[libc-commits] [libc] [libc] Enabling code coverage via Linux syscalls (PR #213271)

[Petr Hosek via libc-commits]

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@@ -91,6 +91,33 @@ endif()
 set(LIBC_LINK_OPTIONS_DEFAULT "" CACHE STRING "Arguments used when linking.")
 set(LIBC_TEST_LINK_OPTIONS_DEFAULT "" CACHE STRING "Common link options for all the tests.")
 
+option(LIBC_ENABLE_COVERAGE "Build libc with coverage instrumentation" OFF)
+if(LIBC_ENABLE_COVERAGE)
+  add_compile_definitions(LIBC_ENABLE_COVERAGE)
+  list(APPEND LIBC_COMPILE_OPTIONS_DEFAULT "-fprofile-instr-generate" "-fcoverage-mapping")
+  list(APPEND LIBC_TEST_COMPILE_OPTIONS_DEFAULT "-fprofile-instr-generate" "-fcoverage-mapping")
+  list(APPEND LIBC_TEST_LINK_OPTIONS_DEFAULT "-fprofile-instr-generate" "-fcoverage-mapping")
+
+  # When building with -nostdlib, the compiler does not automatically link the profiling runtime.
+  # We must explicitly query the compiler for the exact architecture-specific profile library path.
+  execute_process(
+    COMMAND ${CMAKE_CXX_COMPILER} --print-libgcc-file-name --rtlib=compiler-rt
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petrhosek wrote:

`--rtlib=` is only recognized by Clang so you should check that `CMAKE_CXX_COMPILER` is Clang first.

https://github.com/llvm/llvm-project/pull/213271