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-rw-r--r--llvm/include/llvm/Passes/PassBuilder.h6
-rw-r--r--llvm/lib/Passes/PassBuilder.cpp31
-rw-r--r--llvm/lib/Transforms/IPO/PassManagerBuilder.cpp15
-rw-r--r--llvm/test/Other/X86/lto-hot-cold-split.ll6
-rw-r--r--llvm/test/Other/new-pm-pgo.ll2
-rw-r--r--llvm/test/Other/opt-hot-cold-split.ll17
-rw-r--r--llvm/test/Other/pass-pipelines.ll2
7 files changed, 43 insertions, 36 deletions
diff --git a/llvm/include/llvm/Passes/PassBuilder.h b/llvm/include/llvm/Passes/PassBuilder.h
index 9c915c61b96..bb3196533e6 100644
--- a/llvm/include/llvm/Passes/PassBuilder.h
+++ b/llvm/include/llvm/Passes/PassBuilder.h
@@ -274,7 +274,8 @@ public:
/// require some transformations for semantic reasons, they should explicitly
/// build them.
ModulePassManager buildModuleOptimizationPipeline(OptimizationLevel Level,
- bool DebugLogging = false);
+ bool DebugLogging = false,
+ bool LTOPreLink = false);
/// Build a per-module default optimization pipeline.
///
@@ -288,7 +289,8 @@ public:
/// require some transformations for semantic reasons, they should explicitly
/// build them.
ModulePassManager buildPerModuleDefaultPipeline(OptimizationLevel Level,
- bool DebugLogging = false);
+ bool DebugLogging = false,
+ bool LTOPreLink = false);
/// Build a pre-link, ThinLTO-targeting default optimization pipeline to
/// a pass manager.
diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index 2e7d7121249..2072fc3aa26 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -703,14 +703,6 @@ PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
if (EnableSyntheticCounts && !PGOOpt)
MPM.addPass(SyntheticCountsPropagation());
- // Split out cold code. Splitting is done before inlining because 1) the most
- // common kinds of cold regions can (a) be found before inlining and (b) do
- // not grow after inlining, and 2) inhibiting inlining of cold code improves
- // code size & compile time. Split after Mem2Reg to make code model estimates
- // more accurate, but before InstCombine to allow it to clean things up.
- if (EnableHotColdSplit && Phase != ThinLTOPhase::PostLink)
- MPM.addPass(HotColdSplittingPass());
-
// Require the GlobalsAA analysis for the module so we can query it within
// the CGSCC pipeline.
MPM.addPass(RequireAnalysisPass<GlobalsAA, Module>());
@@ -769,9 +761,8 @@ PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
return MPM;
}
-ModulePassManager
-PassBuilder::buildModuleOptimizationPipeline(OptimizationLevel Level,
- bool DebugLogging) {
+ModulePassManager PassBuilder::buildModuleOptimizationPipeline(
+ OptimizationLevel Level, bool DebugLogging, bool LTOPreLink) {
ModulePassManager MPM(DebugLogging);
// Optimize globals now that the module is fully simplified.
@@ -880,6 +871,12 @@ PassBuilder::buildModuleOptimizationPipeline(OptimizationLevel Level,
// alignment information, try to re-derive it here.
OptimizePM.addPass(AlignmentFromAssumptionsPass());
+ // Split out cold code. Splitting is done late to avoid hiding context from
+ // other optimizations and inadvertently regressing performance. The tradeoff
+ // is that this has a higher code size cost than splitting early.
+ if (EnableHotColdSplit && !LTOPreLink)
+ MPM.addPass(HotColdSplittingPass());
+
// LoopSink pass sinks instructions hoisted by LICM, which serves as a
// canonicalization pass that enables other optimizations. As a result,
// LoopSink pass needs to be a very late IR pass to avoid undoing LICM
@@ -923,7 +920,7 @@ PassBuilder::buildModuleOptimizationPipeline(OptimizationLevel Level,
ModulePassManager
PassBuilder::buildPerModuleDefaultPipeline(OptimizationLevel Level,
- bool DebugLogging) {
+ bool DebugLogging, bool LTOPreLink) {
assert(Level != O0 && "Must request optimizations for the default pipeline!");
ModulePassManager MPM(DebugLogging);
@@ -943,7 +940,7 @@ PassBuilder::buildPerModuleDefaultPipeline(OptimizationLevel Level,
DebugLogging));
// Now add the optimization pipeline.
- MPM.addPass(buildModuleOptimizationPipeline(Level, DebugLogging));
+ MPM.addPass(buildModuleOptimizationPipeline(Level, DebugLogging, LTOPreLink));
return MPM;
}
@@ -1027,7 +1024,8 @@ PassBuilder::buildLTOPreLinkDefaultPipeline(OptimizationLevel Level,
bool DebugLogging) {
assert(Level != O0 && "Must request optimizations for the default pipeline!");
// FIXME: We should use a customized pre-link pipeline!
