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Refactored gccld into three C++ source files.

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Added code ignore bytecode link failures when generating native code.
Moved native code and bytecode generation out of the main() function.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8595 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
John Criswell 2003-09-18 16:22:26 +00:00
parent 521f1feb11
commit dc0de4f07b
4 changed files with 606 additions and 313 deletions
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228
tools/gccld/GenerateCode.cpp Normal file
View File

@ -0,0 +1,228 @@
//===- genexec.cpp - Functions for generating executable files ------------===//
//
// 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/Transforms/Utils/Linker.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Module.h"
#include "llvm/PassManager.h"
#include "llvm/Bytecode/WriteBytecodePass.h"
#include "Support/SystemUtils.h"
#include "util.h"
#include <fstream>
#include <string>
#include <vector>
//
// Function: GenerateBytecode ()
//
// Description:
// This function 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.
//
// Outputs:
// None.
//
// Return value:
// 0 - No error.
// 1 - Error.
//
int
GenerateBytecode (Module * M,
bool Strip,
bool Internalize,
std::ofstream * 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;
// Add an appropriate TargetData instance for this module...
Passes.add(new TargetData("gccld", M));
// Linking modules together can lead to duplicated global constants, only keep
// one copy of each constant...
//
Passes.add(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)
Passes.add(createSymbolStrippingPass());
// 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.
//
Passes.add(createFunctionResolvingPass());
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.
//
Passes.add(createInternalizePass());
}
// Remove unused arguments from functions...
//
Passes.add(createDeadArgEliminationPass());
// The FuncResolve pass may leave cruft around if functions were prototyped
// differently than they were defined. Remove this cruft.
//
Passes.add(createInstructionCombiningPass());
// Delete basic blocks, which optimization passes may have killed...
//
Passes.add(createCFGSimplificationPass());
// Now that we have optimized the program, discard unreachable functions...
//
Passes.add(createGlobalDCEPass());
// Add the pass that writes bytecode to the output file...
Passes.add(new WriteBytecodePass(Out));
// Run our queue of passes all at once now, efficiently.
Passes.run(*M);
return 0;
}
//
// Function: generate_assembly ()
//
// Description:
// This function 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.
//
// Outputs:
// None.
//
// Return value:
// 0 - Success
// 1 - Failure
//
int
generate_assembly (std::string OutputFilename,
std::string InputFilename,
std::string llc,
char ** const envp)
{
//
// Run LLC to convert the bytecode file into assembly code.
//
const char * cmd[8];
cmd[0] = llc.c_str();
cmd[1] = "-f";
cmd[2] = "-o";
cmd[3] = OutputFilename.c_str();
cmd[4] = InputFilename.c_str();
cmd[5] = NULL;
if ((ExecWait (cmd, envp)) == -1)
{
return 1;
}
return 0;
}
//
// Function: generate_native ()
//
// Description:
// This function 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.
// gcc - The pathname to use for GGC.
// envp - A copy of the process's current environment.
//
// Outputs:
// None.
//
// Return value:
// 0 - Success
// 1 - Failure
//
int
generate_native (std::string OutputFilename,
std::string InputFilename,
std::vector<std::string> Libraries,
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 it's environment.
//
char ** clean_env = copy_env (envp);
if (clean_env == NULL)
{
return 1;
}
remove_env ("LIBRARY_PATH", clean_env);
remove_env ("COLLECT_GCC_OPTIONS", clean_env);
remove_env ("GCC_EXEC_PREFIX", clean_env);
remove_env ("COMPILER_PATH", clean_env);
remove_env ("COLLECT_GCC", clean_env);
const char * cmd[8 + Libraries.size()];
//
// 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.
