Add a GC plugin for Erlang

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177867 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/GCs.h

@@ -26,6 +26,12 @@ namespace llvm {
   
   /// Creates an ocaml-compatible metadata printer.
   void linkOcamlGCPrinter();
+
+  /// Creates an erlang-compatible garbage collector.
+  void linkErlangGC();
+
+  /// Creates an erlang-compatible metadata printer.
+  void linkErlangGCPrinter();
   
   /// Creates a shadow stack garbage collector. This collector requires no code
   /// generator support.

include/llvm/CodeGen/LinkAllAsmWriterComponents.h

@@ -29,6 +29,7 @@ namespace {
         return;
 
       llvm::linkOcamlGCPrinter();
+      llvm::linkErlangGCPrinter();
 
     }
   } ForceAsmWriterLinking; // Force link by creating a global definition.

include/llvm/CodeGen/LinkAllCodegenComponents.h

@@ -37,6 +37,7 @@ namespace {
       (void) llvm::createDefaultPBQPRegisterAllocator();
 
       llvm::linkOcamlGC();
+      llvm::linkErlangGC();
       llvm::linkShadowStackGC();
 
       (void) llvm::createBURRListDAGScheduler(NULL, llvm::CodeGenOpt::Default);

lib/CodeGen/AsmPrinter/ErlangGCPrinter.cpp

@@ -0,0 +1,120 @@
+//===-- ErlangGCPrinter.cpp - Erlang/OTP frametable emitter -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the compiler plugin that is used in order to emit
+// garbage collection information in a convenient layout for parsing and
+// loading in the Erlang/OTP runtime.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/CodeGen/GCs.h"
+#include "llvm/CodeGen/GCMetadataPrinter.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCSectionELF.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/Target/TargetLoweringObjectFile.h"
+#include "llvm/Target/TargetMachine.h"
+
+using namespace llvm;
+
+namespace {
+
+  class ErlangGCPrinter : public GCMetadataPrinter {
+  public:
+    void beginAssembly(AsmPrinter &AP);
+    void finishAssembly(AsmPrinter &AP);
+  };
+
+}
+
+static GCMetadataPrinterRegistry::Add<ErlangGCPrinter>
+X("erlang", "erlang-compatible garbage collector");
+
+void llvm::linkErlangGCPrinter() { }
+
+void ErlangGCPrinter::beginAssembly(AsmPrinter &AP) { }
+
+void ErlangGCPrinter::finishAssembly(AsmPrinter &AP) {
+  MCStreamer &OS = AP.OutStreamer;
+  unsigned IntPtrSize = AP.TM.getDataLayout()->getPointerSize();
+
+  // Put this in a custom .note section.
+  AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getContext()
+    .getELFSection(".note.gc", ELF::SHT_PROGBITS, 0,
+                   SectionKind::getDataRel()));
+
+  // For each function...
+  for (iterator FI = begin(), FE = end(); FI != FE; ++FI) {
+    GCFunctionInfo &MD = **FI;
+
+    /** A compact GC layout. Emit this data structure:
+     *
+     * struct {
+     *   int16_t PointCount;
+     *   void *SafePointAddress[PointCount];
+     *   int16_t StackFrameSize; (in words)
+     *   int16_t StackArity;
+     *   int16_t LiveCount;
+     *   int16_t LiveOffsets[LiveCount];
+     * } __gcmap_<FUNCTIONNAME>;
+     **/
+
+    // Align to address width.
+    AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);
+
+    // Emit PointCount.
+    OS.AddComment("safe point count");
+    AP.EmitInt16(MD.size());
+
+    // And each safe point...
+    for (GCFunctionInfo::iterator PI = MD.begin(), PE = MD.end(); PI != PE;
+         ++PI) {
+      // Emit the address of the safe point.
+      OS.AddComment("safe point address");
+      MCSymbol *Label = PI->Label;
+      AP.EmitLabelPlusOffset(Label/*Hi*/, 0/*Offset*/, 4/*Size*/);
+    }
+
+    // Stack information never change in safe points! Only print info from the
+    // first call-site.
+    GCFunctionInfo::iterator PI = MD.begin();
+
+    // Emit the stack frame size.
+    OS.AddComment("stack frame size (in words)");
+    AP.EmitInt16(MD.getFrameSize() / IntPtrSize);
+
+    // Emit stack arity, i.e. the number of stacked arguments.
+    unsigned RegisteredArgs = IntPtrSize == 4 ? 5 : 6;
+    unsigned StackArity = MD.getFunction().arg_size() > RegisteredArgs ?
+                          MD.getFunction().arg_size() - RegisteredArgs : 0;
+    OS.AddComment("stack arity");
+    AP.EmitInt16(StackArity);
+
+    // Emit the number of live roots in the function.
+    OS.AddComment("live root count");
+    AP.EmitInt16(MD.live_size(PI));
+
+    // And for each live root...
+    for (GCFunctionInfo::live_iterator LI = MD.live_begin(PI),
+                                       LE = MD.live_end(PI);
+                                       LI != LE; ++LI) {
+      // Emit live root's offset within the stack frame.
+      OS.AddComment("stack index (offset / wordsize)");
+      AP.EmitInt16(LI->StackOffset / IntPtrSize);
+    }
+  }
+}

