c/107305 - avoid ICEing with invalid GIMPLE input to the GIMPLE FE

The GIMPLE FE was designed to defer semantic error checking to the
GIMPLE IL verifier.  But that can end up causing spurious ICEs
earlier and in fact it will report an internal error.  The following
tries to improve the situation by explicitely calling into the
verifier from the parser and intructing it to not ICE but instead
zap the parsed body after an error is discovered.

	PR c/107305
	PR c/107306
gcc/c/
	* gimple-parser.cc (c_parser_parse_gimple_body): Verify
	the parsed IL and zap the body on error.

gcc/
	* tree-cfg.h (verify_gimple_in_seq): Add parameter to
	indicate whether to emit an ICE.  Add return value.
	(verify_gimple_in_cfg): Likewise.
	* tree-cfg.cc (verify_gimple_in_seq): Likewise.
	(verify_gimple_in_cfg): Likewise.

gcc/testsuite/
	* gcc.dg/gimplefe-error-15.c: New testcase.

4 files changed, 35 insertions, 8 deletions

diff --git a/gcc/c/gimple-parser.cc b/gcc/c/gimple-parser.cc
index 5a2da2c..18ed4d4 100644
--- a/gcc/c/gimple-parser.cc
+++ b/gcc/c/gimple-parser.cc
@@ -364,6 +364,16 @@ c_parser_parse_gimple_body (c_parser *cparser, char *gimple_pass,
       cgraph_node::get_create (cfun->decl);
       cgraph_edge::rebuild_edges ();
     }
+
+  /* Perform IL validation and if any error is found abort compilation
+     of this function by zapping its body.  */
+  if ((cfun->curr_properties & PROP_cfg)
+      && verify_gimple_in_cfg (cfun, false, false))
+    init_empty_tree_cfg ();
+  else if (!(cfun->curr_properties & PROP_cfg)
+	   && verify_gimple_in_seq (gimple_body (current_function_decl), false))
+    gimple_set_body (current_function_decl, NULL);
+
   dump_function (TDI_gimple, current_function_decl);
 }
 
diff --git a/gcc/testsuite/gcc.dg/gimplefe-error-15.c b/gcc/testsuite/gcc.dg/gimplefe-error-15.c
new file mode 100644
index 0000000..066cd84
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/gimplefe-error-15.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-fgimple" } */
+
+unsigned a;
+static double *d;
+static _Bool b;
+__GIMPLE int
+foo (int n)
+{
+  b = __builtin_add_overflow (n, *d, &a);
+} /* { dg-error "invalid argument" } */
+
+/* { dg-message "" "" { target *-*-* } 0 } */
diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
index 9b2c0f6..d982988 100644
--- a/gcc/tree-cfg.cc
+++ b/gcc/tree-cfg.cc
@@ -5300,13 +5300,15 @@ verify_gimple_transaction (gtransaction *stmt)
 
 /* Verify the GIMPLE statements inside the statement list STMTS.  */
 
-DEBUG_FUNCTION void
-verify_gimple_in_seq (gimple_seq stmts)
+DEBUG_FUNCTION bool
+verify_gimple_in_seq (gimple_seq stmts, bool ice)
 {
   timevar_push (TV_TREE_STMT_VERIFY);
-  if (verify_gimple_in_seq_2 (stmts))
+  bool res = verify_gimple_in_seq_2 (stmts);
+  if (res && ice)
     internal_error ("%<verify_gimple%> failed");
   timevar_pop (TV_TREE_STMT_VERIFY);
+  return res;
 }
 
 /* Return true when the T can be shared.  */
@@ -5496,8 +5498,8 @@ collect_subblocks (hash_set<tree> *blocks, tree block)
 
 /* Verify the GIMPLE statements in the CFG of FN.  */
 
-DEBUG_FUNCTION void
-verify_gimple_in_cfg (struct function *fn, bool verify_nothrow)
+DEBUG_FUNCTION bool
+verify_gimple_in_cfg (struct function *fn, bool verify_nothrow, bool ice)
 {
   basic_block bb;
   bool err = false;
@@ -5652,11 +5654,13 @@ verify_gimple_in_cfg (struct function *fn, bool verify_nothrow)
     eh_table->traverse<hash_set<gimple *> *, verify_eh_throw_stmt_node>
       (&visited_throwing_stmts);
 
-  if (err || eh_error_found)
+  if (ice && (err || eh_error_found))
     internal_error ("verify_gimple failed");
 
   verify_histograms ();
   timevar_pop (TV_TREE_STMT_VERIFY);
+
+  return (err || eh_error_found);
 }
 
 
diff --git a/gcc/tree-cfg.h b/gcc/tree-cfg.h
index 95ec93e..8c22c3d 100644
--- a/gcc/tree-cfg.h
+++ b/gcc/tree-cfg.h
@@ -63,8 +63,8 @@ extern gphi *get_virtual_phi (basic_block);
 extern gimple *first_stmt (basic_block);
 extern gimple *last_stmt (basic_block);
 extern gimple *last_and_only_stmt (basic_block);
-extern void verify_gimple_in_seq (gimple_seq);
-extern void verify_gimple_in_cfg (struct function *, bool);
+extern bool verify_gimple_in_seq (gimple_seq, bool = true);
+extern bool verify_gimple_in_cfg (struct function *, bool, bool = true);
 extern tree gimple_block_label (basic_block);
 extern void add_phi_args_after_copy_bb (basic_block);
 extern void add_phi_args_after_copy (basic_block *, unsigned, edge);