//
unsigned int index=0;
cmd[index++] = gcc.c_str();
cmd[index++] = "-o";
cmd[index++] = OutputFilename.c_str();
cmd[index++] = InputFilename.c_str();
for (; (index - 4) < Libraries.size(); index++)
{
Libraries[index - 4] = "-l" + Libraries[index - 4];
cmd[index] = Libraries[index-4].c_str();
}
cmd[index++] = NULL;
if ((ExecWait (cmd, clean_env)) == -1)
{
return 1;
}
return 0;
}

373
tools/gccld/gccld.cpp
View File

@ -26,11 +26,34 @@
#include "Support/CommandLine.h"
#include "Support/Signals.h"
#include "Config/unistd.h"
#include "util.h"
#include <fstream>
#include <memory>
#include <set>
#include <algorithm>
//
// External function prototypes
//
extern int
GenerateBytecode (Module * M,
bool Strip,
bool Internalize,
std::ofstream * Out);
extern int
generate_assembly (std::string OutputFilename,
std::string InputFilename,
std::string llc,
char ** const envp);
extern int
generate_native (std::string OutputFilename,
std::string InputFilename,
std::vector<std::string> Libraries,
std::string gcc,
char ** const envp);
namespace {
cl::list<std::string>
InputFilenames(cl::Positional, cl::desc("<input bytecode files>"),
@ -68,7 +91,7 @@ namespace {
cl::opt<bool>
Native("native", cl::desc("Generate a native binary instead of a shell script"));
// Compatibility options that are ignored, but support by LD
// Compatibility options that are ignored but supported by LD
cl::opt<std::string>
CO3("soname", cl::Hidden, cl::desc("Compatibility option: ignored"));
cl::opt<std::string>
@ -125,18 +148,6 @@ static Module *LoadSingleLibraryObject(const std::string &Filename) {
return M.release();
}
// IsArchive - Returns true iff FILENAME appears to be the name of an ar
// archive file. It determines this by checking the magic string at the
// beginning of the file.
static bool IsArchive(const std::string &filename) {
std::string ArchiveMagic("!<arch>\012");
char buf[1 + ArchiveMagic.size()];
std::ifstream f(filename.c_str());
f.read(buf, ArchiveMagic.size());
buf[ArchiveMagic.size()] = '\0';
return ArchiveMagic == buf;
}
// LoadLibraryExactName - This looks for a file with a known name and tries to
// load it, similarly to LoadLibraryFromDirectory().
static inline bool LoadLibraryExactName(const std::string &FileName,
@ -203,50 +214,6 @@ static inline bool LoadLibrary(const std::string &LibName,
return true;
}
static void GetAllDefinedSymbols(Module *M,
std::set<std::string> &DefinedSymbols) {
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
if (I->hasName() && !I->isExternal() && !I->hasInternalLinkage())
DefinedSymbols.insert(I->getName());
for (Module::giterator I = M->gbegin(), E = M->gend(); I != E; ++I)
if (I->hasName() && !I->isExternal() && !I->hasInternalLinkage())
DefinedSymbols.insert(I->getName());
}
// GetAllUndefinedSymbols - This calculates the set of undefined symbols that
// still exist in an LLVM module. This is a bit tricky because there may be two
// symbols with the same name, but different LLVM types that will be resolved to
// each other, but aren't currently (thus we need to treat it as resolved).
//
static void GetAllUndefinedSymbols(Module *M,
std::set<std::string> &UndefinedSymbols) {
std::set<std::string> DefinedSymbols;
UndefinedSymbols.clear(); // Start out empty
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
if (I->hasName()) {
if (I->isExternal())
UndefinedSymbols.insert(I->getName());
else if (!I->hasInternalLinkage())
DefinedSymbols.insert(I->getName());
}
for (Module::giterator I = M->gbegin(), E = M->gend(); I != E; ++I)
if (I->hasName()) {
if (I->isExternal())
UndefinedSymbols.insert(I->getName());
else if (!I->hasInternalLinkage())
DefinedSymbols.insert(I->getName());
}
// Prune out any defined symbols from the undefined symbols set...
for (std::set<std::string>::iterator I = UndefinedSymbols.begin();
I != UndefinedSymbols.end(); )
if (DefinedSymbols.count(*I))
UndefinedSymbols.erase(I++); // This symbol really is defined!
else
++I; // Keep this symbol in the undefined symbols list
}
static bool LinkLibrary(Module *M, const std::string &LibName,
bool search, std::string &ErrorMessage) {
@ -311,152 +278,10 @@ static bool LinkLibrary(Module *M, const std::string &LibName,
return false;
}
static int PrintAndReturn(const char *progname, const std::string &Message,
const std::string &Extra = "") {
std::cerr << progname << Extra << ": " << Message << "\n";
return 1;
}
//
//
// Function: copy_env()
//
// Description:
// 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.
