re PR tree-optimization/17656 (internal compiler error: in…

re PR tree-optimization/17656 (internal compiler error: in replace_immediate_uses, at tree-ssa.c:1041)


	PR tree-optimization/17656
	* tree-ssa.c (replace_immediate_uses): When replacing a
	constant, if the call to fold_stmt produced a different
	statement, get an appropriate statement pointer by scanning
	STMT's basic block.

	PR tree-optimization/17656
	* testsuite/gcc.c-torture/compile/pr17656.c: New test.

From-SVN: r89233

gcc/ChangeLog

+2004-10-18  Diego Novillo  <dnovillo@redhat.com>
+
+	PR tree-optimization/17656
+	* tree-ssa.c (replace_immediate_uses): When replacing a
+	constant, if the call to fold_stmt produced a different
+	statement, get an appropriate statement pointer by scanning
+	STMT's basic block.
+
 2004-10-18  Richard Henderson  <rth@redhat.com>
 
 	* pointer-set.c (hash1): Don't use libm functions in fallback case.

gcc/testsuite/ChangeLog

+2004-10-18  Diego Novillo  <dnovillo@redhat.com>
+
+	PR tree-optimization/17656
+	* testsuite/gcc.c-torture/compile/pr17656.c: New test.
+
 2004-10-18  Nathan Sidwell  <nathan@codesourcery.com>
 
 	* g++.dg/eh/shadow1.C: New.

gcc/testsuite/gcc.c-torture/compile/pr17656.c

+int sprintf (char *s, const char *format, ...);
+
+int foo(int i, int j)
+{
+   char *buf, *str;
+
+   if (i)
+     str = "";
+   else if (j)
+     str = "";
+   else
+     return 1;
+
+   /* We were propagating &""[0] here and not calling fold_stmt with a
+      proper statement pointer.  */
+   sprintf(buf, str);
+   return 0;
+}

gcc/tree-ssa.c

@@ -1093,7 +1093,8 @@ replace_immediate_uses (tree var, tree repl)
 	 with a new expression.  Since the current def-use machinery
 	 does not return pointers to statements, we call fold_stmt
 	 with the address of a local temporary, if that call changes
-	 the temporary then we fall on our swords.
+	 the temporary then we fallback on looking for a proper
+	 pointer to STMT by scanning STMT's basic block.
 
 	 Note that all this will become unnecessary soon.  This
 	 pass is being replaced with a proper copy propagation pass
@@ -1103,7 +1104,22 @@ replace_immediate_uses (tree var, tree repl)
 	  tree tmp = stmt;
 	  fold_stmt (&tmp);
 	  if (tmp != stmt)
-	    abort ();
+	    {
+	      basic_block bb = bb_for_stmt (stmt);
+	      block_stmt_iterator si;
+
+	      /* Start iterating at the start of the basic block
+		 holding STMT until we reach it.  This is slow, but
+		 it's the only way to get a statement pointer
+		 reliably.  */
+	      for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
+		if (bsi_stmt (si) == stmt)
+		  {
+		    fold_stmt (bsi_stmt_ptr (si));
+		    stmt = bsi_stmt (si);
+		    break;
+		  }
+	    }
 	}
 
       /* If REPL is a pointer, it may have different memory tags associated