Allow conditional inclusion of builtin library functions.

1 files changed, 21 insertions, 0 deletions

diff --git a/src/host/buildvm_lib.c b/src/host/buildvm_lib.c
index 3231d3ad..8e10fec1 100644
--- a/src/host/buildvm_lib.c
+++ b/src/host/buildvm_lib.c
@@ -317,6 +317,27 @@ void emit_lib(BuildCtx *ctx)
     regfunc = REGFUNC_OK;
     while (fgets(buf, sizeof(buf), fp) != NULL) {
       char *p;
+      /* Simplistic pre-processor. Only handles top-level #if/#endif. */
+      if (buf[0] == '#' && buf[1] == 'i' && buf[2] == 'f') {
+        int ok = 1;
+        if (!strcmp(buf, "#if LJ_52\n"))
+          ok = LJ_52;
+        else if (!strcmp(buf, "#if LJ_HASJIT\n"))
+          ok = LJ_HASJIT;
+        else if (!strcmp(buf, "#if LJ_HASFFI\n"))
+          ok = LJ_HASFFI;
+        if (!ok) {
+          int lvl = 1;
+          while (fgets(buf, sizeof(buf), fp) != NULL) {
+            if (buf[0] == '#' && buf[1] == 'e' && buf[2] == 'n') {
+              if (--lvl == 0) break;
+            } else if (buf[0] == '#' && buf[1] == 'i' && buf[2] == 'f') {
+              lvl++;
+            }
+          }
+          continue;
+        }
+      }
       for (p = buf; (p = strstr(p, LIBDEF_PREFIX)) != NULL; ) {
         const LibDefHandler *ldh;
         p += sizeof(LIBDEF_PREFIX)-1;