lib/CodeGen/ErlangGC.cpp

@@ -0,0 +1,81 @@
+//===-- ErlangGC.cpp - Erlang/OTP GC strategy -------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the Erlang/OTP runtime-compatible garbage collector
+// (e.g. defines safe points, root initialization etc.)
+//
+// The frametable emitter is in ErlangGCPrinter.cpp.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/GCs.h"
+#include "llvm/CodeGen/GCStrategy.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
+
+using namespace llvm;
+
+namespace {
+
+  class ErlangGC : public GCStrategy {
+    MCSymbol *InsertLabel(MachineBasicBlock &MBB,
+                          MachineBasicBlock::iterator MI,
+                          DebugLoc DL) const;
+  public:
+    ErlangGC();
+    bool findCustomSafePoints(GCFunctionInfo &FI, MachineFunction &MF);
+  };
+
+}
+
+static GCRegistry::Add<ErlangGC>
+X("erlang", "erlang-compatible garbage collector");
+
+void llvm::linkErlangGC() { }
+
+ErlangGC::ErlangGC() {
+  InitRoots = false;
+  NeededSafePoints = 1 << GC::PostCall;
+  UsesMetadata = true;
+  CustomRoots = false;
+  CustomSafePoints = true;
+}
+
+MCSymbol *ErlangGC::InsertLabel(MachineBasicBlock &MBB,
+                                MachineBasicBlock::iterator MI,
+                                DebugLoc DL) const {
+  const TargetInstrInfo* TII = MBB.getParent()->getTarget().getInstrInfo();
+  MCSymbol *Label = MBB.getParent()->getContext().CreateTempSymbol();
+  BuildMI(MBB, MI, DL, TII->get(TargetOpcode::GC_LABEL)).addSym(Label);
+  return Label;
+}
+
+bool ErlangGC::findCustomSafePoints(GCFunctionInfo &FI, MachineFunction &MF) {
+  for (MachineFunction::iterator BBI = MF.begin(), BBE = MF.end(); BBI != BBE;
+       ++BBI)
+    for (MachineBasicBlock::iterator MI = BBI->begin(), ME = BBI->end();
+         MI != ME; ++MI)
+
+      if (MI->getDesc().isCall()) {
+
+        // Do not treat tail call sites as safe points.
+        if (MI->getDesc().isTerminator())
+          continue;
+
+        /* Code copied from VisitCallPoint(...) */
+        MachineBasicBlock::iterator RAI = MI; ++RAI;
+        MCSymbol* Label = InsertLabel(*MI->getParent(), RAI, MI->getDebugLoc());
+        FI.addSafePoint(GC::PostCall, Label, MI->getDebugLoc());
+      }
+
+  return false;
+}

test/CodeGen/X86/GC/erlang-gc.ll

@@ -0,0 +1,25 @@
+; RUN: llc -mtriple=x86_64-linux-gnu < %s | FileCheck %s --check-prefix=CHECK64
+; RUN: llc -mtriple=i686-linux-gnu < %s | FileCheck %s --check-prefix=CHECK32
+
+define i32 @main(i32 %x) nounwind gc "erlang" {
+  %puts = tail call i32 @foo(i32 %x)
+  ret i32 0
+
+; CHECK64:      .section  .note.gc,"",@progbits
+; CHECK64-NEXT: .align 8
+; CHECK64-NEXT: .short 1      # safe point count
+; CHECK64-NEXT: .long  .Ltmp0 # safe point address
+; CHECK64-NEXT: .short 1      # stack frame size (in words)
+; CHECK64-NEXT: .short 0      # stack arity
+; CHECK64-NEXT: .short 0      # live root count
+
+; CHECK32:      .section  .note.gc,"",@progbits
+; CHECK32-NEXT: .align 4
+; CHECK32-NEXT: .short 1      # safe point count
+; CHECK32-NEXT: .long  .Ltmp0 # safe point address
+; CHECK32-NEXT: .short 3      # stack frame size (in words)
+; CHECK32-NEXT: .short 0      # stack arity
+; CHECK32-NEXT: .short 0      # live root count
+}
+
+declare i32 @foo(i32)