On Thu, 25 Aug 2011 18:31:21 +0100
Julian Brown <jul...@codesourcery.com> wrote:
> On Thu, 25 Aug 2011 16:46:50 +0100
> Julian Brown <jul...@codesourcery.com> wrote:
>
> > So, OK to apply this version, assuming testing comes out OK? (And
> > the followup patch [2/2], which remains unchanged?)
>
> FWIW, all tests pass, apart from
> gcc.target/arm/volatile-bitfields-3.c, which regresses. The output
> contains:
>
> ldrh r0, [r3, #2] @ unaligned
>
> I believe that, to conform to the ARM EABI, that GCC must use an
> (aligned) ldr in this case. Is that correct? If so, it looks like the
> middle-end bitfield code does not take the setting of
> -fstrict-volatile-bitfields into account.
This version fixes the last issue, by adding additional checks for
volatile accesses/-fstrict-volatile-bitfields. Tests now show no
regressions.
OK to apply?
Thanks,
Julian
ChangeLog
gcc/
* config/arm/arm.c (arm_override_options): Add unaligned_access
support.
(arm_file_start): Emit attribute for unaligned access as
appropriate.
* config/arm/arm.md (UNSPEC_UNALIGNED_LOAD)
(UNSPEC_UNALIGNED_STORE): Add constants for unspecs.
(insv, extzv): Add unaligned-access support.
(extv): Change to expander. Likewise.
(extzv_t1, extv_regsi): Add helpers.
(unaligned_loadsi, unaligned_loadhis, unaligned_loadhiu)
(unaligned_storesi, unaligned_storehi): New.
(*extv_reg): New (previous extv implementation).
* config/arm/arm.opt (munaligned_access): Add option.
* config/arm/constraints.md (Uw): New constraint.
* expmed.c (store_bit_field_1): Adjust bitfield numbering according
to size of access, not size of unit, when BITS_BIG_ENDIAN !=
BYTES_BIG_ENDIAN. Don't use bitfield accesses for
volatile accesses when -fstrict-volatile-bitfields is in effect.
(extract_bit_field_1): Likewise.
commit 645a7c99ff91ea2841c8101fb3c76e3b1fddb2c7
Author: Julian Brown <jul...@henry8.codesourcery.com>
Date: Tue Aug 23 05:46:22 2011 -0700
Unaligned support for packed structs
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 3162b30..cc1eb80 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -1905,6 +1905,28 @@ arm_option_override (void)
fix_cm3_ldrd = 0;
}
+ /* Enable -munaligned-access by default for
+ - all ARMv6 architecture-based processors
+ - ARMv7-A, ARMv7-R, and ARMv7-M architecture-based processors.
+
+ Disable -munaligned-access by default for
+ - all pre-ARMv6 architecture-based processors
+ - ARMv6-M architecture-based processors. */
+
+ if (unaligned_access == 2)
+ {
+ if (arm_arch6 && (arm_arch_notm || arm_arch7))
+ unaligned_access = 1;
+ else
+ unaligned_access = 0;
+ }
+ else if (unaligned_access == 1
+ && !(arm_arch6 && (arm_arch_notm || arm_arch7)))
+ {
+ warning (0, "target CPU does not support unaligned accesses");
+ unaligned_access = 0;
+ }
+
if (TARGET_THUMB1 && flag_schedule_insns)
{
/* Don't warn since it's on by default in -O2. */
@@ -22145,6 +22167,10 @@ arm_file_start (void)
val = 6;
asm_fprintf (asm_out_file, "\t.eabi_attribute 30, %d\n", val);
+ /* Tag_CPU_unaligned_access. */
+ asm_fprintf (asm_out_file, "\t.eabi_attribute 34, %d\n",
+ unaligned_access);
+
/* Tag_ABI_FP_16bit_format. */
if (arm_fp16_format)
asm_fprintf (asm_out_file, "\t.eabi_attribute 38, %d\n",
diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
index 0f23400..0ea0f7f 100644
--- a/gcc/config/arm/arm.md
+++ b/gcc/config/arm/arm.md
@@ -103,6 +103,10 @@
UNSPEC_SYMBOL_OFFSET ; The offset of the start of the symbol from
; another symbolic address.
UNSPEC_MEMORY_BARRIER ; Represent a memory barrier.
+ UNSPEC_UNALIGNED_LOAD ; Used to represent ldr/ldrh instructions that access
+ ; unaligned locations, on architectures which support
+ ; that.
+ UNSPEC_UNALIGNED_STORE ; Same for str/strh.
])
;; UNSPEC_VOLATILE Usage:
@@ -2468,10 +2472,10 @@
;;; this insv pattern, so this pattern needs to be reevalutated.
