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[Clang][CMake] Support perf, LBR, and Instrument CLANG_BOLT options #69133

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merged 3 commits into from
Jan 22, 2024

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@aaupov aaupov commented Oct 15, 2023

Split up and refactor CLANG_BOLT_INSTRUMENT into support for
perf no-LBR and perf with LBR profiling modes.

Differential Revision: https://reviews.llvm.org/D143617

@llvmbot llvmbot added the clang Clang issues not falling into any other category label Oct 15, 2023
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llvmbot commented Oct 15, 2023

@llvm/pr-subscribers-clang

Author: Amir Ayupov (aaupov)

Changes

Split up and refactor CLANG_BOLT_INSTRUMENT into support for
perf no-LBR and perf with LBR profiling modes.

Differential Revision: https://reviews.llvm.org/D143617


Full diff: https://github.com/llvm/llvm-project/pull/69133.diff

6 Files Affected:

  • (modified) clang/CMakeLists.txt (+30-14)
  • (modified) clang/cmake/caches/BOLT.cmake (+1-1)
  • (modified) clang/utils/perf-training/CMakeLists.txt (+26-3)
  • (modified) clang/utils/perf-training/bolt.lit.cfg (+45-8)
  • (modified) clang/utils/perf-training/bolt.lit.site.cfg.in (+2)
  • (modified) clang/utils/perf-training/perf-helper.py (+65)
diff --git a/clang/CMakeLists.txt b/clang/CMakeLists.txt
index 9b52c58be41e7f7..8f64d95cc394ffe 100644
--- a/clang/CMakeLists.txt
+++ b/clang/CMakeLists.txt
@@ -850,23 +850,38 @@ if (CLANG_ENABLE_BOOTSTRAP)
   endforeach()
 endif()
 
-if (CLANG_BOLT_INSTRUMENT AND NOT LLVM_BUILD_INSTRUMENTED)
+set(CLANG_BOLT "INSTRUMENT" CACHE STRING "Apply BOLT optimization to Clang. \
+  May be specified as Instrument or Perf or LBR to use a particular profiling \
+  mechanism.")
+string(TOUPPER "${CLANG_BOLT}" uppercase_CLANG_BOLT)
+
+if (CLANG_BOLT AND NOT LLVM_BUILD_INSTRUMENTED)
   set(CLANG_PATH ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang)
-  set(CLANG_INSTRUMENTED ${CLANG_PATH}-bolt.inst)
+  set(CLANG_INSTRUMENTED ${LLVM_RUNTIME_OUTPUT_INTDIR}/${CLANG_BOLT_INSTRUMENTED})
   set(BOLT_FDATA ${CMAKE_CURRENT_BINARY_DIR}/utils/perf-training/prof.fdata)
 
-  # Instrument clang with BOLT
-  add_custom_target(clang-instrumented
-    DEPENDS ${CLANG_INSTRUMENTED}
-  )
-  add_custom_command(OUTPUT ${CLANG_INSTRUMENTED}
-    DEPENDS clang llvm-bolt
-    COMMAND llvm-bolt ${CLANG_PATH} -o ${CLANG_INSTRUMENTED}
-      -instrument --instrumentation-file-append-pid
-      --instrumentation-file=${BOLT_FDATA}
-    COMMENT "Instrumenting clang binary with BOLT"
-    VERBATIM
-  )
+  # Pass extra flag in no-LBR mode
+  if (uppercase_CLANG_BOLT STREQUAL "PERF")
+    set(BOLT_NO_LBR "-nl")
+  endif()
+
+  if (uppercase_CLANG_BOLT STREQUAL "INSTRUMENT")
+    # Instrument clang with BOLT
+    add_custom_target(clang-instrumented
+      DEPENDS ${CLANG_INSTRUMENTED}
+    )
+    add_custom_command(OUTPUT ${CLANG_INSTRUMENTED}
+      DEPENDS clang llvm-bolt
+      COMMAND llvm-bolt ${CLANG_PATH} -o ${CLANG_INSTRUMENTED}
+        -instrument --instrumentation-file-append-pid
+        --instrumentation-file=${BOLT_FDATA}
+      COMMENT "Instrumenting clang binary with BOLT"
+      VERBATIM
+    )
+    add_custom_target(clang-bolt-training-deps DEPENDS clang-instrumented)
+  else() # perf or LBR
+    add_custom_target(clang-bolt-training-deps DEPENDS clang)
+  endif()
 
