clang: Add packageconfig knob for opt-viewer

The optimization viewer is a web-based tool that helps developers visualize
and analyze LLVM's optimization passes. It generates reports showing
Which optimizations were applied to specific functions.
Why certain optimizations were or weren't performed.
Performance remarks and missed optimization opportunities
Interactive views of the optimization pipeline.

Its a nice add-on, keep it disabled by default.

(From OE-Core rev: 70c43e35fb7ce0b71f28a91a1864f02338545522)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/clang/clang/0001-llvm-Allow-users-to-set-LLVM_HAVE_OPT_VIEWER_MODULES.patch

@@ -0,0 +1,91 @@
+From e396fbe0e698c80e112af76fcdff8bbd61a30740 Mon Sep 17 00:00:00 2001
+From: Khem Raj <raj.khem@gmail.com>
+Date: Sat, 2 Aug 2025 17:58:20 -0700
+Subject: [PATCH] llvm: Allow users to set LLVM_HAVE_OPT_VIEWER_MODULES
+ manually from the CMake
+
+Check right before setting LLVM_HAVE_OPT_VIEWER_MODULES
+so that if the user specifies the variable on the commandline
+it takes precedence. If not, fall back to the old logic
+
+Upstream-Status: Submitted [https://github.com/llvm/llvm-project/pull/151845]
+
+Signed-off-by: Khem Raj <raj.khem@gmail.com>
+---
+ llvm/CMakeLists.txt                  |  2 ++
+ llvm/cmake/config-ix.cmake           | 13 ++++++++++---
+ llvm/tools/opt-viewer/CMakeLists.txt | 24 +++++++++++++-----------
+ 3 files changed, 25 insertions(+), 14 deletions(-)
+
+diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
+index 4c70b98a32f9..60b786ca39c2 100644
+--- a/llvm/CMakeLists.txt
++++ b/llvm/CMakeLists.txt
+@@ -7,6 +7,8 @@ set(LLVM_COMMON_CMAKE_UTILS ${CMAKE_CURRENT_SOURCE_DIR}/../cmake)
+ include(${LLVM_COMMON_CMAKE_UTILS}/Modules/CMakePolicy.cmake
+   NO_POLICY_SCOPE)
+ 
++option(LLVM_HAVE_OPT_VIEWER_MODULES "Enable opt-viewer modules support" ON)
++
+ # Builds with custom install names and installation rpath setups may not work
+ # in the build tree. Allow these cases to use CMake's default build tree
+ # behavior by setting `LLVM_NO_INSTALL_NAME_DIR_FOR_BUILD_TREE` to do this.
+diff --git a/llvm/cmake/config-ix.cmake b/llvm/cmake/config-ix.cmake
+index a8e4e5a63244..17af3dc1e93f 100644
+--- a/llvm/cmake/config-ix.cmake
++++ b/llvm/cmake/config-ix.cmake
+@@ -805,10 +805,17 @@ foreach(module ${PYTHON_MODULES})
+   find_python_module(${module})
+ endforeach()
+ 
+-if(PY_PYGMENTS_FOUND AND PY_PYGMENTS_LEXERS_C_CPP_FOUND AND PY_YAML_FOUND)
+-  set (LLVM_HAVE_OPT_VIEWER_MODULES 1)
++if(NOT DEFINED LLVM_HAVE_OPT_VIEWER_MODULES)
++  if(PY_PYGMENTS_FOUND AND PY_PYGMENTS_LEXERS_C_CPP_FOUND AND PY_YAML_FOUND)
++    set (LLVM_HAVE_OPT_VIEWER_MODULES 1)
++  else()
++    set (LLVM_HAVE_OPT_VIEWER_MODULES 0)
++  endif()
++elseif(LLVM_HAVE_OPT_VIEWER_MODULES)
++  # Use the user-provided value
++  set(LLVM_HAVE_OPT_VIEWER_MODULES 1)
+ else()
+-  set (LLVM_HAVE_OPT_VIEWER_MODULES 0)
++  set(LLVM_HAVE_OPT_VIEWER_MODULES 0)
+ endif()
+ 
+ function(llvm_get_host_prefixes_and_suffixes)
+diff --git a/llvm/tools/opt-viewer/CMakeLists.txt b/llvm/tools/opt-viewer/CMakeLists.txt
+index 4bcf6932ee77..d231c39bcc5d 100644
+--- a/llvm/tools/opt-viewer/CMakeLists.txt
++++ b/llvm/tools/opt-viewer/CMakeLists.txt
+@@ -6,16 +6,18 @@ set (files
+   "optrecord.py"
+   "style.css")
+ 
+-foreach (file ${files})
+-  install(PROGRAMS ${file}
+-    DESTINATION "${CMAKE_INSTALL_DATADIR}/opt-viewer"
+-    COMPONENT opt-viewer)
+-endforeach (file)
++if(LLVM_HAVE_OPT_VIEWER_MODULES)
++  foreach (file ${files})
++    install(PROGRAMS ${file}
++      DESTINATION "${CMAKE_INSTALL_DATADIR}/opt-viewer"
++      COMPONENT opt-viewer)
++  endforeach (file)
+ 
+-add_custom_target(opt-viewer DEPENDS ${files})
+-set_target_properties(opt-viewer PROPERTIES FOLDER "LLVM/Tools")
+-if(NOT LLVM_ENABLE_IDE)
+-  add_llvm_install_targets("install-opt-viewer"
+-                           DEPENDS opt-viewer
+-                           COMPONENT opt-viewer)
++  add_custom_target(opt-viewer DEPENDS ${files})
++  set_target_properties(opt-viewer PROPERTIES FOLDER "LLVM/Tools")
++  if(NOT LLVM_ENABLE_IDE)
++    add_llvm_install_targets("install-opt-viewer"
++                             DEPENDS opt-viewer
++                             COMPONENT opt-viewer)
++  endif()
+ endif()

