1 //===- Optimize.cpp - Optimize a complete program -------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by Reid Spencer and is distributed under the
6 // University of Illinois Open Source 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/Verifier.h"
19 #include "llvm/Support/CommandLine.h"
20 #include "llvm/System/DynamicLibrary.h"
21 #include "llvm/Target/TargetData.h"
22 #include "llvm/Target/TargetMachine.h"
23 #include "llvm/Transforms/IPO.h"
24 #include "llvm/Transforms/Scalar.h"
25 #include "llvm/Support/PassNameParser.h"
26 #include "llvm/Support/PluginLoader.h"
29 // Pass Name Options as generated by the PassNameParser
30 static cl::list<const PassInfo*, bool, PassNameParser>
31 OptimizationList(cl::desc("Optimizations available:"));
33 // Optimization Enumeration
34 enum OptimizationLevels {
39 OPT_AGGRESSIVE_LINK_TIME = 5
42 // Optimization Options
43 static cl::opt<OptimizationLevels> OptLevel(
44 cl::desc("Choose level of optimization to apply:"),
45 cl::init(OPT_FAST_COMPILE), cl::values(
46 clEnumValN(OPT_FAST_COMPILE,"O0",
47 "An alias for the -O1 option."),
48 clEnumValN(OPT_FAST_COMPILE,"O1",
49 "Optimize for linking speed, not execution speed."),
50 clEnumValN(OPT_SIMPLE,"O2",
51 "Perform only required/minimal optimizations"),
52 clEnumValN(OPT_AGGRESSIVE,"O3",
53 "An alias for the -O2 option."),
54 clEnumValN(OPT_LINK_TIME,"O4",
55 "Perform standard link time optimizations"),
56 clEnumValN(OPT_AGGRESSIVE_LINK_TIME,"O5",
57 "Perform aggressive link time optimizations"),
62 static cl::opt<bool> DisableInline("disable-inlining",
63 cl::desc("Do not run the inliner pass"));
66 DisableOptimizations("disable-opt",
67 cl::desc("Do not run any optimization passes"));
69 static cl::opt<bool> DisableInternalize("disable-internalize",
70 cl::desc("Do not mark all symbols as internal"));
72 static cl::opt<bool> VerifyEach("verify-each",
73 cl::desc("Verify intermediate results of all passes"));
75 static cl::opt<bool> Strip("s",
76 cl::desc("Strip symbol info from executable"));
78 static cl::alias ExportDynamic("export-dynamic",
79 cl::aliasopt(DisableInternalize),
80 cl::desc("Alias for -disable-internalize"));
82 // A utility function that adds a pass to the pass manager but will also add
83 // a verifier pass after if we're supposed to verify.
84 static inline void addPass(PassManager &PM, Pass *P) {
85 // Add the pass to the pass manager...
88 // If we are verifying all of the intermediate steps, add the verifier...
90 PM.add(createVerifierPass());
95 /// Optimize - Perform link time optimizations. This will run the scalar
96 /// optimizations, any loaded plugin-optimization modules, and then the
97 /// inter-procedural optimizations if applicable.
98 void Optimize(Module* M) {
100 // Instantiate the pass manager to organize the passes.
103 // If we're verifying, start off with a verification pass.
105 Passes.add(createVerifierPass());
107 // Add an appropriate TargetData instance for this module...
108 addPass(Passes, new TargetData(M));
110 // Often if the programmer does not specify proper prototypes for the
111 // functions they are calling, they end up calling a vararg version of the
112 // function that does not get a body filled in (the real function has typed
113 // arguments). This pass merges the two functions.
114 addPass(Passes, createFunctionResolvingPass());
116 if (!DisableOptimizations) {
117 // Now that composite has been compiled, scan through the module, looking
118 // for a main function. If main is defined, mark all other functions
120 addPass(Passes, createInternalizePass(!DisableInternalize));
122 // Now that we internalized some globals, see if we can hack on them!
123 addPass(Passes, createGlobalOptimizerPass());
125 // Linking modules together can lead to duplicated global constants, only
126 // keep one copy of each constant...
127 addPass(Passes, createConstantMergePass());
129 // If the -s command line option was specified, strip the symbols out of the
130 // resulting program to make it smaller. -s is a GLD option that we are
133 addPass(Passes, createStripSymbolsPass());
135 // Propagate constants at call sites into the functions they call.
136 addPass(Passes, createIPConstantPropagationPass());
138 // Remove unused arguments from functions...
139 addPass(Passes, createDeadArgEliminationPass());
142 addPass(Passes, createFunctionInliningPass()); // Inline small functions
144 addPass(Passes, createPruneEHPass()); // Remove dead EH info
145 addPass(Passes, createGlobalDCEPass()); // Remove dead functions
147 // If we didn't decide to inline a function, check to see if we can
148 // transform it to pass arguments by value instead of by reference.
149 addPass(Passes, createArgumentPromotionPass());
151 // The IPO passes may leave cruft around. Clean up after them.
152 addPass(Passes, createInstructionCombiningPass());
154 addPass(Passes, createScalarReplAggregatesPass()); // Break up allocas
156 // Run a few AA driven optimizations, to cleanup the code.
157 addPass(Passes, createGlobalsModRefPass()); // IP alias analysis
158 addPass(Passes, createLICMPass()); // Hoist loop invariants
159 addPass(Passes, createLoadValueNumberingPass()); // GVN for load instrs
160 addPass(Passes, createGCSEPass()); // Remove common subexprs
161 addPass(Passes, createDeadStoreEliminationPass()); // Nuke dead stores
163 // Cleanup and simplify the code after the scalar optimizations.
164 addPass(Passes, createInstructionCombiningPass());
166 // Delete basic blocks, which optimization passes may have killed...
167 addPass(Passes, createCFGSimplificationPass());
169 // Now that we have optimized the program, discard unreachable functions...
170 addPass(Passes, createGlobalDCEPass());
173 // Create a new optimization pass for each one specified on the command line
174 std::auto_ptr<TargetMachine> target;
175 for (unsigned i = 0; i < OptimizationList.size(); ++i) {
176 const PassInfo *Opt = OptimizationList[i];
177 if (Opt->getNormalCtor())
178 addPass(Passes, Opt->getNormalCtor()());
179 else if (Opt->getTargetCtor()) {
180 assert(target.get() && "Could not allocate target machine!");
181 addPass(Passes, Opt->getTargetCtor()(*target.get()));
183 std::cerr << "llvm-ld: cannot create pass: " << Opt->getPassName()
187 // The user's passes may leave cruft around. Clean up after them them but
188 // only if we haven't got DisableOptimizations set
189 if (!DisableOptimizations) {
190 addPass(Passes, createInstructionCombiningPass());
191 addPass(Passes, createCFGSimplificationPass());
192 addPass(Passes, createGlobalDCEPass());
195 // Make sure everything is still good.
196 Passes.add(createVerifierPass());
198 // Run our queue of passes all at once now, efficiently.