Patchwork [darwin] do not generate branch islands when the linker can do it.

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Submitter IainS
Date July 15, 2010, 5:10 p.m.
Message ID <01CDBBB5-4E03-4483-ADCC-454819159375@sandoe-acoustics.co.uk>
Download mbox | patch
Permalink /patch/58994/
State New
Headers show

Comments

IainS - July 15, 2010, 5:10 p.m.
Hi,
This hugely  tidies up *-*-darwin{9,10} asm by omitting the branch  
islands where they are not needed.

I've had it in my local tree for a month or so .. and it's been  
bootstrapped on x86_64-unknown-linux-gnu as well as a number of cross- 
targets.

I don't have a second rs6000 target but, by inspection, the changes  
are within code already wrapped by #ifdef MACH_O.

We must not put the "darwin_emit_branch_islands" declaration into  
darwin.h or I think it will mess up the (small amount of) binutils  
stuff that currently works for darwin.  Hence the reason it appears in  
both i386/darwin.h and rs6000/darwin.h

OK for trunk?
Iain


	* config/i386/darwin.h: Define darwin_emit_branch_islands.
	(FUNCTION_PROFILER): Do not emit branch islands unless
	darwin_emit_branch_islands is set.
	* config/i386/i386.c (output_pic_addr_const): Do not emit
	branch islands unless darwin_emit_branch_islands is set.
	(x86_output_mi_thunk): Adjust symbol creation.
	* config/rs6000/darwin.h: Define darwin_emit_branch_islands.
	Remove out of date comment.
	* config/rs6000/rs6000.c (print_operand): Adjust symbol.
	DARWIN_LINKER_GENERATES_ISLANDS: Remove.
	DARWIN_GENERATE_ISLANDS: Ditto.
	(output_call):  Do not emit branch islands unless
	darwin_emit_branch_islands is set.
	* config/darwin.c: Declare darwin_emit_branch_islands.
	(machopic_indirect_data_reference): Do not emit unless
	darwin_emit_branch_islands is set.
	(darwin_override_options): Set darwin_emit_branch_islands
	where it is needed.
	* config/darwin9.h
	DARWIN_LINKER_GENERATES_ISLANDS: Remove.
Richard Henderson - July 15, 2010, 5:38 p.m.
On 07/15/2010 10:10 AM, IainS wrote:
> -      if (! TARGET_MACHO || TARGET_64BIT)
> +      if (! TARGET_MACHO || 
> +#if TARGET_MACHO
> +          ! darwin_emit_branch_islands ||
> +#endif
> +      TARGET_64BIT)

I'd really like to avoid the #if mid if.  Perhaps

  if (TARGET_64BIT || !TARGET_MACHO_BRANCH_ISLANDS)

with

#if TARGET_MACHO
#define TARGET_MACHO_BRANCH_ISLANDS  darwin_emit_branch_islands
#else
#define TARGET_MACHO_BRANCH_ISLANDS  0
#endif

or similar via #undef.



r~

Patch

Index: gcc/config/i386/darwin.h
===================================================================
--- gcc/config/i386/darwin.h	(revision 162209)
+++ gcc/config/i386/darwin.h	(working copy)
@@ -60,6 +60,9 @@  along with GCC; see the file COPYING3.  If not see
 #undef WCHAR_TYPE_SIZE
 #define WCHAR_TYPE_SIZE 32
 
+/* Generate branch islands stubs if this is true.  */
+extern int darwin_emit_branch_islands;
+
 #undef MAX_BITS_PER_WORD
 #define MAX_BITS_PER_WORD 64
 
@@ -225,7 +228,7 @@  along with GCC; see the file COPYING3.  If not see
 #undef FUNCTION_PROFILER
 #define FUNCTION_PROFILER(FILE, LABELNO)				\
     do {								\
-      if (MACHOPIC_INDIRECT && !TARGET_64BIT)				\
+      if (darwin_emit_branch_islands && MACHOPIC_INDIRECT && !TARGET_64BIT)		\
 	{								\
 	  const char *name = machopic_mcount_stub_name ();		\
 	  fprintf (FILE, "\tcall %s\n", name+1);  /*  skip '&'  */	\
Index: gcc/config/i386/i386.c
===================================================================
--- gcc/config/i386/i386.c	(revision 162209)
+++ gcc/config/i386/i386.c	(working copy)
@@ -11510,7 +11510,11 @@  output_pic_addr_const (FILE *file, rtx x, int code
       break;
 
     case SYMBOL_REF:
-      if (! TARGET_MACHO || TARGET_64BIT)
+      if (! TARGET_MACHO || 
+#if TARGET_MACHO
+          ! darwin_emit_branch_islands ||
+#endif
+      TARGET_64BIT)
 	output_addr_const (file, x);
       else
 	{
@@ -27230,10 +27234,11 @@  x86_output_mi_thunk (FILE *file,
 	if (TARGET_MACHO)
 	  {
 	    rtx sym_ref = XEXP (DECL_RTL (function), 0);
-	    tmp = (gen_rtx_SYMBOL_REF
+	    if (darwin_emit_branch_islands)
+	      sym_ref = (gen_rtx_SYMBOL_REF
 		   (Pmode,
 		    machopic_indirection_name (sym_ref, /*stub_p=*/true)));
-	    tmp = gen_rtx_MEM (QImode, tmp);
+	    tmp = gen_rtx_MEM (QImode, sym_ref);
 	    xops[0] = tmp;
 	    output_asm_insn ("jmp\t%0", xops);
 	  }
Index: gcc/config/rs6000/darwin.h
===================================================================
--- gcc/config/rs6000/darwin.h	(revision 162209)
+++ gcc/config/rs6000/darwin.h	(working copy)
@@ -65,6 +65,9 @@ 
     }							\
   while (0)
 
