Enable math functions linking with static library for LTO

In LTO mode, if static library and dynamic library contains same
function and both libraries are passed as arguments, linker will link
the function in dynamic library no matter the sequence.  This patch
will output LTO symbol node as UNDEF if BUILT_IN_NORMAL function FNDECL
is a math function, then the function in static library will be linked
first if its sequence is ahead of the dynamic library.

gcc/ChangeLog

2019-08-14  Xiong Hu Luo  <luoxhu@linux.ibm.com>

	PR lto/91287
	* builtins.c (builtin_with_linkage_p): New function.
	* builtins.h (builtin_with_linkage_p): New function.
	* symtab.c (write_symbol): Remove redundant assert.
	* lto-streamer-out.c (symtab_node::output_to_lto_symbol_table_p):
	Remove FIXME and use builtin_with_linkage_p.

From-SVN: r274411

5 files changed, 109 insertions, 10 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 989431d..b8ee4ed 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2019-08-14  Xiong Hu Luo  <luoxhu@linux.ibm.com>
+
+	PR lto/91287
+	* builtins.c (builtin_with_linkage_p): New function.
+	* builtins.h (builtin_with_linkage_p): New function.
+	* symtab.c (write_symbol): Remove redundant assert.
+	* lto-streamer-out.c (symtab_node::output_to_lto_symbol_table_p):
+	Remove FIXME and use builtin_with_linkage_p.
+
 2019-08-13  Richard Sandiford  <richard.sandiford@arm.com>
 
 	PR middle-end/91421
diff --git a/gcc/builtins.c b/gcc/builtins.c
index cb1a45a..ece9f56 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -11244,3 +11244,90 @@ target_char_cst_p (tree t, char *p)
   *p = (char)tree_to_uhwi (t);
   return true;
 }
+
+/* Return true if the builtin DECL is implemented in a standard library.
+   Otherwise returns false which doesn't guarantee it is not (thus the list of
+   handled builtins below may be incomplete).  */
+
+bool
+builtin_with_linkage_p (tree decl)
+{
+  if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL)
+    switch (DECL_FUNCTION_CODE (decl))
+    {
+      CASE_FLT_FN (BUILT_IN_ACOS):
+      CASE_FLT_FN (BUILT_IN_ACOSH):
+      CASE_FLT_FN (BUILT_IN_ASIN):
+      CASE_FLT_FN (BUILT_IN_ASINH):
+      CASE_FLT_FN (BUILT_IN_ATAN):
+      CASE_FLT_FN (BUILT_IN_ATANH):
+      CASE_FLT_FN (BUILT_IN_ATAN2):
+      CASE_FLT_FN (BUILT_IN_CBRT):
+      CASE_FLT_FN (BUILT_IN_CEIL):
+      CASE_FLT_FN_FLOATN_NX (BUILT_IN_CEIL):
+      CASE_FLT_FN (BUILT_IN_COPYSIGN):
+      CASE_FLT_FN_FLOATN_NX (BUILT_IN_COPYSIGN):
+      CASE_FLT_FN (BUILT_IN_COS):
+      CASE_FLT_FN (BUILT_IN_COSH):
+      CASE_FLT_FN (BUILT_IN_ERF):
+      CASE_FLT_FN (BUILT_IN_ERFC):
+      CASE_FLT_FN (BUILT_IN_EXP):
+      CASE_FLT_FN (BUILT_IN_EXP2):
+      CASE_FLT_FN (BUILT_IN_EXPM1):
+      CASE_FLT_FN (BUILT_IN_FABS):
+      CASE_FLT_FN_FLOATN_NX (BUILT_IN_FABS):
+      CASE_FLT_FN (BUILT_IN_FDIM):
+      CASE_FLT_FN (BUILT_IN_FLOOR):
+      CASE_FLT_FN_FLOATN_NX (BUILT_IN_FLOOR):
+      CASE_FLT_FN (BUILT_IN_FMA):
+      CASE_FLT_FN_FLOATN_NX (BUILT_IN_FMA):
+      CASE_FLT_FN (BUILT_IN_FMAX):
+      CASE_FLT_FN_FLOATN_NX (BUILT_IN_FMAX):
+      CASE_FLT_FN (BUILT_IN_FMIN):
+      CASE_FLT_FN_FLOATN_NX (BUILT_IN_FMIN):
+      CASE_FLT_FN (BUILT_IN_FMOD):
+      CASE_FLT_FN (BUILT_IN_FREXP):
+      CASE_FLT_FN (BUILT_IN_HYPOT):
+      CASE_FLT_FN (BUILT_IN_ILOGB):
+      CASE_FLT_FN (BUILT_IN_LDEXP):
+      CASE_FLT_FN (BUILT_IN_LGAMMA):
+      CASE_FLT_FN (BUILT_IN_LLRINT):
+      CASE_FLT_FN (BUILT_IN_LLROUND):
+      CASE_FLT_FN (BUILT_IN_LOG):
+      CASE_FLT_FN (BUILT_IN_LOG10):
+      CASE_FLT_FN (BUILT_IN_LOG1P):
+      CASE_FLT_FN (BUILT_IN_LOG2):
+      CASE_FLT_FN (BUILT_IN_LOGB):
+      CASE_FLT_FN (BUILT_IN_LRINT):
+      CASE_FLT_FN (BUILT_IN_LROUND):
+      CASE_FLT_FN (BUILT_IN_MODF):
+      CASE_FLT_FN (BUILT_IN_NAN):
+      CASE_FLT_FN (BUILT_IN_NEARBYINT):
+      CASE_FLT_FN_FLOATN_NX (BUILT_IN_NEARBYINT):
+      CASE_FLT_FN (BUILT_IN_NEXTAFTER):
+      CASE_FLT_FN (BUILT_IN_NEXTTOWARD):
+      CASE_FLT_FN (BUILT_IN_POW):
+      CASE_FLT_FN (BUILT_IN_REMAINDER):
+      CASE_FLT_FN (BUILT_IN_REMQUO):
+      CASE_FLT_FN (BUILT_IN_RINT):
+      CASE_FLT_FN_FLOATN_NX (BUILT_IN_RINT):
+      CASE_FLT_FN (BUILT_IN_ROUND):
+      CASE_FLT_FN_FLOATN_NX (BUILT_IN_ROUND):
+      CASE_FLT_FN (BUILT_IN_SCALBLN):
+      CASE_FLT_FN (BUILT_IN_SCALBN):
+      CASE_FLT_FN (BUILT_IN_SIN):
+      CASE_FLT_FN (BUILT_IN_SINH):
+      CASE_FLT_FN (BUILT_IN_SINCOS):
+      CASE_FLT_FN (BUILT_IN_SQRT):
+      CASE_FLT_FN_FLOATN_NX (BUILT_IN_SQRT):
+      CASE_FLT_FN (BUILT_IN_TAN):
+      CASE_FLT_FN (BUILT_IN_TANH):
+      CASE_FLT_FN (BUILT_IN_TGAMMA):
+      CASE_FLT_FN (BUILT_IN_TRUNC):
+      CASE_FLT_FN_FLOATN_NX (BUILT_IN_TRUNC):
+	return true;
+      default:
+	break;
+    }
+  return false;
+}
diff --git a/gcc/builtins.h b/gcc/builtins.h
index 1ffb491..66c9295 100644
--- a/gcc/builtins.h
+++ b/gcc/builtins.h
@@ -150,5 +150,6 @@ extern internal_fn replacement_internal_fn (gcall *);
 
