Don't check tls_model attribute when optimizing TLS access since
1. -ftls-model=initial-exec also can specify tls_model without tls_model
attribute.
2. Linker can optimize TLS access at link-time.
3. LTO should perform the similar optimization.
Since C, C++, and Fortran front-ends now set the TLS access model after
a variable has been fully processed, not in the middle of processing it,
partially revert
commit 82e629c26647313be406c41a01e6868cfad0f289
Author: Alexander Monakov <amona...@ispras.ru>
Date: Wed Oct 26 16:37:34 2022 +0300
ipa-visibility: remove assert in TLS optimization [PR107353]
to restore assert if not compiling for shared library. When compiling
for shared library, the recomputed model may be weaker. Linker may
issue an error if the front-end assigned model isn't supported in shared
library. But compiler doesn't know if the generated code will be linked
into executable or shared library.
gcc/
PR other/107353
PR middle-end/121352
* ipa-visibility.cc (function_and_variable_visibility): Don't
check tls_model attribute. Restore assert if not compiling for
shared library.
* doc/extend.texi: Update the tls_model attribute.
gcc/testsuite/
PR middle-end/121352
* gcc.dg/tls/vis-attr-hidden-gd.c: Scan for tls-local-dynamic.
* gcc.dg/tls/vis-flag-hidden-gd.c: Likewise.
* gcc.dg/tls/vis-pragma-hidden-gd.c: Likewise.
Signed-off-by: H.J. Lu <hjl.to...@gmail.com>
---
gcc/doc/extend.texi | 5 ++++-
gcc/ipa-visibility.cc | 19 ++++++++++++-------
gcc/testsuite/gcc.dg/tls/vis-attr-hidden-gd.c | 4 ++--
gcc/testsuite/gcc.dg/tls/vis-flag-hidden-gd.c | 4 ++--
.../gcc.dg/tls/vis-pragma-hidden-gd.c | 4 ++--
5 files changed, 22 insertions(+), 14 deletions(-)
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 2922d9e9839..879a759714b 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -7563,7 +7563,10 @@ The @code{tls_model} attribute sets thread-local storage
model
overriding @option{-ftls-model=} command-line switch on a per-variable
basis.
The @var{tls_model} argument should be one of @code{global-dynamic},
-@code{local-dynamic}, @code{initial-exec} or @code{local-exec}.
+@code{local-dynamic}, @code{initial-exec} or @code{local-exec}. The
+@code{tls_model} attribute specifies the weakest @acronym{TLS} access
+model. GCC may optimize @acronym{TLS} access to a stronger @acronym{TLS}
+access model.
Not all targets support this attribute.
diff --git a/gcc/ipa-visibility.cc b/gcc/ipa-visibility.cc
index 8097a03e240..d2283507a31 100644
--- a/gcc/ipa-visibility.cc
+++ b/gcc/ipa-visibility.cc
@@ -883,17 +883,22 @@ function_and_variable_visibility (bool whole_program)
tree decl = vnode->decl;
/* Upgrade TLS access model based on optimized visibility status,
- unless it was specified explicitly or no references remain. */
+ unless no references remain. */
if (DECL_THREAD_LOCAL_P (decl)
- && !lookup_attribute ("tls_model", DECL_ATTRIBUTES (decl))
&& vnode->ref_list.referring.length ())
{
enum tls_model new_model = decl_default_tls_model (decl);
- STATIC_ASSERT (TLS_MODEL_GLOBAL_DYNAMIC <
TLS_MODEL_LOCAL_DYNAMIC);
- STATIC_ASSERT (TLS_MODEL_INITIAL_EXEC < TLS_MODEL_LOCAL_EXEC);
- /* We'd prefer to assert that recomputed model is not weaker than
- what the front-end assigned, but cannot: see PR 107353. */
- if (new_model >= decl_tls_model (decl))
+ /* Assert that the recomputed model is not weaker than
+ what the front-end assigned if not comping for shared
+ library. When compiling for shared library, the
+ recomputed model may be weaker. Linker may issue an
+ error if the front-end assigned model isn't supported
+ in shared library. But compiler doesn't know if the
+ generated code will be linked into executable or shared
+ library. */
+ tls_model model = decl_tls_model (decl);
+ gcc_checking_assert (flag_shlib || new_model >= model);
+ if (new_model > model)
set_decl_tls_model (decl, new_model);
}
}
diff --git a/gcc/testsuite/gcc.dg/tls/vis-attr-hidden-gd.c
b/gcc/testsuite/gcc.dg/tls/vis-attr-hidden-gd.c
index e32565588c8..4512bff04ad 100644
--- a/gcc/testsuite/gcc.dg/tls/vis-attr-hidden-gd.c
+++ b/gcc/testsuite/gcc.dg/tls/vis-attr-hidden-gd.c
@@ -3,11 +3,11 @@
/* { dg-require-effective-target tls } */
/* { dg-options "-O2 -fPIC -fdump-ipa-whole-program" } */
-// tls_model should be global-dynamic due to explicitly specified attribute
__attribute__((visibility("hidden")))
__attribute__((tls_model("global-dynamic")))
__thread int x;
void reference() { x++; }
-/* { dg-final { scan-ipa-dump "Varpool flags: tls-global-dynamic"
"whole-program" } } */
+// tls_model should be local-dynamic due to hidden visibility.
+/* { dg-final { scan-ipa-dump "Varpool flags: tls-local-dynamic"
"whole-program" } } */
diff --git a/gcc/testsuite/gcc.dg/tls/vis-flag-hidden-gd.c
b/gcc/testsuite/gcc.dg/tls/vis-flag-hidden-gd.c
index cad41e0c8e6..fba79cfd75a 100644
--- a/gcc/testsuite/gcc.dg/tls/vis-flag-hidden-gd.c
+++ b/gcc/testsuite/gcc.dg/tls/vis-flag-hidden-gd.c
@@ -4,10 +4,10 @@
/* { dg-options "-O2 -fPIC -fdump-ipa-whole-program -fvisibility=hidden" } */
-// tls_model should be global-dynamic due to explicitly specified attribute
__attribute__((tls_model("global-dynamic")))
__thread int x;
void reference() { x++; }
-/* { dg-final { scan-ipa-dump "Varpool flags: tls-global-dynamic"
"whole-program" } } */
+// tls_model should be local-dynamic due to hidden visibility.
+/* { dg-final { scan-ipa-dump "Varpool flags: tls-local-dynamic"
"whole-program" } } */
diff --git a/gcc/testsuite/gcc.dg/tls/vis-pragma-hidden-gd.c
b/gcc/testsuite/gcc.dg/tls/vis-pragma-hidden-gd.c
index 3b3598134fe..3649b6f7272 100644
--- a/gcc/testsuite/gcc.dg/tls/vis-pragma-hidden-gd.c
+++ b/gcc/testsuite/gcc.dg/tls/vis-pragma-hidden-gd.c
@@ -6,7 +6,6 @@
#pragma GCC visibility push(hidden)
-// tls_model should be global-dynamic due to explicitly specified attribute
__attribute__((tls_model("global-dynamic")))
__thread int x;
@@ -14,4 +13,5 @@ __thread int x;
void reference() { x++; }
-/* { dg-final { scan-ipa-dump "Varpool flags: tls-global-dynamic"
"whole-program" } } */
+// tls_model should be local-dynamic due to hidden visibility.
+/* { dg-final { scan-ipa-dump "Varpool flags: tls-local-dynamic"
"whole-program" } } */
--
2.51.0