- return buildPerModuleDefaultPipeline(Level, DebugLogging);
+ return buildPerModuleDefaultPipeline(Level, DebugLogging,
+ /*LTOPreLink=*/true);
}
ModulePassManager
@@ -1208,6 +1206,11 @@ PassBuilder::buildLTODefaultPipeline(OptimizationLevel Level, bool DebugLogging,
// CFI is disabled.
MPM.addPass(LowerTypeTestsPass(ExportSummary, nullptr));
+ // Enable splitting late in the FullLTO post-link pipeline. This is done in
+ // the same stage in the old pass manager (\ref addLateLTOOptimizationPasses).
+ if (EnableHotColdSplit)
+ MPM.addPass(HotColdSplittingPass());
+
// Add late LTO optimization passes.
// Delete basic blocks, which optimization passes may have killed.
MPM.addPass(createModuleToFunctionPassAdaptor(SimplifyCFGPass()));
diff --git a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
index 8f2860ba51b..d52a9c66894 100644
--- a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -529,11 +529,6 @@ void PassManagerBuilder::populateModulePassManager(
if (DefaultOrPreLinkPipeline && !PrepareForThinLTOUsingPGOSampleProfile)
addPGOInstrPasses(MPM);
- // Split out cold code before inlining. See comment in the new PM
- // (\ref buildModuleSimplificationPipeline).
- if (EnableHotColdSplit && DefaultOrPreLinkPipeline)
- MPM.add(createHotColdSplittingPass());
-
// We add a module alias analysis pass here. In part due to bugs in the
// analysis infrastructure this "works" in that the analysis stays alive
// for the entire SCC pass run below.
@@ -730,6 +725,11 @@ void PassManagerBuilder::populateModulePassManager(
MPM.add(createConstantMergePass()); // Merge dup global constants
}
+ // See comment in the new PM for justification of scheduling splitting at
+ // this stage (\ref buildModuleSimplificationPipeline).
+ if (EnableHotColdSplit && !(PrepareForLTO || PrepareForThinLTO))
+ MPM.add(createHotColdSplittingPass());
+
if (MergeFunctions)
MPM.add(createMergeFunctionsPass());
@@ -918,6 +918,11 @@ void PassManagerBuilder::addLTOOptimizationPasses(legacy::PassManagerBase &PM) {
void PassManagerBuilder::addLateLTOOptimizationPasses(
legacy::PassManagerBase &PM) {
+ // See comment in the new PM for justification of scheduling splitting at
+ // this stage (\ref buildLTODefaultPipeline).
+ if (EnableHotColdSplit)
+ PM.add(createHotColdSplittingPass());
+
// Delete basic blocks, which optimization passes may have killed.
PM.add(createCFGSimplificationPass());
diff --git a/llvm/test/Other/X86/lto-hot-cold-split.ll b/llvm/test/Other/X86/lto-hot-cold-split.ll
index 67de630e6e2..1c6a33df21c 100644
--- a/llvm/test/Other/X86/lto-hot-cold-split.ll
+++ b/llvm/test/Other/X86/lto-hot-cold-split.ll
@@ -1,10 +1,10 @@
; RUN: opt -module-summary %s -o %t.bc
-; RUN: llvm-lto -hot-cold-split=true -thinlto-action=run %t.bc -debug-pass=Structure 2>&1 | FileCheck %s -check-prefix=OLDPM-THINLTO-POSTLINK-Os
+; RUN: llvm-lto -hot-cold-split=true -thinlto-action=run %t.bc -debug-pass=Structure 2>&1 | FileCheck %s -check-prefix=OLDPM-ANYLTO-POSTLINK-Os
+; RUN: llvm-lto -hot-cold-split=true %t.bc -debug-pass=Structure 2>&1 | FileCheck %s -check-prefix=OLDPM-ANYLTO-POSTLINK-Os
; REQUIRES: asserts
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
-; OLDPM-THINLTO-POSTLINK-Os-LABEL: Pass Arguments
-; OLDPM-THINLTO-POSTLINK-Os-NOT: Hot Cold Splitting
+; OLDPM-ANYLTO-POSTLINK-Os: Hot Cold Splitting
diff --git a/llvm/test/Other/new-pm-pgo.ll b/llvm/test/Other/new-pm-pgo.ll
index 916309e625b..ab9f084c38c 100644
--- a/llvm/test/Other/new-pm-pgo.ll
