Enable adding prefix to host compiler

To enable cross compile.

Makefile

@@ -16,6 +16,8 @@ LIB_DIR:=lib
 # NO_VLA:=1
 # NO_WCHAR:=1
 
+# HOST_CC_PREFIX=riscv64-unknown-elf-
+
 ifeq ("$(ARCHTYPE)", "")
   ARCHTYPE:=x64
   ARCH:=$(shell arch)
@@ -50,6 +52,10 @@ ifneq ("$(NO_WCHAR)","")
 CFLAGS+=-D__NO_WCHAR
 endif
 
+ifneq ("$(HOST_CC_PREFIX)","")
+CFLAGS+=-DHOST_CC_PREFIX=$(HOST_CC_PREFIX)
+endif
+
 # For release build:
 # CFLAGS+=-DNDEBUG
 

src/xcc/main.c

@@ -260,6 +260,13 @@ int main(int argc, char *argv[]) {
 #if !defined(AS_USE_CC)
   char *as_path = join_exe_prefix(xccpath, prefix, "as");
   char *ld_path = join_exe_prefix(xccpath, prefix, "ld");
+#elif defined(HOST_CC_PREFIX)
+#define S(x)   S2(x)
+#define S2(x)  #x
+  char *as_path = S(HOST_CC_PREFIX) "as";
+  char *ld_path = S(HOST_CC_PREFIX) "gcc";
+#undef S2
+#undef S
 #else
   char *as_path = "/usr/bin/as";
   char *ld_path = "/usr/bin/cc";