[xray] Add XRay support for Mach-O in CodeGen

Currently, XRay only supports emitting the XRay table (xray_instr_map) on ELF binaries. Let's add Mach-O support.

Differential Revision: https://reviews.llvm.org/D26983



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@287734 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 35 insertions, 26 deletions

diff --git a/lib/Target/AArch64/AArch64AsmPrinter.cpp b/lib/Target/AArch64/AArch64AsmPrinter.cpp
index 2d49ccc46d4..b2d96a32fd3 100644
--- a/lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ b/lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -39,6 +39,7 @@
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/MC/MCSymbolELF.h"
 #include "llvm/MC/MCSectionELF.h"
+#include "llvm/MC/MCSectionMachO.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/raw_ostream.h"
@@ -155,10 +156,12 @@ void AArch64AsmPrinter::EmitXRayTable()
   // code duplication as it is now for x86_64, ARM32 and AArch64.
   if (Sleds.empty())
     return;
+
+  auto PrevSection = OutStreamer->getCurrentSectionOnly();
+  auto Fn = MF->getFunction();
+  MCSection *Section;
+
   if (STI->isTargetELF()) {
-    auto PrevSection = OutStreamer->getCurrentSectionOnly();
-    auto Fn = MF->getFunction();
-    MCSection *Section;
     if (Fn->hasComdat())
       Section = OutContext.getELFSection("xray_instr_map", ELF::SHT_PROGBITS,
         ELF::SHF_ALLOC | ELF::SHF_GROUP, 0,
@@ -166,31 +169,37 @@ void AArch64AsmPrinter::EmitXRayTable()
     else
       Section = OutContext.getELFSection("xray_instr_map", ELF::SHT_PROGBITS,
         ELF::SHF_ALLOC);
+  } else if (STI->isTargetMachO()) {
+    Section = OutContext.getMachOSection("__DATA", "xray_instr_map", 0,
+                                         SectionKind::getReadOnlyWithRel());
+  } else {
+    llvm_unreachable("Unsupported target");
+  }
 
-    // Before we switch over, we force a reference to a label inside the
-    // xray_instr_map section. Since EmitXRayTable() is always called just
-    // before the function's end, we assume that this is happening after the
-    // last return instruction.
-    //
-    // We then align the reference to 16 byte boundaries, which we determined
-    // experimentally to be beneficial to avoid causing decoder stalls.
-    MCSymbol *Tmp = OutContext.createTempSymbol("xray_synthetic_", true);
-    OutStreamer->EmitCodeAlignment(16);
-    OutStreamer->EmitSymbolValue(Tmp, 8, false);
-    OutStreamer->SwitchSection(Section);
-    OutStreamer->EmitLabel(Tmp);
-    for (const auto &Sled : Sleds) {
-      OutStreamer->EmitSymbolValue(Sled.Sled, 8);
-      OutStreamer->EmitSymbolValue(CurrentFnSym, 8);
-      auto Kind = static_cast<uint8_t>(Sled.Kind);
-      OutStreamer->EmitBytes(
-        StringRef(reinterpret_cast<const char *>(&Kind), 1));
-      OutStreamer->EmitBytes(
-        StringRef(reinterpret_cast<const char *>(&Sled.AlwaysInstrument), 1));
-      OutStreamer->EmitZeros(14);
-    }
-    OutStreamer->SwitchSection(PrevSection);
+  // Before we switch over, we force a reference to a label inside the
+  // xray_instr_map section. Since EmitXRayTable() is always called just
+  // before the function's end, we assume that this is happening after the
+  // last return instruction.
+  //
+  // We then align the reference to 16 byte boundaries, which we determined
+  // experimentally to be beneficial to avoid causing decoder stalls.
+  MCSymbol *Tmp = OutContext.createTempSymbol("xray_synthetic_", true);
+  OutStreamer->EmitCodeAlignment(16);
+  OutStreamer->EmitSymbolValue(Tmp, 8, false);
+  OutStreamer->SwitchSection(Section);
+  OutStreamer->EmitLabel(Tmp);
+  for (const auto &Sled : Sleds) {
+    OutStreamer->EmitSymbolValue(Sled.Sled, 8);
+    OutStreamer->EmitSymbolValue(CurrentFnSym, 8);
+    auto Kind = static_cast<uint8_t>(Sled.Kind);
+    OutStreamer->EmitBytes(
+      StringRef(reinterpret_cast<const char *>(&Kind), 1));
+    OutStreamer->EmitBytes(
+      StringRef(reinterpret_cast<const char *>(&Sled.AlwaysInstrument), 1));
+    OutStreamer->EmitZeros(14);
   }
+  OutStreamer->SwitchSection(PrevSection);
+
   Sleds.clear();
 }