rtl.h (SYMBOL_REF_WEAK): New macro.

        2001-05-13  Franz Sirl  <Franz.Sirl-kernel@lauterbach.com>

        * rtl.h (SYMBOL_REF_WEAK): New macro.
        * rtlanal.h (rtx_addr_can_trap): Use it, a weak SYMBOL_REF can trap.
        * varasm.c (make_decl_rtl): Mark SYMBOL_REF weak if necessary.
        * rtl.texi (SYMBOL_REF_WEAK): Document it.
        * gcc.texi: Remove wrong description.

From-SVN: r42046

gcc/ChangeLog

+2001-05-13  Franz Sirl  <Franz.Sirl-kernel@lauterbach.com>
+
+	* rtl.h (SYMBOL_REF_WEAK): New macro.
+	* rtlanal.h (rtx_addr_can_trap): Use it, a weak SYMBOL_REF can trap.
+	* varasm.c (make_decl_rtl): Mark SYMBOL_REF weak if necessary.
+	* rtl.texi (SYMBOL_REF_WEAK): Document it.
+	* gcc.texi: Remove wrong description.
+
 2001-05-13  Mark Mitchell  <mark@codesourcery.com>
 
 	* Makefile.in (STAMP): New macro.
@@ -446,7 +454,7 @@ Mon May  7 09:30:14 2001  Jeffrey A Law  (law@cygnus.com)
 	* simplify-rtx.c (simplify_binary_operation): Simplify ~a + 1
 	into -a.
 
-2000-05-04  Franz Sirl  <Franz.Sirl-kernel@lauterbach.com>
+2001-05-04  Franz Sirl  <Franz.Sirl-kernel@lauterbach.com>
 
 	* config/rs6000/rs6000.md (ashldi3 splits): Guard with
 	TARGET_POWERPC64.

gcc/gcc.texi

@@ -2008,13 +2008,6 @@ clutter the program with a cast to @code{void} whenever the value isn't
 useful.
 
 @item
-Assuming (for optimization) that the address of an external symbol is
-never zero.
-
-This assumption is false on certain systems when @samp{#pragma weak} is
-used.
-
-@item
 Making @samp{-fshort-enums} the default.
 
 This would cause storage layout to be incompatible with most other C

gcc/rtl.h

@@ -162,7 +162,8 @@ typedef struct rtx_def
   unsigned int used : 1;
   /* Nonzero if this rtx came from procedure integration.
      In a REG, nonzero means this reg refers to the return value
-     of the current function.  */
+     of the current function.
+     1 in a SYMBOL_REF if the symbol is weak.  */
   unsigned integrated : 1;
   /* 1 in an INSN or a SET if this rtx is related to the call frame,
      either changing how we compute the frame address or saving and
@@ -934,6 +935,9 @@ extern unsigned int subreg_regno 	PARAMS ((rtx));
 /* 1 means a SYMBOL_REF has been the library function in emit_library_call.  */
 #define SYMBOL_REF_USED(RTX) ((RTX)->used)
 
+/* 1 means a SYMBOL_REF is weak.  */
+#define SYMBOL_REF_WEAK(RTX) ((RTX)->integrated)
+
 /* Define a macro to look for REG_INC notes,
    but save time on machines where they never exist.  */
 

gcc/rtl.texi

@@ -496,6 +496,13 @@ once.  Stored in the @code{used} field.
 In a @code{symbol_ref}, this is used as a flag for machine-specific purposes.
 Stored in the @code{volatil} field and printed as @samp{/v}.
 
+@findex SYMBOL_REF_WEAK
+@cindex @code{symbol_ref} and @samp{/i}
+@cindex @code{integrated}, in @code{symbol_ref}
+@item SYMBOL_REF_WEAK (@var{x})
+In a @code{symbol_ref}, indicates that @var{x} has been declared weak.
+Stored in the @code{integrated} field and printed as @samp{/i}.
+
 @findex LABEL_OUTSIDE_LOOP_P
 @cindex @code{label_ref} and @samp{/s}
 @cindex @code{in_struct}, in @code{label_ref}

gcc/rtlanal.c

@@ -207,11 +207,9 @@ rtx_addr_can_trap_p (x)
   switch (code)
     {
     case SYMBOL_REF:
+      return SYMBOL_REF_WEAK (x);
+
     case LABEL_REF:
-      /* SYMBOL_REF is problematic due to the possible presence of
-	 a #pragma weak, but to say that loads from symbols can trap is
-	 *very* costly.  It's not at all clear what's best here.  For
-	 now, we ignore the impact of #pragma weak.  */
       return 0;
 
     case REG:

gcc/varasm.c

@@ -747,6 +747,7 @@ make_decl_rtl (decl, asmspec)
 
   SET_DECL_RTL (decl, gen_rtx_MEM (DECL_MODE (decl),
 				   gen_rtx_SYMBOL_REF (Pmode, name)));
+  SYMBOL_REF_WEAK (XEXP (DECL_RTL (decl), 0)) = DECL_WEAK (decl);
   if (TREE_CODE (decl) != FUNCTION_DECL)
     set_mem_attributes (DECL_RTL (decl), decl, 1);