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https://github.com/c64scene-ar/llvm-6502.git
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MergedLoadStoreMotion pass
Merges equivalent loads on both sides of a hammock/diamond and hoists into into the header. Merges equivalent stores on both sides of a hammock/diamond and sinks it to the footer. Can enable if conversion and tolerate better load misses and store operand latencies. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213396 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Gerolf Hoflehner
parent
63d94561b5
commit
d94715e273
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@ -134,6 +134,12 @@ CAMLprim value llvm_add_tail_call_elimination(LLVMPassManagerRef PM) {
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return Val_unit;
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}
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/* [<Llvm.PassManager.any] Llvm.PassManager.t -> unit */
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CAMLprim value llvm_add_merged_load_store_motion(LLVMPassManagerRef PM) {
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LLVMAddMergedLoadStoreMotionPass(PM);
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return Val_unit;
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}
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/* [<Llvm.PassManager.any] Llvm.PassManager.t -> unit */
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CAMLprim value llvm_add_gvn(LLVMPassManagerRef PM) {
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LLVMAddGVNPass(PM);
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@ -44,6 +44,9 @@ void LLVMAddDeadStoreEliminationPass(LLVMPassManagerRef PM);
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/** See llvm::createScalarizerPass function. */
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void LLVMAddScalarizerPass(LLVMPassManagerRef PM);
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/** See llvm::createMergedLoadStoreMotionPass function. */
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void LLVMAddMergedLoadStoreMotionPass(LLVMPassManagerRef PM);
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/** See llvm::createGVNPass function. */
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void LLVMAddGVNPass(LLVMPassManagerRef PM);
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@ -196,6 +196,7 @@ void initializeMachineVerifierPassPass(PassRegistry&);
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void initializeMemCpyOptPass(PassRegistry&);
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void initializeMemDepPrinterPass(PassRegistry&);
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void initializeMemoryDependenceAnalysisPass(PassRegistry&);
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void initializeMergedLoadStoreMotionPass(PassRegistry &);
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void initializeMetaRenamerPass(PassRegistry&);
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void initializeMergeFunctionsPass(PassRegistry&);
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void initializeModuleDebugInfoPrinterPass(PassRegistry&);
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@ -134,6 +134,7 @@ namespace {
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(void) llvm::createConstantHoistingPass();
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(void) llvm::createCodeGenPreparePass();
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(void) llvm::createEarlyCSEPass();
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(void)llvm::createMergedLoadStoreMotionPass();
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(void) llvm::createGVNPass();
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(void) llvm::createMemCpyOptPass();
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(void) llvm::createLoopDeletionPass();
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@ -286,6 +286,13 @@ extern char &LCSSAID;
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//
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FunctionPass *createEarlyCSEPass();
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//===----------------------------------------------------------------------===//
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//
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// MergedLoadStoreMotion - This pass merges loads and stores in diamonds. Loads
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// are hoisted into the header, while stores sink into the footer.
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//
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FunctionPass *createMergedLoadStoreMotionPass();
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//===----------------------------------------------------------------------===//
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//
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// GVN - This pass performs global value numbering and redundant load
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@ -107,6 +107,7 @@ void LTOCodeGenerator::initializeLTOPasses() {
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initializeFunctionAttrsPass(R);
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initializeGlobalsModRefPass(R);
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initializeLICMPass(R);
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initializeMergedLoadStoreMotionPass(R);
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initializeGVNPass(R);
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initializeMemCpyOptPass(R);
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initializeDCEPass(R);
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@ -207,8 +207,10 @@ void PassManagerBuilder::populateModulePassManager(PassManagerBase &MPM) {
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MPM.add(createSimpleLoopUnrollPass()); // Unroll small loops
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addExtensionsToPM(EP_LoopOptimizerEnd, MPM);
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if (OptLevel > 1)
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if (OptLevel > 1) {
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MPM.add(createMergedLoadStoreMotionPass()); // Merge load/stores in diamond
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MPM.add(createGVNPass()); // Remove redundancies
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}
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MPM.add(createMemCpyOptPass()); // Remove memcpy / form memset
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MPM.add(createSCCPPass()); // Constant prop with SCCP
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@ -346,6 +348,7 @@ void PassManagerBuilder::populateLTOPassManager(PassManagerBase &PM,
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PM.add(createGlobalsModRefPass()); // IP alias analysis.
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PM.add(createLICMPass()); // Hoist loop invariants.
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PM.add(createMergedLoadStoreMotionPass()); // Merge load/stores in diamonds
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PM.add(createGVNPass(DisableGVNLoadPRE)); // Remove redundancies.
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PM.add(createMemCpyOptPass()); // Remove dead memcpys.
