add pgo support to build.cmd

build.bat

@@ -43,6 +43,26 @@ if "%telemetry%"=="1" set auto_compile_flags=%auto_compile_flags% -DPROFILE_TELE
 if "%spall%"=="1"     set auto_compile_flags=%auto_compile_flags% -DPROFILE_SPALL=1 && echo [spall profiling enabled]
 if "%asan%"=="1"      set auto_compile_flags=%auto_compile_flags% -fsanitize=address && echo [asan enabled]
 if "%opengl%"=="1"    set auto_compile_flags=%auto_compile_flags% -DR_BACKEND=R_BACKEND_OPENGL && echo [opengl render backend]
+if "%pgo%"=="1" (
+  if "%no_meta%"=="" echo ERROR: PGO build must have no_meta argument || exit /b 1
+  where llvm-profdata /q || echo llvm-profdata is not in the PATH || exit /b 1
+  
+  if "%clang%"=="1" (
+    if "%pgo_run%" == "1" (
+      call llvm-profdata merge %LLVM_PROFILE_FILE% -output=%~dp0build\build.profdata || exit /b 1
+      set auto_compile_flags=%auto_compile_flags% -fprofile-use=%~dp0build\build.profdata
+      set pgo_run=0
+    ) else (
+      echo [pgo enabled]
+      set auto_compile_flags=%auto_compile_flags% -fprofile-generate -mllvm -vp-counters-per-site=5
+      set LLVM_PROFILE_FILE=%~dp0build\build.profraw
+      set pgo_run=1
+    )
+  ) else (
+    echo ERROR: PGO build is not supported with current compiler
+    exit /b 1
+  )
+)
 
 :: --- Compile/Link Line Definitions ------------------------------------------
 set cl_common=     /I..\src\ /I..\local\ /nologo /FC /Z7
@@ -139,3 +159,15 @@ if "%didbuild%"=="" (
   echo [WARNING] no valid build target specified; must use build target names as arguments to this script, like `build raddbg` or `build rdi_from_pdb`.
   exit /b 1
 )
+
+:: --- PGO Run ---------------------------------------------------------------
+
+if "%pgo_run%"=="1" (
+  if "%radlink%"=="1" (
+    pushd build
+    call radlink lnk.obj /debug:full
+    popd
+  )
+  call %0 %*
+)
+