compiler: add support for $if x32, x64, big_endian, little_endian

vlib/compiler/cheaders.v

@@ -12,6 +12,22 @@ c_headers = '
 #include <stdarg.h> // for va_list
 #include <string.h> // memcpy
 
+#if INTPTR_MAX == INT32_MAX
+    #define TARGET_IS_32BIT 1
+#elif INTPTR_MAX == INT64_MAX
+    #define TARGET_IS_64BIT 1
+#else
+    #error "The environment is not 32 or 64-bit."
+#endif
+
+#if defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ || defined(__BYTE_ORDER) && __BYTE_ORDER == __BIG_ENDIAN || defined(__BIG_ENDIAN__) || defined(__ARMEB__) || defined(__THUMBEB__) || defined(__AARCH64EB__) || defined(_MIBSEB) || defined(__MIBSEB) || defined(__MIBSEB__) 
+    #define TARGET_ORDER_IS_BIG
+#elif defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ || defined(__BYTE_ORDER) && __BYTE_ORDER == __LITTLE_ENDIAN || defined(__LITTLE_ENDIAN__) || defined(__ARMEL__) || defined(__THUMBEL__) || defined(__AARCH64EL__) || defined(_MIPSEL) || defined(__MIPSEL) || defined(__MIPSEL__) || defined(_M_AMD64) || defined(_M_X64) || defined(_M_IX86) 
+    #define TARGET_ORDER_IS_LITTLE
+#else
+    #error "Unknown architecture endianness"
+#endif
+
 #ifndef _WIN32
 #include <ctype.h>
 #include <locale.h> // tolower

vlib/compiler/comptime.v

@@ -62,18 +62,27 @@ fn (p mut Parser) comp_time() {
 				p.genln('#endif')
 			}
 		}
+		else if name == 'x64' {
+			p.comptime_if_block('TARGET_IS_64BIT')
+		}
+		else if name == 'x32' {
+			p.comptime_if_block('TARGET_IS_32BIT')
+		}
+		else if name == 'big_endian' {
+			p.comptime_if_block('TARGET_ORDER_IS_BIG')
+		}
+		else if name == 'little_endian' {
+			p.comptime_if_block('TARGET_ORDER_IS_LITTLE')
+		}
 		else if name == 'debug' {
-			p.genln('#ifdef VDEBUG')
-			p.check(.lcbr)
-			p.statements_no_rcbr()
-			p.genln('#endif')
+			p.comptime_if_block('VDEBUG')
 		}
 		else if name == 'tinyc' {
 			p.comptime_if_block('__TINYC__')
 		}
 		else if name == 'glibc' {
 			p.comptime_if_block('__GLIBC__')
-		}	
+		}
 		else if name == 'mingw' {
 			p.comptime_if_block('__MINGW32__')
 		}

vlib/compiler/tests/comptime_bittness_and_endianess_test.v

@@ -0,0 +1,26 @@
+
+fn test_bitness(){
+  mut x := 0
+  $if x32 {
+    println('system is 32 bit')
+    x = 1
+  }
+  $if x64 {
+    println('system is 64 bit')
+    x = 2
+  }
+  assert x > 0
+}
+
+fn test_endianness(){
+  mut x := 0
+  $if little_endian {
+    println('system is little endian')
+    x = 1
+  }
+  $if big_endian {
+    println('system is big endian')
+    x = 2
+  }
+  assert x > 0
+}