
+; RUN: llc < %s -relocation-model=pic -mark-data-regions -mtriple=i686-apple-darwin -asm-verbose=false \
+; RUN:   | FileCheck %s --check-prefix=CHECK-DATA
 ; RUN: llc < %s -relocation-model=pic -mtriple=i686-apple-darwin -asm-verbose=false \
 ; RUN:   | FileCheck %s
 ; RUN: llc < %s                       -mtriple=x86_64-apple-darwin | not grep 'lJTI'
@@ -16,6 +18,16 @@ entry:
 ; CHECK:       Ltmp0 = LJTI0_0-L0$pb
 ; CHECK-NEXT:  addl Ltmp0(%eax,%ecx,4)
 ; CHECK-NEXT:  jmpl *%eax
+
+;; When data-in-code markers are enabled, we should see them around the jump
+;; table.
+; CHECK-DATA: .data_region jt32
+; CHECK-DATA: LJTI0_0
+; CHECK-DATA: .end_data_region
+
+;; When they're not enabled, make sure we don't see them at all.
+; CHECK-NOT: .data_region
+; CHECK-LINUX-NOT: .data_region
 	%Y_addr = alloca i32		; <i32*> [#uses=2]
 	%"alloca point" = bitcast i32 0 to i32		; <i32> [#uses=0]
 	store i32 %Y, i32* %Y_addr