Initial implementation of llvm-ld: stolen from gccld.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16305 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 353 insertions, 0 deletions

diff --git a/tools/llvm-ld/GenerateCode.cpp b/tools/llvm-ld/GenerateCode.cpp
new file mode 100644
index 0000000000..23b0057a75
--- /dev/null
+++ b/tools/llvm-ld/GenerateCode.cpp
@@ -0,0 +1,353 @@
+//===- GenerateCode.cpp - Functions for generating executable files  ------===//
+// 
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file contains functions for generating executable files once linking
+// has finished.  This includes generating a shell script to run the JIT or
+// a native executable derived from the bytecode.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm-ld.h"
+#include "llvm/Module.h"
+#include "llvm/PassManager.h"
+#include "llvm/Analysis/LoadValueNumbering.h"
+#include "llvm/Analysis/Passes.h"
+#include "llvm/Analysis/Verifier.h"
+#include "llvm/Bytecode/WriteBytecodePass.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Support/Linker.h"
+#include "llvm/Support/SystemUtils.h"
+#include "llvm/Support/CommandLine.h"
+using namespace llvm;
+
+namespace {
+  cl::opt<bool>
+  DisableInline("disable-inlining", cl::desc("Do not run the inliner pass"));
+
+  cl::opt<bool>
+  Verify("verify", cl::desc("Verify intermediate results of all passes"));
+
+  cl::opt<bool>
+  DisableOptimizations("disable-opt",
+                       cl::desc("Do not run any optimization passes"));
+}
+
+/// CopyEnv - This function takes an array of environment variables and makes a
+/// copy of it.  This copy can then be manipulated any way the caller likes
+/// without affecting the process's real environment.
+///
+/// Inputs:
+///  envp - An array of C strings containing an environment.
+///
+/// Return value:
+///  NULL - An error occurred.
+///
+///  Otherwise, a pointer to a new array of C strings is returned.  Every string
+///  in the array is a duplicate of the one in the original array (i.e. we do
+///  not copy the char *'s from one array to another).
+///
+static char ** CopyEnv(char ** const envp) {
+  // Count the number of entries in the old list;
+  unsigned entries;   // The number of entries in the old environment list
+  for (entries = 0; envp[entries] != NULL; entries++)
+    /*empty*/;
+
+  // Add one more entry for the NULL pointer that ends the list.
+  ++entries;
+
+  // If there are no entries at all, just return NULL.
+  if (entries == 0)
+    return NULL;
+
+  // Allocate a new environment list.
+  char **newenv = new char* [entries];
+  if ((newenv = new char* [entries]) == NULL)
+    return NULL;
+
+  // Make a copy of the list.  Don't forget the NULL that ends the list.
+  entries = 0;
+  while (envp[entries] != NULL) {
+    newenv[entries] = new char[strlen (envp[entries]) + 1];
+    strcpy (newenv[entries], envp[entries]);
+    ++entries;
+  }
+  newenv[entries] = NULL;
+
+  return newenv;
+}
+
+
+/// RemoveEnv - Remove the specified environment variable from the environment
+/// array.
+///
+/// Inputs:
+///  name - The name of the variable to remove.  It cannot be NULL.
+///  envp - The array of environment variables.  It cannot be NULL.
+///
+/// Notes:
+///  This is mainly done because functions to remove items from the environment
+///  are not available across all platforms.  In particular, Solaris does not
+///  seem to have an unsetenv() function or a setenv() function (or they are
+///  undocumented if they do exist).
+///
+static void RemoveEnv(const char * name, char ** const envp) {
+  for (unsigned index=0; envp[index] != NULL; index++) {
+    // Find the first equals sign in the array and make it an EOS character.
+    char *p = strchr (envp[index], '=');
+    if (p == NULL)
+      continue;
+    else
+      *p = '\0';
+
+    // Compare the two strings.  If they are equal, zap this string.
+    // Otherwise, restore it.
+    if (!strcmp(name, envp[index]))
+      *envp[index] = '\0';
+    else
+      *p = '=';
+  }
+
+  return;
+}
+
+static inline void addPass(PassManager &PM, Pass *P) {
+  // Add the pass to the pass manager...
+  PM.add(P);
+  
+  // If we are verifying all of the intermediate steps, add the verifier...
+  if (Verify) PM.add(createVerifierPass());
+}
+
+/// GenerateBytecode - generates a bytecode file from the specified module.
