[llvm] r350423 - [ThinLTO] Handle chains of aliases
Teresa Johnson via llvm-commits
llvm-commits at lists.llvm.org
Fri Jan 4 11:04:55 PST 2019
Author: tejohnson
Date: Fri Jan 4 11:04:54 2019
New Revision: 350423
URL: http://llvm.org/viewvc/llvm-project?rev=350423&view=rev
Log:
[ThinLTO] Handle chains of aliases
At -O0, globalopt is not run during the compile step, and we can have a
chain of an alias having an immediate aliasee of another alias. The
summaries are constructed assuming aliases in a canonical form
(flattened chains), and as a result only the base object but no
intermediate aliases were preserved.
Fix by adding a pass that canonicalize aliases, which ensures each
alias is a direct alias of the base object.
Reviewers: pcc, davidxl
Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, arphaman, llvm-commits
Differential Revision: https://reviews.llvm.org/D54507
Added:
llvm/trunk/include/llvm/Transforms/Utils/CanonicalizeAliases.h
llvm/trunk/lib/Transforms/Utils/CanonicalizeAliases.cpp
llvm/trunk/test/Transforms/CanonicalizeAliases/
llvm/trunk/test/Transforms/CanonicalizeAliases/canonicalize.ll
Modified:
llvm/trunk/include/llvm/InitializePasses.h
llvm/trunk/include/llvm/Transforms/Scalar.h
llvm/trunk/lib/Passes/PassBuilder.cpp
llvm/trunk/lib/Passes/PassRegistry.def
llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
llvm/trunk/lib/Transforms/Utils/CMakeLists.txt
llvm/trunk/lib/Transforms/Utils/Utils.cpp
Modified: llvm/trunk/include/llvm/InitializePasses.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/InitializePasses.h?rev=350423&r1=350422&r2=350423&view=diff
==============================================================================
--- llvm/trunk/include/llvm/InitializePasses.h (original)
+++ llvm/trunk/include/llvm/InitializePasses.h Fri Jan 4 11:04:54 2019
@@ -85,6 +85,7 @@ void initializeBranchProbabilityInfoWrap
void initializeBranchRelaxationPass(PassRegistry&);
void initializeBreakCriticalEdgesPass(PassRegistry&);
void initializeBreakFalseDepsPass(PassRegistry&);
+void initializeCanonicalizeAliasesLegacyPassPass(PassRegistry &);
void initializeCFGOnlyPrinterLegacyPassPass(PassRegistry&);
void initializeCFGOnlyViewerLegacyPassPass(PassRegistry&);
void initializeCFGPrinterLegacyPassPass(PassRegistry&);
Modified: llvm/trunk/include/llvm/Transforms/Scalar.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Scalar.h?rev=350423&r1=350422&r2=350423&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Scalar.h (original)
+++ llvm/trunk/include/llvm/Transforms/Scalar.h Fri Jan 4 11:04:54 2019
@@ -471,6 +471,7 @@ FunctionPass *createLoopDataPrefetchPass
///===---------------------------------------------------------------------===//
ModulePass *createNameAnonGlobalPass();
+ModulePass *createCanonicalizeAliasesPass();
//===----------------------------------------------------------------------===//
//
Added: llvm/trunk/include/llvm/Transforms/Utils/CanonicalizeAliases.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/CanonicalizeAliases.h?rev=350423&view=auto
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/CanonicalizeAliases.h (added)
+++ llvm/trunk/include/llvm/Transforms/Utils/CanonicalizeAliases.h Fri Jan 4 11:04:54 2019
@@ -0,0 +1,32 @@
+//===-- CanonicalizeAliases.h - Alias Canonicalization Pass -----*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file canonicalizes aliases.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_UTILS_CANONICALIZE_ALIASES_H
+#define LLVM_TRANSFORMS_UTILS_CANONICALIZE_ALIASES_H
+
+#include "llvm/IR/Module.h"
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+/// Simple pass that canonicalizes aliases.