 extern void warn_string_no_nul (location_t, const char *, tree, tree);
 extern tree unterminated_array (tree, tree * = NULL, bool * = NULL);
+extern bool builtin_with_linkage_p (tree);
 
 #endif /* GCC_BUILTINS_H */
diff --git a/gcc/lto-streamer-out.c b/gcc/lto-streamer-out.c
index b156876..d85b03a 100644
--- a/gcc/lto-streamer-out.c
+++ b/gcc/lto-streamer-out.c
@@ -2642,12 +2642,6 @@ write_symbol (struct streamer_tree_cache_d *cache,
   const char *comdat;
   unsigned char c;
 
-  gcc_checking_assert (TREE_PUBLIC (t)
-		       && (TREE_CODE (t) != FUNCTION_DECL
-			   || !fndecl_built_in_p (t))
-		       && !DECL_ABSTRACT_P (t)
-		       && (!VAR_P (t) || !DECL_HARD_REGISTER (t)));
-
   gcc_assert (VAR_OR_FUNCTION_DECL_P (t));
 
   name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (t));
diff --git a/gcc/symtab.c b/gcc/symtab.c
index 63e2820..ee9723c 100644
--- a/gcc/symtab.c
+++ b/gcc/symtab.c
@@ -2375,10 +2375,18 @@ symtab_node::output_to_lto_symbol_table_p (void)
      first place.  */
   if (VAR_P (decl) && DECL_HARD_REGISTER (decl))
     return false;
-  /* FIXME: Builtins corresponding to real functions probably should have
-     symbol table entries.  */
-  if (TREE_CODE (decl) == FUNCTION_DECL && fndecl_built_in_p (decl))
-    return false;
+  if (TREE_CODE (decl) == FUNCTION_DECL && !definition
+      && fndecl_built_in_p (decl))
+    {
+      /* Builtins like those for most math functions have actual implementations
+	 in libraries so make sure to output references into the symbol table to
+	 make those libraries referenced.  Note this is incomplete handling for
+	 now and only covers math functions.  */
+      if (builtin_with_linkage_p (decl))
+	return true;
+      else
+	return false;
+    }
 
   /* We have real symbol that should be in symbol table.  However try to trim
      down the refernces to libraries bit more because linker will otherwise