+++ b/llvm/test/Other/new-pm-pgo.ll
@@ -13,7 +13,6 @@
; GEN: Running pass: PGOInstrumentationGen
; USE: Running pass: PGOInstrumentationUse
; USE: Running pass: PGOIndirectCallPromotion
-; SPLIT: Running pass: HotColdSplittingPass
; USE: Running pass: PGOMemOPSizeOpt
; SAMPLE_USE_O: Running pass: ModuleToFunctionPassAdaptor<{{.*}}AddDiscriminatorsPass{{.*}}>
; SAMPLE_USE_PRE_LINK: Running pass: ModuleToFunctionPassAdaptor<{{.*}}AddDiscriminatorsPass{{.*}}>
@@ -27,6 +26,7 @@
; SAMPLE_USE_POST_LINK-NOT: Running pass: GlobalOptPass
; SAMPLE_USE_POST_LINK: Running pass: PGOIndirectCallPromotion
; SAMPLE_GEN: Running pass: ModuleToFunctionPassAdaptor<{{.*}}AddDiscriminatorsPass{{.*}}>
+; SPLIT: Running pass: HotColdSplittingPass
define void @foo() {
ret void
diff --git a/llvm/test/Other/opt-hot-cold-split.ll b/llvm/test/Other/opt-hot-cold-split.ll
index 90358bf5567..971fe130b11 100644
--- a/llvm/test/Other/opt-hot-cold-split.ll
+++ b/llvm/test/Other/opt-hot-cold-split.ll
@@ -1,22 +1,19 @@
; RUN: opt -mtriple=x86_64-- -Os -hot-cold-split=true -debug-pass=Structure < %s -o /dev/null 2>&1 | FileCheck %s -check-prefix=DEFAULT-Os
; RUN: opt -mtriple=x86_64-- -Os -hot-cold-split=true -passes='lto-pre-link<Os>' -debug-pass-manager < %s -o /dev/null 2>&1 | FileCheck %s -check-prefix=LTO-PRELINK-Os
; RUN: opt -mtriple=x86_64-- -Os -hot-cold-split=true -passes='thinlto-pre-link<Os>' -debug-pass-manager < %s -o /dev/null 2>&1 | FileCheck %s -check-prefix=THINLTO-PRELINK-Os
+; RUN: opt -mtriple=x86_64-- -Os -hot-cold-split=true -passes='lto<Os>' -debug-pass-manager < %s -o /dev/null 2>&1 | FileCheck %s -check-prefix=LTO-POSTLINK-Os
; RUN: opt -mtriple=x86_64-- -Os -hot-cold-split=true -passes='thinlto<Os>' -debug-pass-manager < %s -o /dev/null 2>&1 | FileCheck %s -check-prefix=THINLTO-POSTLINK-Os
; REQUIRES: asserts
-; Splitting should occur after Mem2Reg and should be followed by InstCombine.
+; Splitting should occur late.
-; DEFAULT-Os: Promote Memory to Register
; DEFAULT-Os: Hot Cold Splitting
-; DEFAULT-Os: Combine redundant instructions
+; DEFAULT-Os: Simplify the CFG
-; LTO-PRELINK-Os-LABEL: Starting llvm::Module pass manager run.
-; LTO-PRELINK-Os: Running pass: {{.*}}PromotePass
-; LTO-PRELINK-Os: Running pass: HotColdSplittingPass
+; LTO-PRELINK-Os-NOT: pass: HotColdSplittingPass
-; THINLTO-PRELINK-Os-LABEL: Running analysis: PassInstrumentationAnalysis
-; THINLTO-PRELINK-Os: Running pass: {{.*}}PromotePass
-; THINLTO-PRELINK-Os: Running pass: HotColdSplittingPass
+; THINLTO-PRELINK-Os-NOT: Running pass: HotColdSplittingPass
-; THINLTO-POSTLINK-Os-NOT: HotColdSplitting
+; LTO-POSTLINK-Os: HotColdSplitting
+; THINLTO-POSTLINK-Os: HotColdSplitting
diff --git a/llvm/test/Other/pass-pipelines.ll b/llvm/test/Other/pass-pipelines.ll
index dfddcee55e8..be14c6cdeb6 100644
--- a/llvm/test/Other/pass-pipelines.ll
+++ b/llvm/test/Other/pass-pipelines.ll
@@ -41,7 +41,6 @@
; PGOUSE: Function Integration/Inlining
; PGOUSE: PGOInstrumentationUsePass
; PGOUSE: PGOIndirectCallPromotion
-; SPLIT: Hot Cold Splitting
; PGOUSE: CallGraph Construction
; CHECK-O2-NEXT: Globals Alias Analysis
; CHECK-O2-NEXT: Call Graph SCC Pass Manager
@@ -100,6 +99,7 @@
; the runtime unrolling though.
; CHECK-O2: Loop Pass Manager
; CHECK-O2-NEXT: Loop Invariant Code Motion
+; SPLIT: Hot Cold Splitting
; CHECK-O2: FunctionPass Manager
; CHECK-O2: Loop Pass Manager
; CHECK-O2-NEXT: Loop Sink
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