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@ -22,6 +22,7 @@ add_llvm_library(LLVMScalarOpts
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LoopUnswitch.cpp
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LowerAtomic.cpp
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MemCpyOptimizer.cpp
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MergedLoadStoreMotion.cpp
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PartiallyInlineLibCalls.cpp
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Reassociate.cpp
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Reg2Mem.cpp
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623
lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
Normal file
623
lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
Normal file
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@ -0,0 +1,623 @@
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//===- MergedLoadStoreMotion.cpp - merge and hoist/sink load/stores -------===//
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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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//! \file
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//! \brief This pass performs merges of loads and stores on both sides of a
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// diamond (hammock). It hoists the loads and sinks the stores.
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//
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// The algorithm iteratively hoists two loads to the same address out of a
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// diamond (hammock) and merges them into a single load in the header. Similar
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// it sinks and merges two stores to the tail block (footer). The algorithm
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// iterates over the instructions of one side of the diamond and attempts to
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// find a matching load/store on the other side. It hoists / sinks when it
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// thinks it safe to do so. This optimization helps with eg. hiding load
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// latencies, triggering if-conversion, and reducing static code size.
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//
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//===----------------------------------------------------------------------===//
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//
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//
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// Example:
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// Diamond shaped code before merge:
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//
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// header:
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// br %cond, label %if.then, label %if.else
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// / \
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// / \
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// / \
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// if.then: if.else:
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// %lt = load %addr_l %le = load %addr_l
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// <use %lt> <use %le>
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// <...> <...>
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// store %st, %addr_s store %se, %addr_s
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// br label %if.end br label %if.end
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// \ /
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// \ /
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// \ /
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// if.end ("footer"):
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// <...>
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//
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// Diamond shaped code after merge:
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//
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// header:
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// %l = load %addr_l
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// br %cond, label %if.then, label %if.else
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// / \
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// / \
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// / \
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// if.then: if.else:
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// <use %l> <use %l>
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// <...> <...>
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// br label %if.end br label %if.end
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// \ /
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// \ /
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// \ /
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// if.end ("footer"):
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// %s.sink = phi [%st, if.then], [%se, if.else]
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// <...>
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// store %s.sink, %addr_s
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// <...>
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//
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//
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//===----------------------- TODO -----------------------------------------===//
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//
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// 1) Generalize to regions other than diamonds
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// 2) Be more aggressive merging memory operations
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// Note that both changes require register pressure control
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/ADT/SetVector.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/Analysis/CFG.h"
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#include "llvm/Analysis/Loads.h"
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#include "llvm/Analysis/MemoryBuiltins.h"
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#include "llvm/Analysis/MemoryDependenceAnalysis.h"
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#include "llvm/IR/Metadata.h"
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#include "llvm/IR/PatternMatch.h"
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#include "llvm/Support/Allocator.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Target/TargetLibraryInfo.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/SSAUpdater.h"
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#include <vector>
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using namespace llvm;
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#define DEBUG_TYPE "mldst-motion"
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//===----------------------------------------------------------------------===//
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// MergedLoadStoreMotion Pass
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//===----------------------------------------------------------------------===//
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static cl::opt<bool>
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EnableMLSM("mlsm", cl::desc("Enable motion of merged load and store"),
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cl::init(true));
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namespace {
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class MergedLoadStoreMotion : public FunctionPass {
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AliasAnalysis *AA;
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MemoryDependenceAnalysis *MD;
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public:
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static char ID; // Pass identification, replacement for typeid
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explicit MergedLoadStoreMotion(void) : FunctionPass(ID), MD(nullptr) {
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initializeMergedLoadStoreMotionPass(*PassRegistry::getPassRegistry());
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}
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bool runOnFunction(Function &F) override;
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private:
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// This transformation requires dominator postdominator info
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.addRequired<TargetLibraryInfo>();
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AU.addRequired<MemoryDependenceAnalysis>();
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AU.addRequired<AliasAnalysis>();
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AU.addPreserved<AliasAnalysis>();
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}
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// Helper routines
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///
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/// \brief Remove instruction from parent and update memory dependence
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/// analysis.
