/* Generic sibling call optimization support
- Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.
+ Copyright (C) 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
This file is part of GCC.
#include "config.h"
#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
#include "rtl.h"
#include "regs.h"
#include "basic-block.h"
#include "output.h"
#include "except.h"
+#include "tree.h"
/* In case alternate_exit_block contains copy from pseudo, to return value,
record the pseudo here. In such case the pseudo must be set to function
/* Examine a CALL_PLACEHOLDER pattern and determine where the call's
return value is located. P_HARD_RETURN receives the hard register
that the function used; P_SOFT_RETURN receives the pseudo register
- that the sequence used. Return non-zero if the values were located. */
+ that the sequence used. Return nonzero if the values were located. */
static int
identify_call_return_value (cp, p_hard_return, p_soft_return)
/* If we didn't get a single hard register (e.g. a parallel), give up. */
if (GET_CODE (hard) != REG)
return 0;
-
+
/* Stack adjustment done after call may appear here. */
insn = skip_stack_adjustment (insn);
if (! insn)
insn = NEXT_INSN (insn);
if (! insn)
return 0;
-
+
/* We're looking for a source of the hard return register. */
set = single_set (insn);
if (! set || SET_SRC (set) != hard)
/* The destination must be the same as the called function's return
value to ensure that any return value is put in the same place by the
- current function and the function we're calling.
+ current function and the function we're calling.
Further, the source must be the same as the pseudo into which the
called function's return value was copied. Otherwise we're returning
}
/* Scan the sequence of insns in SEQ to see if any have an ADDRESSOF
- rtl expression or current_function_internal_arg_pointer occurences
+ rtl expression or current_function_internal_arg_pointer occurrences
not enclosed within a MEM. If an ADDRESSOF expression or
current_function_internal_arg_pointer is found, return nonzero, otherwise
return zero.
sibcall_use_t use;
{
if (use == sibcall_use_tail_recursion)
- emit_insns_before (XEXP (PATTERN (insn), 2), insn);
+ emit_insn_before (XEXP (PATTERN (insn), 2), insn);
else if (use == sibcall_use_sibcall)
- emit_insns_before (XEXP (PATTERN (insn), 1), insn);
+ emit_insn_before (XEXP (PATTERN (insn), 1), insn);
else if (use == sibcall_use_normal)
- emit_insns_before (XEXP (PATTERN (insn), 0), insn);
+ emit_insn_before (XEXP (PATTERN (insn), 0), insn);
else
- abort();
+ abort ();
/* Turn off LABEL_PRESERVE_P for the tail recursion label if it
exists. We only had to set it long enough to keep the jump
pass above from deleting it as unused. */
if (XEXP (PATTERN (insn), 3))
LABEL_PRESERVE_P (XEXP (PATTERN (insn), 3)) = 0;
-
+
/* "Delete" the placeholder insn. */
remove_insn (insn);
}
{
rtx insn, insns;
basic_block alternate_exit = EXIT_BLOCK_PTR;
- int current_function_uses_addressof;
- int successful_sibling_call = 0;
- int replaced_call_placeholder = 0;
+ bool no_sibcalls_this_function = false;
+ bool successful_replacement = false;
+ bool replaced_call_placeholder = false;
edge e;
insns = get_insns ();
- /* We do not perform these calls when flag_exceptions is true, so this
- is probably a NOP at the current time. However, we may want to support
- sibling and tail recursion optimizations in the future, so let's plan
- ahead and find all the EH labels. */
- find_exception_handler_labels ();
-
- rebuild_jump_labels (insns);
- /* We need cfg information to determine which blocks are succeeded
- only by the epilogue. */
- find_basic_blocks (insns, max_reg_num (), 0);
cleanup_cfg (CLEANUP_PRE_SIBCALL | CLEANUP_PRE_LOOP);
/* If there are no basic blocks, then there is nothing to do. */
if (n_basic_blocks == 0)
return;
+ /* If we are using sjlj exceptions, we may need to add a call to
+ _Unwind_SjLj_Unregister at exit of the function. Which means
+ that we cannot do any sibcall transformations. */
+ if (USING_SJLJ_EXCEPTIONS && current_function_has_exception_handlers ())
+ no_sibcalls_this_function = true;
+
return_value_pseudo = NULL_RTX;
/* Find the exit block.
