On Thu, Aug 9, 2012 at 3:04 PM, Uros Bizjak <ubiz...@gmail.com> wrote:
> 2012-08-09 Uros Bizjak <ubiz...@gmail.com>
>
> * config/alpha/alpha.c (alpha_pad_noreturn): Rename to ...
> (alpha_pad_function_end): ... this. Also insert NOP between
> sibling call and GP load.
> (alpha_reorg): Update call to alpha_pad_function_end. Expand comment.
>
> Patch was bootstrapped and regression tested on alphaev68-pc-linux-gnu.
>
> OK for mainline and release branches?
Now with the patch.
Uros.
Index: alpha.c
===================================================================
--- alpha.c (revision 190247)
+++ alpha.c (working copy)
@@ -9258,17 +9258,18 @@ alpha_align_insns (unsigned int max_align,
}
}
-/* Insert an unop between a noreturn function call and GP load. */
+/* Insert an unop between sibcall or noreturn function call and GP load. */
static void
-alpha_pad_noreturn (void)
+alpha_pad_function_end (void)
{
rtx insn, next;
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
{
if (! (CALL_P (insn)
- && find_reg_note (insn, REG_NORETURN, NULL_RTX)))
+ && (SIBLING_CALL_P (insn)
+ || find_reg_note (insn, REG_NORETURN, NULL_RTX))))
continue;
/* Make sure we do not split a call and its corresponding
@@ -9300,11 +9301,31 @@ static void
static void
alpha_reorg (void)
{
- /* Workaround for a linker error that triggers when an
- exception handler immediatelly follows a noreturn function.
+ /* Workaround for a linker error that triggers when an exception
+ handler immediatelly follows a sibcall or a noreturn function.
+In the sibcall case:
+
The instruction stream from an object file:
+ 1d8: 00 00 fb 6b jmp (t12)
+ 1dc: 00 00 ba 27 ldah gp,0(ra)
+ 1e0: 00 00 bd 23 lda gp,0(gp)
+ 1e4: 00 00 7d a7 ldq t12,0(gp)
+ 1e8: 00 40 5b 6b jsr ra,(t12),1ec <__funcZ+0x1ec>
+
+ was converted in the final link pass to:
+
+ 12003aa88: 67 fa ff c3 br 120039428 <...>
+ 12003aa8c: 00 00 fe 2f unop
+ 12003aa90: 00 00 fe 2f unop
+ 12003aa94: 48 83 7d a7 ldq t12,-31928(gp)
+ 12003aa98: 00 40 5b 6b jsr ra,(t12),12003aa9c <__func+0x1ec>
+
+And in the noreturn case:
+
+ The instruction stream from an object file:
+
54: 00 40 5b 6b jsr ra,(t12),58 <__func+0x58>
58: 00 00 ba 27 ldah gp,0(ra)
5c: 00 00 bd 23 lda gp,0(gp)
@@ -9321,11 +9342,11 @@ alpha_reorg (void)
GP load instructions were wrongly cleared by the linker relaxation
pass. This workaround prevents removal of GP loads by inserting
- an unop instruction between a noreturn function call and
+ an unop instruction between a sibcall or noreturn function call and
exception handler prologue. */
if (current_function_has_exception_handlers ())
- alpha_pad_noreturn ();
+ alpha_pad_function_end ();
if (alpha_tp != ALPHA_TP_PROG || flag_exceptions)
alpha_handle_trap_shadows ();