+class CanonicalizeAliasesPass : public PassInfoMixin<CanonicalizeAliasesPass> {
+public:
+ CanonicalizeAliasesPass() = default;
+
+ PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
+};
+
+} // end namespace llvm
+
+#endif // LLVM_TRANSFORMS_UTILS_CANONICALIZE_ALIASESH
Modified: llvm/trunk/lib/Passes/PassBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Passes/PassBuilder.cpp?rev=350423&r1=350422&r2=350423&view=diff
==============================================================================
--- llvm/trunk/lib/Passes/PassBuilder.cpp (original)
+++ llvm/trunk/lib/Passes/PassBuilder.cpp Fri Jan 4 11:04:54 2019
@@ -153,6 +153,7 @@
#include "llvm/Transforms/Scalar/WarnMissedTransforms.h"
#include "llvm/Transforms/Utils/AddDiscriminators.h"
#include "llvm/Transforms/Utils/BreakCriticalEdges.h"
+#include "llvm/Transforms/Utils/CanonicalizeAliases.h"
#include "llvm/Transforms/Utils/EntryExitInstrumenter.h"
#include "llvm/Transforms/Utils/LCSSA.h"
#include "llvm/Transforms/Utils/LibCallsShrinkWrap.h"
Modified: llvm/trunk/lib/Passes/PassRegistry.def
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Passes/PassRegistry.def?rev=350423&r1=350422&r2=350423&view=diff
==============================================================================
--- llvm/trunk/lib/Passes/PassRegistry.def (original)
+++ llvm/trunk/lib/Passes/PassRegistry.def Fri Jan 4 11:04:54 2019
@@ -42,6 +42,7 @@ MODULE_ALIAS_ANALYSIS("globals-aa", Glob
#endif
MODULE_PASS("always-inline", AlwaysInlinerPass())
MODULE_PASS("called-value-propagation", CalledValuePropagationPass())
+MODULE_PASS("canonicalize-aliases", CanonicalizeAliasesPass())
MODULE_PASS("cg-profile", CGProfilePass())
MODULE_PASS("constmerge", ConstantMergePass())
MODULE_PASS("cross-dso-cfi", CrossDSOCFIPass())
Modified: llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp?rev=350423&r1=350422&r2=350423&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp Fri Jan 4 11:04:54 2019
@@ -462,12 +462,14 @@ void PassManagerBuilder::populateModuleP
addExtensionsToPM(EP_EnabledOnOptLevel0, MPM);
- // Rename anon globals to be able to export them in the summary.
- // This has to be done after we add the extensions to the pass manager
- // as there could be passes (e.g. Adddress sanitizer) which introduce
- // new unnamed globals.
- if (PrepareForLTO || PrepareForThinLTO)
+ if (PrepareForLTO || PrepareForThinLTO) {
+ MPM.add(createCanonicalizeAliasesPass());
+ // Rename anon globals to be able to export them in the summary.
+ // This has to be done after we add the extensions to the pass manager
+ // as there could be passes (e.g. Adddress sanitizer) which introduce
+ // new unnamed globals.
MPM.add(createNameAnonGlobalPass());
+ }
return;
}
@@ -585,6 +587,7 @@ void PassManagerBuilder::populateModuleP
// Ensure we perform any last passes, but do so before renaming anonymous
// globals in case the passes add any.
addExtensionsToPM(EP_OptimizerLast, MPM);
+ MPM.add(createCanonicalizeAliasesPass());
// Rename anon globals to be able to export them in the summary.