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///
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void removeInstruction(Instruction *Inst);
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BasicBlock *getDiamondTail(BasicBlock *BB);
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bool isDiamondHead(BasicBlock *BB);
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// Routines for hoisting loads
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bool isLoadHoistBarrier(Instruction *Inst);
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LoadInst *canHoistFromBlock(BasicBlock *BB, LoadInst *LI);
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void hoistInstruction(BasicBlock *BB, Instruction *HoistCand,
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Instruction *ElseInst);
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bool isSafeToHoist(Instruction *I) const;
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bool hoistLoad(BasicBlock *BB, LoadInst *HoistCand, LoadInst *ElseInst);
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bool mergeLoads(BasicBlock *BB);
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// Routines for sinking stores
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StoreInst *canSinkFromBlock(BasicBlock *BB, StoreInst *SI);
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PHINode *getPHIOperand(BasicBlock *BB, StoreInst *S0, StoreInst *S1);
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bool isStoreSinkBarrier(Instruction *Inst);
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bool sinkStore(BasicBlock *BB, StoreInst *SinkCand, StoreInst *ElseInst);
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bool mergeStores(BasicBlock *BB);
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// The mergeLoad/Store algorithms could have Size0 * Size1 complexity,
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// where Size0 and Size1 are the #instructions on the two sides of
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// the diamond. The constant chosen here is arbitrary. Compiler Time
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// Control is enforced by the check Size0 * Size1 < MagicCompileTimeControl.
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const int MagicCompileTimeControl = 250;
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};
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char MergedLoadStoreMotion::ID = 0;
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}
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///
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/// \brief createMergedLoadStoreMotionPass - The public interface to this file.
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///
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FunctionPass *llvm::createMergedLoadStoreMotionPass() {
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return new MergedLoadStoreMotion();
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}
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INITIALIZE_PASS_BEGIN(MergedLoadStoreMotion, "mldst-motion",
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"MergedLoadStoreMotion", false, false)
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INITIALIZE_PASS_DEPENDENCY(MemoryDependenceAnalysis)
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INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
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INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
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INITIALIZE_PASS_END(MergedLoadStoreMotion, "mldst-motion",
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"MergedLoadStoreMotion", false, false)
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///
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/// \brief Remove instruction from parent and update memory dependence analysis.
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///
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void MergedLoadStoreMotion::removeInstruction(Instruction *Inst) {
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// Notify the memory dependence analysis.
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if (MD) {
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MD->removeInstruction(Inst);
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if (LoadInst *LI = dyn_cast<LoadInst>(Inst))
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MD->invalidateCachedPointerInfo(LI->getPointerOperand());
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if (Inst->getType()->getScalarType()->isPointerTy()) {
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MD->invalidateCachedPointerInfo(Inst);
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}
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}
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Inst->eraseFromParent();
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}
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///
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/// \brief Return tail block of a diamond.
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///
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BasicBlock *MergedLoadStoreMotion::getDiamondTail(BasicBlock *BB) {
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assert(isDiamondHead(BB) && "Basic block is not head of a diamond");
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BranchInst *BI = (BranchInst *)(BB->getTerminator());
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BasicBlock *Succ0 = BI->getSuccessor(0);
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BasicBlock *Tail = Succ0->getTerminator()->getSuccessor(0);
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return Tail;
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}
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///
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/// \brief True when BB is the head of a diamond (hammock)
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///
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bool MergedLoadStoreMotion::isDiamondHead(BasicBlock *BB) {
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if (!BB)
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return false;
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if (!isa<BranchInst>(BB->getTerminator()))
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return false;
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if (BB->getTerminator()->getNumSuccessors() != 2)
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return false;
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BranchInst *BI = (BranchInst *)(BB->getTerminator());
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BasicBlock *Succ0 = BI->getSuccessor(0);
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BasicBlock *Succ1 = BI->getSuccessor(1);
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if (!Succ0->getSinglePredecessor() ||
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Succ0->getTerminator()->getNumSuccessors() != 1)
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return false;
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if (!Succ1->getSinglePredecessor() ||
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Succ1->getTerminator()->getNumSuccessors() != 1)
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return false;
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BasicBlock *Tail = Succ0->getTerminator()->getSuccessor(0);
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// Ignore triangles.
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if (Succ1->getTerminator()->getSuccessor(0) != Tail)
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return false;
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return true;
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}
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///
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/// \brief True when instruction is a hoist barrier for a load
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///
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/// Whenever an instruction could possibly modify the value
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/// being loaded or protect against the load from happening
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/// it is considered a hoist barrier.
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///
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bool MergedLoadStoreMotion::isLoadHoistBarrier(Instruction *Inst) {
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// FIXME: A call with no side effects should not be a barrier.
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// Aren't all such calls covered by mayHaveSideEffects() below?
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// Then this check can be removed.
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if (isa<CallInst>(Inst))
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return true;
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if (isa<TerminatorInst>(Inst))
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return true;
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// Note: mayHaveSideEffects covers all instructions that could
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// trigger a change to state. Eg. in-flight stores have to be executed
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// before ordered loads or fences, calls could invoke functions that store
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// data to memory etc.
