From 56ef450a24956aa6aaa3afec439af5195e4aa235 Mon Sep 17 00:00:00 2001
From: Sergei Marochkin <xziggix@gmail.com>
Date: Tue, 25 Oct 2016 06:27:56 +0300
Subject: [PATCH] Add detailed recursion report with call chains Applied path
 from https://github.com/Zeex/pawn/tree/recursion branch.

Example:

f1() {
	f2();
}

f2() {
	f3();
}

f3() {
	f4();
}

f4() {
	f1();
}

will output:

recursion detected: function f1 indirectly calls itself:
f1 <- f4 <- f3 <- f2 <- f1
recursion detected: function f2 indirectly calls itself:
f2 <- f1 <- f4 <- f3 <- f2
recursion detected: function f3 indirectly calls itself:
f3 <- f2 <- f1 <- f4 <- f3
recursion detected: function f4 indirectly calls itself:
f4 <- f3 <- f2 <- f1 <- f4
---
 source/compiler/sc1.c | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/source/compiler/sc1.c b/source/compiler/sc1.c
index 61a62f8..63fb705 100644
--- a/source/compiler/sc1.c
+++ b/source/compiler/sc1.c
@@ -4501,7 +4501,7 @@ static void reduce_referrers(symbol *root)
 }
 
 #if !defined SC_LIGHT
-static long max_stacksize_recurse(symbol **sourcesym,symbol *sym,long basesize,int *pubfuncparams,int *recursion)
+static long max_stacksize_recurse(symbol **sourcesym,symbol *sym,symbol **rsourcesym,long basesize,int *pubfuncparams,int *recursion)
 {
   long size,maxsize;
   int i,stkpos;
@@ -4517,6 +4517,8 @@ static long max_stacksize_recurse(symbol **sourcesym,symbol *sym,long basesize,i
     if (sym->refer[i]!=NULL) {
       assert(sym->refer[i]->ident==iFUNCTN);
       assert((sym->refer[i]->usage & uNATIVE)==0); /* a native function cannot refer to a user-function */
+      *(rsourcesym)=sym;
+      *(rsourcesym+1)=NULL;
       for (stkpos=0; sourcesym[stkpos]!=NULL; stkpos++) {
         if (sym->refer[i]==sourcesym[stkpos]) {   /* recursion detection */
           *recursion=1;
@@ -4527,7 +4529,7 @@ static long max_stacksize_recurse(symbol **sourcesym,symbol *sym,long basesize,i
       sourcesym[stkpos]=sym;
       sourcesym[stkpos+1]=NULL;
       /* check size of callee */
-      size=max_stacksize_recurse(sourcesym,sym->refer[i],sym->x.stacksize,pubfuncparams,recursion);
+      size=max_stacksize_recurse(sourcesym,sym->refer[i],rsourcesym+1,sym->x.stacksize,pubfuncparams,recursion);
       if (maxsize<size)
         maxsize=size;
       /* remove this symbol from the stack */
@@ -4570,7 +4572,7 @@ static long max_stacksize(symbol *root,int *recursion)
   long size,maxsize;
   int maxparams,numfunctions;
   symbol *sym;
-  symbol **symstack;
+  symbol **symstack,**rsymstack;
 
   assert(root!=NULL);
   assert(recursion!=NULL);
@@ -4585,27 +4587,46 @@ static long max_stacksize(symbol *root,int *recursion)
   } /* if */
   /* allocate function symbol stack */
   symstack=(symbol **)malloc((numfunctions+1)*sizeof(symbol*));
-  if (symstack==NULL)
+  rsymstack=(symbol **)malloc((numfunctions+1)*sizeof(symbol*));
+  if (symstack==NULL || rsymstack==NULL)
     error(103);         /* insufficient memory (fatal error) */
   memset(symstack,0,(numfunctions+1)*sizeof(symbol*));
+  memset(rsymstack,0,(numfunctions+1)*sizeof(symbol*));
 
   maxsize=0;
   maxparams=0;
   *recursion=0;         /* assume no recursion */
   for (sym=root->next; sym!=NULL; sym=sym->next) {
+    int recursion_detected;
     /* drop out if this is not a user-implemented function */
     if (sym->ident!=iFUNCTN || (sym->usage & uNATIVE)!=0)
       continue;
     /* accumulate stack size for this symbol */
     symstack[0]=sym;
     assert(symstack[1]==NULL);
-    size=max_stacksize_recurse(symstack,sym,0L,&maxparams,recursion);
+    recursion_detected=0;
+    size=max_stacksize_recurse(symstack,sym,rsymstack,0L,&maxparams,&recursion_detected);
+    if (recursion_detected) {
+      if (rsymstack[1]==NULL) {
+        pc_printf("recursion detected: function %s directly calls itself\n", sym->name);
+      } else {
+        int i;
+        pc_printf("recursion detected: function %s indirectly calls itself:\n", sym->name);
+        pc_printf("%s ", sym->name);
+        for (i=1; rsymstack[i]!=NULL; i++) {
+          pc_printf("<- %s ", rsymstack[i]->name);
+        }
+        pc_printf("<- %s\n", sym->name);
+      }
+      *recursion=recursion_detected;
+    }
     assert(size>=0);
     if (maxsize<size)
       maxsize=size;
   } /* for */
 
   free((void*)symstack);
+  free((void*)rsymstack);
   maxsize++;                  /* +1 because a zero cell is always pushed on top
                                * of the stack to catch stack overwrites */
   return maxsize+(maxparams+1);/* +1 because # of parameters is always pushed on entry */