MPM.add(createNameAnonGlobalPass());
return;
@@ -744,9 +747,11 @@ void PassManagerBuilder::populateModuleP
addExtensionsToPM(EP_OptimizerLast, MPM);
- // Rename anon globals to be able to handle them in the summary
- if (PrepareForLTO)
+ if (PrepareForLTO) {
+ MPM.add(createCanonicalizeAliasesPass());
+ // Rename anon globals to be able to handle them in the summary
MPM.add(createNameAnonGlobalPass());
+ }
}
void PassManagerBuilder::addLTOOptimizationPasses(legacy::PassManagerBase &PM) {
Modified: llvm/trunk/lib/Transforms/Utils/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/CMakeLists.txt?rev=350423&r1=350422&r2=350423&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/CMakeLists.txt (original)
+++ llvm/trunk/lib/Transforms/Utils/CMakeLists.txt Fri Jan 4 11:04:54 2019
@@ -6,6 +6,7 @@ add_llvm_library(LLVMTransformUtils
BuildLibCalls.cpp
BypassSlowDivision.cpp
CallPromotionUtils.cpp
+ CanonicalizeAliases.cpp
CloneFunction.cpp
CloneModule.cpp
CodeExtractor.cpp
Added: llvm/trunk/lib/Transforms/Utils/CanonicalizeAliases.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/CanonicalizeAliases.cpp?rev=350423&view=auto
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/CanonicalizeAliases.cpp (added)
+++ llvm/trunk/lib/Transforms/Utils/CanonicalizeAliases.cpp Fri Jan 4 11:04:54 2019
@@ -0,0 +1,105 @@
+//===- CanonicalizeAliases.cpp - ThinLTO Support: Canonicalize Aliases ----===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Currently this file implements partial alias canonicalization, to
+// flatten chains of aliases (also done by GlobalOpt, but not on for
+// O0 compiles). E.g.
+// @a = alias i8, i8 *@b
+// @b = alias i8, i8 *@g
+//
+// will be converted to:
+// @a = alias i8, i8 *@g <-- @a is now an alias to base object @g
+// @b = alias i8, i8 *@g
+//
+// Eventually this file will implement full alias canonicalation, so that
+// all aliasees are private anonymous values. E.g.
+// @a = alias i8, i8 *@g
+// @g = global i8 0
+//
+// will be converted to:
+// @0 = private global
+// @a = alias i8, i8* @0
+// @g = alias i8, i8* @0
+//
+// This simplifies optimization and ThinLTO linking of the original symbols.
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/CanonicalizeAliases.h"
+
+#include "llvm/IR/Operator.h"
+#include "llvm/IR/ValueHandle.h"
+
+using namespace llvm;
+
+namespace {
+
+static Constant *canonicalizeAlias(Constant *C, bool &Changed) {
+ if (auto *GA = dyn_cast<GlobalAlias>(C)) {
+ auto *NewAliasee = canonicalizeAlias(GA->getAliasee(), Changed);
+ if (NewAliasee != GA->getAliasee()) {
+ GA->setAliasee(NewAliasee);
+ Changed = true;
+ }
+ return NewAliasee;
+ }
+
+ auto *CE = dyn_cast<ConstantExpr>(C);
+ if (!CE)
+ return C;
+
+ std::vector<Constant *> Ops;
+ for (Use &U : CE->operands())
+ Ops.push_back(canonicalizeAlias(cast<Constant>(U), Changed));
+ return CE->getWithOperands(Ops);
+}
+
+/// Convert aliases to canonical form.
+static bool canonicalizeAliases(Module &M) {
+ bool Changed = false;
+ for (auto &GA : M.aliases())
+ canonicalizeAlias(&GA, Changed);
+ return Changed;
+}
+
+// Legacy pass that canonicalizes aliases.