+/* Generate branch islands stubs if this is true.  */
+extern int darwin_emit_branch_islands;
+
 #define SUBTARGET_OVERRIDE_OPTIONS darwin_rs6000_override_options ()
 
 #define C_COMMON_OVERRIDE_OPTIONS do {					\
@@ -385,8 +388,6 @@ 
 #define BLOCK_REG_PADDING(MODE, TYPE, FIRST) \
   (!(FIRST) ? upward : FUNCTION_ARG_PADDING (MODE, TYPE))
 
-/* XXX: Darwin supports neither .quad, or .llong, but it also doesn't
-   support 64 bit PowerPC either, so this just keeps things happy.  */
 #define DOUBLE_INT_ASM_OP "\t.quad\t"
 
 /* For binary compatibility with 2.95; Darwin C APIs use bool from
Index: gcc/config/rs6000/rs6000.c
===================================================================
--- gcc/config/rs6000/rs6000.c	(revision 162209)
+++ gcc/config/rs6000/rs6000.c	(working copy)
@@ -15392,7 +15392,8 @@  print_operand (FILE *file, rtx x, int code)
 	{
 	  const char *name = XSTR (x, 0);
 #if TARGET_MACHO
-	  if (MACHOPIC_INDIRECT
+	  if (darwin_emit_branch_islands
+	      && MACHOPIC_INDIRECT
 	      && machopic_classify_symbol (x) == MACHOPIC_UNDEFINED_FUNCTION)
 	    name = machopic_indirection_name (x, /*stub_p=*/true);
 #endif
@@ -24513,14 +24514,6 @@  get_prev_label (tree function_name)
   return 0;
 }
 
-#ifndef DARWIN_LINKER_GENERATES_ISLANDS
-#define DARWIN_LINKER_GENERATES_ISLANDS 0
-#endif
-
-/* KEXTs still need branch islands.  */
-#define DARWIN_GENERATE_ISLANDS (!DARWIN_LINKER_GENERATES_ISLANDS \
-				 || flag_mkernel || flag_apple_kext)
-
 /* INSN is either a function call or a millicode call.  It may have an
    unconditional jump in its delay slot.
 
@@ -24531,7 +24524,7 @@  output_call (rtx insn, rtx *operands, int dest_ope
 	     int cookie_operand_number)
 {
   static char buf[256];
-  if (DARWIN_GENERATE_ISLANDS
+  if (darwin_emit_branch_islands
       && GET_CODE (operands[dest_operand_number]) == SYMBOL_REF
       && (INTVAL (operands[cookie_operand_number]) & CALL_LONG))
     {
Index: gcc/config/darwin.c
===================================================================
--- gcc/config/darwin.c	(revision 162209)
+++ gcc/config/darwin.c	(working copy)
@@ -79,6 +79,12 @@  along with GCC; see the file COPYING3.  If not see
    of MACHO_SYMBOL_STATIC for the code that handles @code{static}
    symbol indirection.  */
 
+/* For darwin >= 9  (OSX 10.5) the linker is capable of making the necessary
+   branch islands and we no longer need to emit darwin stubs.
+   However, if we are generating code for earlier systems (or for use in the 
+   kernel) the stubs might still be required, and this will be set true.  */
+int darwin_emit_branch_islands = false;
+
 /* Section names.  */
 section * darwin_sections[NUM_DARWIN_SECTIONS];
 
@@ -625,6 +631,9 @@  machopic_indirect_data_reference (rtx orig, rtx re
 rtx
 machopic_indirect_call_target (rtx target)
 {
+  if (! darwin_emit_branch_islands)
+    return target;
+
   if (GET_CODE (target) != MEM)
     return target;
 
@@ -1888,12 +1917,19 @@  darwin_override_options (void)
       flag_exceptions = 0;
       /* No -fnon-call-exceptions data in kexts.  */
       flag_non_call_exceptions = 0;
+      /* We still need to emit branch islands for kernel context.  */
+      darwin_emit_branch_islands = true;
     }
   if (flag_var_tracking
       && strverscmp (darwin_macosx_version_min, "10.5") >= 0
       && debug_info_level >= DINFO_LEVEL_NORMAL
       && debug_hooks->var_location != do_nothing_debug_hooks.var_location)
     flag_var_tracking_uninit = 1;
+
+  /* It is assumed that branch island stubs are needed for earlier systems.  */
+  if (darwin_macosx_version_min
+      && strverscmp (darwin_macosx_version_min, "10.5") < 0)
+    darwin_emit_branch_islands = true;
 }
 
 /* Add $LDBL128 suffix to long double builtins.  */
Index: gcc/config/darwin9.h
===================================================================
--- gcc/config/darwin9.h	(revision 162209)
+++ gcc/config/darwin9.h	(working copy)
@@ -44,9 +44,6 @@  along with GCC; see the file COPYING3.  If not see
 /* libSystem contains unwind information for signal frames.  */
 #define DARWIN_LIBSYSTEM_HAS_UNWIND
 
-/* The linker can generate branch islands.  */
-#define DARWIN_LINKER_GENERATES_ISLANDS 1
-
 #undef  ASM_OUTPUT_ALIGNED_COMMON
 #define ASM_OUTPUT_ALIGNED_COMMON(FILE, NAME, SIZE, ALIGN)		\
   do {									\