   # Optimize original (pre-bolt) Clang using the collected profile
   set(CLANG_OPTIMIZED ${CMAKE_CURRENT_BINARY_DIR}/clang.bolt)
@@ -880,6 +895,7 @@ if (CLANG_BOLT_INSTRUMENT AND NOT LLVM_BUILD_INSTRUMENTED)
       -data ${BOLT_FDATA}
       -reorder-blocks=ext-tsp -reorder-functions=hfsort+ -split-functions
       -split-all-cold -split-eh -dyno-stats -icf=1 -use-gnu-stack
+      ${BOLT_NO_LBR}
     COMMAND ${CMAKE_COMMAND} -E rename ${CLANG_OPTIMIZED} $<TARGET_FILE:clang>
     COMMENT "Optimizing Clang with BOLT"
     VERBATIM
diff --git a/clang/cmake/caches/BOLT.cmake b/clang/cmake/caches/BOLT.cmake
index 0442f73e5426ac7..eba2346b2f4ca12 100644
--- a/clang/cmake/caches/BOLT.cmake
+++ b/clang/cmake/caches/BOLT.cmake
@@ -1,5 +1,5 @@
 set(CMAKE_BUILD_TYPE Release CACHE STRING "")
-set(CLANG_BOLT_INSTRUMENT ON CACHE BOOL "")
+set(CLANG_BOLT "INSTRUMENT" CACHE STRING "")
 set(CMAKE_EXE_LINKER_FLAGS "-Wl,--emit-relocs,-znow" CACHE STRING "")
 
 set(LLVM_ENABLE_PROJECTS "bolt;clang" CACHE STRING "")
diff --git a/clang/utils/perf-training/CMakeLists.txt b/clang/utils/perf-training/CMakeLists.txt
index c6d51863fb1b5c2..48fbee62a8636d1 100644
--- a/clang/utils/perf-training/CMakeLists.txt
+++ b/clang/utils/perf-training/CMakeLists.txt
@@ -62,7 +62,9 @@ if(APPLE AND DTRACE AND NOT LLVM_TOOL_LLVM_DRIVER_BUILD)
     DEPENDS generate-dtrace-logs)
 endif()
 
-if(CLANG_BOLT_INSTRUMENT AND NOT LLVM_BUILD_INSTRUMENTED)
+if(CLANG_BOLT AND NOT LLVM_BUILD_INSTRUMENTED)
+  set(CLANG_BOLT_INSTRUMENTED "clang-bolt.inst" CACHE STRING
+    "Name of BOLT-instrumented Clang binary")
   configure_lit_site_cfg(
     ${CMAKE_CURRENT_SOURCE_DIR}/bolt.lit.site.cfg.in
     ${CMAKE_CURRENT_BINARY_DIR}/bolt-fdata/lit.site.cfg
@@ -71,16 +73,37 @@ if(CLANG_BOLT_INSTRUMENT AND NOT LLVM_BUILD_INSTRUMENTED)
   add_lit_testsuite(generate-bolt-fdata "Generating BOLT profile for Clang"
     ${CMAKE_CURRENT_BINARY_DIR}/bolt-fdata/
     EXCLUDE_FROM_CHECK_ALL
-    DEPENDS clang-instrumented clear-bolt-fdata
+    DEPENDS clang-bolt-training-deps clear-bolt-fdata clear-perf-data
     )
 
   add_custom_target(clear-bolt-fdata
     COMMAND "${Python3_EXECUTABLE}" ${CMAKE_CURRENT_SOURCE_DIR}/perf-helper.py clean ${CMAKE_CURRENT_BINARY_DIR} fdata
     COMMENT "Clearing old BOLT fdata")
 
