/* Alias analysis for GNU C
- Copyright (C) 1997, 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
+ Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
+ Free Software Foundation, Inc.
Contributed by John Carr (jfc@mit.edu).
This file is part of GCC.
#include "config.h"
#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
#include "rtl.h"
#include "tree.h"
#include "tm_p.h"
#include "splay-tree.h"
#include "ggc.h"
#include "langhooks.h"
+#include "target.h"
/* The alias sets assigned to MEMs assist the back-end in determining
which MEMs can alias which other MEMs. In general, two MEMs in
To see whether two alias sets can point to the same memory, we must
see if either alias set is a subset of the other. We need not trace
- past immediate descendents, however, since we propagate all
+ past immediate descendants, however, since we propagate all
grandchildren up one level.
Alias set zero is implicitly a superset of all other alias sets.
HOST_WIDE_INT alias_set;
/* The children of the alias set. These are not just the immediate
- children, but, in fact, all descendents. So, if we have:
+ children, but, in fact, all descendants. So, if we have:
struct T { struct S s; float f; }
static int nonlocal_referenced_p PARAMS ((rtx));
static int nonlocal_set_p_1 PARAMS ((rtx *, void *));
static int nonlocal_set_p PARAMS ((rtx));
+static void memory_modified_1 PARAMS ((rtx, rtx, void *));
/* Set up all info needed to perform alias analysis on memory references. */
current function performs nonlocal memory memory references for the
purposes of marking the function as a constant function. */
-static rtx *reg_base_value;
+static GTY((length ("reg_base_value_size"))) rtx *reg_base_value;
static rtx *new_reg_base_value;
static unsigned int reg_base_value_size; /* size of reg_base_value array */
+/* Static hunks of RTL used by the aliasing code; these are initialized
+ once per function to avoid unnecessary RTL allocations. */
+static GTY (()) rtx static_reg_base_value[FIRST_PSEUDO_REGISTER];
+
#define REG_BASE_VALUE(X) \
(REGNO (X) < reg_base_value_size \
? reg_base_value[REGNO (X)] : 0)
/* True when scanning insns from the start of the rtl to the
NOTE_INSN_FUNCTION_BEG note. */
-static int copying_arguments;
+static bool copying_arguments;
/* The splay-tree used to store the various alias set entries. */
static splay_tree alias_sets;
then they may not conflict. */
if ((t1 != 0 && readonly_fields_p (t1))
|| (t2 != 0 && readonly_fields_p (t2))
- || (t1 != 0 && TYPE_READONLY (t1))
- || (t2 != 0 && TYPE_READONLY (t2)))
+ || (t1 != 0 && lang_hooks.honor_readonly && TYPE_READONLY (t1))
+ || (t2 != 0 && lang_hooks.honor_readonly && TYPE_READONLY (t2)))
return 0;
/* If they are the same type, they must conflict. */
and references to functions, but that's different.) */
else if (TREE_CODE (t) == FUNCTION_TYPE)
set = 0;
+
+ /* Unless the language specifies otherwise, let vector types alias
+ their components. This avoids some nasty type punning issues in
+ normal usage. And indeed lets vectors be treated more like an
+ array slice. */
+ else if (TREE_CODE (t) == VECTOR_TYPE)
+ set = get_alias_set (TREE_TYPE (t));
+
else
/* Otherwise make a new alias set for this type. */
set = new_alias_set ();
The test above is not sufficient because the scheduler may move
a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
if ((regno >= FIRST_PSEUDO_REGISTER || fixed_regs[regno])
- && regno < reg_base_value_size
- && reg_base_value[regno])
- return reg_base_value[regno];
+ && regno < reg_base_value_size)
+ {
+ /* If we're inside init_alias_analysis, use new_reg_base_value
