Use -fprofile-use= when TEST_SUITE_USE_IR_PGO is enabled

[MatzeB]

Summary

TEST_SUITE_USE_IR_PGO changes the test-suite to use -fprofile-generate=xxx (instead of -fprofile-instr-gen=xxx). This changes cmake to also use -fprofile-use=xxx (instead of -fprofile-instr-use=xxx).

This change is cosmetic: It turns out -fprofile-instr-use does automatically detect the profile format used and works either way. But picking the matching use-flag can avoid confusion for people inspecting the compiler flags.

[fhahn]

This looks reasonable, LGTM, thanks!

[fhahn]

cmake/modules/TestSuite.cmake

62

I missed that this also changes to path passed to -fprofile-instr-use from ${target_path}.profdata to ${TEST_SUITE_PROFILE_PATH}/${target}.profdata. The new path doesn't appear to work correctly when using lnt + PGO.

From the description, it doesn't seem like this change was intentional, so I reverted the change for now to get that original configuration working again.

cmake/modules/TestSuite.cmake

function(llvm_test_executable_no_test target)
   append_target_flags(COMPILE_FLAGS ${target} ${CFLAGS})
   append_target_flags(COMPILE_FLAGS ${target} ${CPPFLAGS})
   append_target_flags(COMPILE_FLAGS ${target} ${CXXFLAGS})
   # Note that we cannot use target_link_libraries() here because that one
   # only interprets inputs starting with '-' as flags.
   append_target_flags(LINK_LIBRARIES ${target} ${LDFLAGS})
   set(target_path ${CMAKE_CURRENT_BINARY_DIR}/${target})
   if(TEST_SUITE_PROFILE_USE)
-    append_target_flags(COMPILE_FLAGS ${target} -fprofile-instr-use=${target_path}.profdata)
-    append_target_flags(LINK_LIBRARIES ${target} -fprofile-instr-use=${target_path}.profdata)
+    if(TEST_SUITE_USE_IR_PGO)
+      append_target_flags(COMPILE_FLAGS ${target} -fprofile-use=${TEST_SUITE_PROFILE_PATH}/${target}.profdata)
+      append_target_flags(LINK_LIBRARIES ${target} -fprofile-use=${TEST_SUITE_PROFILE_PATH}/${target}.profdata)
+    else()
+      append_target_flags(COMPILE_FLAGS ${target} -fprofile-instr-use=${TEST_SUITE_PROFILE_PATH}/${target}.profdata)
+      append_target_flags(LINK_LIBRARIES ${target} -fprofile-instr-use=${TEST_SUITE_PROFILE_PATH}/${target}.profdata)
+    endif()
   endif()
 
   llvm_codesign(${target})
   set_property(GLOBAL APPEND PROPERTY TEST_SUITE_TARGETS ${target})
   test_suite_add_build_dependencies(${target})
 
   if(TEST_SUITE_LLVM_SIZE)
     add_custom_command(TARGET ${target} POST_BUILD