[PATCH] Fix ICE in categorize_decl_for_section with TLS decl (PR middle-end/82095)

[Jakub Jelinek]

Hi!

If a DECL_THREAD_LOCAL_P decl has NULL DECL_INITIAL and
-fzero-initialized-in-bss (the default), we ICE starting with
r251602, which changed bss_initializer_p:
+  /* Do not put constants into the .bss section, they belong in a readonly
+     section.  */
+  return (!TREE_READONLY (decl)
+         &&
to:
          (DECL_INITIAL (decl) == NULL
              /* In LTO we have no errors in program; error_mark_node is used
                 to mark offlined constructors.  */
              || (DECL_INITIAL (decl) == error_mark_node
                  && !in_lto_p)
              || (flag_zero_initialized_in_bss
                  && initializer_zerop (DECL_INITIAL (decl))))
Previously because bss_initializer_p for these returned true, ret was
SECCAT_BSS and therefore we set it to SECCAT_TBSS as intended, but now ret
is not SECCAT_BSS, but as TLS has only tbss and tdata possibilities, we
still want to use tbss.  DECL_INITIAL NULL for a decl means implicit zero
initialization.

Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?

2017-09-05  Jakub Jelinek  <ja...@redhat.com>

        PR middle-end/82095
        * varasm.c (categorize_decl_for_section): Use SECCAT_TBSS for TLS vars 
with
        NULL DECL_INITIAL.

        * gcc.dg/tls/pr82095.c: New test.

--- gcc/varasm.c.jj     2017-09-01 18:43:29.000000000 +0200
+++ gcc/varasm.c        2017-09-04 12:29:10.166564776 +0200
@@ -6562,8 +6562,9 @@ categorize_decl_for_section (const_tree
       /* Note that this would be *just* SECCAT_BSS, except that there's
         no concept of a read-only thread-local-data section.  */
       if (ret == SECCAT_BSS
-              || (flag_zero_initialized_in_bss
-                  && initializer_zerop (DECL_INITIAL (decl))))
+         || DECL_INITIAL (decl) == NULL
+         || (flag_zero_initialized_in_bss
+             && initializer_zerop (DECL_INITIAL (decl))))
        ret = SECCAT_TBSS;
       else
        ret = SECCAT_TDATA;
--- gcc/testsuite/gcc.dg/tls/pr82095.c.jj       2017-09-04 12:44:16.650538220 
+0200
+++ gcc/testsuite/gcc.dg/tls/pr82095.c  2017-09-04 12:44:08.000000000 +0200
@@ -0,0 +1,16 @@
+/* PR middle-end/82095 */
+/* { dg-do compile } */
+/* { dg-options "-Og -fno-tree-ccp" } */
+/* { dg-require-effective-target tls } */
+/* { dg-add-options tls } */
+
+static int b;
+static __thread int c;
+
+void
+foo (void)
+{
+  if (b)
+    if (c)
+      b = 1;
+}

        Jakub