1 //===-- Passes.h - Target independent code generation passes ----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines interfaces to access the target independent code generation
11 // passes provided by the LLVM backend.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CODEGEN_PASSES_H
16 #define LLVM_CODEGEN_PASSES_H
27 /// createUnreachableBlockEliminationPass - The LLVM code generator does not
28 /// work well with unreachable basic blocks (what live ranges make sense for a
29 /// block that cannot be reached?). As such, a code generator should either
30 /// not instruction select unreachable blocks, or it can run this pass as it's
31 /// last LLVM modifying pass to clean up blocks that are not reachable from
33 FunctionPass *createUnreachableBlockEliminationPass();
35 /// MachineFunctionPrinter pass - This pass prints out the machine function to
36 /// standard error, as a debugging tool.
37 FunctionPass *createMachineFunctionPrinterPass(std::ostream *OS,
38 const std::string &Banner ="");
40 /// PHIElimination pass - This pass eliminates machine instruction PHI nodes
41 /// by inserting copy instructions. This destroys SSA information, but is the
42 /// desired input for some register allocators. This pass is "required" by
43 /// these register allocator like this: AU.addRequiredID(PHIEliminationID);
45 extern const PassInfo *PHIEliminationID;
47 /// SimpleRegisterCoalescing pass. Aggressively coalesces every register
50 extern const PassInfo *SimpleRegisterCoalescingID;
52 /// TwoAddressInstruction pass - This pass reduces two-address instructions to
53 /// use two operands. This destroys SSA information but it is desired by
54 /// register allocators.
55 extern const PassInfo *TwoAddressInstructionPassID;
57 /// Creates a register allocator as the user specified on the command line.
59 FunctionPass *createRegisterAllocator();
61 /// SimpleRegisterAllocation Pass - This pass converts the input machine code
62 /// from SSA form to use explicit registers by spilling every register. Wow,
65 FunctionPass *createSimpleRegisterAllocator();
67 /// LocalRegisterAllocation Pass - This pass register allocates the input code
68 /// a basic block at a time, yielding code better than the simple register
69 /// allocator, but not as good as a global allocator.
71 FunctionPass *createLocalRegisterAllocator();
73 /// BigBlockRegisterAllocation Pass - The BigBlock register allocator
74 /// munches single basic blocks at a time, like the local register
75 /// allocator. While the BigBlock allocator is a little slower, and uses
76 /// somewhat more memory than the local register allocator, it tends to
77 /// yield the best allocations (of any of the allocators) for blocks that
78 /// have hundreds or thousands of instructions in sequence.
80 FunctionPass *createBigBlockRegisterAllocator();
82 /// LinearScanRegisterAllocation Pass - This pass implements the linear scan
83 /// register allocation algorithm, a global register allocator.
85 FunctionPass *createLinearScanRegisterAllocator();
87 /// PrologEpilogCodeInserter Pass - This pass inserts prolog and epilog code,
88 /// and eliminates abstract frame references.
90 FunctionPass *createPrologEpilogCodeInserter();
92 /// LowerSubregs Pass - This pass lowers subregs to register-register copies
93 /// which yields suboptimal, but correct code if the register allocator
94 /// cannot coalesce all subreg operations during allocation.
96 FunctionPass *createLowerSubregsPass();
98 /// createPostRAScheduler - under development.
99 FunctionPass *createPostRAScheduler();
101 /// BranchFolding Pass - This pass performs machine code CFG based
102 /// optimizations to delete branches to branches, eliminate branches to
103 /// successor blocks (creating fall throughs), and eliminating branches over
105 FunctionPass *createBranchFoldingPass(bool DefaultEnableTailMerge);
107 /// IfConverter Pass - This pass performs machine code if conversion.
108 FunctionPass *createIfConverterPass();
110 /// DebugLabelFoldingPass - This pass prunes out redundant debug labels. This
111 /// allows a debug emitter to determine if the range of two labels is empty,
112 /// by seeing if the labels map to the same reduced label.
113 FunctionPass *createDebugLabelFoldingPass();
115 /// MachineCodeDeletion Pass - This pass deletes all of the machine code for
116 /// the current function, which should happen after the function has been
117 /// emitted to a .s file or to memory.
118 FunctionPass *createMachineCodeDeleter();
120 /// getRegisterAllocator - This creates an instance of the register allocator
122 FunctionPass *getRegisterAllocator(TargetMachine &T);
124 } // End llvm namespace