+  add_custom_target(clear-perf-data
+    COMMAND "${Python3_EXECUTABLE}" ${CMAKE_CURRENT_SOURCE_DIR}/perf-helper.py clean ${CMAKE_CURRENT_BINARY_DIR} perf.data
+    COMMENT "Clearing old perf data")
+
+  string(TOUPPER "${CLANG_BOLT}" uppercase_CLANG_BOLT)
+  if (uppercase_CLANG_BOLT STREQUAL "LBR")
+    set(BOLT_LBR "--lbr")
+  endif()
+
+  add_custom_target(merge-fdata-deps)
+  if (uppercase_CLANG_BOLT STREQUAL "INSTRUMENT")
+    add_dependencies(merge-fdata-deps generate-bolt-fdata)
+  else()
+    # Convert perf profiles into fdata
+    add_custom_target(convert-perf-fdata
+      COMMAND "${Python3_EXECUTABLE}" ${CMAKE_CURRENT_SOURCE_DIR}/perf-helper.py perf2bolt $<TARGET_FILE:llvm-bolt> ${CMAKE_CURRENT_BINARY_DIR} $<TARGET_FILE:clang> ${BOLT_LBR}
+      COMMENT "Converting perf files to BOLT fdata"
+      DEPENDS llvm-bolt generate-bolt-fdata)
+    add_dependencies(merge-fdata-deps convert-perf-fdata)
+  endif()
+
   # Merge profiles into one using merge-fdata
   add_custom_target(clang-bolt-profile
     COMMAND "${Python3_EXECUTABLE}" ${CMAKE_CURRENT_SOURCE_DIR}/perf-helper.py merge-fdata $<TARGET_FILE:merge-fdata> ${CMAKE_CURRENT_BINARY_DIR}/prof.fdata ${CMAKE_CURRENT_BINARY_DIR}
     COMMENT "Merging BOLT fdata"
-    DEPENDS merge-fdata generate-bolt-fdata)
+    DEPENDS merge-fdata merge-fdata-deps)
 endif()
diff --git a/clang/utils/perf-training/bolt.lit.cfg b/clang/utils/perf-training/bolt.lit.cfg
index 234ac855bd67c65..d2b6042a1627e19 100644
--- a/clang/utils/perf-training/bolt.lit.cfg
+++ b/clang/utils/perf-training/bolt.lit.cfg
@@ -6,15 +6,52 @@ import lit.util
 import os
 import subprocess
 
-config.clang = os.path.realpath(lit.util.which('clang-bolt.inst', config.clang_tools_dir)).replace('\\', '/')
+clang_binary = "clang"
+perf_wrapper = ""
+if config.clang_bolt_mode.lower() == "instrument":
+    clang_binary = config.clang_bolt_name
+else:  # perf or LBR
+    perf_wrapper = "%s %s/perf-helper.py perf" % (
+        config.python_exe,
+        config.perf_helper_dir,
+    )
+    if config.clang_bolt_mode.lower() == "lbr":
+        perf_wrapper += " --lbr"
+    perf_wrapper += " -- "
 
-config.name = 'Clang Perf Training'
-config.suffixes = ['.c', '.cc', '.cpp', '.m', '.mm', '.cu', '.ll', '.cl', '.s', '.S', '.modulemap', '.test']
+config.clang = os.path.realpath(
+    lit.util.which(clang_binary, config.clang_tools_dir)
+).replace("\\", "/")
+
+config.name = "Clang Perf Training"
+config.suffixes = [
+    ".c",
+    ".cc",
+    ".cpp",
+    ".m",
+    ".mm",
+    ".cu",
+    ".ll",
+    ".cl",
+    ".s",
+    ".S",
+    ".modulemap",
+    ".test",
+]
 
 use_lit_shell = os.environ.get("LIT_USE_INTERNAL_SHELL")
 config.test_format = lit.formats.ShTest(use_lit_shell == "0")
-config.substitutions.append( ('%clang_cpp_skip_driver', ' %s --driver-mode=g++ ' % (config.clang)))
-config.substitutions.append( ('%clang_cpp', ' %s --driver-mode=g++ ' % (config.clang)))
-config.substitutions.append( ('%clang_skip_driver', ' %s ' % (config.clang)))
-config.substitutions.append( ('%clang', ' %s ' % (config.clang) ) )
-config.substitutions.append( ('%test_root', config.test_exec_root ) )
+config.substitutions.append(
+    (
+        "%clang_cpp_skip_driver",
+        " %s %s --driver-mode=g++ " % (perf_wrapper, config.clang),
+    )
+)
+config.substitutions.append(
+    ("%clang_cpp", " %s %s --driver-mode=g++ " % (perf_wrapper, config.clang))
+)
+config.substitutions.append(
+    ("%clang_skip_driver", " %s %s " % (perf_wrapper, config.clang))
+)
+config.substitutions.append(("%clang", " %s %s " % (perf_wrapper, config.clang)))
+config.substitutions.append(("%test_root", config.test_exec_root))
diff --git a/clang/utils/perf-training/bolt.lit.site.cfg.in b/clang/utils/perf-training/bolt.lit.site.cfg.in
index 3029319673fc26c..54de12701c1ae91 100644
--- a/clang/utils/perf-training/bolt.lit.site.cfg.in
+++ b/clang/utils/perf-training/bolt.lit.site.cfg.in
@@ -9,6 +9,8 @@ config.test_source_root = "@CLANG_PGO_TRAINING_DATA@"
 config.target_triple = "@LLVM_TARGET_TRIPLE@"
 config.python_exe = "@Python3_EXECUTABLE@"
 config.clang_obj_root = path(r"@CLANG_BINARY_DIR@")
+config.clang_bolt_mode = "@CLANG_BOLT@"
+config.clang_bolt_name = "@CLANG_BOLT_INSTRUMENTED@"
 
