Revert DSE workarounds, this was causing some problems in main.

Revert "[clangd] Fix builds after 4ddae8b"

This reverts commit ae42196.

Revert "[clangd] Fix test failure when it's built with compiler flags unknown by clang"

This reverts commit 21f3dfb.

Revert "[cmake] Disable GCC lifetime DSE"

This reverts commit d5cce0a.

Revert "[clang-tidy][test] Add trailing -- to suppress compile_commands.json read"

This reverts commit 57262bb.

clang-tools-extra/clangd/test/CMakeLists.txt

@@ -28,13 +28,6 @@ configure_lit_site_cfg(
   ${CMAKE_CURRENT_SOURCE_DIR}/lit.cfg.py
   )
 
-# Copy an empty compile_flags.txt to make sure tests don't pick up arbitrary
-# commands from parents.
-file(
-  TOUCH
-  ${CMAKE_CURRENT_BINARY_DIR}/compile_flags.txt
-)
-
 add_lit_testsuite(check-clangd "Running the Clangd regression tests"
   # clangd doesn't put unittest configs in test/unit like every other project.
   # Because of that, this needs to pass two folders here, while every other

clang-tools-extra/test/clang-tidy/checkers/performance/trivially-destructible.cpp

@@ -1,7 +1,7 @@
 // RUN: %check_clang_tidy %s performance-trivially-destructible %t
 // RUN: grep -Ev "// *[A-Z-]+:" %s > %t.cpp
-// RUN: clang-tidy %t.cpp -checks='-*,performance-trivially-destructible' -fix --
-// RUN: clang-tidy %t.cpp -checks='-*,performance-trivially-destructible' -warnings-as-errors='-*,performance-trivially-destructible' --
+// RUN: clang-tidy %t.cpp -checks='-*,performance-trivially-destructible' -fix
+// RUN: clang-tidy %t.cpp -checks='-*,performance-trivially-destructible' -warnings-as-errors='-*,performance-trivially-destructible'
 
 struct TriviallyDestructible1 {
   int a;

llvm/cmake/modules/HandleLLVMOptions.cmake

@@ -582,16 +582,6 @@ if ( LLVM_COMPILER_IS_GCC_COMPATIBLE OR CMAKE_CXX_COMPILER_ID MATCHES "XL" )
   add_flag_if_supported("-Werror=unguarded-availability-new" WERROR_UNGUARDED_AVAILABILITY_NEW)
 endif( LLVM_COMPILER_IS_GCC_COMPATIBLE OR CMAKE_CXX_COMPILER_ID MATCHES "XL" )
 
-if ( LLVM_COMPILER_IS_GCC_COMPATIBLE )
-  # LLVM data structures like llvm::User and llvm::MDNode rely on
-  # the value of object storage persisting beyond the lifetime of the
-  # object (#24952).  This is not standard compliant and causes a runtime
-  # crash if LLVM is built with GCC and LTO enabled (#57740).  Until
-  # these bugs are fixed, we need to disable dead store eliminations
-  # based on object lifetime.
-  add_flag_if_supported("-fno-lifetime-dse" CMAKE_CXX_FLAGS)
-endif ( LLVM_COMPILER_IS_GCC_COMPATIBLE )
-
 # Modules enablement for GCC-compatible compilers:
 if ( LLVM_COMPILER_IS_GCC_COMPATIBLE AND LLVM_ENABLE_MODULES )
   set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})