Add a sanitizer to check if there is a definition of vreg before its (#1224)

Author: lum1n0us

core/iwasm/fast-jit/jit_regalloc.c

@@ -6,6 +6,10 @@
 #include "jit_utils.h"
 #include "jit_compiler.h"
 
+#if BH_DEBUG != 0
+#define VREG_DEF_SANITIZER
+#endif
+
 /**
  * A uint16 stack for storing distances of occurrences of virtual
  * registers.
@@ -350,6 +354,29 @@ is_alloc_candidate(JitCompContext *cc, JitReg reg)
             && (!jit_cc_is_hreg(cc, reg) || !jit_cc_is_hreg_fixed(cc, reg)));
 }
 
+#ifdef VREG_DEF_SANITIZER
+static void
+check_vreg_definition(RegallocContext *rc, JitInsn *insn)
+{
+    unsigned j;
+    JitRegVec regvec = jit_insn_opnd_regs(insn);
+    unsigned first_use = jit_insn_opnd_first_use(insn);
+    JitReg *regp;
+
+    /* check if there is the definition of an vr before its references */
+    JIT_REG_VEC_FOREACH_USE(regvec, j, regp, first_use)
+    {
+        VirtualReg *vr = NULL;
+
+        if (!is_alloc_candidate(rc->cc, *regp))
+            continue;
+
+        vr = rc_get_vr(rc, *regp);
+        bh_assert(vr->distances);
+    }
+}
+#endif
+
 /**
  * Collect distances from the beginning of basic block of all occurrences of
  * each virtual register.
@@ -371,6 +398,10 @@ collect_distances(RegallocContext *rc, JitBasicBlock *basic_block)
         unsigned i;
         JitReg *regp;
 
+#ifdef VREG_DEF_SANITIZER
+        check_vreg_definition(rc, insn);
+#endif
+
         /* NOTE: the distance may be pushed more than once if the
            virtual register occurs multiple times in the
            instruction.  */