llvm/tools/gccld/GenerateCode.cpp

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//===- 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 "gccld.h"
#include "llvm/Linker.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/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.
/// StripLevel - 2 if we should strip all symbols, 1 if we should strip
/// debug info.
/// 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, int StripLevel, 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 hack on them!
addPass(Passes, createGlobalOptimizerPass());
// Linking modules together can lead to duplicated global constants, only
// keep one copy of each constant...
addPass(Passes, createConstantMergePass());
// Propagate constants at call sites into the functions they call.
addPass(Passes, createIPSCCPPass());
// 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, createGlobalOptimizerPass()); // Optimize globals again.
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());
}
// If the -s or -S command line options were specified, strip the symbols out
// of the resulting program to make it smaller. -s and -S are GLD options
// that we are supporting.
if (StripLevel)
addPass(Passes, createStripSymbolsPass(StripLevel == 1));
// 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);
}