return 0;
}
+/* Return true iff it would be profitable to turn a sequence of NOPS loads
+ or stores (depending on IS_STORE) into a load-multiple or store-multiple
+ instruction. ADD_OFFSET is nonzero if the base address register needs
+ to be modified with an add instruction before we can use it. */
+
+static bool
+multiple_operation_profitable_p (bool is_store ATTRIBUTE_UNUSED,
+ int nops, HOST_WIDE_INT add_offset)
+ {
+ /* For ARM8,9 & StrongARM, 2 ldr instructions are faster than an ldm
+ if the offset isn't small enough. The reason 2 ldrs are faster
+ is because these ARMs are able to do more than one cache access
+ in a single cycle. The ARM9 and StrongARM have Harvard caches,
+ whilst the ARM8 has a double bandwidth cache. This means that
+ these cores can do both an instruction fetch and a data fetch in
+ a single cycle, so the trick of calculating the address into a
+ scratch register (one of the result regs) and then doing a load
+ multiple actually becomes slower (and no smaller in code size).
+ That is the transformation
+
+ ldr rd1, [rbase + offset]
+ ldr rd2, [rbase + offset + 4]
+
+ to
+
+ add rd1, rbase, offset
+ ldmia rd1, {rd1, rd2}
+
+ produces worse code -- '3 cycles + any stalls on rd2' instead of
+ '2 cycles + any stalls on rd2'. On ARMs with only one cache
+ access per cycle, the first sequence could never complete in less
+ than 6 cycles, whereas the ldm sequence would only take 5 and
+ would make better use of sequential accesses if not hitting the
+ cache.
+
+ We cheat here and test 'arm_ld_sched' which we currently know to
+ only be true for the ARM8, ARM9 and StrongARM. If this ever
+ changes, then the test below needs to be reworked. */
+ if (nops == 2 && arm_ld_sched && add_offset != 0)
+ return false;
+
+ return true;
+}
+
+/* Subroutine of load_multiple_sequence and store_multiple_sequence.
+ Given an array of UNSORTED_OFFSETS, of which there are NOPS, compute
+ an array ORDER which describes the sequence to use when accessing the
+ offsets that produces an ascending order. In this sequence, each
+ offset must be larger by exactly 4 than the previous one. ORDER[0]
+ must have been filled in with the lowest offset by the caller.
+ If UNSORTED_REGS is nonnull, it is an array of register numbers that
+ we use to verify that ORDER produces an ascending order of registers.
+ Return true if it was possible to construct such an order, false if
+ not. */
+
+static bool
+compute_offset_order (int nops, HOST_WIDE_INT *unsorted_offsets, int *order,
+ int *unsorted_regs)
+{
+ int i;
+ for (i = 1; i < nops; i++)
+ {
+ int j;
+
+ order[i] = order[i - 1];
+ for (j = 0; j < nops; j++)
+ if (unsorted_offsets[j] == unsorted_offsets[order[i - 1]] + 4)
+ {
+ /* We must find exactly one offset that is higher than the
+ previous one by 4. */
+ if (order[i] != order[i - 1])
+ return false;
+ order[i] = j;
+ }
+ if (order[i] == order[i - 1])
+ return false;
+ /* The register numbers must be ascending. */
+ if (unsorted_regs != NULL
+ && unsorted_regs[order[i]] <= unsorted_regs[order[i - 1]])
+ return false;
+ }
+ return true;
+}
+
int
load_multiple_sequence (rtx *operands, int nops, int *regs, int *base,
HOST_WIDE_INT *load_offset)
{
- int unsorted_regs[4];
- HOST_WIDE_INT unsorted_offsets[4];
- int order[4];
+ int unsorted_regs[MAX_LDM_STM_OPS];
+ HOST_WIDE_INT unsorted_offsets[MAX_LDM_STM_OPS];
+ int order[MAX_LDM_STM_OPS];
int base_reg = -1;
- int i;
+ int i, ldm_case;
- /* Can only handle 2, 3, or 4 insns at present,
- though could be easily extended if required. */
- gcc_assert (nops >= 2 && nops <= 4);
+ /* Can only handle up to MAX_LDM_STM_OPS insns at present, though could be
+ easily extended if required. */
+ gcc_assert (nops >= 2 && nops <= MAX_LDM_STM_OPS);
- memset (order, 0, 4 * sizeof (int));
+ memset (order, 0, MAX_LDM_STM_OPS * sizeof (int));
/* Loop over the operands and check that the memory references are
suitable (i.e. immediate offsets from the same base register). At
== CONST_INT)))
{
if (i == 0)
- {
- base_reg = REGNO (reg);
- unsorted_regs[0] = (GET_CODE (operands[i]) == REG
- ? REGNO (operands[i])
- : REGNO (SUBREG_REG (operands[i])));
- order[0] = 0;
