From f6cdabe973a284dddf9783c48c861329e5d15f72 Mon Sep 17 00:00:00 2001
From: Dr-Noob <peibolms@gmail.com>
Date: Tue, 6 Aug 2024 08:57:37 +0100
Subject: [PATCH] [v1.05][ARM] Another try at properly implement SVE detection

---
 Makefile        |  5 +++++
 src/arm/midr.c  | 19 +++++++++++++------
 src/arm/uarch.c |  2 +-
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/Makefile b/Makefile
index 4606f97..8c3b9e6 100644
--- a/Makefile
+++ b/Makefile
@@ -42,6 +42,11 @@ ifneq ($(OS),Windows_NT)
 		HEADERS += $(COMMON_HDR) $(SRC_DIR)midr.h $(SRC_DIR)uarch.h  $(SRC_COMMON)soc.h $(SRC_DIR)soc.h $(SRC_COMMON)pci.h $(SRC_DIR)udev.c $(SRC_DIR)socs.h
 		CFLAGS += -DARCH_ARM -Wno-unused-parameter -std=c99 -fstack-protector-all
 
+		is_sve_flag_supported := $(shell touch foo.c && $(CC) -march=armv8-a+sve -c foo.c -o foo.o &> /dev/null && echo 'yes'; rm -f foo.c foo.o)
+		ifeq ($(is_sve_flag_supported), yes)
+			CFLAGS += -march=armv8-a+sve
+		endif
+
 		ifeq ($(os), Darwin)
 			SOURCE += $(SRC_COMMON)sysctl.c
 			HEADERS += $(SRC_COMMON)sysctl.h
diff --git a/src/arm/midr.c b/src/arm/midr.c
index ee677ea..44f25d1 100644
--- a/src/arm/midr.c
+++ b/src/arm/midr.c
@@ -144,15 +144,16 @@ void init_cpu_info(struct cpuInfo* cpu) {
 
 // https://learn.arm.com/learning-paths/servers-and-cloud-computing/sve/sve_basics/#:~:text=Using%20a%20text%20editor%20of%20your%20choice%2C%20copy,svcntb%28%29%29%3B%20%7D%20This%20program%20prints%20the%20vector%20length
 static inline uint32_t sve_cntb(void) {
+  #ifdef __ARM_FEATURE_SVE
     uint32_t x0 = 0;
-
-#ifdef __ARM_FEATURE_SVE
     __asm volatile("cntb %0"
          : "=r"(x0));
     printf("cntb=%d\n", x0);
-#endif
-
     return x0;
+  #else
+    printBug("sve_cntb: SVE not enabled by the compiler");
+    return 0;
+  #endif
 }
 
 
@@ -221,8 +222,14 @@ struct features* get_features_info(void) {
   feat->SVE2 = false;
 #endif  // ifdef __linux__
 
-  if (feat->SVE || feat->SVE2)
-    feat->cntb = sve_cntb();
+  if (feat->SVE || feat->SVE2) {
+    #ifdef __ARM_FEATURE_SVE
+      feat->cntb = sve_cntb();
+    #else
+      printWarn("Hardware supports SVE, but not the compiler");
+      feat->cntb = 0;
+    #endif
+  }
 
   return feat;
 }
diff --git a/src/arm/uarch.c b/src/arm/uarch.c
index 802434a..32d6e33 100644
--- a/src/arm/uarch.c
+++ b/src/arm/uarch.c
@@ -294,7 +294,7 @@ int get_vpus_width(struct cpuInfo* cpu) {
     case UARCH_NEOVERSE_V1:
       return 256;
     default:
-      if (cpu->feat->SVE) {
+      if (cpu->feat->SVE && cpu->feat->cntb > 0) {
         return cpu->feat->cntb * 8;
       }
       else if (cpu->feat->NEON) {