+ to reduce the number of relaxation iterations. */
+ if (new_reg_base_value && new_reg_base_value[regno]
+ && REG_N_SETS (regno) == 1)
+ return new_reg_base_value[regno];
+
+ if (reg_base_value[regno])
+ return reg_base_value[regno];
+ }
return src;
{
unsigned regno;
rtx src;
+ int n;
if (GET_CODE (dest) != REG)
return;
if (regno >= reg_base_value_size)
abort ();
+ /* If this spans multiple hard registers, then we must indicate that every
+ register has an unusable value. */
+ if (regno < FIRST_PSEUDO_REGISTER)
+ n = HARD_REGNO_NREGS (regno, GET_MODE (dest));
+ else
+ n = 1;
+ if (n != 1)
+ {
+ while (--n >= 0)
+ {
+ reg_seen[regno + n] = 1;
+ new_reg_base_value[regno + n] = 0;
+ }
+ return;
+ }
+
if (set)
{
/* A CLOBBER wipes out any old value but does not prevent a previously
return GEN_INT (ioffset);
}
-/* Return nonzero if we can deterimine the exprs corresponding to memrefs
+/* Return nonzero if we can determine the exprs corresponding to memrefs
X and Y and they do not overlap. */
static int
moffsetx = adjust_offset_for_component_ref (exprx, moffsetx);
exprx = t;
}
+ else if (TREE_CODE (exprx) == INDIRECT_REF)
+ {
+ exprx = TREE_OPERAND (exprx, 0);
+ if (flag_argument_noalias < 2
+ || TREE_CODE (exprx) != PARM_DECL)
+ return 0;
+ }
+
moffsety = MEM_OFFSET (y);
if (TREE_CODE (expry) == COMPONENT_REF)
{
moffsety = adjust_offset_for_component_ref (expry, moffsety);
expry = t;
}
+ else if (TREE_CODE (expry) == INDIRECT_REF)
+ {
+ expry = TREE_OPERAND (expry, 0);
+ if (flag_argument_noalias < 2
+ || TREE_CODE (expry) != PARM_DECL)
+ return 0;
+ }
if (! DECL_P (exprx) || ! DECL_P (expry))
return 0;
/* If we don't know the size of the lower-offset value, we can't tell
if they conflict. Otherwise, we do the test. */
- return sizex >= 0 && offsety > offsetx + sizex;
+ return sizex >= 0 && offsety >= offsetx + sizex;
}
/* True dependence: X is read after store in MEM takes place. */
varies);
}
-/* Returns non-zero if a write to X might alias a previous read from
- (or, if WRITEP is non-zero, a write to) MEM. */
+/* Returns nonzero if a write to X might alias a previous read from
+ (or, if WRITEP is nonzero, a write to) MEM. */
static int
write_dependence_p (mem, x, writep)
return 0;
}
-/* Returns non-zero if X might mention something which is not
+/* Returns nonzero if X might mention something which is not
local to the function and is not constant. */
static int
return 0;
}
-/* Returns non-zero if X might reference something which is not
+/* Returns nonzero if X might reference something which is not
local to the function and is not constant. */
static int
return 0;
}
-/* Returns non-zero if X might set something which is not
+/* Returns nonzero if X might set something which is not
local to the function and is not constant. */
static int
rtx insn;
int nonlocal_memory_referenced;
- if (TREE_PUBLIC (current_function_decl)
- || TREE_READONLY (current_function_decl)
+ if (TREE_READONLY (current_function_decl)
|| DECL_IS_PURE (current_function_decl)
|| TREE_THIS_VOLATILE (current_function_decl)
|| TYPE_MODE (TREE_TYPE (current_function_decl)) == VOIDmode
- || current_function_has_nonlocal_goto)
+ || current_function_has_nonlocal_goto
+ || !(*targetm.binds_local_p) (current_function_decl))
return;
/* A loop might not return which counts as a side effect. */
}
\f
-static HARD_REG_SET argument_registers;
-
void
init_alias_once ()
{
numbers, so translate if necessary due to register windows. */
if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i))
&& HARD_REGNO_MODE_OK (i, Pmode))
- SET_HARD_REG_BIT (argument_registers, i);