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if (Inst->mayHaveSideEffects()) {
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return true;
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}
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DEBUG(dbgs() << "No Hoist Barrier\n");
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return false;
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}
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///
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/// \brief Decide if a load can be hoisted
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///
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/// When there is a load in \p BB to the same address as \p LI
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/// and it can be hoisted from \p BB, return that load.
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/// Otherwise return Null.
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///
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LoadInst *MergedLoadStoreMotion::canHoistFromBlock(BasicBlock *BB,
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LoadInst *LI) {
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LoadInst *I = nullptr;
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assert(isa<LoadInst>(LI));
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if (LI->isUsedOutsideOfBlock(LI->getParent()))
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return nullptr;
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for (BasicBlock::iterator BBI = BB->begin(), BBE = BB->end(); BBI != BBE;
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++BBI) {
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Instruction *Inst = BBI;
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// Only merge and hoist loads when their result in used only in BB
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if (isLoadHoistBarrier(Inst))
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break;
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if (!isa<LoadInst>(Inst))
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continue;
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if (Inst->isUsedOutsideOfBlock(Inst->getParent()))
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continue;
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AliasAnalysis::Location LocLI = AA->getLocation(LI);
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AliasAnalysis::Location LocInst = AA->getLocation((LoadInst *)Inst);
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if (AA->isMustAlias(LocLI, LocInst) && LI->getType() == Inst->getType()) {
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I = (LoadInst *)Inst;
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break;
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}
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}
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return I;
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}
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///
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/// \brief Merge two equivalent instructions \p HoistCand and \p ElseInst into
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/// \p BB
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///
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/// BB is the head of a diamond
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///
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void MergedLoadStoreMotion::hoistInstruction(BasicBlock *BB,
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Instruction *HoistCand,
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Instruction *ElseInst) {
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DEBUG(dbgs() << " Hoist Instruction into BB \n"; BB->dump();
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dbgs() << "Instruction Left\n"; HoistCand->dump(); dbgs() << "\n";
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dbgs() << "Instruction Right\n"; ElseInst->dump(); dbgs() << "\n");
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// Hoist the instruction.
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assert(HoistCand->getParent() != BB);
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// Intersect optional metadata.
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HoistCand->intersectOptionalDataWith(ElseInst);
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HoistCand->dropUnknownMetadata();
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// Prepend point for instruction insert
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Instruction *HoistPt = BB->getTerminator();
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// Merged instruction
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Instruction *HoistedInst = HoistCand->clone();
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// Notify AA of the new value.
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if (isa<LoadInst>(HoistCand))
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AA->copyValue(HoistCand, HoistedInst);
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// Hoist instruction.
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HoistedInst->insertBefore(HoistPt);
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HoistCand->replaceAllUsesWith(HoistedInst);
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removeInstruction(HoistCand);
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// Replace the else block instruction.
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ElseInst->replaceAllUsesWith(HoistedInst);
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removeInstruction(ElseInst);
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}
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///
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/// \brief Return true if no operand of \p I is defined in I's parent block
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///
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bool MergedLoadStoreMotion::isSafeToHoist(Instruction *I) const {
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BasicBlock *Parent = I->getParent();
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for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
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Instruction *Instr = dyn_cast<Instruction>(I->getOperand(i));
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if (Instr && Instr->getParent() == Parent)
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return false;
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}
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return true;
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}
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///
|
||||
/// \brief Merge two equivalent loads and GEPs and hoist into diamond head
|
||||
///
|
||||
bool MergedLoadStoreMotion::hoistLoad(BasicBlock *BB, LoadInst *L0,
|
||||
LoadInst *L1) {
|
||||
// Only one definition?
|
||||
Instruction *A0 = dyn_cast<Instruction>(L0->getPointerOperand());
|
||||
Instruction *A1 = dyn_cast<Instruction>(L1->getPointerOperand());
|
||||
if (A0 && A1 && A0->isIdenticalTo(A1) && isSafeToHoist(A0) &&
|
||||
A0->hasOneUse() && (A0->getParent() == L0->getParent()) &&
|
||||
A1->hasOneUse() && (A1->getParent() == L1->getParent()) &&
|
||||
isa<GetElementPtrInst>(A0)) {
|
||||
DEBUG(dbgs() << "Hoist Instruction into BB \n"; BB->dump();
|
||||
dbgs() << "Instruction Left\n"; L0->dump(); dbgs() << "\n";
|
||||
dbgs() << "Instruction Right\n"; L1->dump(); dbgs() << "\n");
|
||||
hoistInstruction(BB, A0, A1);
|
||||
hoistInstruction(BB, L0, L1);
|
||||
return true;
|
||||
} else
|
||||
return false;
|
||||
}
|
||||
|
||||
///
|
||||
/// \brief Try to hoist two loads to same address into diamond header
|
||||
///
|
||||
/// Starting from a diamond head block, iterate over the instructions in one
|
||||
/// successor block and try to match a load in the second successor.
