Bug fix for commit 553242c18a2387fb896df66eb9b5a502f0e87ff0.

In gtst, vtop->c.i is not usually zero, but it is when compiling:

int f(void) { return 1 && 1 ? 1 : 1; }

2 files changed, 14 insertions, 10 deletions

diff --git a/i386-gen.c b/i386-gen.c
index d202925..c18b9c3 100644
--- a/i386-gen.c
+++ b/i386-gen.c
@@ -678,12 +678,14 @@ ST_FUNC int gtst(int inv, int t)
     } else if (v == VT_JMP || v == VT_JMPI) {
         /* && or || optimization */
         if ((v & 1) == inv) {
-            uint32_t n1, n = vtop->c.i;
             /* insert vtop->c jump list in t */
-            while ((n1 = read32le(cur_text_section->data + n)))
-                n = n1;
-            write32le(cur_text_section->data + n, t);
-            t = vtop->c.i;
+            uint32_t n1, n = vtop->c.i;
+            if (n) {
+                while ((n1 = read32le(cur_text_section->data + n)))
+                    n = n1;
+                write32le(cur_text_section->data + n, t);
+                t = vtop->c.i;
+            }
         } else {
             t = gjmp(t);
             gsym(vtop->c.i);
diff --git a/x86_64-gen.c b/x86_64-gen.c
index 4ac1e93..692b420 100644
--- a/x86_64-gen.c
+++ b/x86_64-gen.c
@@ -1716,12 +1716,14 @@ int gtst(int inv, int t)
     } else if (v == VT_JMP || v == VT_JMPI) {
         /* && or || optimization */
         if ((v & 1) == inv) {
-            uint32_t n1, n = vtop->c.i;
             /* insert vtop->c jump list in t */
-            while ((n1 = read32le(cur_text_section->data + n)))
-                n = n1;
-            write32le(cur_text_section->data + n, t);
-            t = vtop->c.i;
+            uint32_t n1, n = vtop->c.i;
+            if (n) {
+                while ((n1 = read32le(cur_text_section->data + n)))
+                    n = n1;
+                write32le(cur_text_section->data + n, t);
+                t = vtop->c.i;
+            }
         } else {
             t = gjmp(t);
             gsym(vtop->c.i);