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"
30 // Pass Name Options as generated by the PassNameParser
31 static cl::list<const PassInfo*, bool, PassNameParser>
32 OptimizationList(cl::desc("Optimizations available:"));
34 // Optimization Enumeration
35 enum OptimizationLevels {
40 OPT_AGGRESSIVE_LINK_TIME = 5
43 // Optimization Options
44 static cl::opt<OptimizationLevels> OptLevel(
45 cl::desc("Choose level of optimization to apply:"),
46 cl::init(OPT_FAST_COMPILE), cl::values(
47 clEnumValN(OPT_FAST_COMPILE,"O0",
48 "An alias for the -O1 option."),
49 clEnumValN(OPT_FAST_COMPILE,"O1",
50 "Optimize for linking speed, not execution speed."),
51 clEnumValN(OPT_SIMPLE,"O2",
52 "Perform only required/minimal optimizations"),
53 clEnumValN(OPT_AGGRESSIVE,"O3",
54 "An alias for the -O2 option."),
55 clEnumValN(OPT_LINK_TIME,"O4",
56 "Perform standard link time optimizations"),
57 clEnumValN(OPT_AGGRESSIVE_LINK_TIME,"O5",
58 "Perform aggressive link time optimizations"),
63 static cl::opt<bool> DisableInline("disable-inlining",
64 cl::desc("Do not run the inliner pass"));
67 DisableOptimizations("disable-opt",
68 cl::desc("Do not run any optimization passes"));
70 static cl::opt<bool> DisableInternalize("disable-internalize",
71 cl::desc("Do not mark all symbols as internal"));
73 static cl::opt<bool> VerifyEach("verify-each",
74 cl::desc("Verify intermediate results of all passes"));
76 static cl::opt<bool> Strip("s",
77 cl::desc("Strip symbol info from executable"));
79 static cl::alias ExportDynamic("export-dynamic",
80 cl::aliasopt(DisableInternalize),
81 cl::desc("Alias for -disable-internalize"));
83 // A utility function that adds a pass to the pass manager but will also add
84 // a verifier pass after if we're supposed to verify.
85 static inline void addPass(PassManager &PM, Pass *P) {
86 // Add the pass to the pass manager...
89 // If we are verifying all of the intermediate steps, add the verifier...
91 PM.add(createVerifierPass());
96 /// Optimize - Perform link time optimizations. This will run the scalar
97 /// optimizations, any loaded plugin-optimization modules, and then the
98 /// inter-procedural optimizations if applicable.
99 void Optimize(Module* M) {
101 // Instantiate the pass manager to organize the passes.
104 // If we're verifying, start off with a verification pass.
106 Passes.add(createVerifierPass());
108 // Add an appropriate TargetData instance for this module...
109 addPass(Passes, new TargetData(M));
111 // Often if the programmer does not specify proper prototypes for the
112 // functions they are calling, they end up calling a vararg version of the
113 // function that does not get a body filled in (the real function has typed
114 // arguments). This pass merges the two functions.
115 addPass(Passes, createFunctionResolvingPass());
117 if (!DisableOptimizations) {
118 // Now that composite has been compiled, scan through the module, looking
119 // for a main function. If main is defined, mark all other functions
121 addPass(Passes, createInternalizePass(!DisableInternalize));
123 // Now that we internalized some globals, see if we can hack on them!
124 addPass(Passes, createGlobalOptimizerPass());
126 // Linking modules together can lead to duplicated global constants, only
127 // keep one copy of each constant...
128 addPass(Passes, createConstantMergePass());
130 // If the -s command line option was specified, strip the symbols out of the
131 // resulting program to make it smaller. -s is a GLD option that we are
134 addPass(Passes, createStripSymbolsPass());
136 // Propagate constants at call sites into the functions they call.
137 addPass(Passes, createIPConstantPropagationPass());
139 // Remove unused arguments from functions...
140 addPass(Passes, createDeadArgEliminationPass());
143 addPass(Passes, createFunctionInliningPass()); // Inline small functions
145 addPass(Passes, createPruneEHPass()); // Remove dead EH info
146 addPass(Passes, createGlobalDCEPass()); // Remove dead functions
148 // If we didn't decide to inline a function, check to see if we can
149 // transform it to pass arguments by value instead of by reference.
150 addPass(Passes, createArgumentPromotionPass());
152 // The IPO passes may leave cruft around. Clean up after them.
153 addPass(Passes, createInstructionCombiningPass());
155 addPass(Passes, createScalarReplAggregatesPass()); // Break up allocas
157 // Run a few AA driven optimizations, to cleanup the code.
158 addPass(Passes, createGlobalsModRefPass()); // IP alias analysis
159 addPass(Passes, createLICMPass()); // Hoist loop invariants
160 addPass(Passes, createLoadValueNumberingPass()); // GVN for load instrs
161 addPass(Passes, createGCSEPass()); // Remove common subexprs
162 addPass(Passes, createDeadStoreEliminationPass()); // Nuke dead stores
164 // Cleanup and simplify the code after the scalar optimizations.
165 addPass(Passes, createInstructionCombiningPass());
167 // Delete basic blocks, which optimization passes may have killed...
168 addPass(Passes, createCFGSimplificationPass());
170 // Now that we have optimized the program, discard unreachable functions...
171 addPass(Passes, createGlobalDCEPass());
174 // Create a new optimization pass for each one specified on the command line
175 std::auto_ptr<TargetMachine> target;
176 for (unsigned i = 0; i < OptimizationList.size(); ++i) {
177 const PassInfo *Opt = OptimizationList[i];
178 if (Opt->getNormalCtor())
179 addPass(Passes, Opt->getNormalCtor()());
181 std::cerr << "llvm-ld: cannot create pass: " << Opt->getPassName()
185 // The user's passes may leave cruft around. Clean up after them them but
186 // only if we haven't got DisableOptimizations set
187 if (!DisableOptimizations) {
188 addPass(Passes, createInstructionCombiningPass());
189 addPass(Passes, createCFGSimplificationPass());
190 addPass(Passes, createGlobalDCEPass());
193 // Make sure everything is still good.
194 Passes.add(createVerifierPass());
196 // Run our queue of passes all at once now, efficiently.