|
||||
///
|
||||
bool MergedLoadStoreMotion::mergeLoads(BasicBlock *BB) {
|
||||
bool MergedLoads = false;
|
||||
assert(isDiamondHead(BB));
|
||||
BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
|
||||
BasicBlock *Succ0 = BI->getSuccessor(0);
|
||||
BasicBlock *Succ1 = BI->getSuccessor(1);
|
||||
// #Instructions in Succ1 for Compile Time Control
|
||||
int Size1 = Succ1->size();
|
||||
int NLoads = 0;
|
||||
for (BasicBlock::iterator BBI = Succ0->begin(), BBE = Succ0->end();
|
||||
BBI != BBE;) {
|
||||
|
||||
Instruction *I = BBI;
|
||||
++BBI;
|
||||
if (isLoadHoistBarrier(I))
|
||||
break;
|
||||
|
||||
// Only move non-simple (atomic, volatile) loads.
|
||||
if (!isa<LoadInst>(I))
|
||||
continue;
|
||||
|
||||
LoadInst *L0 = (LoadInst *)I;
|
||||
if (!L0->isSimple())
|
||||
continue;
|
||||
|
||||
++NLoads;
|
||||
if (NLoads * Size1 >= MagicCompileTimeControl)
|
||||
break;
|
||||
if (LoadInst *L1 = canHoistFromBlock(Succ1, L0)) {
|
||||
bool Res = hoistLoad(BB, L0, L1);
|
||||
MergedLoads |= Res;
|
||||
// Don't attempt to hoist above loads that had not been hoisted.
|
||||
if (!Res)
|
||||
break;
|
||||
}
|
||||
}
|
||||
return MergedLoads;
|
||||
}
|
||||
|
||||
///
|
||||
/// \brief True when instruction is sink barrier for a store
|
||||
///
|
||||
bool MergedLoadStoreMotion::isStoreSinkBarrier(Instruction *Inst) {
|
||||
if (isa<CallInst>(Inst))
|
||||
return true;
|
||||
if (isa<TerminatorInst>(Inst) && !isa<BranchInst>(Inst))
|
||||
return true;
|
||||
// Note: mayHaveSideEffects covers all instructions that could
|
||||
// trigger a change to state. Eg. in-flight stores have to be executed
|
||||
// before ordered loads or fences, calls could invoke functions that store
|
||||
// data to memory etc.
|
||||
if (!isa<StoreInst>(Inst) && Inst->mayHaveSideEffects()) {
|
||||
return true;
|
||||
}
|
||||
DEBUG(dbgs() << "No Sink Barrier\n");
|
||||
return false;
|
||||
}
|
||||
|
||||
///
|
||||
/// \brief Check if \p BB contains a store to the same address as \p SI
|
||||
///
|
||||
/// \return The store in \p when it is safe to sink. Otherwise return Null.
|
||||
///
|
||||
StoreInst *MergedLoadStoreMotion::canSinkFromBlock(BasicBlock *BB,
|
||||
StoreInst *SI) {
|
||||
StoreInst *I = 0;
|
||||
DEBUG(dbgs() << "can Sink? : "; SI->dump(); dbgs() << "\n");
|
||||
for (BasicBlock::reverse_iterator RBI = BB->rbegin(), RBE = BB->rend();
|
||||
RBI != RBE; ++RBI) {
|
||||
Instruction *Inst = &*RBI;
|
||||
|
||||
// Only move loads if they are used in the block.
|
||||
if (isStoreSinkBarrier(Inst))
|
||||
break;
|
||||
if (isa<StoreInst>(Inst)) {
|
||||
AliasAnalysis::Location LocSI = AA->getLocation(SI);
|
||||
AliasAnalysis::Location LocInst = AA->getLocation((StoreInst *)Inst);
|
||||
if (AA->isMustAlias(LocSI, LocInst)) {
|
||||
I = (StoreInst *)Inst;
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
return I;
|
||||
}
|
||||
|
||||
///
|
||||
/// \brief Create a PHI node in BB for the operands of S0 and S1
|
||||
///
|
||||
PHINode *MergedLoadStoreMotion::getPHIOperand(BasicBlock *BB, StoreInst *S0,
|
||||
StoreInst *S1) {
|
||||
// Create a phi if the values mismatch.
