On Mon, Jul 11, 2011 at 9:55 AM, H.J. Lu <hjl.to...@gmail.com> wrote:
> On Mon, Jul 11, 2011 at 8:54 AM, H.J. Lu <hjl.to...@gmail.com> wrote:
>> On Mon, Jul 11, 2011 at 4:03 AM, Paolo Bonzini <bonz...@gnu.org> wrote:
>>> On 07/11/2011 02:04 AM, H.J. Lu wrote:
>>>>
>>>> With my original change, I got
>>>>
>>>> (const:DI (plus:DI (symbol_ref:DI ("iplane.1577") [flags 0x2]
>>>> <var_decl 0x7ffff0857960 iplane>)
>>>> (const_int -4 [0xfffffffffffffffc])))
>>>>
>>>> I think it is safe to permute the conversion and addition operation
>>>> if one operand is a constant and we are zero-extending. This is
>>>> how zero-extending works.
>>>
>>> Ok, I think I understand what you mean. The key is the
>>>
>>> XEXP (x, 1) == convert_memory_address_addr_space
>>> (to_mode, XEXP (x, 1), as)
>>>
>>> test. It ensures basically that the constant has 31-bit precision, because
>>> otherwise the constant would change from e.g. (const_int -0x7ffffffc) to
>>> (const_int 0x80000004) when zero-extending it from SImode to DImode.
>>>
>>> But I'm not sure it's safe. You have,
>>>
>>> (zero_extend:DI (plus:SI FOO:SI) (const_int Y))
>>>
>>> and you want to convert it to
>>>
>>> (plus:DI FOO:DI (zero_extend:DI (const_int Y)))
>>>
>>> (where the zero_extend is folded). Ignore that FOO is a SYMBOL_REF (this
>>> piece of code does not assume anything about its shape); if FOO ==
>>> 0xfffffffc and Y = 8, the result will be respectively 0x4 (valid) and
>>> 0x100000004 (invalid).
>>
>> This example contradicts what you said above "It ensures basically that the
>> constant has 31-bit precision". For zero-extend, the issue is address-wrap.
>> As I understand, to support address-wrap, you need to use ptr_mode.
>>
>
> I am totally confused what the current code
>
> /* For addition we can safely permute the conversion and addition
> operation if one operand is a constant and converting the constant
> does not change it or if one operand is a constant and we are
> using a ptr_extend instruction (POINTERS_EXTEND_UNSIGNED < 0).
> We can always safely permute them if we are making the address
> narrower. */
> if (GET_MODE_SIZE (to_mode) < GET_MODE_SIZE (from_mode)
> || (GET_CODE (x) == PLUS
> && CONST_INT_P (XEXP (x, 1))
> && (XEXP (x, 1) == convert_memory_address_addr_space
> (to_mode, XEXP (x, 1), as)
> || POINTERS_EXTEND_UNSIGNED < 0)))
> return gen_rtx_fmt_ee (GET_CODE (x), to_mode,
> convert_memory_address_addr_space
> (to_mode, XEXP (x, 0), as),
> XEXP (x, 1));
>
> is trying to do. It doesn't support address-wrap at all, regardless if
> converting the constant changes the constant. I think it should be
> OK to permute if no instructions are allowed, like:
>
> if (GET_MODE_SIZE (to_mode) < GET_MODE_SIZE (from_mode)
> || (GET_CODE (x) == PLUS
> && CONST_INT_P (XEXP (x, 1))
> && POINTERS_EXTEND_UNSIGNED != 0
> && no_emit))
> return gen_rtx_fmt_ee (GET_CODE (x), to_mode,
> convert_memory_address_addr_space_1
> (to_mode, XEXP (x, 0), as, no_emit),
> XEXP (x, 1));
>
>
This patch implements it.
--
H.J.
---2011-07-11 H.J. Lu <hongjiu...@intel.com>
PR middle-end/47727
* explow.c (convert_memory_address_addr_space_1): New.
(convert_memory_address_addr_space): Use it.
* expr.c (convert_modes_1): New.
(convert_modes): Use it.
* expr.h (convert_modes_1): New.
* rtl.h (convert_memory_address_addr_space_1): New.
(convert_memory_address_1): Likewise.
* simplify-rtx.c (simplify_unary_operation_1): Call
convert_memory_address_1 instead of convert_memory_address.
2011-07-11 H.J. Lu <hongjiu...@intel.com>
PR middle-end/47727
* explow.c (convert_memory_address_addr_space_1): New.
(convert_memory_address_addr_space): Use it.
