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Diffstat (limited to 'tools/llvm-ld/Optimize.cpp')
-rw-r--r-- | tools/llvm-ld/Optimize.cpp | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/tools/llvm-ld/Optimize.cpp b/tools/llvm-ld/Optimize.cpp new file mode 100644 index 0000000..308fd54 --- /dev/null +++ b/tools/llvm-ld/Optimize.cpp @@ -0,0 +1,216 @@ +//===- Optimize.cpp - Optimize a complete program -------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file was developed by Reid Spencer and is distributed under the +// University of Illinois Open Source License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements all optimization of the linked module for llvm-ld. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Module.h" +#include "llvm/PassManager.h" +#include "llvm/Analysis/LoadValueNumbering.h" +#include "llvm/Analysis/Passes.h" +#include "llvm/Analysis/LoopPass.h" +#include "llvm/Analysis/Verifier.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/System/DynamicLibrary.h" +#include "llvm/Target/TargetData.h" +#include "llvm/Target/TargetMachine.h" +#include "llvm/Transforms/IPO.h" +#include "llvm/Transforms/Scalar.h" +#include "llvm/Support/PassNameParser.h" +#include "llvm/Support/PluginLoader.h" +#include <iostream> +using namespace llvm; + +// Pass Name Options as generated by the PassNameParser +static cl::list<const PassInfo*, bool, PassNameParser> + OptimizationList(cl::desc("Optimizations available:")); + +// Optimization Enumeration +enum OptimizationLevels { + OPT_FAST_COMPILE = 1, + OPT_SIMPLE = 2, + OPT_AGGRESSIVE = 3, + OPT_LINK_TIME = 4, + OPT_AGGRESSIVE_LINK_TIME = 5 +}; + +// Optimization Options +static cl::opt<OptimizationLevels> OptLevel( + cl::desc("Choose level of optimization to apply:"), + cl::init(OPT_FAST_COMPILE), cl::values( + clEnumValN(OPT_FAST_COMPILE,"O0", + "An alias for the -O1 option."), + clEnumValN(OPT_FAST_COMPILE,"O1", + "Optimize for linking speed, not execution speed."), + clEnumValN(OPT_SIMPLE,"O2", + "Perform only required/minimal optimizations"), + clEnumValN(OPT_AGGRESSIVE,"O3", + "An alias for the -O2 option."), + clEnumValN(OPT_LINK_TIME,"O4", + "Perform standard link time optimizations"), + clEnumValN(OPT_AGGRESSIVE_LINK_TIME,"O5", + "Perform aggressive link time optimizations"), + clEnumValEnd + ) +); + +static cl::opt<bool> DisableInline("disable-inlining", + cl::desc("Do not run the inliner pass")); + +static cl::opt<bool> +DisableOptimizations("disable-opt", + cl::desc("Do not run any optimization passes")); + +static cl::opt<bool> DisableInternalize("disable-internalize", + cl::desc("Do not mark all symbols as internal")); + +static cl::opt<bool> VerifyEach("verify-each", + cl::desc("Verify intermediate results of all passes")); + +static cl::alias ExportDynamic("export-dynamic", + cl::aliasopt(DisableInternalize), + cl::desc("Alias for -disable-internalize")); + +static cl::opt<bool> Strip("strip-all", + cl::desc("Strip all symbol info from executable")); + +static cl::alias A0("s", cl::desc("Alias for --strip-all"), + cl::aliasopt(Strip)); + +static cl::opt<bool> StripDebug("strip-debug", + cl::desc("Strip debugger symbol info from executable")); + +static cl::alias A1("S", cl::desc("Alias for --strip-debug"), + cl::aliasopt(StripDebug)); + +// A utility function that adds a pass to the pass manager but will also add +// a verifier pass after if we're supposed to verify. +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 (VerifyEach) + PM.add(createVerifierPass()); +} + +namespace llvm { + +/// Optimize - Perform link time optimizations. This will run the scalar +/// optimizations, any loaded plugin-optimization modules, and then the +/// inter-procedural optimizations if applicable. +void Optimize(Module* M) { + + // Instantiate the pass manager to organize the passes. + PassManager Passes; + + // If we're verifying, start off with a verification pass. + if (VerifyEach) + Passes.add(createVerifierPass()); + + // Add an appropriate TargetData instance for this module... + addPass(Passes, new TargetData(M)); + + if (!DisableOptimizations) { + // Now that composite has been compiled, scan through the module, looking + // for a main function. If main is defined, mark all other functions + // internal. + if (!DisableInternalize) + addPass(Passes, createInternalizePass(true)); + + // Propagate constants at call sites into the functions they call. This + // opens opportunities for globalopt (and inlining) by substituting function + // pointers passed as arguments to direct uses of functions. + addPass(Passes, createIPSCCPPass()); + + // 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()); + + // Remove unused arguments from functions... + addPass(Passes, createDeadArgEliminationPass()); + + // Reduce the code after globalopt and ipsccp. Both can open up significant + // simplification opportunities, and both can propagate functions through + // function pointers. When this happens, we often have to resolve varargs + // calls, etc, so let instcombine do this. + addPass(Passes, createInstructionCombiningPass()); + + 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, createFastDeadStoreEliminationPass()); // 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 GNU ld options + // that we are supporting; they alias -strip-all and -strip-debug. + if (Strip || StripDebug) + addPass(Passes, createStripSymbolsPass(StripDebug && !Strip)); + + // Create a new optimization pass for each one specified on the command line + std::auto_ptr<TargetMachine> target; + for (unsigned i = 0; i < OptimizationList.size(); ++i) { + const PassInfo *Opt = OptimizationList[i]; + if (Opt->getNormalCtor()) + addPass(Passes, Opt->getNormalCtor()()); + else + std::cerr << "llvm-ld: cannot create pass: " << Opt->getPassName() + << "\n"; + } + + // The user's passes may leave cruft around. Clean up after them them but + // only if we haven't got DisableOptimizations set + if (!DisableOptimizations) { + addPass(Passes, createInstructionCombiningPass()); + addPass(Passes, createCFGSimplificationPass()); + addPass(Passes, createDeadCodeEliminationPass()); + addPass(Passes, createGlobalDCEPass()); + } + + // Make sure everything is still good. + Passes.add(createVerifierPass()); + + // Run our queue of passes all at once now, efficiently. + Passes.run(*M); +} + +} |