|
||||
PHINode *NewPN = 0;
|
||||
Value *Opd1 = S0->getValueOperand();
|
||||
Value *Opd2 = S1->getValueOperand();
|
||||
if (Opd1 != Opd2) {
|
||||
NewPN = PHINode::Create(Opd1->getType(), 2, Opd2->getName() + ".sink",
|
||||
BB->begin());
|
||||
NewPN->addIncoming(Opd1, S0->getParent());
|
||||
NewPN->addIncoming(Opd2, S1->getParent());
|
||||
if (NewPN->getType()->getScalarType()->isPointerTy()) {
|
||||
// Notify AA of the new value.
|
||||
AA->copyValue(Opd1, NewPN);
|
||||
AA->copyValue(Opd2, NewPN);
|
||||
// AA needs to be informed when a PHI-use of the pointer value is added
|
||||
for (unsigned I = 0, E = NewPN->getNumIncomingValues(); I != E; ++I) {
|
||||
unsigned J = PHINode::getOperandNumForIncomingValue(I);
|
||||
AA->addEscapingUse(NewPN->getOperandUse(J));
|
||||
}
|
||||
if (MD)
|
||||
MD->invalidateCachedPointerInfo(NewPN);
|
||||
}
|
||||
}
|
||||
return NewPN;
|
||||
}
|
||||
|
||||
///
|
||||
/// \brief Merge two stores to same address and sink into \p BB
|
||||
///
|
||||
/// Also sinks GEP instruction computing the store address
|
||||
///
|
||||
bool MergedLoadStoreMotion::sinkStore(BasicBlock *BB, StoreInst *S0,
|
||||
StoreInst *S1) {
|
||||
// Only one definition?
|
||||
Instruction *A0 = dyn_cast<Instruction>(S0->getPointerOperand());
|
||||
Instruction *A1 = dyn_cast<Instruction>(S1->getPointerOperand());
|
||||
if (A0 && A1 && A0->isIdenticalTo(A1) && A0->hasOneUse() &&
|
||||
(A0->getParent() == S0->getParent()) && A1->hasOneUse() &&
|
||||
(A1->getParent() == S1->getParent()) && isa<GetElementPtrInst>(A0)) {
|
||||
DEBUG(dbgs() << "Sink Instruction into BB \n"; BB->dump();
|
||||
dbgs() << "Instruction Left\n"; S0->dump(); dbgs() << "\n";
|
||||
dbgs() << "Instruction Right\n"; S1->dump(); dbgs() << "\n");
|
||||
// Hoist the instruction.
|
||||
BasicBlock::iterator InsertPt = BB->getFirstInsertionPt();
|
||||
// Intersect optional metadata.
|
||||
S0->intersectOptionalDataWith(S1);
|
||||
S0->dropUnknownMetadata();
|
||||
|
||||
// Create the new store to be inserted at the join point.
|
||||
StoreInst *SNew = (StoreInst *)(S0->clone());
|
||||
Instruction *ANew = A0->clone();
|
||||
AA->copyValue(S0, SNew);
|
||||
SNew->insertBefore(InsertPt);
|
||||
ANew->insertBefore(SNew);
|
||||
|
||||
assert(S0->getParent() == A0->getParent());
|
||||
assert(S1->getParent() == A1->getParent());
|
||||
|
||||
PHINode *NewPN = getPHIOperand(BB, S0, S1);
|
||||
// New PHI operand? Use it.
|
||||
if (NewPN)
|
||||
SNew->setOperand(0, NewPN);
|
||||
removeInstruction(S0);
|
||||
removeInstruction(S1);
|
||||
A0->replaceAllUsesWith(ANew);
|
||||
removeInstruction(A0);
|
||||
A1->replaceAllUsesWith(ANew);
|
||||
removeInstruction(A1);
|
||||
return true;
|
||||
}
|
||||
return false;
|
||||
}
|
||||
|
||||
///
|
||||
/// \brief True when two stores are equivalent and can sink into the footer
|
||||
///
|
||||
/// Starting from a diamond tail block, iterate over the instructions in one
|
||||
/// predecessor block and try to match a store in the second predecessor.
|
||||
///
|
||||
bool MergedLoadStoreMotion::mergeStores(BasicBlock *T) {
|
||||
|
||||
bool MergedStores = false;
|
||||
assert(T && "Footer of a diamond cannot be empty");
|
||||
|
||||
pred_iterator PI = pred_begin(T), E = pred_end(T);
|
||||
assert(PI != E);
|
||||
BasicBlock *Pred0 = *PI;
|
||||
++PI;
|
||||
BasicBlock *Pred1 = *PI;
|
||||
++PI;
|
||||
// tail block of a diamond/hammock?
|
||||
if (Pred0 == Pred1)
|
||||
return false; // No.
|
||||
if (PI != E)
|
||||
return false; // No. More than 2 predecessors.
