1 //===- Optimize.cpp - Optimize a complete program -------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements all optimization of the linked module for llvm-ld.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Module.h"
15 #include "llvm/PassManager.h"
16 #include "llvm/Analysis/LoadValueNumbering.h"
17 #include "llvm/Analysis/Passes.h"
18 #include "llvm/Analysis/LoopPass.h"
19 #include "llvm/Analysis/Verifier.h"
20 #include "llvm/Support/CommandLine.h"
21 #include "llvm/System/DynamicLibrary.h"
22 #include "llvm/Target/TargetData.h"
23 #include "llvm/Target/TargetMachine.h"
24 #include "llvm/Transforms/IPO.h"
25 #include "llvm/Transforms/Scalar.h"
26 #include "llvm/Support/PassNameParser.h"
27 #include "llvm/Support/PluginLoader.h"
31 // Pass Name Options as generated by the PassNameParser
32 static cl::list<const PassInfo*, bool, PassNameParser>
33 OptimizationList(cl::desc("Optimizations available:"));
35 //Don't verify at the end
36 static cl::opt<bool> DontVerify("disable-verify", cl::ReallyHidden);
38 static cl::opt<bool> DisableInline("disable-inlining",
39 cl::desc("Do not run the inliner pass"));
42 DisableOptimizations("disable-opt",
43 cl::desc("Do not run any optimization passes"));
45 static cl::opt<bool> DisableInternalize("disable-internalize",
46 cl::desc("Do not mark all symbols as internal"));
48 static cl::opt<bool> VerifyEach("verify-each",
49 cl::desc("Verify intermediate results of all passes"));
51 static cl::alias ExportDynamic("export-dynamic",
52 cl::aliasopt(DisableInternalize),
53 cl::desc("Alias for -disable-internalize"));
55 static cl::opt<bool> Strip("strip-all",
56 cl::desc("Strip all symbol info from executable"));
58 static cl::alias A0("s", cl::desc("Alias for --strip-all"),
61 static cl::opt<bool> StripDebug("strip-debug",
62 cl::desc("Strip debugger symbol info from executable"));
64 static cl::alias A1("S", cl::desc("Alias for --strip-debug"),
65 cl::aliasopt(StripDebug));
67 // A utility function that adds a pass to the pass manager but will also add
68 // a verifier pass after if we're supposed to verify.
69 static inline void addPass(PassManager &PM, Pass *P) {
70 // Add the pass to the pass manager...
73 // If we are verifying all of the intermediate steps, add the verifier...
75 PM.add(createVerifierPass());
80 /// Optimize - Perform link time optimizations. This will run the scalar
81 /// optimizations, any loaded plugin-optimization modules, and then the
82 /// inter-procedural optimizations if applicable.
83 void Optimize(Module* M) {
85 // Instantiate the pass manager to organize the passes.
88 // If we're verifying, start off with a verification pass.
90 Passes.add(createVerifierPass());
92 // Add an appropriate TargetData instance for this module...
93 addPass(Passes, new TargetData(M));
95 if (!DisableOptimizations) {
96 // Now that composite has been compiled, scan through the module, looking
97 // for a main function. If main is defined, mark all other functions
99 if (!DisableInternalize)
100 addPass(Passes, createInternalizePass(true));
102 // Propagate constants at call sites into the functions they call. This
103 // opens opportunities for globalopt (and inlining) by substituting function
104 // pointers passed as arguments to direct uses of functions.
105 addPass(Passes, createIPSCCPPass());
107 // Now that we internalized some globals, see if we can hack on them!
108 addPass(Passes, createGlobalOptimizerPass());
110 // Linking modules together can lead to duplicated global constants, only
111 // keep one copy of each constant...
112 addPass(Passes, createConstantMergePass());
114 // Remove unused arguments from functions...
115 addPass(Passes, createDeadArgEliminationPass());
117 // Reduce the code after globalopt and ipsccp. Both can open up significant
118 // simplification opportunities, and both can propagate functions through
119 // function pointers. When this happens, we often have to resolve varargs
120 // calls, etc, so let instcombine do this.
121 addPass(Passes, createInstructionCombiningPass());
124 addPass(Passes, createFunctionInliningPass()); // Inline small functions
126 addPass(Passes, createPruneEHPass()); // Remove dead EH info
127 addPass(Passes, createGlobalOptimizerPass()); // Optimize globals again.
128 addPass(Passes, createGlobalDCEPass()); // Remove dead functions
130 // If we didn't decide to inline a function, check to see if we can
131 // transform it to pass arguments by value instead of by reference.
132 addPass(Passes, createArgumentPromotionPass());
134 // The IPO passes may leave cruft around. Clean up after them.
135 addPass(Passes, createInstructionCombiningPass());
136 addPass(Passes, createJumpThreadingPass()); // Thread jumps.
137 addPass(Passes, createScalarReplAggregatesPass()); // Break up allocas
139 // Run a few AA driven optimizations here and now, to cleanup the code.
140 addPass(Passes, createGlobalsModRefPass()); // IP alias analysis
142 addPass(Passes, createLICMPass()); // Hoist loop invariants
143 addPass(Passes, createGVNPass()); // Remove redundancies
144 addPass(Passes, createMemCpyOptPass()); // Remove dead memcpy's
145 addPass(Passes, createDeadStoreEliminationPass()); // Nuke dead stores
147 // Cleanup and simplify the code after the scalar optimizations.
148 addPass(Passes, createInstructionCombiningPass());
150 addPass(Passes, createJumpThreadingPass()); // Thread jumps.
151 addPass(Passes, createPromoteMemoryToRegisterPass()); // Cleanup jumpthread.
153 // Delete basic blocks, which optimization passes may have killed...
154 addPass(Passes, createCFGSimplificationPass());
156 // Now that we have optimized the program, discard unreachable functions...
157 addPass(Passes, createGlobalDCEPass());
160 // If the -s or -S command line options were specified, strip the symbols out
161 // of the resulting program to make it smaller. -s and -S are GNU ld options
162 // that we are supporting; they alias -strip-all and -strip-debug.
163 if (Strip || StripDebug)
164 addPass(Passes, createStripSymbolsPass(StripDebug && !Strip));
166 // Create a new optimization pass for each one specified on the command line
167 std::auto_ptr<TargetMachine> target;
168 for (unsigned i = 0; i < OptimizationList.size(); ++i) {
169 const PassInfo *Opt = OptimizationList[i];
170 if (Opt->getNormalCtor())
171 addPass(Passes, Opt->getNormalCtor()());
173 std::cerr << "llvm-ld: cannot create pass: " << Opt->getPassName()
177 // The user's passes may leave cruft around. Clean up after them them but
178 // only if we haven't got DisableOptimizations set
179 if (!DisableOptimizations) {
180 addPass(Passes, createInstructionCombiningPass());
181 addPass(Passes, createCFGSimplificationPass());
182 addPass(Passes, createDeadCodeEliminationPass());
183 addPass(Passes, createGlobalDCEPass());
186 // Make sure everything is still good.
188 Passes.add(createVerifierPass());
190 // Run our queue of passes all at once now, efficiently.