[gcc(refs/users/marxin/heads/marxin-gcc-benchmark-branch)] c++: Emit DFP typeinfos even when DFP is disabled [PR92906]

[gcc(refs/users/marxin/heads/marxin-gcc-benchmark-branch)] c++: Emit DFP typeinfos even when DFP is disabled [PR92906]

[Martin Liska]

https://gcc.gnu.org/g:994e0ad41529f5518fd013474a657968807d9ca5

commit 994e0ad41529f5518fd013474a657968807d9ca5
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Feb 14 00:11:24 2020 +0100

    c++: Emit DFP typeinfos even when DFP is disabled [PR92906]
    
    Before Joseph's changes when compiling
    libstdc++-v3/libsupc++/fundamental_type_info.cc
    we were emitting
    _ZTIPDd, _ZTIPDe, _ZTIPDf, _ZTIPKDd, _ZTIPKDe, _ZTIPKDf, _ZTIDd, _ZTIDe, _ZTIDf
    symbols even when DFP wasn't usable, but now we don't and thus those 9
    symbols @@CXXABI_1.3.4 are gone from libstdc++.  While nothing could
    probably use it (except perhaps dlsym etc.), various tools don't really like
    symbols disappearing from symbol versioned shared libraries with stable ABI.
    Adding those in assembly would be possible, but would be a portability
    nightmare (the PR has something Red Hat uses in libstdc++_nonshared.a, but that
    can handle only a handful of linux ELF targets we care about).
    So, instead this patch hacks up the FE, so that it emits those, but in a way
    that won't make the DFP types available again on targets that don't support
    them.
    
    2020-02-14  Jakub Jelinek  <jakub@redhat.com>
    
            PR libstdc++/92906
            * cp-tree.h (enum cp_tree_index): Add CPTI_FALLBACK_DFLOAT32_TYPE,
            CPTI_FALLBACK_DFLOAT64_TYPE and CPTI_FALLBACK_DFLOAT128_TYPE.
            (fallback_dfloat32_type, fallback_dfloat64_type,
            fallback_dfloat128_type): Define.
            * mangle.c (write_builtin_type): Handle fallback_dfloat*_type like
            dfloat*_type_node.
            * rtti.c (emit_support_tinfos): Emit DFP typeinfos even when dfp
            is disabled for compatibility.

Diff:
---
 gcc/cp/ChangeLog | 12 ++++++++++++
 gcc/cp/cp-tree.h | 10 ++++++++++
 gcc/cp/mangle.c  |  6 +++---
 gcc/cp/rtti.c    | 14 ++++++++++++++
 4 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 793e4afffcb..11acab7008e 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,15 @@
+2020-02-14  Jakub Jelinek  <jakub@redhat.com>
+
+	PR libstdc++/92906
+	* cp-tree.h (enum cp_tree_index): Add CPTI_FALLBACK_DFLOAT32_TYPE,
+	CPTI_FALLBACK_DFLOAT64_TYPE and CPTI_FALLBACK_DFLOAT128_TYPE.
+	(fallback_dfloat32_type, fallback_dfloat64_type,
+	fallback_dfloat128_type): Define.
+	* mangle.c (write_builtin_type): Handle fallback_dfloat*_type like
+	dfloat*_type_node.
+	* rtti.c (emit_support_tinfos): Emit DFP typeinfos even when dfp
+	is disabled for compatibility.
+
 2020-02-13  Jason Merrill  <jason@redhat.com>
 
 	PR c++/93713
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 53de2b0afe7..c1aafa1de3a 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -206,6 +206,10 @@ enum cp_tree_index
 
     CPTI_SOURCE_LOCATION_IMPL,
 
+    CPTI_FALLBACK_DFLOAT32_TYPE,
+    CPTI_FALLBACK_DFLOAT64_TYPE,
+    CPTI_FALLBACK_DFLOAT128_TYPE,
+
     CPTI_MAX
 };
 
@@ -366,6 +370,12 @@ extern GTY(()) tree cp_global_trees[CPTI_MAX];
 
 #define access_default_node		null_node
 
+/* Variant of dfloat{32,64,128}_type_node only used for fundamental
+   rtti purposes if DFP is disabled.  */
+#define fallback_dfloat32_type		cp_global_trees[CPTI_FALLBACK_DFLOAT32_TYPE]
+#define fallback_dfloat64_type		cp_global_trees[CPTI_FALLBACK_DFLOAT64_TYPE]
+#define fallback_dfloat128_type		cp_global_trees[CPTI_FALLBACK_DFLOAT128_TYPE]
+
 \f
 #include "name-lookup.h"
 
diff --git a/gcc/cp/mangle.c b/gcc/cp/mangle.c
index 23baa382ed9..a0e888fde62 100644
--- a/gcc/cp/mangle.c
+++ b/gcc/cp/mangle.c
@@ -2569,11 +2569,11 @@ write_builtin_type (tree type)
 	write_char ('d');
       else if (type == long_double_type_node)
 	write_char ('e');
-      else if (type == dfloat32_type_node)
+      else if (type == dfloat32_type_node || type == fallback_dfloat32_type)
 	write_string ("Df");
-      else if (type == dfloat64_type_node)
+      else if (type == dfloat64_type_node || type == fallback_dfloat64_type)
 	write_string ("Dd");
-      else if (type == dfloat128_type_node)
+      else if (type == dfloat128_type_node || type == fallback_dfloat128_type)
 	write_string ("De");
       else
 	gcc_unreachable ();
diff --git a/gcc/cp/rtti.c b/gcc/cp/rtti.c
index 36c1b4ed7bc..f20941c413b 100644
--- a/gcc/cp/rtti.c
+++ b/gcc/cp/rtti.c
@@ -1588,6 +1588,20 @@ emit_support_tinfos (void)
       }
   for (tree t = registered_builtin_types; t; t = TREE_CHAIN (t))
     emit_support_tinfo_1 (TREE_VALUE (t));
+  /* For compatibility, emit DFP typeinfos even when DFP isn't enabled,
+     because we've emitted that in the past.  */
+  if (!targetm.decimal_float_supported_p ())
+    {
+      gcc_assert (dfloat32_type_node == NULL_TREE
+		  && dfloat64_type_node == NULL_TREE
+		  && dfloat128_type_node == NULL_TREE);
+      fallback_dfloat32_type = make_node (REAL_TYPE);
+      fallback_dfloat64_type = make_node (REAL_TYPE);
+      fallback_dfloat128_type = make_node (REAL_TYPE);
+      emit_support_tinfo_1 (fallback_dfloat32_type);
+      emit_support_tinfo_1 (fallback_dfloat64_type);
+      emit_support_tinfo_1 (fallback_dfloat128_type);
+    }
   input_location = saved_loc;
 }