|
||||
|
||||
// #Instructions in Succ1 for Compile Time Control
|
||||
int Size1 = Pred1->size();
|
||||
int NStores = 0;
|
||||
|
||||
for (BasicBlock::reverse_iterator RBI = Pred0->rbegin(), RBE = Pred0->rend();
|
||||
RBI != RBE;) {
|
||||
|
||||
Instruction *I = &*RBI;
|
||||
++RBI;
|
||||
if (isStoreSinkBarrier(I))
|
||||
break;
|
||||
// Sink move non-simple (atomic, volatile) stores
|
||||
if (!isa<StoreInst>(I))
|
||||
continue;
|
||||
StoreInst *S0 = (StoreInst *)I;
|
||||
if (!S0->isSimple())
|
||||
continue;
|
||||
|
||||
++NStores;
|
||||
if (NStores * Size1 >= MagicCompileTimeControl)
|
||||
break;
|
||||
if (StoreInst *S1 = canSinkFromBlock(Pred1, S0)) {
|
||||
bool Res = sinkStore(T, S0, S1);
|
||||
MergedStores |= Res;
|
||||
// Don't attempt to sink below stores that had to stick around
|
||||
// But after removal of a store and some of its feeding
|
||||
// instruction search again from the beginning since the iterator
|
||||
// is likely stale at this point.
|
||||
if (!Res)
|
||||
break;
|
||||
else {
|
||||
RBI = Pred0->rbegin();
|
||||
RBE = Pred0->rend();
|
||||
DEBUG(dbgs() << "Search again\n"; Instruction *I = &*RBI; I->dump());
|
||||
}
|
||||
}
|
||||
}
|
||||
return MergedStores;
|
||||
}
|
||||
///
|
||||
/// \brief Run the transformation for each function
|
||||
///
|
||||
bool MergedLoadStoreMotion::runOnFunction(Function &F) {
|
||||
MD = &getAnalysis<MemoryDependenceAnalysis>();
|
||||
AA = &getAnalysis<AliasAnalysis>();
|
||||
|
||||
bool Changed = false;
|
||||
if (!EnableMLSM)
|
||||
return false;
|
||||
DEBUG(dbgs() << "Instruction Merger\n");
|
||||
|
||||
// Merge unconditional branches, allowing PRE to catch more
|
||||
// optimization opportunities.
|
||||
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) {
|
||||
BasicBlock *BB = FI++;
|
||||
|
||||
// Hoist equivalent loads and sink stores
|
||||
// outside diamonds when possible
|
||||
// Run outside core GVN
|
||||
if (isDiamondHead(BB)) {
|
||||
Changed |= mergeLoads(BB);
|
||||
Changed |= mergeStores(getDiamondTail(BB));
|
||||
}
|
||||
}
|
||||
return Changed;
|
||||
}
|
||||
|
|
@ -52,6 +52,7 @@ void llvm::initializeScalarOpts(PassRegistry &Registry) {
|
|||
initializeLowerAtomicPass(Registry);
|
||||
initializeLowerExpectIntrinsicPass(Registry);
|
||||
initializeMemCpyOptPass(Registry);
|
||||
initializeMergedLoadStoreMotionPass(Registry);
|
||||
initializePartiallyInlineLibCallsPass(Registry);
|
||||
initializeReassociatePass(Registry);
|
||||
initializeRegToMemPass(Registry);
|
||||
|
|
@ -92,6 +93,10 @@ void LLVMAddGVNPass(LLVMPassManagerRef PM) {
|
|||
unwrap(PM)->add(createGVNPass());
|
||||
}
|
||||
|
||||
void LLVMAddMergedLoadStoreMotionPass(LLVMPassManagerRef PM) {
|
||||
unwrap(PM)->add(createMergedLoadStoreMotionPass());
|
||||
}
|
||||
|
||||
void LLVMAddIndVarSimplifyPass(LLVMPassManagerRef PM) {
|
||||
unwrap(PM)->add(createIndVarSimplifyPass());
|
||||
}
|
||||
|
|
|
|||
84
test/Transforms/InstMerge/ld_hoist_st_sink.ll
Normal file
84
test/Transforms/InstMerge/ld_hoist_st_sink.ll
Normal file
|
|
@ -0,0 +1,84 @@
|
|||
; Tests to make sure that loads and stores in a diamond get merged
|
||||
; Loads are hoisted into the header. Stores sunks into the footer.