meta/recipes-devtools/clang/clang_git.bb

@@ -59,6 +59,9 @@ PACKAGECONFIG[libedit] = "-DLLVM_ENABLE_LIBEDIT=ON,-DLLVM_ENABLE_LIBEDIT=OFF,lib
 PACKAGECONFIG[libomp] = "-DCLANG_DEFAULT_OPENMP_RUNTIME=libomp,,"
 PACKAGECONFIG[lld] = "-DCLANG_DEFAULT_LINKER=lld,,,"
 PACKAGECONFIG[lto] = "-DLLVM_ENABLE_LTO=Full -DLLVM_BINUTILS_INCDIR=${STAGING_INCDIR},,binutils,"
+PACKAGECONFIG[opt-viewer] = "-DLLVM_HAVE_OPT_VIEWER_MODULES=ON,-DLLVM_HAVE_OPT_VIEWER_MODULES=OFF, \
+                             python3-pyyaml-native python3-pygments-native python3-pyyaml python3-pygments, \
+                             python3-pyyaml python3-pygments,"
 PACKAGECONFIG[pfm] = "-DLLVM_ENABLE_LIBPFM=ON,-DLLVM_ENABLE_LIBPFM=OFF,libpfm,"
 PACKAGECONFIG[rtti] = "-DLLVM_ENABLE_RTTI=ON,-DLLVM_ENABLE_RTTI=OFF,,"
 PACKAGECONFIG[shared-libs] = "-DLLVM_BUILD_LLVM_DYLIB=ON -DLLVM_LINK_LLVM_DYLIB=ON,,,"

meta/recipes-devtools/clang/common.inc

@@ -61,6 +61,7 @@ SRC_URI = "\
     file://0038-compiler-rt-Hardcode-uptr-sptr-typedefs-on-Mips-Linu.patch \
     file://0001-libclc-allow-existing-prepare-builtins-in-standalone.patch \
     file://no-c-index-test.patch \
+    file://0001-llvm-Allow-users-to-set-LLVM_HAVE_OPT_VIEWER_MODULES.patch \
 "
 # Fallback to no-PIE if not set
 GCCPIE ??= ""