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a56dc5d07f
Summary:
Control height reduction merges conditional blocks of code and reduces the
number of conditional branches in the hot path based on profiles.
if (hot_cond1) { // Likely true.
do_stg_hot1();
}
if (hot_cond2) { // Likely true.
do_stg_hot2();
}
->
if (hot_cond1 && hot_cond2) { // Hot path.
do_stg_hot1();
do_stg_hot2();
} else { // Cold path.
if (hot_cond1) {
do_stg_hot1();
}
if (hot_cond2) {
do_stg_hot2();
}
}
This speeds up some internal benchmarks up to ~30%.
Reviewers: davidxl
Reviewed By: davidxl
Subscribers: xbolva00, dmgreen, mehdi_amini, llvm-commits, mgorny
Differential Revision: https://reviews.llvm.org/D50591
llvm-svn: 341386
126 lines
4.3 KiB
C++
126 lines
4.3 KiB
C++
//===- llvm/Transforms/Utils.h - Utility Transformations --------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This header file defines prototypes for accessor functions that expose passes
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// in the Utils transformations library.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TRANSFORMS_UTILS_H
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#define LLVM_TRANSFORMS_UTILS_H
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namespace llvm {
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class ModulePass;
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class FunctionPass;
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class Pass;
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//===----------------------------------------------------------------------===//
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// createMetaRenamerPass - Rename everything with metasyntatic names.
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//
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ModulePass *createMetaRenamerPass();
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//===----------------------------------------------------------------------===//
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//
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// LowerInvoke - This pass removes invoke instructions, converting them to call
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// instructions.
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//
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FunctionPass *createLowerInvokePass();
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extern char &LowerInvokePassID;
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//===----------------------------------------------------------------------===//
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//
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// InstructionNamer - Give any unnamed non-void instructions "tmp" names.
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//
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FunctionPass *createInstructionNamerPass();
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extern char &InstructionNamerID;
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//===----------------------------------------------------------------------===//
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//
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// LowerSwitch - This pass converts SwitchInst instructions into a sequence of
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// chained binary branch instructions.
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//
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FunctionPass *createLowerSwitchPass();
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extern char &LowerSwitchID;
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//===----------------------------------------------------------------------===//
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//
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// EntryExitInstrumenter pass - Instrument function entry/exit with calls to
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// mcount(), @__cyg_profile_func_{enter,exit} and the like. There are two
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// variants, intended to run pre- and post-inlining, respectively.
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//
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FunctionPass *createEntryExitInstrumenterPass();
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FunctionPass *createPostInlineEntryExitInstrumenterPass();
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//===----------------------------------------------------------------------===//
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//
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// BreakCriticalEdges - Break all of the critical edges in the CFG by inserting
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// a dummy basic block. This pass may be "required" by passes that cannot deal
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// with critical edges. For this usage, a pass must call:
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//
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// AU.addRequiredID(BreakCriticalEdgesID);
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//
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// This pass obviously invalidates the CFG, but can update forward dominator
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// (set, immediate dominators, tree, and frontier) information.
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//
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FunctionPass *createBreakCriticalEdgesPass();
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extern char &BreakCriticalEdgesID;
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//===----------------------------------------------------------------------===//
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//
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// LCSSA - This pass inserts phi nodes at loop boundaries to simplify other loop
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// optimizations.
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//
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Pass *createLCSSAPass();
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extern char &LCSSAID;
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//===----------------------------------------------------------------------===//
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//
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// AddDiscriminators - Add DWARF path discriminators to the IR.
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FunctionPass *createAddDiscriminatorsPass();
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//===----------------------------------------------------------------------===//
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//
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// PromoteMemoryToRegister - This pass is used to promote memory references to
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// be register references. A simple example of the transformation performed by
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// this pass is:
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//
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// FROM CODE TO CODE
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// %X = alloca i32, i32 1 ret i32 42
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// store i32 42, i32 *%X
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// %Y = load i32* %X
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// ret i32 %Y
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//
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FunctionPass *createPromoteMemoryToRegisterPass();
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//===----------------------------------------------------------------------===//
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//
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// LoopSimplify - Insert Pre-header blocks into the CFG for every function in
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// the module. This pass updates dominator information, loop information, and
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// does not add critical edges to the CFG.
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//
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// AU.addRequiredID(LoopSimplifyID);
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//
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Pass *createLoopSimplifyPass();
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extern char &LoopSimplifyID;
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/// This function returns a new pass that downgrades the debug info in the
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/// module to line tables only.
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ModulePass *createStripNonLineTableDebugInfoPass();
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//===----------------------------------------------------------------------===//
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//
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// ControlHeightReudction - Merges conditional blocks of code and reduces the
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// number of conditional branches in the hot paths based on profiles.
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//
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FunctionPass *createControlHeightReductionLegacyPass();
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}
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#endif
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