/* Walk forwards through the last normal block and see if it
does nothing except fall into the exit block. */
- for (insn = BLOCK_HEAD (n_basic_blocks - 1);
+ for (insn = EXIT_BLOCK_PTR->prev_bb->head;
insn;
insn = NEXT_INSN (insn))
{
/* If the function uses ADDRESSOF, we can't (easily) determine
at this point if the value will end up on the stack. */
- current_function_uses_addressof = sequence_uses_addressof (insns);
+ no_sibcalls_this_function |= sequence_uses_addressof (insns);
/* Walk the insn chain and find any CALL_PLACEHOLDER insns. We need to
select one of the insn sequences attached to each CALL_PLACEHOLDER.
sibling call optimizations, but not tail recursion.
Similarly if we use varargs or stdarg since they implicitly
may take the address of an argument. */
- if (current_function_calls_alloca
- || current_function_varargs || current_function_stdarg)
+ if (current_function_calls_alloca || current_function_stdarg)
sibcall = 0;
/* See if there are any reasons we can't perform either sibling or
tail call optimizations. We must be careful with stack slots
- which are live at potential optimization sites. ??? The first
- test is overly conservative and should be replaced. */
- if (frame_offset
- /* Can't take address of local var if used by recursive call. */
- || current_function_uses_addressof
+ which are live at potential optimization sites. */
+ if (no_sibcalls_this_function
+ /* ??? Overly conservative. */
+ || frame_offset
/* Any function that calls setjmp might have longjmp called from
any called function. ??? We really should represent this
properly in the CFG so that this needn't be special cased. */
|| current_function_calls_setjmp
/* Can't if more than one successor or single successor is not
exit block. These two tests prevent tail call optimization
- in the presense of active exception handlers. */
+ in the presence of active exception handlers. */
|| call_block->succ == NULL
|| call_block->succ->succ_next != NULL
|| (call_block->succ->dest != EXIT_BLOCK_PTR
/* Select a set of insns to implement the call and emit them.
Tail recursion is the most efficient, so select it over
a tail/sibling call. */
- if (sibcall)
- successful_sibling_call = 1;
- replaced_call_placeholder = 1;
- replace_call_placeholder (insn,
- tailrecursion != 0
+ if (sibcall || tailrecursion)
+ successful_replacement = true;
+ replaced_call_placeholder = true;
+
+ replace_call_placeholder (insn,
+ tailrecursion != 0
? sibcall_use_tail_recursion
: sibcall != 0
? sibcall_use_sibcall
}
}
- if (successful_sibling_call)
+ if (successful_replacement)
{
rtx insn;
+ tree arg;
/* A sibling call sequence invalidates any REG_EQUIV notes made for
- this function's incoming arguments.
+ this function's incoming arguments.
At the start of RTL generation we know the only REG_EQUIV notes
in the rtl chain are those for incoming arguments, so we can safely
- flush any REG_EQUIV note.
+ flush any REG_EQUIV note.
This is (slight) overkill. We could keep track of the highest
argument we clobber and be more selective in removing notes, but it
/* A sibling call sequence also may invalidate RTX_UNCHANGING_P
flag of some incoming arguments MEM RTLs, because it can write into
those slots. We clear all those bits now.
-
+
This is (slight) overkill, we could keep track of which arguments
we actually write into. */
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
{
- if (GET_CODE (insn) == NOTE)
- {
- if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_BEG)
- break;
- }
- else if (INSN_P (insn))
+ if (INSN_P (insn))
purge_mem_unchanging_flag (PATTERN (insn));
}
+
+ /* Similarly, invalidate RTX_UNCHANGING_P for any incoming
+ arguments passed in registers. */
+ for (arg = DECL_ARGUMENTS (current_function_decl);
+ arg;
+ arg = TREE_CHAIN (arg))
+ {
+ if (REG_P (DECL_RTL (arg)))
+ RTX_UNCHANGING_P (DECL_RTL (arg)) = false;
+ }
}
- /* There may have been NOTE_INSN_BLOCK_{BEGIN,END} notes in the
+ /* There may have been NOTE_INSN_BLOCK_{BEGIN,END} notes in the
CALL_PLACEHOLDER alternatives that we didn't emit. Rebuild the
lexical block tree to correspond to the notes that still exist. */
if (replaced_call_placeholder)
/* This information will be invalid after inline expansion. Kill it now. */
free_basic_block_vars (0);
+ free_EXPR_LIST_list (&tail_recursion_label_list);
}