[llvm] r282733 - [thinlto] Add cold-callsite import heuristic
Piotr Padlewski via llvm-commits
llvm-commits at lists.llvm.org
Thu Sep 29 10:32:07 PDT 2016
Author: prazek
Date: Thu Sep 29 12:32:07 2016
New Revision: 282733
URL: http://llvm.org/viewvc/llvm-project?rev=282733&view=rev
Log:
[thinlto] Add cold-callsite import heuristic
Summary:
Not tunned up heuristic, but with this small heuristic there is about
+0.10% improvement on SPEC 2006
Reviewers: tejohnson, mehdi_amini, eraman
Subscribers: mehdi_amini, llvm-commits
Differential Revision: https://reviews.llvm.org/D24940
Modified:
llvm/trunk/lib/Transforms/IPO/FunctionImport.cpp
llvm/trunk/test/Transforms/FunctionImport/hotness_based_import.ll
Modified: llvm/trunk/lib/Transforms/IPO/FunctionImport.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/FunctionImport.cpp?rev=282733&r1=282732&r2=282733&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/FunctionImport.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/FunctionImport.cpp Thu Sep 29 12:32:07 2016
@@ -48,10 +48,15 @@ static cl::opt<float>
cl::desc("As we import functions, multiply the "
"`import-instr-limit` threshold by this factor "
"before processing newly imported functions"));
+
static cl::opt<float> ImportHotMultiplier(
"import-hot-multiplier", cl::init(3.0), cl::Hidden, cl::value_desc("x"),
- cl::ZeroOrMore, cl::desc("Multiply the `import-instr-limit` threshold for "
- "hot callsites"));
+ cl::desc("Multiply the `import-instr-limit` threshold for hot callsites"));
+
+// FIXME: This multiplier was not really tuned up.
+static cl::opt<float> ImportColdMultiplier(
+ "import-cold-multiplier", cl::init(0), cl::Hidden, cl::value_desc("N"),
+ cl::desc("Multiply the `import-instr-limit` threshold for cold callsites"));
static cl::opt<bool> PrintImports("print-imports", cl::init(false), cl::Hidden,
cl::desc("Print imported functions"));
@@ -285,11 +290,16 @@ static void computeImportForFunction(
continue;
}
- // FIXME: Also lower the threshold for cold callsites.
+ auto GetBonusMultiplier = [](CalleeInfo::HotnessType Hotness) -> float {
+ if (Hotness == CalleeInfo::HotnessType::Hot)
+ return ImportHotMultiplier;
+ if (Hotness == CalleeInfo::HotnessType::Cold)
+ return ImportColdMultiplier;
+ return 1.0;
+ };
+
const auto NewThreshold =
- Edge.second.Hotness == CalleeInfo::HotnessType::Hot
- ? Threshold * ImportHotMultiplier
- : Threshold;
+ Threshold * GetBonusMultiplier(Edge.second.Hotness);
auto *CalleeSummary = selectCallee(GUID, NewThreshold, Index);
if (!CalleeSummary) {
DEBUG(dbgs() << "ignored! No qualifying callee with summary found.\n");
Modified: llvm/trunk/test/Transforms/FunctionImport/hotness_based_import.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/FunctionImport/hotness_based_import.ll?rev=282733&r1=282732&r2=282733&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/FunctionImport/hotness_based_import.ll (original)
+++ llvm/trunk/test/Transforms/FunctionImport/hotness_based_import.ll Thu Sep 29 12:32:07 2016
@@ -5,12 +5,13 @@
; Test import with default hot multiplier (3)
; RUN: opt -function-import -summary-file %t3.thinlto.bc %t.bc -import-instr-limit=1 --S | FileCheck %s --check-prefix=CHECK --check-prefix=HOT-DEFAULT
-; RUN: opt -function-import -summary-file %t3.thinlto.bc %t.bc -import-instr-limit=1 --S -import-hot-multiplier=3.0 | FileCheck %s --check-prefix=CHECK --check-prefix=HOT-DEFAULT
+; RUN: opt -function-import -summary-file %t3.thinlto.bc %t.bc -import-instr-limit=1 --S -import-hot-multiplier=3.0 -import-cold-multiplier=0.0 | FileCheck %s --check-prefix=CHECK --check-prefix=HOT-DEFAULT
+
; HOT-DEFAULT-DAG: define available_externally void @hot1()
; HOT-DEFAULT-DAG: define available_externally void @hot2()
-; HOT-DEFAULT-DAG: define available_externally void @cold()
; HOT-DEFAULT-DAG: define available_externally void @none1()
+; HOT-DEFAULT-NOT: define available_externally void @cold()
; HOT-DEFAULT-NOT: define available_externally void @hot3()
; HOT-DEFAULT-NOT: define available_externally void @none2()
; HOT-DEFAULT-NOT: define available_externally void @none3()
@@ -20,17 +21,26 @@
; Test import with hot multiplier 1.0 - treat hot callsites as normal.
; RUN: opt -function-import -summary-file %t3.thinlto.bc %t.bc -import-instr-limit=1 -import-hot-multiplier=1.0 --S | FileCheck %s --check-prefix=CHECK --check-prefix=HOT-ONE
; HOT-ONE-DAG: define available_externally void @hot1()
-; HOT-ONE-DAG: define available_externally void @cold()
; HOT-ONE-DAG: define available_externally void @none1()
+; HOT-ONE-NOT: define available_externally void @cold()
; HOT-ONE-NOT: define available_externally void @hot2()
; HOT-ONE-NOT: define available_externally void @hot3()
; HOT-ONE-NOT: define available_externally void @none2()
; HOT-ONE-NOT: define available_externally void @none3()
; HOT-ONE-NOT: define available_externally void @cold2()
+; RUN: opt -function-import -summary-file %t3.thinlto.bc %t.bc -import-instr-limit=1 -import-hot-multiplier=1.0 -import-cold-multiplier=1.0 --S | FileCheck %s --check-prefix=CHECK --check-prefix=HOT-COLD-ONE
+; HOT-COLD-ONE-DAG: define available_externally void @hot1()
+; HOT-COLD-ONE-DAG: define available_externally void @cold()
+; HOT-COLD-ONE-DAG: define available_externally void @none1()
+; HOT-COLD-ONE-NOT: define available_externally void @hot2()
+; HOT-COLD-ONE-NOT: define available_externally void @hot3()
+; HOT-COLD-ONE-NOT: define available_externally void @none2()
+; HOT-COLD-ONE-NOT: define available_externally void @none3()
+; HOT-COLD-ONE-NOT: define available_externally void @cold2()
; Test import with hot multiplier 0.0 and high threshold - don't import functions called from hot callsite.
-; RUN: opt -function-import -summary-file %t3.thinlto.bc %t.bc -import-instr-limit=10 -import-hot-multiplier=0.0 --S | FileCheck %s --check-prefix=CHECK --check-prefix=HOT-ZERO
+; RUN: opt -function-import -summary-file %t3.thinlto.bc %t.bc -import-instr-limit=10 -import-hot-multiplier=0.0 -import-cold-multiplier=1.0 --S | FileCheck %s --check-prefix=CHECK --check-prefix=HOT-ZERO
; HOT-ZERO-DAG: define available_externally void @cold()
; HOT-ZERO-DAG: define available_externally void @none1()
; HOT-ZERO-DAG: define available_externally void @none2()
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