 # Let the main config do the real work.
 lit_config.load_config(config, "@CLANG_SOURCE_DIR@/utils/perf-training/bolt.lit.cfg")
diff --git a/clang/utils/perf-training/perf-helper.py b/clang/utils/perf-training/perf-helper.py
index 99d6a3333b6ef08..c1ec68a9f6e2d4e 100644
--- a/clang/utils/perf-training/perf-helper.py
+++ b/clang/utils/perf-training/perf-helper.py
@@ -67,6 +67,69 @@ def merge_fdata(args):
     return 0
 
 
+def perf(args):
+    parser = argparse.ArgumentParser(
+        prog="perf-helper perf", description="perf wrapper for BOLT profile collection"
+    )
+    parser.add_argument(
+        "--lbr", action="store_true", help="Use perf with branch stacks"
+    )
+    parser.add_argument("cmd", nargs="*", help="")
+
+    # Use python's arg parser to handle all leading option arguments, but pass
+    # everything else through to perf
+    first_cmd = next(arg for arg in args if not arg.startswith("--"))
+    last_arg_idx = args.index(first_cmd)
+
+    opts = parser.parse_args(args[:last_arg_idx])
+    cmd = args[last_arg_idx:]
+
+    perf_args = [
+        "perf",
+        "record",
+        "--event=cycles:u",
+        "--freq=max",
+        "--output=%d.perf.data" % os.getpid(),
+    ]
+    if opts.lbr:
+        perf_args += ["--branch-filter=any,u"]
+    perf_args.extend(cmd)
+
+    start_time = time.time()
+    subprocess.check_call(perf_args)
+
+    elapsed = time.time() - start_time
+    print("... data collection took %.4fs" % elapsed)
+    return 0
+
+
+def perf2bolt(args):
+    parser = argparse.ArgumentParser(
+        prog="perf-helper perf2bolt",
+        description="perf2bolt conversion wrapper for perf.data files",
+    )
+    parser.add_argument("bolt", help="Path to llvm-bolt")
+    parser.add_argument("path", help="Path containing perf.data files")
+    parser.add_argument("binary", help="Input binary")
+    parser.add_argument(
+        "--lbr", action="store_true", help="Use LBR perf2bolt mode"
+    )
+    opts = parser.parse_args(args)
+
+    p2b_args = [
+        opts.bolt,
+        opts.binary,
+        "--aggregate-only",
+        "--profile-format=yaml",
+    ]
+    if not opts.lbr:
+        p2b_args += ["-nl"]
+    p2b_args += ["-p"]
+    for filename in findFilesWithExtension(opts.path, "perf.data"):
+        subprocess.check_call(p2b_args + [filename, "-o", filename + ".fdata"])
+    return 0
+
+
 def dtrace(args):
     parser = argparse.ArgumentParser(
         prog="perf-helper dtrace",
@@ -507,6 +570,8 @@ def genOrderFile(args):
     "cc1": cc1,
     "gen-order-file": genOrderFile,
     "merge-fdata": merge_fdata,
+    "perf": perf,
+    "perf2bolt": perf2bolt,
 }
 
 

@aaupov aaupov added cmake Build system in general and CMake in particular and removed clang Clang issues not falling into any other category labels Oct 15, 2023
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github-actions bot commented Oct 15, 2023

✅ With the latest revision this PR passed the Python code formatter.

@llvmbot llvmbot added the clang Clang issues not falling into any other category label Oct 15, 2023
clang/CMakeLists.txt Outdated Show resolved Hide resolved
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aaupov commented Nov 7, 2023

@petrhosek – thank you for a review!

aaupov and others added 3 commits November 7, 2023 20:40
Split up and refactor CLANG_BOLT_INSTRUMENT into support for
perf no-LBR and perf with LBR profiling modes.