+///
+/// Inputs:
+///  M           - The module for which bytecode should be generated.
+///  Strip       - Flags whether symbols should be stripped from the output.
+///  Internalize - Flags whether all symbols should be marked internal.
+///  Out         - Pointer to file stream to which to write the output.
+///
+/// Returns non-zero value on error.
+///
+int llvm::GenerateBytecode(Module *M, bool Strip, bool Internalize,
+                           std::ostream *Out) {
+  // In addition to just linking the input from GCC, we also want to spiff it up
+  // a little bit.  Do this now.
+  PassManager Passes;
+
+  if (Verify) Passes.add(createVerifierPass());
+
+  // Add an appropriate TargetData instance for this module...
+  addPass(Passes, new TargetData("gccld", M));
+
+  // Often if the programmer does not specify proper prototypes for the
+  // functions they are calling, they end up calling a vararg version of the
+  // function that does not get a body filled in (the real function has typed
+  // arguments).  This pass merges the two functions.
+  addPass(Passes, createFunctionResolvingPass());
+
+  if (!DisableOptimizations) {
+    if (Internalize) {
+      // Now that composite has been compiled, scan through the module, looking
+      // for a main function.  If main is defined, mark all other functions
+      // internal.
+      addPass(Passes, createInternalizePass());
+    }
+
+    // Now that we internalized some globals, see if we can mark any globals as
+    // being constant!
+    addPass(Passes, createGlobalConstifierPass());
+
+    // Linking modules together can lead to duplicated global constants, only
+    // keep one copy of each constant...
+    addPass(Passes, createConstantMergePass());
+
+    // If the -s command line option was specified, strip the symbols out of the
+    // resulting program to make it smaller.  -s is a GCC option that we are
+    // supporting.
+    if (Strip)
+      addPass(Passes, createSymbolStrippingPass());
+
+    // Propagate constants at call sites into the functions they call.
+    addPass(Passes, createIPConstantPropagationPass());
+
+    // Remove unused arguments from functions...
+    addPass(Passes, createDeadArgEliminationPass());
+
+    if (!DisableInline)
+      addPass(Passes, createFunctionInliningPass()); // Inline small functions
+
+    addPass(Passes, createPruneEHPass());            // Remove dead EH info
+    addPass(Passes, createGlobalDCEPass());          // Remove dead functions
+
+    // If we didn't decide to inline a function, check to see if we can
+    // transform it to pass arguments by value instead of by reference.
+    addPass(Passes, createArgumentPromotionPass());
+
+    // The IPO passes may leave cruft around.  Clean up after them.
+    addPass(Passes, createInstructionCombiningPass());
+
+    addPass(Passes, createScalarReplAggregatesPass()); // Break up allocas
+
+    // Run a few AA driven optimizations here and now, to cleanup the code.
+    addPass(Passes, createGlobalsModRefPass());      // IP alias analysis
+
+    addPass(Passes, createLICMPass());               // Hoist loop invariants
+    addPass(Passes, createLoadValueNumberingPass()); // GVN for load instrs
+    addPass(Passes, createGCSEPass());               // Remove common subexprs
+    addPass(Passes, createDeadStoreEliminationPass()); // Nuke dead stores
+
+    // Cleanup and simplify the code after the scalar optimizations.
+    addPass(Passes, createInstructionCombiningPass());
+
+    // Delete basic blocks, which optimization passes may have killed...
+    addPass(Passes, createCFGSimplificationPass());
+
+    // Now that we have optimized the program, discard unreachable functions...
+    addPass(Passes, createGlobalDCEPass());
+  }
+
+  // Make sure everything is still good.
+  Passes.add(createVerifierPass());
+
+  // Add the pass that writes bytecode to the output file...
+  addPass(Passes, new WriteBytecodePass(Out));
+
+  // Run our queue of passes all at once now, efficiently.
+  Passes.run(*M);
+
+  return 0;
+}
+
+/// GenerateAssembly - generates a native assembly language source file from the
+/// specified bytecode file.
+///
+/// Inputs:
+///  InputFilename  - The name of the output bytecode file.
+///  OutputFilename - The name of the file to generate.
+///  llc            - The pathname to use for LLC.
+///  envp           - The environment to use when running LLC.
+///
+/// Return non-zero value on error.
