/* Subroutines for manipulating rtx's in semantically interesting ways.
Copyright (C) 1987, 1991, 1994, 1995, 1996, 1997, 1998,
- 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
Free Software Foundation, Inc.
This file is part of GCC.
#include "system.h"
#include "coretypes.h"
#include "tm.h"
+#include "diagnostic-core.h"
#include "toplev.h"
#include "rtl.h"
#include "tree.h"
#include "function.h"
#include "expr.h"
#include "optabs.h"
+#include "libfuncs.h"
#include "hard-reg-set.h"
#include "insn-config.h"
#include "ggc.h"
#include "output.h"
static rtx break_out_memory_refs (rtx);
-static void emit_stack_probe (rtx);
/* Truncate and perhaps sign-extend C as appropriate for MODE. */
if (SYMBOL_REF_DECL (s) && DECL_P (SYMBOL_REF_DECL (s)))
sa = DECL_ALIGN (SYMBOL_REF_DECL (s));
- ca = exact_log2 (INTVAL (c) & -INTVAL (c)) * BITS_PER_UNIT;
-
- align = MIN (sa, ca);
+ if (INTVAL (c) == 0)
+ align = sa;
+ else
+ {
+ ca = ctz_hwi (INTVAL (c)) * BITS_PER_UNIT;
+ align = MIN (sa, ca);
+ }
}
if (align || (MEM_P (x) && MEM_POINTER (x)))
static rtx
round_push (rtx size)
{
- int align = PREFERRED_STACK_BOUNDARY / BITS_PER_UNIT;
-
- if (align == 1)
- return size;
+ rtx align_rtx, alignm1_rtx;
- if (CONST_INT_P (size))
+ if (!SUPPORTS_STACK_ALIGNMENT
+ || crtl->preferred_stack_boundary == MAX_SUPPORTED_STACK_ALIGNMENT)
{
- HOST_WIDE_INT new_size = (INTVAL (size) + align - 1) / align * align;
+ int align = crtl->preferred_stack_boundary / BITS_PER_UNIT;
- if (INTVAL (size) != new_size)
- size = GEN_INT (new_size);
+ if (align == 1)
+ return size;
+
+ if (CONST_INT_P (size))
+ {
+ HOST_WIDE_INT new_size = (INTVAL (size) + align - 1) / align * align;
+
+ if (INTVAL (size) != new_size)
+ size = GEN_INT (new_size);
+ return size;
+ }
+
+ align_rtx = GEN_INT (align);
+ alignm1_rtx = GEN_INT (align - 1);
}
else
{
- /* CEIL_DIV_EXPR needs to worry about the addition overflowing,
- but we know it can't. So add ourselves and then do
- TRUNC_DIV_EXPR. */
- size = expand_binop (Pmode, add_optab, size, GEN_INT (align - 1),
- NULL_RTX, 1, OPTAB_LIB_WIDEN);
- size = expand_divmod (0, TRUNC_DIV_EXPR, Pmode, size, GEN_INT (align),
- NULL_RTX, 1);
- size = expand_mult (Pmode, size, GEN_INT (align), NULL_RTX, 1);
+ /* If crtl->preferred_stack_boundary might still grow, use
+ virtual_preferred_stack_boundary_rtx instead. This will be
+ substituted by the right value in vregs pass and optimized
+ during combine. */
+ align_rtx = virtual_preferred_stack_boundary_rtx;
+ alignm1_rtx = force_operand (plus_constant (align_rtx, -1), NULL_RTX);
}
+ /* CEIL_DIV_EXPR needs to worry about the addition overflowing,
+ but we know it can't. So add ourselves and then do
+ TRUNC_DIV_EXPR. */
+ size = expand_binop (Pmode, add_optab, size, alignm1_rtx,
+ NULL_RTX, 1, OPTAB_LIB_WIDEN);
+ size = expand_divmod (0, TRUNC_DIV_EXPR, Pmode, size, align_rtx,
+ NULL_RTX, 1);
+ size = expand_mult (Pmode, size, align_rtx, NULL_RTX, 1);
+
return size;
}
\f
SIZE is an rtx representing the size of the area.
TARGET is a place in which the address can be placed.
- KNOWN_ALIGN is the alignment (in bits) that we know SIZE has. */
+ KNOWN_ALIGN is the alignment (in bits) that we know SIZE has.