|
||||
; RUN: opt -basicaa -memdep -mldst-motion -S < %s | FileCheck %s
|
||||
target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
|
||||
|
||||
%struct.node = type { i64, %struct.node*, %struct.node*, %struct.node*, i64, %struct.arc*, i64, i64, i64 }
|
||||
%struct.arc = type { i64, i64, i64 }
|
||||
|
||||
define i64 @foo(%struct.node* nocapture readonly %r) nounwind {
|
||||
entry:
|
||||
%node.0.in16 = getelementptr inbounds %struct.node* %r, i64 0, i32 2
|
||||
%node.017 = load %struct.node** %node.0.in16, align 8
|
||||
%tobool18 = icmp eq %struct.node* %node.017, null
|
||||
br i1 %tobool18, label %while.end, label %while.body.preheader
|
||||
|
||||
; CHECK-LABEL: while.body.preheader
|
||||
while.body.preheader: ; preds = %entry
|
||||
; CHECK: load
|
||||
br label %while.body
|
||||
|
||||
while.body: ; preds = %while.body.preheader, %if.end
|
||||
%node.020 = phi %struct.node* [ %node.0, %if.end ], [ %node.017, %while.body.preheader ]
|
||||
%sum.019 = phi i64 [ %inc, %if.end ], [ 0, %while.body.preheader ]
|
||||
%orientation = getelementptr inbounds %struct.node* %node.020, i64 0, i32 4
|
||||
%0 = load i64* %orientation, align 8
|
||||
%cmp = icmp eq i64 %0, 1
|
||||
br i1 %cmp, label %if.then, label %if.else
|
||||
; CHECK: if.then
|
||||
if.then: ; preds = %while.body
|
||||
%a = getelementptr inbounds %struct.node* %node.020, i64 0, i32 5
|
||||
; CHECK-NOT: load %struct.arc
|
||||
%1 = load %struct.arc** %a, align 8
|
||||
%cost = getelementptr inbounds %struct.arc* %1, i64 0, i32 0
|
||||
; CHECK-NOT: load i64*
|
||||
%2 = load i64* %cost, align 8
|
||||
%pred = getelementptr inbounds %struct.node* %node.020, i64 0, i32 1
|
||||
; CHECK-NOT: load %struct.node**
|
||||
%3 = load %struct.node** %pred, align 8
|
||||
%p = getelementptr inbounds %struct.node* %3, i64 0, i32 6
|
||||
; CHECK-NOT: load i64*
|
||||
%4 = load i64* %p, align 8
|
||||
%add = add nsw i64 %4, %2
|
||||
%p1 = getelementptr inbounds %struct.node* %node.020, i64 0, i32 6
|
||||
; CHECK-NOT: store i64
|
||||
store i64 %add, i64* %p1, align 8
|
||||
br label %if.end
|
||||
|
||||
; CHECK: if.else
|
||||
if.else: ; preds = %while.body
|
||||
%pred2 = getelementptr inbounds %struct.node* %node.020, i64 0, i32 1
|
||||
; CHECK-NOT: load %struct.node**
|
||||
%5 = load %struct.node** %pred2, align 8
|
||||
%p3 = getelementptr inbounds %struct.node* %5, i64 0, i32 6
|
||||
; CHECK-NOT: load i64*
|
||||
%6 = load i64* %p3, align 8
|
||||
%a4 = getelementptr inbounds %struct.node* %node.020, i64 0, i32 5
|
||||
; CHECK-NOT: load %struct.arc**
|
||||
%7 = load %struct.arc** %a4, align 8
|
||||
%cost5 = getelementptr inbounds %struct.arc* %7, i64 0, i32 0
|
||||
; CHECK-NOT: load i64*
|
||||
%8 = load i64* %cost5, align 8
|
||||
%sub = sub nsw i64 %6, %8
|
||||
%p6 = getelementptr inbounds %struct.node* %node.020, i64 0, i32 6
|
||||
; CHECK-NOT: store i64
|
||||
store i64 %sub, i64* %p6, align 8
|
||||
br label %if.end
|
||||
|
||||
; CHECK: if.end
|
||||
if.end: ; preds = %if.else, %if.then
|
||||
; CHECK: store
|
||||
%inc = add nsw i64 %sum.019, 1
|
||||
%node.0.in = getelementptr inbounds %struct.node* %node.020, i64 0, i32 2
|
||||
%node.0 = load %struct.node** %node.0.in, align 8
|
||||
%tobool = icmp eq %struct.node* %node.0, null
|
||||
br i1 %tobool, label %while.end.loopexit, label %while.body
|
||||
|
||||
while.end.loopexit: ; preds = %if.end
|
||||
%inc.lcssa = phi i64 [ %inc, %if.end ]
|
||||
br label %while.end
|
||||
|
||||
while.end: ; preds = %while.end.loopexit, %entry
|
||||
%sum.0.lcssa = phi i64 [ 0, %entry ], [ %inc.lcssa, %while.end.loopexit ]
|
||||
ret i64 %sum.0.lcssa
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user