[llvm][NFC] Simplify alignment calculations in TrailingObjects

[localspook]

No description provided.

[llvmbot]

@llvm/pr-subscribers-llvm-support

Author: Victor Chernyakin (localspook)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/161134.diff

1 Files Affected:

• (modified) llvm/include/llvm/Support/TrailingObjects.h (+8-25)

diff --git a/llvm/include/llvm/Support/TrailingObjects.h b/llvm/include/llvm/Support/TrailingObjects.h
index d7211a930ae49..3eb7c0bd1f379 100644
--- a/llvm/include/llvm/Support/TrailingObjects.h
+++ b/llvm/include/llvm/Support/TrailingObjects.h
@@ -57,25 +57,9 @@
 namespace llvm {
 
 namespace trailing_objects_internal {
-/// Helper template to calculate the max alignment requirement for a set of
-/// objects.
-template <typename First, typename... Rest> class AlignmentCalcHelper {
-private:
-  enum {
-    FirstAlignment = alignof(First),
-    RestAlignment = AlignmentCalcHelper<Rest...>::Alignment,
-  };
 
-public:
-  enum {
-    Alignment = FirstAlignment > RestAlignment ? FirstAlignment : RestAlignment
-  };
-};
-
-template <typename First> class AlignmentCalcHelper<First> {
-public:
-  enum { Alignment = alignof(First) };
-};
+template <typename... T>
+inline constexpr size_t MaxAlignment = std::max({alignof(T)...});
 
 /// The base class for TrailingObjects* classes.
 class TrailingObjectsBase {
@@ -209,11 +193,10 @@ class alignas(Align) TrailingObjectsImpl<Align, BaseTy, TopTrailingObj, PrevTy>
 /// See the file comment for details on the usage of the
 /// TrailingObjects type.
 template <typename BaseTy, typename... TrailingTys>
-class TrailingObjects : private trailing_objects_internal::TrailingObjectsImpl<
-                            trailing_objects_internal::AlignmentCalcHelper<
-                                TrailingTys...>::Alignment,
-                            BaseTy, TrailingObjects<BaseTy, TrailingTys...>,
-                            BaseTy, TrailingTys...> {
+class TrailingObjects
+    : private trailing_objects_internal::TrailingObjectsImpl<
+          trailing_objects_internal::MaxAlignment<TrailingTys...>, BaseTy,
+          TrailingObjects<BaseTy, TrailingTys...>, BaseTy, TrailingTys...> {
 
   template <int A, typename B, typename T, typename P, typename... M>
   friend class trailing_objects_internal::TrailingObjectsImpl;
@@ -221,8 +204,8 @@ class TrailingObjects : private trailing_objects_internal::TrailingObjectsImpl<
   template <typename... Tys> class Foo {};
 
   typedef trailing_objects_internal::TrailingObjectsImpl<
-      trailing_objects_internal::AlignmentCalcHelper<TrailingTys...>::Alignment,
-      BaseTy, TrailingObjects<BaseTy, TrailingTys...>, BaseTy, TrailingTys...>
+      trailing_objects_internal::MaxAlignment<TrailingTys...>, BaseTy,
+      TrailingObjects<BaseTy, TrailingTys...>, BaseTy, TrailingTys...>
       ParentType;
   using TrailingObjectsBase = trailing_objects_internal::TrailingObjectsBase;
 

[kazutakahirata]

Very nice! Thanks!

[llvm-ci]

LLVM Buildbot has detected a new failure on builder llvm-clang-aarch64-darwin running on doug-worker-5 while building llvm at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/190/builds/28331

Here is the relevant piece of the build log for the reference

Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: ExecutionEngine/OrcLazy/multiple-compile-threads-basic.ll' FAILED ********************
Exit Code: 2

Command Output (stdout):
--
# RUN: at line 1
/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/lli -jit-kind=orc-lazy -compile-threads=2 -thread-entry hello /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/ExecutionEngine/OrcLazy/multiple-compile-threads-basic.ll | /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/FileCheck /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/ExecutionEngine/OrcLazy/multiple-compile-threads-basic.ll
# executed command: /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/lli -jit-kind=orc-lazy -compile-threads=2 -thread-entry hello /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/ExecutionEngine/OrcLazy/multiple-compile-threads-basic.ll
# .---command stderr------------
# | PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and instructions to reproduce the bug.
# | Stack dump:
# | 0.	Program arguments: /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/lli -jit-kind=orc-lazy -compile-threads=2 -thread-entry hello /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/ExecutionEngine/OrcLazy/multiple-compile-threads-basic.ll
# |  #0 0x0000000101101dfc llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/lli+0x100f1ddfc)
# |  #1 0x00000001010ffbac llvm::sys::RunSignalHandlers() (/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/lli+0x100f1bbac)
# |  #2 0x00000001011028fc SignalHandler(int, __siginfo*, void*) (/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/lli+0x100f1e8fc)
# |  #3 0x0000000182f63584 (/usr/lib/system/libsystem_platform.dylib+0x18047b584)
# |  #4 0x0000010100c5bd50
# |  #5 0x0000000100c671a0 llvm::orc::ExecutionSession::removeJITDylibs(std::__1::vector<llvm::IntrusiveRefCntPtr<llvm::orc::JITDylib>, std::__1::allocator<llvm::IntrusiveRefCntPtr<llvm::orc::JITDylib>>>) (/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/lli+0x100a831a0)
# |  #6 0x0000000100c66f50 llvm::orc::ExecutionSession::endSession() (/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/lli+0x100a82f50)
# |  #7 0x0000000100cf2a80 llvm::orc::LLJIT::~LLJIT() (/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/lli+0x100b0ea80)
# |  #8 0x0000000100cf740c llvm::orc::LLLazyJIT::~LLLazyJIT() (/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/lli+0x100b1340c)
# |  #9 0x00000001001ee1bc runOrcJIT(char const*) (/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/lli+0x10000a1bc)
# | #10 0x00000001001e98ec main (/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/lli+0x1000058ec)
# | #11 0x0000000182ba7154
# `-----------------------------
# error: command failed with exit status: -11
# executed command: /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/FileCheck /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/ExecutionEngine/OrcLazy/multiple-compile-threads-basic.ll
# .---command stderr------------
# | FileCheck error: '<stdin>' is empty.
# | FileCheck command line:  /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/FileCheck /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/ExecutionEngine/OrcLazy/multiple-compile-threads-basic.ll
# `-----------------------------
# error: command failed with exit status: 2

--

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