[PATCH] Fix ICE: in function_and_variable_visibility, at ipa-visibility.c:795 (PR99466)

[Iain Buclaw]

Excerpts from Iain Sandoe's message of March 13, 2021 6:09 pm:
> Hi Iain,
> 
> Iain Buclaw via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> 
>> This patch fixes an ICE caused by emutls routines generating a weak,
>> non-public symbol for storing the initializer of a weak TLS variable.
>>
>> In get_emutls_init_templ_addr, only declarations that were DECL_ONE_ONLY
>> would get a public initializer symbol, ignoring variables that were
>> declared with __attribute__((weak)).
>>
>> Because DECL_VISIBILITY is also copied to the emutls initializer, a
>> second test is included which checks that the expected visibility is
>> emitted too.
>>
>> Tested on x86_64-apple-darwin10, OK for mainline?
>>
>> The oldest version of gcc I've checked is 7.5.0, and the ICE is present
>> there too.  Is this OK for backporting, and if so which versions should
>> it be backported to?
>>
>> Regards,
>> Iain.
>>
>> ---
>> gcc/ChangeLog:
>>
>> 	PR ipa/99466
>> 	* tree-emutls.c (get_emutls_init_templ_addr): Mark initializer of weak
>> 	TLS declarations as public.
>>
>> gcc/testsuite/ChangeLog:
>>
>> 	* gcc.dg/tls/pr98607-1.c: New test.
>> 	* gcc.dg/tls/pr98607-2.c: New test.
> 
> ^^^ s/98607/99466/ ?
> 

Oops, good catch.  I must have copied the number from the wrong tab.
Mechanically updated the PR numbers and trying again...

---
gcc/ChangeLog:

	PR ipa/99466
	* tree-emutls.c (get_emutls_init_templ_addr): Mark initializer of weak
	TLS declarations as public.

gcc/testsuite/ChangeLog:

	PR ipa/99466
	* gcc.dg/tls/pr99466-1.c: New test.
	* gcc.dg/tls/pr99466-2.c: New test.
---
 gcc/testsuite/gcc.dg/tls/pr99466-1.c |  8 ++++++++
 gcc/testsuite/gcc.dg/tls/pr99466-2.c | 10 ++++++++++
 gcc/tree-emutls.c                    |  6 ++++--
 3 files changed, 22 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/tls/pr99466-1.c
 create mode 100644 gcc/testsuite/gcc.dg/tls/pr99466-2.c

diff --git a/gcc/testsuite/gcc.dg/tls/pr99466-1.c b/gcc/testsuite/gcc.dg/tls/pr99466-1.c
new file mode 100644
index 00000000000..446850e148b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tls/pr99466-1.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-require-weak "" } */
+/* { dg-require-effective-target tls_emulated } */
+/* { dg-add-options tls } */
+__attribute__((weak))
+__thread int tlsvar = 3;
+/* { dg-final { scan-assembler ".weak_definition ___emutls_t.tlsvar" { target *-*-darwin* } } } */
+/* { dg-final { scan-assembler-not ".private_extern ___emutls_t.tlsvar" { target *-*-darwin* } } } */
diff --git a/gcc/testsuite/gcc.dg/tls/pr99466-2.c b/gcc/testsuite/gcc.dg/tls/pr99466-2.c
new file mode 100644
index 00000000000..86ffaad7f48
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tls/pr99466-2.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-require-weak "" } */
+/* { dg-require-visibility "" } */
+/* { dg-require-effective-target tls_emulated } */
+/* { dg-add-options tls } */
+__attribute__((weak))
+__attribute__((visibility ("hidden")))
+__thread int tlsvar = 3;
+/* { dg-final { scan-assembler ".weak_definition ___emutls_t.tlsvar" { target *-*-darwin* } } } */
+/* { dg-final { scan-assembler ".private_extern ___emutls_t.tlsvar" { target *-*-darwin* } } } */
diff --git a/gcc/tree-emutls.c b/gcc/tree-emutls.c
index f1053385944..1c9c5d5aee1 100644
--- a/gcc/tree-emutls.c
+++ b/gcc/tree-emutls.c
@@ -242,16 +242,18 @@ get_emutls_init_templ_addr (tree decl)
   DECL_PRESERVE_P (to) = DECL_PRESERVE_P (decl);
 
   DECL_WEAK (to) = DECL_WEAK (decl);
-  if (DECL_ONE_ONLY (decl))
+  if (DECL_ONE_ONLY (decl) || DECL_WEAK (decl))
     {
       TREE_STATIC (to) = TREE_STATIC (decl);
       TREE_PUBLIC (to) = TREE_PUBLIC (decl);
       DECL_VISIBILITY (to) = DECL_VISIBILITY (decl);
-      make_decl_one_only (to, DECL_ASSEMBLER_NAME (to));
     }
   else
     TREE_STATIC (to) = 1;
 
+  if (DECL_ONE_ONLY (decl))
+    make_decl_one_only (to, DECL_ASSEMBLER_NAME (to));
+
   DECL_VISIBILITY_SPECIFIED (to) = DECL_VISIBILITY_SPECIFIED (decl);
   DECL_INITIAL (to) = DECL_INITIAL (decl);
   DECL_INITIAL (decl) = NULL;
-- 
2.27.0