* expr.c (convert_modes_1): New.
(convert_modes): Use it.
* expr.h (convert_modes_1): New.
* rtl.h (convert_memory_address_addr_space_1): New.
(convert_memory_address_1): Likewise.
* simplify-rtx.c (simplify_unary_operation_1): Call
convert_memory_address_1 instead of convert_memory_address.
diff --git a/gcc/explow.c b/gcc/explow.c
index 3c692f4..d2c54ff 100644
--- a/gcc/explow.c
+++ b/gcc/explow.c
@@ -320,8 +320,9 @@ break_out_memory_refs (rtx x)
arithmetic insns can be used. */
rtx
-convert_memory_address_addr_space (enum machine_mode to_mode ATTRIBUTE_UNUSED,
- rtx x, addr_space_t as ATTRIBUTE_UNUSED)
+convert_memory_address_addr_space_1 (enum machine_mode to_mode
ATTRIBUTE_UNUSED,
+ rtx x, addr_space_t as ATTRIBUTE_UNUSED,
+ bool no_emit ATTRIBUTE_UNUSED)
{
#ifndef POINTERS_EXTEND_UNSIGNED
gcc_assert (GET_MODE (x) == to_mode || GET_MODE (x) == VOIDmode);
@@ -378,27 +379,25 @@ convert_memory_address_addr_space (enum machine_mode
to_mode ATTRIBUTE_UNUSED,
case CONST:
return gen_rtx_CONST (to_mode,
- convert_memory_address_addr_space
- (to_mode, XEXP (x, 0), as));
+ convert_memory_address_addr_space_1
+ (to_mode, XEXP (x, 0), as, no_emit));
break;
case PLUS:
case MULT:
- /* For addition we can safely permute the conversion and addition
- operation if one operand is a constant and converting the constant
- does not change it or if one operand is a constant and we are
- using a ptr_extend instruction (POINTERS_EXTEND_UNSIGNED < 0).
- We can always safely permute them if we are making the address
- narrower. */
+ /* For addition, we permute the conversion and addition operation
+ if one operand is a constant, no new instructions are allowed
+ and we are using a ptr_extend instruction or zero-extending
+ (POINTERS_EXTEND_UNSIGNED != 0). We can always safely permute
+ them if we are making the address narrower. */
if (GET_MODE_SIZE (to_mode) < GET_MODE_SIZE (from_mode)
|| (GET_CODE (x) == PLUS
&& CONST_INT_P (XEXP (x, 1))
- && (XEXP (x, 1) == convert_memory_address_addr_space
- (to_mode, XEXP (x, 1), as)
- || POINTERS_EXTEND_UNSIGNED < 0)))
+ && POINTERS_EXTEND_UNSIGNED != 0
+ && no_emit))
return gen_rtx_fmt_ee (GET_CODE (x), to_mode,
- convert_memory_address_addr_space
- (to_mode, XEXP (x, 0), as),
+ convert_memory_address_addr_space_1
+ (to_mode, XEXP (x, 0), as, no_emit),
XEXP (x, 1));
break;
@@ -406,10 +405,17 @@ convert_memory_address_addr_space (enum machine_mode
to_mode ATTRIBUTE_UNUSED,
break;
}
- return convert_modes (to_mode, from_mode,
- x, POINTERS_EXTEND_UNSIGNED);
+ return convert_modes_1 (to_mode, from_mode, x,
+ POINTERS_EXTEND_UNSIGNED, no_emit);
#endif /* defined(POINTERS_EXTEND_UNSIGNED) */
}
+
+rtx
+convert_memory_address_addr_space (enum machine_mode to_mode,
+ rtx x, addr_space_t as)
+{
+ return convert_memory_address_addr_space_1 (to_mode, x, as, false);
+}
/* Return something equivalent to X but valid as a memory address for something
of mode MODE in the named address space AS. When X is not itself valid,
diff --git a/gcc/expr.c b/gcc/expr.c
index fb4379f..de7f150 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -693,13 +693,16 @@ convert_to_mode (enum machine_mode mode, rtx x, int
unsignedp)
Both modes may be floating, or both integer.
UNSIGNEDP is nonzero if X is an unsigned value.
+ If NO_EMIT is true, don't emit any instructions.
+
This can be done by referring to a part of X in place
or by copying to a new temporary with conversion.
