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IRGen, benchmarks: add an option -align-module-to-page-size for benchmarking #18318

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Merged
merged 2 commits into from
Jul 28, 2018
Merged

IRGen, benchmarks: add an option -align-module-to-page-size for benchmarking #18318

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aafb780
IRGen: add an option -align-module-to-page-size for benchmarking
eeckstein Jul 27, 2018
1a161c2
benchmarks: compile with the new -align-module-to-page-size option, i…
eeckstein Jul 28, 2018
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1 change: 1 addition & 0 deletions benchmark/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -272,6 +272,7 @@ message("-- SWIFT_LIBRARY_PATH = ${SWIFT_LIBRARY_PATH}")
message("-- CLANG_EXEC = ${CLANG_EXEC}")
message("-- SWIFT_OPTIMIZATION_LEVELS = ${SWIFT_OPTIMIZATION_LEVELS}")
message("-- ONLY_PLATFORMS = ${ONLY_PLATFORMS}")
message("-- PAGE_ALIGNMENT_OPTION = ${PAGE_ALIGNMENT_OPTION}")

message("-- found platforms: ${platforms}")
message("-- found sdks:")
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15 changes: 14 additions & 1 deletion benchmark/cmake/modules/AddSwiftBenchmarkSuite.cmake
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Expand Up @@ -40,6 +40,19 @@ macro(configure_build)
message(FATAL_ERROR "Unsupported platform?!")
endif()

set(PAGE_ALIGNMENT_OPTION "-Xllvm" "-align-module-to-page-size")
execute_process(
COMMAND "touch" "empty.swift"
RESULT_VARIABLE result
ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
execute_process(
COMMAND "${SWIFT_EXEC}" ${PAGE_ALIGNMENT_OPTION} "empty.swift"
RESULT_VARIABLE result
ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
if(NOT "${result}" MATCHES "0")
set(PAGE_ALIGNMENT_OPTION "")
endif()

# We always infer the SWIFT_LIBRARY_PATH from SWIFT_EXEC unless
# SWIFT_LIBRARY_PATH is specified explicitly.
if(NOT SWIFT_LIBRARY_PATH)
Expand Down Expand Up @@ -293,7 +306,7 @@ function (swift_benchmark_compile_archopts)
set(common_options
"-c"
"-target" "${target}"
"-${BENCH_COMPILE_ARCHOPTS_OPT}")
"-${BENCH_COMPILE_ARCHOPTS_OPT}" ${PAGE_ALIGNMENT_OPTION})

if (is_darwin)
list(APPEND common_options
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29 changes: 29 additions & 0 deletions lib/IRGen/IRGen.cpp
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Expand Up @@ -74,6 +74,10 @@

#include <thread>

#if HAVE_UNISTD_H
#include <unistd.h>
#endif

using namespace swift;
using namespace irgen;
using namespace llvm;
Expand All @@ -82,6 +86,14 @@ static cl::opt<bool> DisableObjCARCContract(
"disable-objc-arc-contract", cl::Hidden,
cl::desc("Disable running objc arc contract for testing purposes"));

// This option is for performance benchmarking: to ensure a consistent
// performance data, modules are aligned to the page size.
// Warning: this blows up the text segment size. So use this option only for
// performance benchmarking.
static cl::opt<bool> AlignModuleToPageSize(
"align-module-to-page-size", cl::Hidden,
cl::desc("Align the text section of all LLVM modules to the page size"));

namespace {
// We need this to access IRGenOptions from extension functions
class PassManagerBuilderWrapper : public PassManagerBuilder {
Expand Down Expand Up @@ -274,6 +286,23 @@ void swift::performLLVMOptimizations(IRGenOptions &Opts, llvm::Module *Module,

// Do it.
ModulePasses.run(*Module);

if (AlignModuleToPageSize) {
// For performance benchmarking: Align the module to the page size by
// aligning the first function of the module.
unsigned pageSize =
#if HAVE_UNISTD_H
sysconf(_SC_PAGESIZE));
#else
4096; // Use a default value
#endif
for (auto I = Module->begin(), E = Module->end(); I != E; ++I) {
if (!I->isDeclaration()) {
I->setAlignment(pageSize);
break;
}
}
}
}

namespace {
Expand Down