+
+ If CANNOT_ACCUMULATE is set to TRUE, the caller guarantees that the
+ stack space allocated by the generated code cannot be added with itself
+ in the course of the execution of the function. It is always safe to
+ pass FALSE here and the following criterion is sufficient in order to
+ pass TRUE: every path in the CFG that starts at the allocation point and
+ loops to it executes the associated deallocation code. */
rtx
-allocate_dynamic_stack_space (rtx size, rtx target, int known_align)
+allocate_dynamic_stack_space (rtx size, rtx target, int known_align,
+ bool cannot_accumulate)
{
+ HOST_WIDE_INT stack_usage_size = -1;
+ bool known_align_valid = true;
+ rtx final_label, final_target;
+
/* If we're asking for zero bytes, it doesn't matter what we point
to since we can't dereference it. But return a reasonable
address anyway. */
/* Otherwise, show we're calling alloca or equivalent. */
cfun->calls_alloca = 1;
+ /* If stack usage info is requested, look into the size we are passed.
+ We need to do so this early to avoid the obfuscation that may be
+ introduced later by the various alignment operations. */
+ if (flag_stack_usage)
+ {
+ if (CONST_INT_P (size))
+ stack_usage_size = INTVAL (size);
+ else if (REG_P (size))
+ {
+ /* Look into the last emitted insn and see if we can deduce
+ something for the register. */
+ rtx insn, set, note;
+ insn = get_last_insn ();
+ if ((set = single_set (insn)) && rtx_equal_p (SET_DEST (set), size))
+ {
+ if (CONST_INT_P (SET_SRC (set)))
+ stack_usage_size = INTVAL (SET_SRC (set));
+ else if ((note = find_reg_equal_equiv_note (insn))
+ && CONST_INT_P (XEXP (note, 0)))
+ stack_usage_size = INTVAL (XEXP (note, 0));
+ }
+ }
+
+ /* If the size is not constant, we can't say anything. */
+ if (stack_usage_size == -1)
+ {
+ current_function_has_unbounded_dynamic_stack_size = 1;
+ stack_usage_size = 0;
+ }
+ }
+
/* Ensure the size is in the proper mode. */
if (GET_MODE (size) != VOIDmode && GET_MODE (size) != Pmode)
size = convert_to_mode (Pmode, size, 1);
/* We can't attempt to minimize alignment necessary, because we don't
know the final value of preferred_stack_boundary yet while executing
this code. */
- crtl->preferred_stack_boundary = PREFERRED_STACK_BOUNDARY;
+ if (crtl->preferred_stack_boundary < PREFERRED_STACK_BOUNDARY)
+ crtl->preferred_stack_boundary = PREFERRED_STACK_BOUNDARY;
/* We will need to ensure that the address we return is aligned to
BIGGEST_ALIGNMENT. If STACK_DYNAMIC_OFFSET is defined, we don't
#if defined (STACK_DYNAMIC_OFFSET) || defined (STACK_POINTER_OFFSET)
#define MUST_ALIGN 1
#else
-#define MUST_ALIGN (PREFERRED_STACK_BOUNDARY < BIGGEST_ALIGNMENT)
+#define MUST_ALIGN (crtl->preferred_stack_boundary < BIGGEST_ALIGNMENT)
#endif
if (MUST_ALIGN)
- size
- = force_operand (plus_constant (size,
- BIGGEST_ALIGNMENT / BITS_PER_UNIT - 1),
- NULL_RTX);
+ {
+ size
+ = force_operand (plus_constant (size,
+ BIGGEST_ALIGNMENT / BITS_PER_UNIT - 1),
+ NULL_RTX);
+
+ if (flag_stack_usage)
+ stack_usage_size += BIGGEST_ALIGNMENT / BITS_PER_UNIT - 1;
+
+ known_align_valid = false;
+ }
#ifdef SETJMP_VIA_SAVE_AREA
/* If setjmp restores regs from a save area in the stack frame,
would use reg notes to store the "optimized" size and fix things
up later. These days we know this information before we ever
start building RTL so the reg notes are unnecessary. */
- if (!cfun->calls_setjmp)
- {
- int align = PREFERRED_STACK_BOUNDARY / BITS_PER_UNIT;
-
- /* ??? Code below assumes that the save area needs maximal
- alignment. This constraint may be too strong. */
- gcc_assert (PREFERRED_STACK_BOUNDARY == BIGGEST_ALIGNMENT);
-
- if (CONST_INT_P (size))
- {
- HOST_WIDE_INT new_size = INTVAL (size) / align * align;
-
- if (INTVAL (size) != new_size)
- size = GEN_INT (new_size);
- }
- else
- {
- /* Since we know overflow is not possible, we avoid using
- CEIL_DIV_EXPR and use TRUNC_DIV_EXPR instead. */
- size = expand_divmod (0, TRUNC_DIV_EXPR, Pmode, size,
- GEN_INT (align), NULL_RTX, 1);
- size = expand_mult (Pmode, size,
- GEN_INT (align), NULL_RTX, 1);
- }
- }
- else
+ if (cfun->calls_setjmp)
{
rtx dynamic_offset