+ static_reg_base_value[i]
+ = gen_rtx_ADDRESS (VOIDmode, gen_rtx_REG (Pmode, i));
+
+ static_reg_base_value[STACK_POINTER_REGNUM]
+ = gen_rtx_ADDRESS (Pmode, stack_pointer_rtx);
+ static_reg_base_value[ARG_POINTER_REGNUM]
+ = gen_rtx_ADDRESS (Pmode, arg_pointer_rtx);
+ static_reg_base_value[FRAME_POINTER_REGNUM]
+ = gen_rtx_ADDRESS (Pmode, frame_pointer_rtx);
+#if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
+ static_reg_base_value[HARD_FRAME_POINTER_REGNUM]
+ = gen_rtx_ADDRESS (Pmode, hard_frame_pointer_rtx);
+#endif
alias_sets = splay_tree_new (splay_tree_compare_ints, 0, 0);
}
+/* Set MEMORY_MODIFIED when X modifies DATA (that is assumed
+ to be memory reference. */
+static bool memory_modified;
+static void
+memory_modified_1 (x, pat, data)
+ rtx x, pat ATTRIBUTE_UNUSED;
+ void *data;
+{
+ if (GET_CODE (x) == MEM)
+ {
+ if (anti_dependence (x, (rtx)data) || output_dependence (x, (rtx)data))
+ memory_modified = true;
+ }
+}
+
+
+/* Return true when INSN possibly modify memory contents of MEM
+ (ie address can be modified). */
+bool
+memory_modified_in_insn_p (mem, insn)
+ rtx mem, insn;
+{
+ if (!INSN_P (insn))
+ return false;
+ memory_modified = false;
+ note_stores (PATTERN (insn), memory_modified_1, mem);
+ return memory_modified;
+}
+
/* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
array. */
optimization. Loop unrolling can create a large number of
registers. */
reg_base_value_size = maxreg * 2;
- reg_base_value = (rtx *) xcalloc (reg_base_value_size, sizeof (rtx));
- ggc_add_rtx_root (reg_base_value, reg_base_value_size);
+ reg_base_value = (rtx *) ggc_alloc_cleared (reg_base_value_size
+ * sizeof (rtx));
new_reg_base_value = (rtx *) xmalloc (reg_base_value_size * sizeof (rtx));
reg_seen = (char *) xmalloc (reg_base_value_size);
/* We're at the start of the function each iteration through the
loop, so we're copying arguments. */
- copying_arguments = 1;
+ copying_arguments = true;
/* Wipe the potential alias information clean for this pass. */
memset ((char *) new_reg_base_value, 0, reg_base_value_size * sizeof (rtx));
The address expression is VOIDmode for an argument and
Pmode for other registers. */
- for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
- if (TEST_HARD_REG_BIT (argument_registers, i))
- new_reg_base_value[i] = gen_rtx_ADDRESS (VOIDmode,
- gen_rtx_REG (Pmode, i));
-
- new_reg_base_value[STACK_POINTER_REGNUM]
- = gen_rtx_ADDRESS (Pmode, stack_pointer_rtx);
- new_reg_base_value[ARG_POINTER_REGNUM]
- = gen_rtx_ADDRESS (Pmode, arg_pointer_rtx);
- new_reg_base_value[FRAME_POINTER_REGNUM]
- = gen_rtx_ADDRESS (Pmode, frame_pointer_rtx);
-#if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
- new_reg_base_value[HARD_FRAME_POINTER_REGNUM]
- = gen_rtx_ADDRESS (Pmode, hard_frame_pointer_rtx);
-#endif
+ memcpy (new_reg_base_value, static_reg_base_value,
+ FIRST_PSEUDO_REGISTER * sizeof (rtx));
/* Walk the insns adding values to the new_reg_base_value array. */
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
}
else if (GET_CODE (insn) == NOTE
&& NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_BEG)
- copying_arguments = 0;
+ copying_arguments = false;
}
/* Now propagate values from new_reg_base_value to reg_base_value. */
reg_known_value_size = 0;
free (reg_known_equiv_p + FIRST_PSEUDO_REGISTER);
reg_known_equiv_p = 0;
- if (reg_base_value)
- {
- ggc_del_root (reg_base_value);
- free (reg_base_value);
- reg_base_value = 0;
- }
+ reg_base_value = 0;
reg_base_value_size = 0;
if (alias_invariant)
{
alias_invariant = 0;
}
}
+
+#include "gt-alias.h"
OSDN Git Service