//
// Outputs:
// None.
//
// 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 **
copy_env (char ** const envp)
int
main(int argc, char **argv, char ** envp)
{
// The new environment list
char ** newenv;
// The number of entries in the old environment list
int entries;
//
// Count the number of entries in the old list;
//
for (entries = 0; envp[entries] != NULL; entries++)
{
;
}
//
// 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.
//
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;
}
//
// Function: remove_env()
//
// Description:
// 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.
//
// Outputs:
// envp - The pointer to the specified variable name is removed.
//
// Return value:
// None.
//
// 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
remove_env (const char * name, char ** const envp)
{
// Pointer for scanning arrays
register char * p;
// Index for selecting elements of the environment array
register int index;
for (index=0; envp[index] != NULL; index++)
{
//
// Find the first equals sign in the array and make it an EOS character.
//
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;
}
int main(int argc, char **argv, char ** envp) {
cl::ParseCommandLineOptions(argc, argv, " llvm linker for GCC\n");
std::string ErrorMessage;
@ -502,77 +327,44 @@ int main(int argc, char **argv, char ** envp) {
for (unsigned i = 0; i != Libraries.size(); ++i) {
if (Verbose) std::cerr << "Linking in library: -l" << Libraries[i] << "\n";
if (LinkLibrary(Composite.get(), Libraries[i], true, ErrorMessage))
return PrintAndReturn(argv[0], ErrorMessage);
if (!Native)
return PrintAndReturn(argv[0], ErrorMessage);
}
// In addition to just linking the input from GCC, we also want to spiff it up
// a little bit. Do this now.
//
PassManager Passes;
// Add an appropriate TargetData instance for this module...
Passes.add(new TargetData("gccld", Composite.get()));
// Linking modules together can lead to duplicated global constants, only keep
// one copy of each constant...
// Create the output file.
//
Passes.add(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)
Passes.add(createSymbolStrippingPass());
// 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.
//
Passes.add(createFunctionResolvingPass());
if (!NoInternalize) {
// Now that composite has been compiled, scan through the module, looking
// for a main function. If main is defined, mark all other functions
// internal.
//
Passes.add(createInternalizePass());
}
// Remove unused arguments from functions...
//
Passes.add(createDeadArgEliminationPass());
// The FuncResolve pass may leave cruft around if functions were prototyped
// differently than they were defined. Remove this cruft.
//
Passes.add(createInstructionCombiningPass());
// Delete basic blocks, which optimization passes may have killed...
//
Passes.add(createCFGSimplificationPass());
// Now that we have optimized the program, discard unreachable functions...
//
Passes.add(createGlobalDCEPass());
// Add the pass that writes bytecode to the output file...
std::string RealBytecodeOutput = OutputFilename;
if (!LinkAsLibrary) RealBytecodeOutput += ".bc";
std::ofstream Out(RealBytecodeOutput.c_str());
if (!Out.good())
return PrintAndReturn(argv[0], "error opening '" + RealBytecodeOutput +
"' for writing!");
Passes.add(new WriteBytecodePass(&Out)); // Write bytecode to file...
// Make sure that the Out file gets unlink'd from the disk if we get a SIGINT
//
// Ensure that the bytecode file gets removed from the disk if we get a
// SIGINT signal.
//
RemoveFileOnSignal(RealBytecodeOutput);
// Run our queue of passes all at once now, efficiently.
Passes.run(*Composite.get());
//
// Generate the bytecode file.
//
if (GenerateBytecode (Composite.get(), Strip, !NoInternalize, &Out))
{
Out.close();
return PrintAndReturn(argv[0], "error generating bytcode");
}
//
// Close the bytecode file.
//
Out.close();
//
// If we are not linking a library, generate either a native executable
// or a JIT shell script, depending upon what the user wants.
