1 files changed, 186 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/AsmPrinter/OcamlGCPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/OcamlGCPrinter.cpp
new file mode 100644
index 000000000000..b4eda5fa8c58
--- /dev/null
+++ b/llvm/lib/CodeGen/AsmPrinter/OcamlGCPrinter.cpp
@@ -0,0 +1,186 @@
+//===- OcamlGCPrinter.cpp - Ocaml frametable emitter ----------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements printing the assembly code for an Ocaml frametable.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/CodeGen/BuiltinGCs.h"
+#include "llvm/CodeGen/GCMetadata.h"
+#include "llvm/CodeGen/GCMetadataPrinter.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Mangler.h"
+#include "llvm/IR/Module.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCDirectives.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Target/TargetLoweringObjectFile.h"
+#include <cctype>
+#include <cstddef>
+#include <cstdint>
+#include <string>
+
+using namespace llvm;
+
+namespace {
+
+class OcamlGCMetadataPrinter : public GCMetadataPrinter {
+public:
+  void beginAssembly(Module &M, GCModuleInfo &Info, AsmPrinter &AP) override;
+  void finishAssembly(Module &M, GCModuleInfo &Info, AsmPrinter &AP) override;
+};
+
+} // end anonymous namespace
+
+static GCMetadataPrinterRegistry::Add<OcamlGCMetadataPrinter>
+    Y("ocaml", "ocaml 3.10-compatible collector");
+
+void llvm::linkOcamlGCPrinter() {}
+
+static void EmitCamlGlobal(const Module &M, AsmPrinter &AP, const char *Id) {
+  const std::string &MId = M.getModuleIdentifier();
+
+  std::string SymName;
+  SymName += "caml";
+  size_t Letter = SymName.size();
+  SymName.append(MId.begin(), llvm::find(MId, '.'));
+  SymName += "__";
+  SymName += Id;
+
+  // Capitalize the first letter of the module name.
+  SymName[Letter] = toupper(SymName[Letter]);
+
+  SmallString<128> TmpStr;
+  Mangler::getNameWithPrefix(TmpStr, SymName, M.getDataLayout());
+
+  MCSymbol *Sym = AP.OutContext.getOrCreateSymbol(TmpStr);
+
+  AP.OutStreamer->EmitSymbolAttribute(Sym, MCSA_Global);
+  AP.OutStreamer->EmitLabel(Sym);
+}
+
+void OcamlGCMetadataPrinter::beginAssembly(Module &M, GCModuleInfo &Info,
+                                           AsmPrinter &AP) {
+  AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getTextSection());
+  EmitCamlGlobal(M, AP, "code_begin");
+
+  AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getDataSection());
+  EmitCamlGlobal(M, AP, "data_begin");
+}
+
+/// emitAssembly - Print the frametable. The ocaml frametable format is thus:
+///
+///   extern "C" struct align(sizeof(intptr_t)) {
+///     uint16_t NumDescriptors;
+///     struct align(sizeof(intptr_t)) {
+///       void *ReturnAddress;
+///       uint16_t FrameSize;
+///       uint16_t NumLiveOffsets;
+///       uint16_t LiveOffsets[NumLiveOffsets];
+///     } Descriptors[NumDescriptors];
+///   } caml${module}__frametable;
+///
+/// Note that this precludes programs from stack frames larger than 64K
+/// (FrameSize and LiveOffsets would overflow). FrameTablePrinter will abort if
+/// either condition is detected in a function which uses the GC.
+///
+void OcamlGCMetadataPrinter::finishAssembly(Module &M, GCModuleInfo &Info,
+                                            AsmPrinter &AP) {
+  unsigned IntPtrSize = M.getDataLayout().getPointerSize();
+
+  AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getTextSection());
+  EmitCamlGlobal(M, AP, "code_end");
+
+  AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getDataSection());
+  EmitCamlGlobal(M, AP, "data_end");
+
+  // FIXME: Why does ocaml emit this??
+  AP.OutStreamer->EmitIntValue(0, IntPtrSize);
+
+  AP.OutStreamer->SwitchSection(AP.getObjFileLowering().getDataSection());
+  EmitCamlGlobal(M, AP, "frametable");
+
+  int NumDescriptors = 0;
+  for (GCModuleInfo::FuncInfoVec::iterator I = Info.funcinfo_begin(),
+                                           IE = Info.funcinfo_end();
+       I != IE; ++I) {
+    GCFunctionInfo &FI = **I;
+    if (FI.getStrategy().getName() != getStrategy().getName())
+      // this function is managed by some other GC
+      continue;
+    for (GCFunctionInfo::iterator J = FI.begin(), JE = FI.end(); J != JE; ++J) {
+      NumDescriptors++;
+    }
+  }
+
+  if (NumDescriptors >= 1 << 16) {
+    // Very rude!
+    report_fatal_error(" Too much descriptor for ocaml GC");
+  }
+  AP.emitInt16(NumDescriptors);
+  AP.EmitAlignment(IntPtrSize == 4 ? Align(4) : Align(8));
+
+  for (GCModuleInfo::FuncInfoVec::iterator I = Info.funcinfo_begin(),
+                                           IE = Info.funcinfo_end();
+       I != IE; ++I) {
+    GCFunctionInfo &FI = **I;
+    if (FI.getStrategy().getName() != getStrategy().getName())
+      // this function is managed by some other GC
+      continue;
+
+    uint64_t FrameSize = FI.getFrameSize();
+    if (FrameSize >= 1 << 16) {
+      // Very rude!
+      report_fatal_error("Function '" + FI.getFunction().getName() +
+                         "' is too large for the ocaml GC! "
+                         "Frame size " +
+                         Twine(FrameSize) + ">= 65536.\n"
+                                            "(" +
+                         Twine(uintptr_t(&FI)) + ")");
+    }
+
+    AP.OutStreamer->AddComment("live roots for " +
+                               Twine(FI.getFunction().getName()));
+    AP.OutStreamer->AddBlankLine();
+
+    for (GCFunctionInfo::iterator J = FI.begin(), JE = FI.end(); J != JE; ++J) {
+      size_t LiveCount = FI.live_size(J);
+      if (LiveCount >= 1 << 16) {
+        // Very rude!
+        report_fatal_error("Function '" + FI.getFunction().getName() +
+                           "' is too large for the ocaml GC! "
+                           "Live root count " +
+                           Twine(LiveCount) + " >= 65536.");
+      }
+
+      AP.OutStreamer->EmitSymbolValue(J->Label, IntPtrSize);
+      AP.emitInt16(FrameSize);
+      AP.emitInt16(LiveCount);
+
+      for (GCFunctionInfo::live_iterator K = FI.live_begin(J),
+                                         KE = FI.live_end(J);
+           K != KE; ++K) {
+        if (K->StackOffset >= 1 << 16) {
+          // Very rude!
+          report_fatal_error(
+              "GC root stack offset is outside of fixed stack frame and out "
+              "of range for ocaml GC!");
+        }
+        AP.emitInt16(K->StackOffset);
+      }
+
+      AP.EmitAlignment(IntPtrSize == 4 ? Align(4) : Align(8));
+    }
+  }
+}