Add new API lto_codegen_compile_parallel().

This API is proposed by Nick Kledzik. The semantic is:

  --------------------------------------------------------------------------
   Generate code for merged module into an array of native object files. On 
   success returns a pointer to an array of NativeObjectFile.  The count 
   parameter returns the number of elements in the array.  Each element is 
   a pointer/length for a generated mach-o/ELF buffer.  The buffer is owned
   by the lto_code_gen_t and will be freed when lto_codegen_dispose() is called, 
   or lto_codegen_compile() is called again. On failure, returns NULL 
   (check lto_get_error_message() for details).

   extern const struct  NativeObjectFile*
   lto_codegen_compile_parallel(lto_code_gen_t cg, size_t *count);
  ---------------------------------------------------------------------------

  This API is currently only called on OSX platform. Linux or other Unixes
using GNU gold are not supposed to call this function, because on these systems, 
object files are fed back to linker via disk file instead of memory buffer.

  In this commit, lto_codegen_compile_parallel() simply calls
lto_codegen_compile() to return a single object file. In the near future,
this function is the entry point for compilation with partition. Linker can
blindly call this function even if partition is turned off; in this case,
compiler will return only one object file.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189297 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm-c/lto.h

@@ -27,7 +27,7 @@
  * @{
  */
 
-#define LTO_API_VERSION 4
+#define LTO_API_VERSION 5
 
 typedef enum {
     LTO_SYMBOL_ALIGNMENT_MASK              = 0x0000001F, /* log2 of alignment */
@@ -284,6 +284,22 @@ lto_codegen_compile(lto_code_gen_t cg, size_t* length);
 extern bool
 lto_codegen_compile_to_file(lto_code_gen_t cg, const char** name);
 
+struct NativeObjectFile {
+  const void *content;
+  size_t length;
+};
+
+/**
+ * Generates code for merged module into an array of native object files.
+ * On success returns a pointer to an array of NativeObjectFile.  The
+ * count parameter returns the number of elements in the array.  Each
+ * element is a pointer/length for a generated mach-o/ELF buffer. The
+ * buffer is owned by the lto_code_gen_t and will be freed when
+ * lto_codegen_dispose() is called, or lto_codegen_compile() is called again.
+ * On failure, returns NULL (check lto_get_error_message() for details).
+ */
+extern const struct NativeObjectFile*
+lto_codegen_compile_parallel(lto_code_gen_t cg, size_t *count);
 
 /**
  * Sets options to help debug codegen bugs.

tools/lto/LTOCodeGenerator.cpp

@@ -74,7 +74,7 @@ LTOCodeGenerator::LTOCodeGenerator()
     _linker(new Module("ld-temp.o", _context)), _target(NULL),
     _emitDwarfDebugInfo(false), _scopeRestrictionsDone(false),
     _codeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC),
-    _nativeObjectFile(NULL) {
+    _nativeObjectFile(NULL), ObjBufVect(0) {
   InitializeAllTargets();
   InitializeAllTargetMCs();
   InitializeAllAsmPrinters();
@@ -85,6 +85,7 @@ LTOCodeGenerator::~LTOCodeGenerator() {
   delete _target;
   delete _nativeObjectFile;
   delete _linker.getModule();
+  delete[] ObjBufVect;
 
   for (std::vector<char*>::iterator I = _codegenOptions.begin(),
          E = _codegenOptions.end(); I != E; ++I)
@@ -246,6 +247,23 @@ const void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg) {
   return _nativeObjectFile->getBufferStart();
 }
 
+// Currently compile() and compile_parallel() have no difference.
+NativeObjectFile *LTOCodeGenerator::compile_parallel(size_t *count,
+                                                     std::string &ErrMsg) {
+  assert(ObjBufVect == 0 && "Should be NULL");
+
+  size_t Len;
+  const void *Buf = compile(&Len, ErrMsg);
+  if (!Buf)
+    return 0;
+
+  *count = 1;
+  ObjBufVect = new NativeObjectFile[1];
+  ObjBufVect[0].content = Buf;
+  ObjBufVect[0].length = Len;
+  return ObjBufVect;
+}
+
 bool LTOCodeGenerator::determineTarget(std::string &errMsg) {
   if (_target != NULL)
     return true;

tools/lto/LTOCodeGenerator.h

@@ -102,6 +102,17 @@ struct LTOCodeGenerator {
   //
   const void *compile(size_t *length, std::string &errMsg);
 
+  // Corresponding to lto_codegen_compile_parallel() API. 
+  // Generates code for merged module into an array of native object files.
+  // On success returns a pointer to an array of NativeObjectFile.  The count
+  // parameter returns the number of elements in the array.  Each element is
+  // a pointer/length for a generated mach-o/ELF buffer. The buffer is owned
+  // by the lto_code_gen_t and will be freed when lto_codegen_dispose() is
+  // called, or lto_codegen_compile() is called again. On failure, returns
+  // NULL (check lto_get_error_message() for details).
+  //
+  NativeObjectFile *compile_parallel(size_t *count, std::string &ErrMsg);
+
 private:
   void initializeLTOPasses();
 
@@ -127,6 +138,7 @@ private:
   std::vector<char*>          _codegenOptions;
   std::string                 _mCpu;
   std::string                 _nativeObjectPath;
+  NativeObjectFile *ObjBufVect;
 };
 
 #endif // LTO_CODE_GENERATOR_H

tools/lto/lto.cpp

@@ -207,6 +207,11 @@ bool lto_codegen_compile_to_file(lto_code_gen_t cg, const char **name) {
   return !cg->compile_to_file(name, sLastErrorString);
 }
 
+extern const struct NativeObjectFile *
+lto_codegen_compile_parallel(lto_code_gen_t cg, size_t *count) {
+  return cg->compile_parallel(count, sLastErrorString);
+}
+
 /// lto_codegen_debug_options - Used to pass extra options to the code
 /// generator.
 void lto_codegen_debug_options(lto_code_gen_t cg, const char *opt) {

tools/lto/lto.exports

@@ -28,6 +28,7 @@ lto_codegen_set_assembler_args
 lto_codegen_set_assembler_path
 lto_codegen_set_cpu
 lto_codegen_compile_to_file
+lto_codegen_compile_parallel
 LLVMCreateDisasm
 LLVMCreateDisasmCPU
 LLVMDisasmDispose