//
if (!LinkAsLibrary) {
//
// If the user wants to generate a native executable, compile it from the
@ -582,25 +374,14 @@ int main(int argc, char **argv, char ** envp) {
//
if (Native)
{
// Name of the Assembly Language output file
std::string AssemblyFile = OutputFilename + ".s";
//
// 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.
// Mark the output files for removal if we get an interrupt.
//
// However, when we invoke GCC below, we want it to use its normal
// configuration. Hence, we must sanitize it's environment.
//
char ** clean_env = copy_env (envp);
if (clean_env == NULL)
{
return PrintAndReturn (argv[0], "Failed to duplicate environment");
}
remove_env ("LIBRARY_PATH", clean_env);
remove_env ("COLLECT_GCC_OPTIONS", clean_env);
remove_env ("GCC_EXEC_PREFIX", clean_env);
remove_env ("COMPILER_PATH", clean_env);
remove_env ("COLLECT_GCC", clean_env);
RemoveFileOnSignal (AssemblyFile);
RemoveFileOnSignal (OutputFilename);
//
// Determine the locations of the llc and gcc programs.
@ -618,49 +399,15 @@ int main(int argc, char **argv, char ** envp) {
}
//
// Run LLC to convert the bytecode file into assembly code.
// Generate an assembly language file for the bytecode.
//
const char * cmd[8];
std::string AssemblyFile = OutputFilename + ".s";
cmd[0] = llc.c_str();
cmd[1] = "-f";
cmd[2] = "-o";
cmd[3] = AssemblyFile.c_str();
cmd[4] = RealBytecodeOutput.c_str();
cmd[5] = NULL;
if ((ExecWait (cmd, clean_env)) == -1)
{
return PrintAndReturn (argv[0], "Failed to compile bytecode");
}
generate_assembly (AssemblyFile, RealBytecodeOutput, llc, envp);
generate_native (OutputFilename, AssemblyFile, Libraries, gcc, envp);
//
// Run GCC to assemble and link the program into native code.
// Remove the assembly language file.
//
// 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[0] = gcc.c_str();
cmd[1] = "-o";
cmd[2] = OutputFilename.c_str();
cmd[3] = AssemblyFile.c_str();
cmd[4] = NULL;
if ((ExecWait (cmd, clean_env)) == -1)
{
return PrintAndReturn (argv[0], "Failed to link native code file");
}
//
// The assembly file is no longer needed. Remove it, but do not exit
// if we fail to unlink it.
//
if (((access (AssemblyFile.c_str(), F_OK)) != -1) &&
((unlink (AssemblyFile.c_str())) == -1))
{
std::cerr << "Warning: Failed to unlink " << AssemblyFile << "\n";
}
removeFile (AssemblyFile);
}
else
{

287
tools/gccld/util.cpp Normal file
View File

@ -0,0 +1,287 @@
//===- util.cpp - Utility functions ---------------------------------------===//
//
// This file contains utility functions for gccld. It essentially holds
// anything from the original gccld.cpp source that was either incidental
// or not inlined.
//
//===----------------------------------------------------------------------===//
#include "llvm/Module.h"
#include "Config/string.h"
#include <fstream>
#include <string>
#include <set>
//
// Function: PrintAndReturn ()
//
// Description:
// Prints a message (usually error message) to standard error (stderr) and
// returns a value usable for an exit status.
//
// Inputs:
// progname - The name of the program (i.e. argv[0]).
// Message - The message to print to standard error.
// Extra - Extra information to print between the program name and thei
// message. It is optional.
//
// Outputs:
// None.
//
// Return value:
// Returns a value that can be used as the exit status (i.e. for exit()).
//
int
PrintAndReturn (const char *progname,
const std::string &Message,
const std::string &Extra = "")
{
std::cerr << progname << Extra << ": " << Message << "\n";
return 1;
}
//
// Function: IsArchive ()
//
// Description:
// Determine if the specified file is an ar archive. It determines this by
// checking the magic string at the beginning of the file.
//
// Inputs:
// filename - A C++ string containing the name of the file.
//
// Outputs:
// None.
//
// Return value:
// TRUE - The file is an archive.
// FALSE - The file is not an archive.