- }
+ base_reg = REGNO (reg);
else
{
if (base_reg != (int) REGNO (reg))
/* Not addressed from the same base register. */
return 0;
-
- unsorted_regs[i] = (GET_CODE (operands[i]) == REG
- ? REGNO (operands[i])
- : REGNO (SUBREG_REG (operands[i])));
- if (unsorted_regs[i] < unsorted_regs[order[0]])
- order[0] = i;
}
+ unsorted_regs[i] = (GET_CODE (operands[i]) == REG
+ ? REGNO (operands[i])
+ : REGNO (SUBREG_REG (operands[i])));
/* If it isn't an integer register, or if it overwrites the
base register but isn't the last insn in the list, then
return 0;
unsorted_offsets[i] = INTVAL (offset);
+ if (i == 0 || unsorted_offsets[i] < unsorted_offsets[order[0]])
+ order[0] = i;
}
else
/* Not a suitable memory address. */
/* All the useful information has now been extracted from the
operands into unsorted_regs and unsorted_offsets; additionally,
- order[0] has been set to the lowest numbered register in the
- list. Sort the registers into order, and check that the memory
- offsets are ascending and adjacent. */
-
- for (i = 1; i < nops; i++)
- {
- int j;
-
- order[i] = order[i - 1];
- for (j = 0; j < nops; j++)
- if (unsorted_regs[j] > unsorted_regs[order[i - 1]]
- && (order[i] == order[i - 1]
- || unsorted_regs[j] < unsorted_regs[order[i]]))
- order[i] = j;
-
- /* Have we found a suitable register? if not, one must be used more
- than once. */
- if (order[i] == order[i - 1])
- return 0;
-
- /* Is the memory address adjacent and ascending? */
- if (unsorted_offsets[order[i]] != unsorted_offsets[order[i - 1]] + 4)
- return 0;
- }
+ order[0] has been set to the lowest offset in the list. Sort
+ the offsets into order, verifying that they are adjacent, and
+ check that the register numbers are ascending. */
+ if (!compute_offset_order (nops, unsorted_offsets, order, unsorted_regs))
+ return 0;
if (base)
{
}
if (unsorted_offsets[order[0]] == 0)
- return 1; /* ldmia */
-
- if (TARGET_ARM && unsorted_offsets[order[0]] == 4)
- return 2; /* ldmib */
-
- if (TARGET_ARM && unsorted_offsets[order[nops - 1]] == 0)
- return 3; /* ldmda */
-
- if (unsorted_offsets[order[nops - 1]] == -4)
- return 4; /* ldmdb */
-
- /* For ARM8,9 & StrongARM, 2 ldr instructions are faster than an ldm
- if the offset isn't small enough. The reason 2 ldrs are faster
- is because these ARMs are able to do more than one cache access
- in a single cycle. The ARM9 and StrongARM have Harvard caches,
- whilst the ARM8 has a double bandwidth cache. This means that
- these cores can do both an instruction fetch and a data fetch in
- a single cycle, so the trick of calculating the address into a
- scratch register (one of the result regs) and then doing a load
- multiple actually becomes slower (and no smaller in code size).
- That is the transformation
-
- ldr rd1, [rbase + offset]
- ldr rd2, [rbase + offset + 4]
-
- to
-
- add rd1, rbase, offset
- ldmia rd1, {rd1, rd2}
-
- produces worse code -- '3 cycles + any stalls on rd2' instead of
- '2 cycles + any stalls on rd2'. On ARMs with only one cache
- access per cycle, the first sequence could never complete in less
- than 6 cycles, whereas the ldm sequence would only take 5 and
- would make better use of sequential accesses if not hitting the
- cache.
+ ldm_case = 1; /* ldmia */
+ else if (TARGET_ARM && unsorted_offsets[order[0]] == 4)
+ ldm_case = 2; /* ldmib */
+ else if (TARGET_ARM && unsorted_offsets[order[nops - 1]] == 0)
+ ldm_case = 3; /* ldmda */
+ else if (unsorted_offsets[order[nops - 1]] == -4)
+ ldm_case = 4; /* ldmdb */
+ else if (const_ok_for_arm (unsorted_offsets[order[0]])
+ || const_ok_for_arm (-unsorted_offsets[order[0]]))
+ ldm_case = 5;
+ else
+ return 0;
- We cheat here and test 'arm_ld_sched' which we currently know to
- only be true for the ARM8, ARM9 and StrongARM. If this ever
- changes, then the test below needs to be reworked. */
- if (nops == 2 && arm_ld_sched)
+ if (!multiple_operation_profitable_p (false, nops,
+ ldm_case == 5
+ ? unsorted_offsets[order[0]] : 0))
return 0;
- /* Can't do it without setting up the offset, only do this if it takes
- no more than one insn. */
- return (const_ok_for_arm (unsorted_offsets[order[0]])
