[compiler-rt][builtins] Add missing flag for builtins standalone build (#133046)

yingcong-wu · KornevNikita · commit 72a583be82a6 · 2025-06-03T16:09:31.000+02:00
When builtins are built with runtimes, it is built before compiler-rt,
and this makes some of the HAS_XXX_FLAGs missing. In this case, the
COMPILER_RT_HAS_FCF_PROTECTION_FLAG is missing which makes it impossible
to enable CET in this case. This patch addresses this issue by also
check for such flag in standalone build instead of relying on the
compiler-rt's detection.
diff --git a/compiler-rt/cmake/builtin-config-ix.cmake b/compiler-rt/cmake/builtin-config-ix.cmake
@@ -25,6 +25,7 @@ builtin_check_c_compiler_flag(-fconvergent-functions COMPILER_RT_HAS_FCONVERGENT
 builtin_check_c_compiler_flag("-Xclang -mcode-object-version=none" COMPILER_RT_HAS_CODE_OBJECT_VERSION_FLAG)
 builtin_check_c_compiler_flag(-Wbuiltin-declaration-mismatch COMPILER_RT_HAS_WBUILTIN_DECLARATION_MISMATCH_FLAG)
 builtin_check_c_compiler_flag(/Zl COMPILER_RT_HAS_ZL_FLAG)
+builtin_check_c_compiler_flag(-fcf-protection=full COMPILER_RT_HAS_FCF_PROTECTION_FLAG)
 
 builtin_check_c_compiler_source(COMPILER_RT_HAS_ATOMIC_KEYWORD
 "

Original file line number	Diff line number	Diff line change
`@@ -25,6 +25,7 @@ builtin_check_c_compiler_flag(-fconvergent-functions COMPILER_RT_HAS_FCONVERGENT`
`25`	`25`	`builtin_check_c_compiler_flag("-Xclang -mcode-object-version=none" COMPILER_RT_HAS_CODE_OBJECT_VERSION_FLAG)`
`26`	`26`	`builtin_check_c_compiler_flag(-Wbuiltin-declaration-mismatch COMPILER_RT_HAS_WBUILTIN_DECLARATION_MISMATCH_FLAG)`
`27`	`27`	`builtin_check_c_compiler_flag(/Zl COMPILER_RT_HAS_ZL_FLAG)`
	`28`	`+builtin_check_c_compiler_flag(-fcf-protection=full COMPILER_RT_HAS_FCF_PROTECTION_FLAG)`
`28`	`29`
`29`	`30`	`builtin_check_c_compiler_source(COMPILER_RT_HAS_ATOMIC_KEYWORD`
`30`	`31`	`"`