Differential Revision: https://reviews.llvm.org/D143617
@aaupov aaupov merged commit 745883b into llvm:main Jan 22, 2024
3 checks passed
@aaupov aaupov deleted the arcpatch-D143617_1 branch January 22, 2024 06:03
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dyung commented Jan 22, 2024

@aaupov I believe this change is somehow causing cmake failures on several bots I oversee, although I cannot explain why it passed when building your commit. For example:

https://lab.llvm.org/buildbot/#/builders/139/builds/57628

CMake Error at /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/clang/utils/perf-training/CMakeLists.txt:105 (add_custom_target):
  Error evaluating generator expression:
    $<TARGET_FILE:merge-fdata>
  No target "merge-fdata"

Any idea what might be going wrong here?

@DavidSpickett
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I think because bots don't always clean their cmake files, revert incoming.

DavidSpickett added a commit that referenced this pull request Jan 22, 2024
…ptions (#69133)"

This reverts commit 745883b.

This is failing to configure on many of our bots:
https://lab.llvm.org/buildbot/#/builders/245/builds/19468

This did not get caught right away because generally bots only
clean the build every so often.
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https://lab.llvm.org/buildbot/#/builders/245/builds/19468

CMake Error at /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/utils/perf-training/CMakeLists.txt:105 (add_custom_target):
  Error evaluating generator expression:
    $<TARGET_FILE:merge-fdata>
  No target "merge-fdata"

This particular bot is clang+llvm and only the ARM target, but we've seen it on our AArch64 bots too.

@@ -850,23 +850,38 @@ if (CLANG_ENABLE_BOOTSTRAP)
endforeach()
endif()

if (CLANG_BOLT_INSTRUMENT AND NOT LLVM_BUILD_INSTRUMENTED)
set(CLANG_BOLT "INSTRUMENT" CACHE STRING "Apply BOLT optimization to Clang. \
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Wild guess, this defaults to INSTRUMENT, but it should default to some OFF value?

aaupov added a commit that referenced this pull request Jan 22, 2024
…tions (#69133)

This reverts commit 6c47419.

Default to CLANG_BOLT=OFF

Test Plan:
Build a regular Clang build.
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nickdesaulniers commented Jan 22, 2024

aaupov added a commit that referenced this pull request Jan 22, 2024
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aaupov commented Jan 22, 2024

Reverted. Strangely I couldn't repro the failure from https://lab.llvm.org/buildbot/#/builders/225/builds/29950 locally. But will get to the bottom of it.

aaupov added a commit that referenced this pull request Jan 28, 2024
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aaupov commented Jan 28, 2024

These are all annotated builders. I tried triggering rebuilds with clean build dir through buildbot UI but it didn't have an effect. I don't think it's a reasonable expectation that every change must configure cleanly from an existing build directory.

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jplehr commented Jan 28, 2024

Hi @aaupov I think this did break the AMD Hip build bot (another annotated builder).
Are you looking into the potential issue?

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lntue commented Jan 28, 2024

These are all annotated builders. I tried triggering rebuilds with clean build dir through buildbot UI but it didn't have an effect. I don't think it's a reasonable expectation that every change must configure cleanly from an existing build directory.

I'm sorry but I also don't think it is reasonable to re-landing a change that is known for breaking builders during the weekends, when not many people are around to react to the breakage.

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aaupov commented Jan 28, 2024

Status of the builders that reported breakage:

In short, this diff is a red herring for the reported breakages. The real cause is annotated builders not handling build dir cleanup properly. Still, I'm reaching out to all of the broken buildbot owners asking to clean the build directory manually.

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aaupov commented Jan 28, 2024

This issue with incremental builds is explicitly mentioned in HowToAddABuilder:

Use CCache and NOT incremental builds
Using ccache materially improves average build times. Incremental builds can be slightly faster, but introduce the risk of build corruption due to e.g. state changes, etc… At this point, the recommendation is not to use incremental builds and instead use ccache as the latter captures the majority of the benefit with less risk of false positives.

I've sent an email to builders owners. Still, sorry about landing it on a weekend. I expected that builders are configured according to the guidelines so the issues will clear automatically. Apologies for those depending on these broken builders.

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aaupov commented Jan 29, 2024

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