= expand_binop (Pmode, sub_optab, virtual_stack_dynamic_rtx,
size = expand_binop (Pmode, add_optab, size, dynamic_offset,
NULL_RTX, 1, OPTAB_LIB_WIDEN);
+
+ /* The above dynamic offset cannot be computed statically at this
+ point, but it will be possible to do so after RTL expansion is
+ done. Record how many times we will need to add it. */
+ if (flag_stack_usage)
+ current_function_dynamic_alloc_count++;
+
+ known_align_valid = false;
}
#endif /* SETJMP_VIA_SAVE_AREA */
insns. Since this is an extremely rare event, we have no reliable
way of knowing which systems have this problem. So we avoid even
momentarily mis-aligning the stack. */
+ if (!known_align_valid || known_align % MAX_SUPPORTED_STACK_ALIGNMENT != 0)
+ {
+ size = round_push (size);
- /* If we added a variable amount to SIZE,
- we can no longer assume it is aligned. */
-#if !defined (SETJMP_VIA_SAVE_AREA)
- if (MUST_ALIGN || known_align % PREFERRED_STACK_BOUNDARY != 0)
+ if (flag_stack_usage)
+ {
+ int align = crtl->preferred_stack_boundary / BITS_PER_UNIT;
+ stack_usage_size = (stack_usage_size + align - 1) / align * align;
+ }
+ }
+
+ /* Don't use a TARGET that isn't a pseudo or is the wrong mode. */
+ if (target == 0 || !REG_P (target)
+ || REGNO (target) < FIRST_PSEUDO_REGISTER
+ || GET_MODE (target) != Pmode)
+ target = gen_reg_rtx (Pmode);
+
+ mark_reg_pointer (target, known_align);
+
+ /* The size is supposed to be fully adjusted at this point so record it
+ if stack usage info is requested. */
+ if (flag_stack_usage)
+ {
+ current_function_dynamic_stack_size += stack_usage_size;
+
+ /* ??? This is gross but the only safe stance in the absence
+ of stack usage oriented flow analysis. */
+ if (!cannot_accumulate)
+ current_function_has_unbounded_dynamic_stack_size = 1;
+ }
+
+ final_label = NULL_RTX;
+ final_target = NULL_RTX;
+
+ /* If we are splitting the stack, we need to ask the backend whether
+ there is enough room on the current stack. If there isn't, or if
+ the backend doesn't know how to tell is, then we need to call a
+ function to allocate memory in some other way. This memory will
+ be released when we release the current stack segment. The
+ effect is that stack allocation becomes less efficient, but at
+ least it doesn't cause a stack overflow. */
+ if (flag_split_stack)
+ {
+ rtx available_label, space, func;
+
+ available_label = NULL_RTX;
+
+#ifdef HAVE_split_stack_space_check
+ if (HAVE_split_stack_space_check)
+ {
+ available_label = gen_label_rtx ();
+
+ /* This instruction will branch to AVAILABLE_LABEL if there
+ are SIZE bytes available on the stack. */
+ emit_insn (gen_split_stack_space_check (size, available_label));
+ }
#endif
- size = round_push (size);
+
+ func = init_one_libfunc ("__morestack_allocate_stack_space");
+
+ space = emit_library_call_value (func, target, LCT_NORMAL, Pmode,
+ 1, size, Pmode);
+
+ if (available_label == NULL_RTX)
+ return space;
+
+ final_target = gen_reg_rtx (Pmode);
+ mark_reg_pointer (final_target, known_align);
+
+ emit_move_insn (final_target, space);
+
+ final_label = gen_label_rtx ();
+ emit_jump (final_label);
+
+ emit_label (available_label);
+ }
do_pending_stack_adjust ();
else if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK)
probe_stack_range (STACK_CHECK_PROTECT, size);
- /* Don't use a TARGET that isn't a pseudo or is the wrong mode. */
- if (target == 0 || !REG_P (target)
- || REGNO (target) < FIRST_PSEUDO_REGISTER
- || GET_MODE (target) != Pmode)
- target = gen_reg_rtx (Pmode);
-
- mark_reg_pointer (target, known_align);
-
/* Perform the required allocation from the stack. Some systems do
this differently than simply incrementing/decrementing from the
stack pointer, such as acquiring the space by calling malloc(). */
else
#endif
{
+ int saved_stack_pointer_delta;
+
#ifndef STACK_GROWS_DOWNWARD
emit_move_insn (target, virtual_stack_dynamic_rtx);
#endif
emit_label (space_available);
}
+ saved_stack_pointer_delta = stack_pointer_delta;
if (flag_stack_check && STACK_CHECK_MOVING_SP)
anti_adjust_stack_and_probe (size, false);
else
anti_adjust_stack (size);
+ /* Even if size is constant, don't modify stack_pointer_delta.