You can give VOIDmode for OLDMODE, if you are sure X has a nonvoid mode. */
rtx
-convert_modes (enum machine_mode mode, enum machine_mode oldmode, rtx x, int
unsignedp)
+convert_modes_1 (enum machine_mode mode, enum machine_mode oldmode,
+ rtx x, int unsignedp, bool no_emit)
{
rtx temp;
@@ -709,7 +712,12 @@ convert_modes (enum machine_mode mode, enum machine_mode
oldmode, rtx x, int uns
if (GET_CODE (x) == SUBREG && SUBREG_PROMOTED_VAR_P (x)
&& GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))) >= GET_MODE_SIZE (mode)
&& SUBREG_PROMOTED_UNSIGNED_P (x) == unsignedp)
- x = gen_lowpart (mode, x);
+ {
+ if (no_emit)
+ x = rtl_hooks.gen_lowpart_no_emit (mode, x);
+ else
+ x = gen_lowpart (mode, x);
+ }
if (GET_MODE (x) != VOIDmode)
oldmode = GET_MODE (x);
@@ -773,7 +781,10 @@ convert_modes (enum machine_mode mode, enum machine_mode
oldmode, rtx x, int uns
return gen_int_mode (val, mode);
}
- return gen_lowpart (mode, x);
+ if (no_emit)
+ return rtl_hooks.gen_lowpart_no_emit (mode, x);
+ else
+ return gen_lowpart (mode, x);
}
/* Converting from integer constant into mode is always equivalent to an
@@ -784,10 +795,18 @@ convert_modes (enum machine_mode mode, enum machine_mode
oldmode, rtx x, int uns
return simplify_gen_subreg (mode, x, oldmode, 0);
}
+ gcc_assert (!no_emit);
temp = gen_reg_rtx (mode);
convert_move (temp, x, unsignedp);
return temp;
}
+
+rtx
+convert_modes (enum machine_mode mode, enum machine_mode oldmode,
+ rtx x, int unsignedp)
+{
+ return convert_modes_1 (mode, oldmode, x, unsignedp, false);
+}
/* Return the largest alignment we can use for doing a move (or store)
of MAX_PIECES. ALIGN is the largest alignment we could use. */
diff --git a/gcc/expr.h b/gcc/expr.h
index cb4050d..2ac9788 100644
--- a/gcc/expr.h
+++ b/gcc/expr.h
@@ -267,6 +267,8 @@ extern rtx convert_to_mode (enum machine_mode, rtx, int);
/* Convert an rtx to MODE from OLDMODE and return the result. */
extern rtx convert_modes (enum machine_mode, enum machine_mode, rtx, int);
+extern rtx convert_modes_1 (enum machine_mode, enum machine_mode, rtx,
+ int, bool);
/* Emit code to move a block Y to a block X. */
diff --git a/gcc/rtl.h b/gcc/rtl.h
index e3ceecd..b01eef8 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -1638,8 +1638,13 @@ extern int byte_lowpart_offset (enum machine_mode, enum
machine_mode);
extern rtx make_safe_from (rtx, rtx);
extern rtx convert_memory_address_addr_space (enum machine_mode, rtx,
addr_space_t);
+extern rtx convert_memory_address_addr_space_1 (enum machine_mode, rtx,
+ addr_space_t, bool);
#define convert_memory_address(to_mode,x) \
convert_memory_address_addr_space ((to_mode), (x), ADDR_SPACE_GENERIC)
+#define convert_memory_address_1(to_mode,x,no_emit) \
+ convert_memory_address_addr_space_1 ((to_mode), (x), \
+ ADDR_SPACE_GENERIC, (no_emit))
extern const char *get_insn_name (int);
extern rtx get_last_insn_anywhere (void);
extern rtx get_first_nonnote_insn (void);
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index 82b818b..189c201 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -1150,7 +1150,7 @@ simplify_unary_operation_1 (enum rtx_code code, enum
machine_mode mode, rtx op)
&& REG_P (SUBREG_REG (op))
&& REG_POINTER (SUBREG_REG (op))
&& GET_MODE (SUBREG_REG (op)) == Pmode)))
- return convert_memory_address (Pmode, op);
+ return convert_memory_address_1 (Pmode, op, true);
#endif
break;
@@ -1243,7 +1243,7 @@ simplify_unary_operation_1 (enum rtx_code code, enum
machine_mode mode, rtx op)
&& REG_P (SUBREG_REG (op))
&& REG_POINTER (SUBREG_REG (op))
&& GET_MODE (SUBREG_REG (op)) == Pmode)))
- return convert_memory_address (Pmode, op);
+ return convert_memory_address_1 (Pmode, op, true);
#endif
break;
