Add a new attribute called 'jumptable' that creates jump-instruction tables for funct...

[oota-llvm.git] / lib / CodeGen / AsmPrinter / AsmPrinter.cpp

diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 49c2ee20c2060beb8156088cab486a65e8c6317d..cb7cacbb00c1449371427376739c237935ec1281 100644 (file)
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -18,6 +18,7 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Analysis/JumpInstrTableInfo.h"
 #include "llvm/CodeGen/GCMetadataPrinter.h"
 #include "llvm/CodeGen/MachineConstantPool.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
@@ -889,6 +890,54 @@ bool AsmPrinter::doFinalization(Module &M) {
     EmitVisibility(Name, V, false);
   }
 
+  // Get information about jump-instruction tables to print.
+  JumpInstrTableInfo *JITI = getAnalysisIfAvailable<JumpInstrTableInfo>();
+
+  if (JITI && !JITI->getTables().empty()) {
+    unsigned Arch = Triple(getTargetTriple()).getArch();
+    bool IsThumb = (Arch == Triple::thumb || Arch == Triple::thumbeb);
+    MCInst TrapInst;
+    TM.getInstrInfo()->getTrap(TrapInst);
+    for (const auto &KV : JITI->getTables()) {
+      uint64_t Count = 0;
+      for (const auto &FunPair : KV.second) {
+        // Emit the function labels to make this be a function entry point.
+        MCSymbol *FunSym =
+          OutContext.GetOrCreateSymbol(FunPair.second->getName());
+        OutStreamer.EmitSymbolAttribute(FunSym, MCSA_Global);
+        // FIXME: JumpTableInstrInfo should store information about the required
+        // alignment of table entries and the size of the padding instruction.
+        EmitAlignment(3);
+        if (IsThumb)
+          OutStreamer.EmitThumbFunc(FunSym);
+        if (MAI->hasDotTypeDotSizeDirective())
+          OutStreamer.EmitSymbolAttribute(FunSym, MCSA_ELF_TypeFunction);
+        OutStreamer.EmitLabel(FunSym);
+
+        // Emit the jump instruction to transfer control to the original
+        // function.
+        MCInst JumpToFun;
+        MCSymbol *TargetSymbol =
+          OutContext.GetOrCreateSymbol(FunPair.first->getName());
+        const MCSymbolRefExpr *TargetSymRef =
+          MCSymbolRefExpr::Create(TargetSymbol, MCSymbolRefExpr::VK_PLT,
+                                  OutContext);
+        TM.getInstrInfo()->getUnconditionalBranch(JumpToFun, TargetSymRef);
+        OutStreamer.EmitInstruction(JumpToFun, getSubtargetInfo());
+        ++Count;
+      }
+
+      // Emit enough padding instructions to fill up to the next power of two.
+      // This assumes that the trap instruction takes 8 bytes or fewer.
+      uint64_t Remaining = NextPowerOf2(Count) - Count;
+      for (uint64_t C = 0; C < Remaining; ++C) {
+        EmitAlignment(3);
+        OutStreamer.EmitInstruction(TrapInst, getSubtargetInfo());
+      }
+
+    }
+  }
+
   // Emit module flags.
   SmallVector<Module::ModuleFlagEntry, 8> ModuleFlags;
   M.getModuleFlagsMetadata(ModuleFlags);