patch that caused regression PR optimization/4382

patch that caused regression PR optimization/4382

[Janis Johnson]

The regression reported in PR optimization/4382 showed up starting
with this patch:

2000-12-20  Richard Henderson  <rth@redhat.com>

	* rtl.h (REG_NON_LOCAL_GOTO): New.
	* rtl.c (reg_note_name): Update.
	* stmt.c (expand_goto): Emit a REG_NON_LOCAL_GOTO note.
	* builtins.c (expand_builtin_longjmp): Likewise.
	* flow.c (make_edges): Check for REG_NON_LOCAL_GOTO and do
	not emit an edge.

Here's the test case I used, which is in the PR.  There's also a
smaller one in the PR that causes the same ICE.

-------------------
struct jmp_buf {
  void *p[5];
};

static void jumpaway(struct jmp_buf *ptr)
{
  __builtin_longjmp(ptr ,1);
  abort();
}

int main(void)
{
  struct jmp_buf buf;
  if (__builtin_setjmp(&buf) == 0) {
  } else
    return 0;
  jumpaway(&buf);
  abort();
  return 0;
}
-------------------

Output from the compiler when compiled with -O3 using mainline:

4382.c: In function `main':
4382.c:20: error: Wrong amount of branch edges after unconditional jump 0
4382.c:20: internal compiler error: verify_flow_info failed
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://www.gnu.org/software/gcc/bugs.html> for instructions.

I'll add this information to the PR.

Janis

Re: patch that caused regression PR optimization/4382

[Richard Henderson]

On Thu, Dec 19, 2002 at 03:25:13PM -0800, Janis Johnson wrote:
> The regression reported in PR optimization/4382 showed up ...

This is _really_ borderline, but ok.  We'll hack around
this problem like so.

If you call both __builtin_setjmp and __builtin_longjmp in
the same function, expect things to crash again, however.
All I can say is, Don't Do That.


r~


        * tree-inline.c (find_builtin_longjmp_call_1): New.
        (find_builtin_longjmp_call): New.
        (inlinable_function_p): Use it.

Index: tree-inline.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-inline.c,v
retrieving revision 1.40
diff -c -p -d -r1.40 tree-inline.c
*** tree-inline.c	24 Dec 2002 08:30:33 -0000	1.40
--- tree-inline.c	24 Jan 2003 21:14:47 -0000
*************** static tree add_stmt_to_compound PARAMS 
*** 125,130 ****
--- 125,132 ----
  #endif /* INLINER_FOR_JAVA */
  static tree find_alloca_call_1 PARAMS ((tree *, int *, void *));
  static tree find_alloca_call PARAMS ((tree));
+ static tree find_builtin_longjmp_call_1 PARAMS ((tree *, int *, void *));
+ static tree find_builtin_longjmp_call PARAMS ((tree));
  
  /* The approximate number of instructions per statement.  This number
     need not be particularly accurate; it is used only to make
*************** tree_inlinable_function_p (fn)
*** 873,879 ****
    return inlinable_function_p (fn, NULL);
  }
  
! /* if *TP is possibly call to alloca, return nonzero.  */
  static tree
  find_alloca_call_1 (tp, walk_subtrees, data)
       tree *tp;
--- 875,881 ----
    return inlinable_function_p (fn, NULL);
  }
  
! /* If *TP is possibly call to alloca, return nonzero.  */
  static tree
  find_alloca_call_1 (tp, walk_subtrees, data)
       tree *tp;
*************** find_alloca_call_1 (tp, walk_subtrees, d
*** 885,892 ****
    return NULL;
  }
  
! /* Return subexpression representing possible alloca call,
!    if any.  */
  static tree
  find_alloca_call (exp)
       tree exp;
--- 887,893 ----
    return NULL;
  }
  
! /* Return subexpression representing possible alloca call, if any.  */
  static tree
  find_alloca_call (exp)
       tree exp;
*************** find_alloca_call (exp)
*** 894,899 ****
--- 895,926 ----
    return walk_tree (&exp, find_alloca_call_1, NULL, NULL);
  }
  
+ static tree
+ find_builtin_longjmp_call_1 (tp, walk_subtrees, data)
+      tree *tp;
+      int *walk_subtrees ATTRIBUTE_UNUSED;
+      void *data ATTRIBUTE_UNUSED;
+ {
+   tree exp = *tp, decl;
+ 
+   if (TREE_CODE (exp) == CALL_EXPR
+       && TREE_CODE (TREE_OPERAND (exp, 0)) == ADDR_EXPR
+       && (decl = TREE_OPERAND (TREE_OPERAND (exp, 0), 0),
+ 	  TREE_CODE (decl) == FUNCTION_DECL)
+       && DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL
+       && DECL_FUNCTION_CODE (decl) == BUILT_IN_LONGJMP)
+     return decl;
+ 
+   return NULL;
+ }
+ 
+ static tree
+ find_builtin_longjmp_call (exp)
+      tree exp;
+ {
+   return walk_tree (&exp, find_builtin_longjmp_call_1, NULL, NULL);
+ }
+ 
  /* Returns nonzero if FN is a function that can be inlined into the
     inlining context ID_.  If ID_ is NULL, check whether the function
     can be inlined at all.  */
*************** inlinable_function_p (fn, id)
*** 933,938 ****
--- 960,973 ----
       allowance for extern inline functions, though.  */
    else if (! (*lang_hooks.tree_inlining.disregard_inline_limits) (fn)
  	   && currfn_insns > MAX_INLINE_INSNS_SINGLE)
+     ;
+   /* We can't inline functions that call __builtin_longjmp at all.
+      The non-local goto machenery really requires the destination
+      be in a different function.  If we allow the function calling
+      __builtin_longjmp to be inlined into the function calling
+      __builtin_setjmp, Things will Go Awry.  */
+   /* ??? Need front end help to identify "regular" non-local goto.  */
+   else if (find_builtin_longjmp_call (DECL_SAVED_TREE (fn)))
      ;
    /* Refuse to inline alloca call unless user explicitly forced so as this may
       change program's memory overhead drastically when the function using alloca