From 7e8a818d95e820f8e9c63233d670f5b843820081 Mon Sep 17 00:00:00 2001
From: Aidan MacDonald <amachronic@protonmail.com>
Date: Thu, 14 Nov 2024 12:06:27 +0000
Subject: [PATCH] arm: add ARM architecture profile detection

Add some logic to detect classic and M-profile cores, and make
this info available to the build system. All existing targets
are classic profile.

Change-Id: I07bfcd418bcaa6297b9bbf889fc189f167147428
---
 firmware/export/config.h |  8 +++++-
 tools/configure          | 53 ++++++++++++++++++++++++++++++++++++----
 2 files changed, 55 insertions(+), 6 deletions(-)

diff --git a/firmware/export/config.h b/firmware/export/config.h
index 4a33ae26cf..b7ba0dc86f 100644
--- a/firmware/export/config.h
+++ b/firmware/export/config.h
@@ -696,7 +696,13 @@ Lyre prototype 1 */
 /* define for all cpus from ARM family */
 #if ARCH == ARCH_ARM
 #define CPU_ARM
-#define ARM_ARCH ARCH_VERSION /* ARMv{4,5,6,7} */
+#define ARM_ARCH    ARCH_VERSION /* ARMv{4,5,6,7} */
+#define ARM_PROFILE ARCH_PROFILE /* Classic, Microcontroller */
+# if ARM_PROFILE == ARM_PROFILE_MICRO
+#  define CPU_ARM_MICRO
+# elif ARM_PROFILE == ARM_PROFILE_CLASSIC
+#  define CPU_ARM_CLASSIC
+# endif
 #endif
 
 #if ARCH == ARCH_MIPS
diff --git a/tools/configure b/tools/configure
index 629e29465f..4da644fe5f 100755
--- a/tools/configure
+++ b/tools/configure
@@ -4634,10 +4634,41 @@ if [ -z "$arch" ]; then
         arch="arm"
         # cpp defines like "#define __ARM_ARCH_4TE__ 1" (where we want to extract the 4)
         arch_version="$(echo $cpp_defines | tr ' ' '\012' | grep __ARM_ARCH | sed -e 's,.*\([0-9]\).*,\1,' | grep -v __ARM_ARCH | head -1)"
+        arch_profile="$(echo "$cpp_defines" | grep 'define __ARM_ARCH_PROFILE' | sed -e 's,.* \([0-9]\+\)$,\1,')"
 	if test "$gccnum" -ge "800"; then
 	    # GCC8+ can natively emit unified asm syntax
 	    GCCOPTS="$GCCOPTS -masm-syntax-unified"
 	fi
+        case "$arch_profile" in
+            77)
+                arch_profile=micro
+
+                # We have a lot of assembly written for ARM32, which won't
+                # successfully assemble on a Thumb-only core due to missing
+                # IT blocks. The recommended practice for portable assembly
+                # is to add explicit IT blocks nowadays.
+                #
+                # This option instructs the assembler to add IT blocks
+                # automatically as needed, which allows the old assembly to
+                # compile unchanged (although it might be sub-optimal).
+                GCCOPTS="$GCCOPTS -Wa,-mimplicit-it=thumb"
+
+                # Disable this option -- it only makes sense for cores that
+                # support both ARM and Thumb instruction sets.
+                if [ "$ARG_ARM_THUMB" = "1" ]; then
+                    echo "Warning: --thumb option has no effect on ARM M profile cores"
+                    ARG_ARM_THUMB=0
+                fi
+                ;;
+            *)
+                # On classic ARM we expect an empty string, so only warn if it's nonempty
+                if [ -n "$arch_profile" ]; then
+                    echo "Warning: Cannot determine target ARM profile, assuming classic"
+                fi
+
+                arch_profile=classic
+                ;;
+        esac
     elif [ -n "$(echo $cpp_defines | grep -w __mips__)" ]; then
         arch="mips"
         arch_version="$(echo $cpp_defines | tr ' ' '\012' | grep _MIPS_ARCH_MIPS | sed -e 's,.*\([0-9][0-9]\).*,\1,' | grep -v _MIPS_ARCH_MIPS)"
@@ -4651,7 +4682,11 @@ if [ -z "$arch" ]; then
     fi
     if [ "$arch" != "none" ]; then
         if [ -n "$arch_version" ]; then
-            echo "Automatically selected arch: $arch (ver $arch_version)"
+            if [ -n "$arch_profile" ]; then
+                echo "Automatically selected arch: $arch (ver $arch_version, profile $arch_profile)"
+            else
+                echo "Automatically selected arch: $arch (ver $arch_version)"
+            fi
         else
             echo "Automatically selected arch: $arch"
         fi
@@ -4664,10 +4699,13 @@ else
     fi
 fi
 
-arch="arch_$arch"
+Darch="#define ARCH arch_$arch"
 if [ -n "$arch_version" ]; then
     Darch_version="#define ARCH_VERSION $arch_version"
 fi
+if [ -n "$arch_profile" ]; then
+    Darch_profile="#define ARCH_PROFILE $(echo ${arch}_PROFILE_${arch_profile} | tr [a-z] [A-Z])"
+fi
 
 if test -n "$ccache"; then
   CC="$ccache $CC"
@@ -4722,10 +4760,14 @@ cat > autoconf.h.new <<EOF
 #define arch_amd64 6
 #define ARCH_AMD64 6
 
+#define ARM_PROFILE_CLASSIC     0       /* Classic ARM cores (<= ARMv6) */
+#define ARM_PROFILE_MICRO       1       /* ARMv6/ARMv7+ M-profile cores */
+
 /* Define target machine architecture */
-#define ARCH ${arch}
-/* Optionally define architecture version */
+${Darch}
+/* Optionally define architecture version and/or profile */
 ${Darch_version}
+${Darch_profile}
 
 /* Define endianess for the target or simulator platform */
 #define ${defendian} 1
@@ -4843,8 +4885,9 @@ export FLASHFILE=${flash}
 export TARGET_ID=${target_id}
 export TARGET=-D${target}
 export SYSFONT=${sysfont}
-export ARCH=${arch}
+export ARCH=arch_${arch}
 export ARCH_VERSION=${arch_version}
+export ARCH_PROFILE=${arch_profile}
 export CPU=${t_cpu}
 export MANUFACTURER=${t_manufacturer}
 export OBJDIR=${pwd}