+ The constant size alloca should preserve
+ crtl->preferred_stack_boundary alignment. */
+ stack_pointer_delta = saved_stack_pointer_delta;
#ifdef STACK_GROWS_DOWNWARD
emit_move_insn (target, virtual_stack_dynamic_rtx);
if (cfun->nonlocal_goto_save_area != 0)
update_nonlocal_goto_save_area ();
+ /* Finish up the split stack handling. */
+ if (final_label != NULL_RTX)
+ {
+ gcc_assert (flag_split_stack);
+ emit_move_insn (final_target, target);
+ emit_label (final_label);
+ target = final_target;
+ }
+
return target;
}
\f
static GTY(()) rtx stack_check_libfunc;
void
-set_stack_check_libfunc (rtx libfunc)
+set_stack_check_libfunc (const char *libfunc_name)
{
- stack_check_libfunc = libfunc;
+ gcc_assert (stack_check_libfunc == NULL_RTX);
+ stack_check_libfunc = gen_rtx_SYMBOL_REF (Pmode, libfunc_name);
}
\f
/* Emit one stack probe at ADDRESS, an address within the stack. */
-static void
+void
emit_stack_probe (rtx address)
{
rtx memref = gen_rtx_MEM (word_mode, address);
emit_insn (gen_probe_stack (memref));
else
#endif
- if (STACK_CHECK_PROBE_LOAD)
- emit_move_insn (gen_reg_rtx (word_mode), memref);
- else
emit_move_insn (memref, const0_rtx);
}
{
rtx addr;
- if (GET_CODE (temp) == CONST_INT)
+ if (CONST_INT_P (temp))
{
/* Use [base + disp} addressing mode if supported. */
HOST_WIDE_INT offset = INTVAL (temp);
/* If we have a constant small number of probes to generate, that's the
easy case. */
- if (GET_CODE (size) == CONST_INT && INTVAL (size) < 7 * PROBE_INTERVAL)
+ if (CONST_INT_P (size) && INTVAL (size) < 7 * PROBE_INTERVAL)
{
HOST_WIDE_INT isize = INTVAL (size), i;
bool first_probe = true;
- /* Adjust SP and probe to PROBE_INTERVAL + N * PROBE_INTERVAL for
+ /* Adjust SP and probe at PROBE_INTERVAL + N * PROBE_INTERVAL for
values of N from 1 until it exceeds SIZE. If only one probe is
needed, this will not generate any code. Then adjust and probe
to PROBE_INTERVAL + SIZE. */
/* Step 3: the loop
- while (SP != LAST_ADDR)
- {
- SP = SP + PROBE_INTERVAL
- probe at SP
- }
+ while (SP != LAST_ADDR)
+ {
+ SP = SP + PROBE_INTERVAL
+ probe at SP
+ }
- adjusts SP and probes to PROBE_INTERVAL + N * PROBE_INTERVAL for
+ adjusts SP and probes at PROBE_INTERVAL + N * PROBE_INTERVAL for
values of N from 1 until it is equal to ROUNDED_SIZE. */
emit_label (loop_lab);
emit_label (end_lab);
- /* Step 4: adjust SP and probe to PROBE_INTERVAL + SIZE if we cannot
+ /* Step 4: adjust SP and probe at PROBE_INTERVAL + SIZE if we cannot
assert at compile-time that SIZE is equal to ROUNDED_SIZE. */
/* TEMP = SIZE - ROUNDED_SIZE. */
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