From b3499f6bea8bc49f92b5dcfc250da90e86fc5ebb Mon Sep 17 00:00:00 2001
From: Yves Chemisky <yves.chemisky@gmail.com>
Date: Fri, 13 Feb 2026 23:14:09 +0100
Subject: [PATCH] Guard CPUID/rdtsc for non-x86 and add stubs

Add explicit x86/x86_64 guards and non-x86 fallbacks for CPUID and rdtsc. In Fastor/config/cpuid.h, avoid using inline asm on non-x86 targets by checking for __x86_64__/__i386__ and provide a safe zeroed fallback for regs otherwise. In Fastor/util/timeit.h, restrict the GCC inline-asm rdtsc implementation to x86 and add ARM/non-x86 stub implementations that return 0. These changes prevent build failures on non-x86 platforms and make the codebase more portable.
---
 Fastor/config/cpuid.h | 5 ++++-
 Fastor/util/timeit.h  | 7 ++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/Fastor/config/cpuid.h b/Fastor/config/cpuid.h
index 498883f..cb0cd5e 100644
--- a/Fastor/config/cpuid.h
+++ b/Fastor/config/cpuid.h
@@ -43,11 +43,14 @@ class CPUID {
 #ifdef _WIN32
     __cpuid((int *)regs, (int)i);
 
-#else
+#elif defined(__x86_64__) || defined(__i386__)
     asm volatile
       ("cpuid" : "=a" (regs[0]), "=b" (regs[1]), "=c" (regs[2]), "=d" (regs[3])
        : "a" (i), "c" (0));
     // ECX is set to zero for CPUID function 4
+#else
+    (void)i;
+    regs[0] = regs[1] = regs[2] = regs[3] = 0;
 #endif
   }
 
diff --git a/Fastor/util/timeit.h b/Fastor/util/timeit.h
index 3fae970..9539886 100644
--- a/Fastor/util/timeit.h
+++ b/Fastor/util/timeit.h
@@ -101,7 +101,7 @@ inline uint64_t rdtsc_end() {
     return __rdtsc();
 }
 //  Linux/GCC
-#else
+#elif defined(__x86_64__) || defined(__i386__)
 inline uint64_t rdtsc() {
     unsigned int lo, hi;
     // This does not clobber the register so rdtsc overwrites
@@ -158,6 +158,11 @@ inline uint64_t rdtsc_end() {
 inline uint64_t rdtsc_begin() { return rdtsc();}
 inline uint64_t rdtsc_end() { return rdtsc();}
 #endif
+#else
+// ARM/non-x86 stubs
+inline uint64_t rdtsc() { return 0; }
+inline uint64_t rdtsc_begin() { return 0; }
+inline uint64_t rdtsc_end() { return 0; }
 #endif