+///
+int llvm::GenerateAssembly(const std::string &OutputFilename,
+                           const std::string &InputFilename,
+                           const std::string &llc,
+                           char ** const envp) {
+  // Run LLC to convert the bytecode file into assembly code.
+  const char *cmd[6];
+  cmd[0] = llc.c_str();
+  cmd[1] = "-f";
+  cmd[2] = "-o";
+  cmd[3] = OutputFilename.c_str();
+  cmd[4] = InputFilename.c_str();
+  cmd[5] = 0;
+
+  return ExecWait(cmd, envp);
+}
+
+/// GenerateAssembly - generates a native assembly language source file from the
+/// specified bytecode file.
+int llvm::GenerateCFile(const std::string &OutputFile,
+                        const std::string &InputFile,
+                        const std::string &llc, char ** const envp) {
+  // Run LLC to convert the bytecode file into C.
+  const char *cmd[7];
+
+  cmd[0] = llc.c_str();
+  cmd[1] = "-march=c";
+  cmd[2] = "-f";
+  cmd[3] = "-o";
+  cmd[4] = OutputFile.c_str();
+  cmd[5] = InputFile.c_str();
+  cmd[6] = 0;
+  return ExecWait(cmd, envp);
+}
+
+/// GenerateNative - generates a native assembly language source file from the
+/// specified assembly source file.
+///
+/// Inputs:
+///  InputFilename  - The name of the output bytecode file.
+///  OutputFilename - The name of the file to generate.
+///  Libraries      - The list of libraries with which to link.
+///  LibPaths       - The list of directories in which to find libraries.
+///  gcc            - The pathname to use for GGC.
+///  envp           - A copy of the process's current environment.
+///
+/// Outputs:
+///  None.
+///
+/// Returns non-zero value on error.
+///
+int llvm::GenerateNative(const std::string &OutputFilename,
+                         const std::string &InputFilename,
+                         const std::vector<std::string> &Libraries,
+                         const std::vector<std::string> &LibPaths,
+                         const std::string &gcc, char ** const envp) {
+  // Remove these environment variables from the environment of the
+  // programs that we will execute.  It appears that GCC sets these
+  // environment variables so that the programs it uses can configure
+  // themselves identically.
+  //
+  // However, when we invoke GCC below, we want it to use its normal
+  // configuration.  Hence, we must sanitize its environment.
+  char ** clean_env = CopyEnv(envp);
+  if (clean_env == NULL)
+    return 1;
+  RemoveEnv("LIBRARY_PATH", clean_env);
+  RemoveEnv("COLLECT_GCC_OPTIONS", clean_env);
+  RemoveEnv("GCC_EXEC_PREFIX", clean_env);
+  RemoveEnv("COMPILER_PATH", clean_env);
+  RemoveEnv("COLLECT_GCC", clean_env);
+
+  std::vector<const char *> cmd;
+
+  // Run GCC to assemble and link the program into native code.
+  //
+  // Note:
+  //  We can't just assemble and link the file with the system assembler
+  //  and linker because we don't know where to put the _start symbol.
+  //  GCC mysteriously knows how to do it.
+  cmd.push_back(gcc.c_str());
+  cmd.push_back("-fno-strict-aliasing");
+  cmd.push_back("-O3");
+  cmd.push_back("-o");
+  cmd.push_back(OutputFilename.c_str());
+  cmd.push_back(InputFilename.c_str());
+
+  // Adding the library paths creates a problem for native generation.  If we
+  // include the search paths from llvmgcc, then we'll be telling normal gcc
+  // to look inside of llvmgcc's library directories for libraries.  This is
+  // bad because those libraries hold only bytecode files (not native object
+  // files).  In the end, we attempt to link the bytecode libgcc into a native
+  // program.
+#if 0
+  // Add in the library path options.
+  for (unsigned index=0; index < LibPaths.size(); index++) {
+    cmd.push_back("-L");
+    cmd.push_back(LibPaths[index].c_str());
+  }
+#endif
+
+  // Add in the libraries to link.
+  std::vector<std::string> Libs(Libraries);
+  for (unsigned index = 0; index < Libs.size(); index++) {
+    if (Libs[index] != "crtend") {
+      Libs[index] = "-l" + Libs[index];
+      cmd.push_back(Libs[index].c_str());
+    }
+  }
+  cmd.push_back(NULL);
+
+  // Run the compiler to assembly and link together the program.
+  return ExecWait(&(cmd[0]), clean_env);
+}
+