Merge pull request #5468 from Unity-Technologies/mbedtls-2.28-windows-arm64-workaround
Backport 2.28: Don't inline mbedtls_mpi_safe_cond_assign on MSVC/ARM64 to avoid a compiler bug
diff --git a/library/constant_time.c b/library/constant_time.c
index 18f1b20..5f79e28 100644
--- a/library/constant_time.c
+++ b/library/constant_time.c
@@ -533,6 +533,13 @@
* about whether the assignment was made or not.
* (Leaking information about the respective sizes of X and Y is ok however.)
*/
+#if defined(_MSC_VER) && defined(_M_ARM64) && (_MSC_FULL_VER < 193131103)
+/*
+ * MSVC miscompiles this function if it's inlined prior to Visual Studio 2022 version 17.1. See:
+ * https://developercommunity.visualstudio.com/t/c-compiler-miscompiles-part-of-mbedtls-library-on/1646989
+ */
+__declspec(noinline)
+#endif
int mbedtls_mpi_safe_cond_assign( mbedtls_mpi *X,
const mbedtls_mpi *Y,
unsigned char assign )