[PATCH] c/100625 - avoid building invalid labels in the GIMPLE FE

[Richard Biener]

When duplicate labes are diagnosed, avoid building a GIMPLE_LABEL.

Bootstrapped / tested on x86_64-unknown-linux-gnu, pushed.

2021-05-17  Richard Biener  <rguent...@suse.de>

        PR c/100625
gcc/c/
        * gimple-parser.c (c_parser_gimple_label): Avoid building
        a GIMPLE label with NULL label decl.

        * gcc.dg/gimplefe-error-9.c: New testcase.
---
 gcc/c/gimple-parser.c                   | 3 ++-
 gcc/testsuite/gcc.dg/gimplefe-error-9.c | 9 +++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.dg/gimplefe-error-9.c

diff --git a/gcc/c/gimple-parser.c b/gcc/c/gimple-parser.c
index 3a6e72ef002..398e21631d9 100644
--- a/gcc/c/gimple-parser.c
+++ b/gcc/c/gimple-parser.c
@@ -1887,7 +1887,8 @@ c_parser_gimple_label (gimple_parser &parser, gimple_seq 
*seq)
   gcc_assert (c_parser_next_token_is (parser, CPP_COLON));
   c_parser_consume_token (parser);
   tree label = define_label (loc1, name);
-  gimple_seq_add_stmt_without_update (seq, gimple_build_label (label));
+  if (label)
+    gimple_seq_add_stmt_without_update (seq, gimple_build_label (label));
   return;
 }
 
diff --git a/gcc/testsuite/gcc.dg/gimplefe-error-9.c 
b/gcc/testsuite/gcc.dg/gimplefe-error-9.c
new file mode 100644
index 00000000000..87014c1cbbf
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/gimplefe-error-9.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-fgimple" } */
+
+void __GIMPLE
+foo()
+{
+bb1:
+bb1:; /* { dg-error "duplicate" } */
+}
-- 
2.26.2