//
bool
IsArchive (const std::string &filename)
{
std::string ArchiveMagic("!<arch>\012");
char buf[1 + ArchiveMagic.size()];
std::ifstream f(filename.c_str());
f.read(buf, ArchiveMagic.size());
buf[ArchiveMagic.size()] = '\0';
return ArchiveMagic == buf;
}
//
// Function: GetAllDefinedSymbols ()
//
// Description:
// Find all of the defined symbols in the specified module.
//
// Inputs:
// M - The module in which to find defined symbols.
//
// Outputs:
// DefinedSymbols - A set of C++ strings that will contain the name of all
// defined symbols.
//
// Return value:
// None.
//
void
GetAllDefinedSymbols (Module *M, std::set<std::string> &DefinedSymbols)
{
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
if (I->hasName() && !I->isExternal() && !I->hasInternalLinkage())
DefinedSymbols.insert(I->getName());
for (Module::giterator I = M->gbegin(), E = M->gend(); I != E; ++I)
if (I->hasName() && !I->isExternal() && !I->hasInternalLinkage())
DefinedSymbols.insert(I->getName());
}
//
// Function: GetAllUndefinedSymbols ()
//
// Description:
// This calculates the set of undefined symbols that still exist in an LLVM
// module. This is a bit tricky because there may be two symbols with the
// same name but different LLVM types that will be resolved to each other but
// aren't currently (thus we need to treat it as resolved).
//
// Inputs:
// M - The module in which to find undefined symbols.
//
// Outputs:
// UndefinedSymbols - A set of C++ strings containing the name of all
// undefined symbols.
//
// Return value:
// None.
//
void
GetAllUndefinedSymbols(Module *M, std::set<std::string> &UndefinedSymbols)
{
std::set<std::string> DefinedSymbols;
UndefinedSymbols.clear(); // Start out empty
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
if (I->hasName()) {
if (I->isExternal())
UndefinedSymbols.insert(I->getName());
else if (!I->hasInternalLinkage())
DefinedSymbols.insert(I->getName());
}
for (Module::giterator I = M->gbegin(), E = M->gend(); I != E; ++I)
if (I->hasName()) {
if (I->isExternal())
UndefinedSymbols.insert(I->getName());
else if (!I->hasInternalLinkage())
DefinedSymbols.insert(I->getName());
}
// Prune out any defined symbols from the undefined symbols set...
for (std::set<std::string>::iterator I = UndefinedSymbols.begin();
I != UndefinedSymbols.end(); )
if (DefinedSymbols.count(*I))
UndefinedSymbols.erase(I++); // This symbol really is defined!
else
++I; // Keep this symbol in the undefined symbols list
}
//
//
// Function: copy_env()
//
// Description:
// 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.
//
// Outputs:
// None.
//
// 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).
//
char **
copy_env (char ** const envp)
{
// The new environment list
char ** newenv;
// The number of entries in the old environment list
int entries;
//
// Count the number of entries in the old list;
//
for (entries = 0; envp[entries] != NULL; entries++)
{
;
}
//
// 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.
//
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;
}
//
// Function: remove_env()
//
// Description:
// 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.
//
// Outputs:
// envp - The pointer to the specified variable name is removed.
//
// Return value:
// None.
//
// 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).
//
void
remove_env (const char * name, char ** const envp)
{
// Pointer for scanning arrays
register char * p;
// Index for selecting elements of the environment array
register int index;
for (index=0; envp[index] != NULL; index++)
{
//
// Find the first equals sign in the array and make it an EOS character.
//
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;
}

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//===- util.h - Utility functions header file -----------------------------===//
//
// This file contains function prototypes for the functions in util.cpp.
//
//===----------------------------------------------------------------------===//
#include "llvm/Module.h"
#include <string>
#include <set>
extern int
PrintAndReturn (const char *progname,
const std::string &Message,
const std::string &Extra = "");
extern bool
IsArchive (const std::string &filename);
extern void
GetAllDefinedSymbols (Module *M, std::set<std::string> &DefinedSymbols);
extern void
GetAllUndefinedSymbols(Module *M, std::set<std::string> &UndefinedSymbols);
extern char **
copy_env (char ** const envp);
extern void
remove_env (const char * name, char ** const envp);