- || const_ok_for_arm (-unsorted_offsets[order[0]])) ? 5 : 0;
+ return ldm_case;
}
const char *
emit_ldm_seq (rtx *operands, int nops)
{
- int regs[4];
+ int regs[MAX_LDM_STM_OPS];
int base_reg;
HOST_WIDE_INT offset;
char buf[100];
store_multiple_sequence (rtx *operands, int nops, int *regs, int *base,
HOST_WIDE_INT * load_offset)
{
- int unsorted_regs[4];
- HOST_WIDE_INT unsorted_offsets[4];
- int order[4];
+ int unsorted_regs[MAX_LDM_STM_OPS];
+ HOST_WIDE_INT unsorted_offsets[MAX_LDM_STM_OPS];
+ int order[MAX_LDM_STM_OPS];
int base_reg = -1;
- int i;
+ int i, stm_case;
- /* Can only handle 2, 3, or 4 insns at present, though could be easily
- extended if required. */
- gcc_assert (nops >= 2 && nops <= 4);
+ /* Can only handle up to MAX_LDM_STM_OPS insns at present, though could be
+ easily extended if required. */
+ gcc_assert (nops >= 2 && nops <= MAX_LDM_STM_OPS);
- memset (order, 0, 4 * sizeof (int));
+ memset (order, 0, MAX_LDM_STM_OPS * sizeof (int));
/* Loop over the operands and check that the memory references are
suitable (i.e. immediate offsets from the same base register). At
&& (GET_CODE (offset = XEXP (XEXP (operands[nops + i], 0), 1))
== CONST_INT)))
{
+ unsorted_regs[i] = (GET_CODE (operands[i]) == REG
+ ? REGNO (operands[i])
+ : REGNO (SUBREG_REG (operands[i])));
if (i == 0)
- {
- base_reg = REGNO (reg);
- unsorted_regs[0] = (GET_CODE (operands[i]) == REG
- ? REGNO (operands[i])
- : REGNO (SUBREG_REG (operands[i])));
- order[0] = 0;
- }
- else
- {
- if (base_reg != (int) REGNO (reg))
- /* Not addressed from the same base register. */
- return 0;
-
- unsorted_regs[i] = (GET_CODE (operands[i]) == REG
- ? REGNO (operands[i])
- : REGNO (SUBREG_REG (operands[i])));
- if (unsorted_regs[i] < unsorted_regs[order[0]])
- order[0] = i;
- }
+ base_reg = REGNO (reg);
+ else if (base_reg != (int) REGNO (reg))
+ /* Not addressed from the same base register. */
+ return 0;
/* If it isn't an integer register, then we can't do this. */
if (unsorted_regs[i] < 0 || unsorted_regs[i] > 14)
return 0;
unsorted_offsets[i] = INTVAL (offset);
+ if (i == 0 || unsorted_offsets[i] < unsorted_offsets[order[0]])
+ order[0] = i;
}
else
/* Not a suitable memory address. */
/* All the useful information has now been extracted from the
operands into unsorted_regs and unsorted_offsets; additionally,
- order[0] has been set to the lowest numbered register in the
- list. Sort the registers into order, and check that the memory
- offsets are ascending and adjacent. */
-
- for (i = 1; i < nops; i++)
- {
- int j;
-
- order[i] = order[i - 1];
- for (j = 0; j < nops; j++)
- if (unsorted_regs[j] > unsorted_regs[order[i - 1]]
- && (order[i] == order[i - 1]
- || unsorted_regs[j] < unsorted_regs[order[i]]))
- order[i] = j;
-
- /* Have we found a suitable register? if not, one must be used more
- than once. */
- if (order[i] == order[i - 1])
- return 0;
-
- /* Is the memory address adjacent and ascending? */
- if (unsorted_offsets[order[i]] != unsorted_offsets[order[i - 1]] + 4)
- return 0;
- }
+ order[0] has been set to the lowest offset in the list. Sort
+ the offsets into order, verifying that they are adjacent, and
+ check that the register numbers are ascending. */
+ if (!compute_offset_order (nops, unsorted_offsets, order, unsorted_regs))
+ return 0;
if (base)
{
}
if (unsorted_offsets[order[0]] == 0)
- return 1; /* stmia */
-
- if (unsorted_offsets[order[0]] == 4)
- return 2; /* stmib */
-
- if (unsorted_offsets[order[nops - 1]] == 0)
- return 3; /* stmda */
+ stm_case = 1; /* stmia */
+ else if (TARGET_ARM && unsorted_offsets[order[0]] == 4)
+ stm_case = 2; /* stmib */
+ else if (TARGET_ARM && unsorted_offsets[order[nops - 1]] == 0)
+ stm_case = 3; /* stmda */
+ else if (unsorted_offsets[order[nops - 1]] == -4)
+ stm_case = 4; /* stmdb */
+ else
+ return 0;
- if (unsorted_offsets[order[nops - 1]] == -4)
- return 4; /* stmdb */
+ if (!multiple_operation_profitable_p (false, nops, 0))
+ return 0;
- return 0;
+ return stm_case;
}
const char *
emit_stm_seq (rtx *operands, int nops)
{
- int regs[4];
+ int regs[MAX_LDM_STM_OPS];
int base_reg;
HOST_WIDE_INT offset;
char buf[100];
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