+class CanonicalizeAliasesLegacyPass : public ModulePass {
+
+public:
+ /// Pass identification, replacement for typeid
+ static char ID;
+
+ /// Specify pass name for debug output
+ StringRef getPassName() const override { return "Canonicalize Aliases"; }
+
+ explicit CanonicalizeAliasesLegacyPass() : ModulePass(ID) {}
+
+ bool runOnModule(Module &M) override { return canonicalizeAliases(M); }
+};
+char CanonicalizeAliasesLegacyPass::ID = 0;
+
+} // anonymous namespace
+
+PreservedAnalyses CanonicalizeAliasesPass::run(Module &M,
+ ModuleAnalysisManager &AM) {
+ if (!canonicalizeAliases(M))
+ return PreservedAnalyses::all();
+
+ return PreservedAnalyses::none();
+}
+
+INITIALIZE_PASS_BEGIN(CanonicalizeAliasesLegacyPass, "canonicalize-aliases",
+ "Canonicalize aliases", false, false)
+INITIALIZE_PASS_END(CanonicalizeAliasesLegacyPass, "canonicalize-aliases",
+ "Canonicalize aliases", false, false)
+
+namespace llvm {
+ModulePass *createCanonicalizeAliasesPass() {
+ return new CanonicalizeAliasesLegacyPass();
+}
+} // namespace llvm
Modified: llvm/trunk/lib/Transforms/Utils/Utils.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/Utils.cpp?rev=350423&r1=350422&r2=350423&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/Utils.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/Utils.cpp Fri Jan 4 11:04:54 2019
@@ -26,6 +26,7 @@ using namespace llvm;
void llvm::initializeTransformUtils(PassRegistry &Registry) {
initializeAddDiscriminatorsLegacyPassPass(Registry);
initializeBreakCriticalEdgesPass(Registry);
+ initializeCanonicalizeAliasesLegacyPassPass(Registry);
initializeInstNamerPass(Registry);
initializeLCSSAWrapperPassPass(Registry);
initializeLibCallsShrinkWrapLegacyPassPass(Registry);
Added: llvm/trunk/test/Transforms/CanonicalizeAliases/canonicalize.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/CanonicalizeAliases/canonicalize.ll?rev=350423&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/CanonicalizeAliases/canonicalize.ll (added)
+++ llvm/trunk/test/Transforms/CanonicalizeAliases/canonicalize.ll Fri Jan 4 11:04:54 2019
@@ -0,0 +1,37 @@
+; RUN: opt -S -canonicalize-aliases < %s | FileCheck %s
+; RUN: opt -prepare-for-thinlto -O0 -module-summary -o - < %s | llvm-dis -o - | FileCheck %s
+; RUN: opt -S -passes=canonicalize-aliases < %s | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; CHECK-DAG: @analias = alias void (), void ()* @aliasee
+; CHECK-DAG: @anotheralias = alias void (), void ()* @aliasee
+; CHECK-DAG: define void @aliasee()
+
+ at analias = alias void (), void ()* @anotheralias
+ at anotheralias = alias void (), bitcast (void ()* @aliasee to void ()*)
+
+; Function Attrs: nounwind uwtable
+define void @aliasee() #0 {
+entry:
+ ret void
+}
+
+%struct.S1 = type { i32, i32, i32 }
+
+; CHECK-DAG: @S = global %struct.S1 { i32 31, i32 32, i32 33 }
+; CHECK-DAG: @Salias = alias i32, getelementptr inbounds (%struct.S1, %struct.S1* @S, i32 0, i32 1)
+; CHECK-DAG: @Salias2 = alias i32, getelementptr inbounds (%struct.S1, %struct.S1* @S, i32 0, i32 1)
+; CHECK-DAG: @Salias3 = alias i32, getelementptr inbounds (%struct.S1, %struct.S1* @S, i32 0, i32 1)
+
+ at S = global %struct.S1 { i32 31, i32 32, i32 33 }, align 4
+ at Salias = alias i32, getelementptr inbounds (%struct.S1, %struct.S1* @S, i32 0, i32 1)
+ at Salias2 = alias i32, i32* @Salias
+ at Salias3 = alias i32, i32* @Salias2
+
+; CHECK-DAG: @Salias4 = alias %struct.S1, %struct.S1* @S
+; CHECK-DAG: @Salias5 = alias i32, getelementptr inbounds (%struct.S1, %struct.S1* @S, i32 0, i32 1)
+
+ at Salias4 = alias %struct.S1, %struct.S1* @S
+ at Salias5 = alias i32, getelementptr inbounds (%struct.S1, %struct.S1* @Salias4, i32 0, i32 1)
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