From 64e5d4a2cdb64c274c0001a281b3c5c583c87f0c Mon Sep 17 00:00:00 2001
From: Jerry Yu <jerry.h.yu@arm.com>
Date: Wed, 15 Feb 2023 11:46:57 +0800
Subject: [PATCH] Replace error output with target pragma if possible

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
---
 library/sha256.c | 24 ++++++++++++++++++++-
 library/sha512.c | 54 +++++++++++++++++++++++++++++-------------------
 2 files changed, 56 insertions(+), 22 deletions(-)

diff --git a/library/sha256.c b/library/sha256.c
index 010f4bc02..432176551 100644
--- a/library/sha256.c
+++ b/library/sha256.c
@@ -39,7 +39,29 @@
     defined(MBEDTLS_SHA256_USE_A64_CRYPTO_ONLY)
 /* *INDENT-OFF* */
 #    if !defined(__ARM_FEATURE_CRYPTO)
-#       error "Must use minimum -march=armv8-a+crypto for MBEDTLS_SHA256_USE_A64_CRYPTO_*"
+#      if defined(__clang__)
+#        if __clang_major__ < 18
+           /* TODO: Re-consider above after https://reviews.llvm.org/D131064
+            *       merged.
+            *
+            * The intrinsic declaration are guarded with ACLE predefined macros
+            * in clang, and those macros are only enabled with command line.
+            * Define the macros can enable those declaration and avoid compile
+            * error on it.
+            */
+#          define __ARM_FEATURE_CRYPTO 1
+#        endif
+#        pragma clang attribute push (__attribute__((target("crypto"))), apply_to=function)
+#        define MBEDTLS_POP_TARGET_PRAGMA
+#      elif defined(__GNUC__)
+#        if __GNUC__ < 6 /* TODO: check sha256 compatible for GCC */
+#          error "A more recent GCC is required for MBEDTLS_SHA256_USE_A64_CRYPTO_*"
+#        else
+#          pragma GCC target ("arch=armv8-a+crypto")
+#        endif
+#      else
+#        error "Only GCC and Clang supported for MBEDTLS_SHA256_USE_A64_CRYPTO_*"
+#      endif
 #    endif
 /* *INDENT-ON* */
 #    include <arm_neon.h>
diff --git a/library/sha512.c b/library/sha512.c
index 767857f34..fec974a36 100644
--- a/library/sha512.c
+++ b/library/sha512.c
@@ -58,29 +58,41 @@
  * Clang == 13.0.0 same as clang 12 (only seen on macOS)
  * Clang >= 13.0.1 has __ARM_FEATURE_SHA512 and intrinsics
  */
-#if !defined(__ARM_FEATURE_SHA512)
-   /* Test Clang first, as it defines __GNUC__ */
-#  if defined(__clang__)
-#    if __clang_major__ < 7
-#      error "A more recent Clang is required for MBEDTLS_SHA512_USE_A64_CRYPTO_*"
-#    elif __clang_major__ < 13 || \
-         (__clang_major__ == 13 && __clang_minor__ == 0 && __clang_patchlevel__ == 0)
-       /* We implement the intrinsics with inline assembler, so don't error */
-#    else
-#      error "Must use minimum -march=armv8.2-a+sha3 for MBEDTLS_SHA512_USE_A64_CRYPTO_*"
+#    if !defined(__ARM_FEATURE_SHA512)
+       /* Test Clang first, as it defines __GNUC__ */
+#      if defined(__clang__)
+#        if __clang_major__ < 7
+#          error "A more recent Clang is required for MBEDTLS_SHA512_USE_A64_CRYPTO_*"
+#        elif __clang_major__ < 13 || \
+              (__clang_major__ == 13 && __clang_minor__ == 0 && \
+               __clang_patchlevel__ == 0)
+           /* We implement the intrinsics with inline assembler, so don't error */
+#        else
+#          if __clang_major__ < 18
+           /* TODO: Re-consider above after https://reviews.llvm.org/D131064
+            *       merged.
+            *
+            * The intrinsic declaration are guarded with ACLE predefined macros
+            * in clang, and those macros are only enabled with command line.
+            * Define the macros can enable those declaration and avoid compile
+            * error on it.
+            */
+#            define __ARM_FEATURE_SHA512 1
+#          endif
+#          pragma clang attribute push (__attribute__((target("sha3"))), apply_to=function)
+#          define MBEDTLS_POP_TARGET_PRAGMA
+#        endif
+#      elif defined(__GNUC__)
+#        if __GNUC__ < 8
+#          error "A more recent GCC is required for MBEDTLS_SHA512_USE_A64_CRYPTO_*"
+#        else
+#          pragma GCC target ("arch=armv8.2-a+sha3")
+#        endif
+#      else
+#        error "Only GCC and Clang supported for MBEDTLS_SHA512_USE_A64_CRYPTO_*"
+#      endif
 #    endif
-#  elif defined(__GNUC__)
-#    if __GNUC__ < 8
-#      error "A more recent GCC is required for MBEDTLS_SHA512_USE_A64_CRYPTO_*"
-#    else
-#      error "Must use minimum -march=armv8.2-a+sha3 for MBEDTLS_SHA512_USE_A64_CRYPTO_*"
-#    endif
-#  else
-#    error "Only GCC and Clang supported for MBEDTLS_SHA512_USE_A64_CRYPTO_*"
-#  endif
-#endif
 /* *INDENT-ON* */
-
 #    include <arm_neon.h>
 #  endif
 #  if defined(MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT)