Avoid use of __builtin_ctz for portability

riscv/arith.h

@@ -120,4 +120,39 @@ static inline uint64_t make_mask64(int pos, int len)
     assert(pos >= 0 && len > 0 && pos < 64 && len <= 64);
     return (UINT64_MAX >> (64 - len)) << pos;
 }
+
+static inline int ctz(uint64_t val)
+{
+  if (!val)
+    return 0;
+
+  int res = 0;
+
+  if ((val << 32) == 0) res += 32, val >>= 32;
+  if ((val << 48) == 0) res += 16, val >>= 16;
+  if ((val << 56) == 0) res += 8, val >>= 8;
+  if ((val << 60) == 0) res += 4, val >>= 4;
+  if ((val << 62) == 0) res += 2, val >>= 2;
+  if ((val << 63) == 0) res += 1, val >>= 1;
+
+  return res;
+}
+
+static inline int clz(uint64_t val)
+{
+  if (!val)
+    return 0;
+
+  int res = 0;
+
+  if ((val >> 32) == 0) res += 32, val <<= 32;
+  if ((val >> 48) == 0) res += 16, val <<= 16;
+  if ((val >> 56) == 0) res += 8, val <<= 8;
+  if ((val >> 60) == 0) res += 4, val <<= 4;
+  if ((val >> 62) == 0) res += 2, val <<= 2;
+  if ((val >> 63) == 0) res += 1, val <<= 1;
+
+  return res;
+}
+
 #endif

riscv/insns/bdep.h

@@ -2,7 +2,7 @@ require_extension('B');
 uint64_t c = 0, i = 0, data = zext_xlen(RS1), mask = zext_xlen(RS2);
 while (mask) {
 	uint64_t b = mask & ~((mask | (mask-1)) + 1);
-	c |= (data << (__builtin_ctzl(b) - i)) & b;
+	c |= (data << (ctz(b) - i)) & b;
 	i += __builtin_popcountl(b);
 	mask -= b;
 }

riscv/insns/bdepw.h

@@ -3,7 +3,7 @@ require_extension('B');
 uint64_t c = 0, i = 0, data = zext32(RS1), mask = zext32(RS2);
 while (mask) {
 	uint64_t b = mask & ~((mask | (mask-1)) + 1);
-	c |= (data << (__builtin_ctzl(b) - i)) & b;
+	c |= (data << (ctz(b) - i)) & b;
 	i += __builtin_popcountl(b);
 	mask -= b;
 }

riscv/insns/bext.h

@@ -2,7 +2,7 @@ require_extension('B');
 uint64_t c = 0, i = 0, data = zext_xlen(RS1), mask = zext_xlen(RS2);
 while (mask) {
 	uint64_t b = mask & ~((mask | (mask-1)) + 1);
-	c |= (data & b) >> (__builtin_ctzl(b) - i);
+	c |= (data & b) >> (ctz(b) - i);
 	i += __builtin_popcountl(b);
 	mask -= b;
 }

riscv/insns/bextw.h

@@ -3,7 +3,7 @@ require_extension('B');
 uint64_t c = 0, i = 0, data = zext32(RS1), mask = zext32(RS2);
 while (mask) {
 	uint64_t b = mask & ~((mask | (mask-1)) + 1);
-	c |= (data & b) >> (__builtin_ctzl(b) - i);
+	c |= (data & b) >> (ctz(b) - i);
 	i += __builtin_popcountl(b);
 	mask -= b;
 }

riscv/processor.cc

@@ -478,16 +478,6 @@ void processor_t::reset()
     sim->proc_reset(id);
 }
 
-// Count number of contiguous 0 bits starting from the LSB.
-static int ctz(reg_t val)
-{
-  int res = 0;
-  if (val)
-    while ((val & 1) == 0)
-      val >>= 1, res++;
-  return res;
-}
-
 void processor_t::set_pmp_num(reg_t n)
 {
   // check the number of pmp is in a reasonable range