(define_expand "insv"
- [(set (zero_extract:SI (match_operand:SI 0 "s_register_operand" "")
- (match_operand:SI 1 "general_operand" "")
- (match_operand:SI 2 "general_operand" ""))
- (match_operand:SI 3 "reg_or_int_operand" ""))]
+ [(set (zero_extract (match_operand 0 "nonimmediate_operand" "")
+ (match_operand 1 "general_operand" "")
+ (match_operand 2 "general_operand" ""))
+ (match_operand 3 "reg_or_int_operand" ""))]
"TARGET_ARM || arm_arch_thumb2"
"
{
@@ -2482,35 +2486,70 @@
if (arm_arch_thumb2)
{
- bool use_bfi = TRUE;
-
- if (GET_CODE (operands[3]) == CONST_INT)
+ if (unaligned_access && MEM_P (operands[0])
+ && s_register_operand (operands[3], GET_MODE (operands[3]))
+ && (width == 16 || width == 32) && (start_bit % BITS_PER_UNIT) == 0)
{
- HOST_WIDE_INT val = INTVAL (operands[3]) & mask;
+ rtx base_addr;
+
+ if (BYTES_BIG_ENDIAN)
+ start_bit = GET_MODE_BITSIZE (GET_MODE (operands[3])) - width
+ - start_bit;
- if (val == 0)
+ if (width == 32)
{
- emit_insn (gen_insv_zero (operands[0], operands[1],
- operands[2]));
- DONE;
+ base_addr = adjust_address (operands[0], SImode,
+ start_bit / BITS_PER_UNIT);
+ emit_insn (gen_unaligned_storesi (base_addr, operands[3]));
}
+ else
+ {
+ rtx tmp = gen_reg_rtx (HImode);
- /* See if the set can be done with a single orr instruction. */
- if (val == mask && const_ok_for_arm (val << start_bit))
- use_bfi = FALSE;
+ base_addr = adjust_address (operands[0], HImode,
+ start_bit / BITS_PER_UNIT);
+ emit_move_insn (tmp, gen_lowpart (HImode, operands[3]));
+ emit_insn (gen_unaligned_storehi (base_addr, tmp));
+ }
+ DONE;
}
-
- if (use_bfi)
+ else if (s_register_operand (operands[0], GET_MODE (operands[0])))
{
- if (GET_CODE (operands[3]) != REG)
- operands[3] = force_reg (SImode, operands[3]);
+ bool use_bfi = TRUE;
- emit_insn (gen_insv_t2 (operands[0], operands[1], operands[2],
- operands[3]));
- DONE;
+ if (GET_CODE (operands[3]) == CONST_INT)
+ {
+ HOST_WIDE_INT val = INTVAL (operands[3]) & mask;
+
+ if (val == 0)
+ {
+ emit_insn (gen_insv_zero (operands[0], operands[1],
+ operands[2]));
+ DONE;
+ }
+
+ /* See if the set can be done with a single orr instruction. */
+ if (val == mask && const_ok_for_arm (val << start_bit))
+ use_bfi = FALSE;
+ }
+
+ if (use_bfi)
+ {
+ if (GET_CODE (operands[3]) != REG)
+ operands[3] = force_reg (SImode, operands[3]);
+
+ emit_insn (gen_insv_t2 (operands[0], operands[1], operands[2],
+ operands[3]));
+ DONE;
+ }
}
+ else
+ FAIL;
}
+ if (!s_register_operand (operands[0], GET_MODE (operands[0])))
+ FAIL;
+
target = copy_rtx (operands[0]);
/* Avoid using a subreg as a subtarget, and avoid writing a paradoxical
subreg as the final target. */
@@ -3702,12 +3741,10 @@
;; to reduce register pressure later on.
(define_expand "extzv"
- [(set (match_dup 4)
- (ashift:SI (match_operand:SI 1 "register_operand" "")
- (match_operand:SI 2 "const_int_operand" "")))
- (set (match_operand:SI 0 "register_operand" "")
- (lshiftrt:SI (match_dup 4)
- (match_operand:SI 3 "const_int_operand" "")))]
+ [(set (match_operand 0 "s_register_operand" "")
+ (zero_extract (match_operand 1 "nonimmediate_operand" "")
+ (match_operand 2 "const_int_operand" "")
+ (match_operand 3 "const_int_operand" "")))]
"TARGET_THUMB1 || arm_arch_thumb2"
"
{
@@ -3716,10 +3753,57 @@
if (arm_arch_thumb2)
{
- emit_insn (gen_extzv_t2 (operands[0], operands[1], operands[2],
- operands[3]));
- DONE;
+ HOST_WIDE_INT width = INTVAL (operands[2]);
+ HOST_WIDE_INT bitpos = INTVAL (operands[3]);
+
+ if (unaligned_access && MEM_P (operands[1])
+ && (width == 16 || width == 32) && (bitpos % BITS_PER_UNIT) == 0)
+ {
+ rtx base_addr;
+
+ if (BYTES_BIG_ENDIAN)
+ bitpos = GET_MODE_BITSIZE (GET_MODE (operands[0])) - width
+ - bitpos;
+
+ if (width == 32)
+ {
+ base_addr = adjust_address (operands[1], SImode,
+ bitpos / BITS_PER_UNIT);
+ emit_insn (gen_unaligned_loadsi (operands[0], base_addr));
+ }
+ else
+ {
+ rtx dest = operands[0];
+ rtx tmp = gen_reg_rtx (SImode);
+
+ /* We may get a paradoxical subreg here. Strip it off. */
+ if (GET_CODE (dest) == SUBREG
+ && GET_MODE (dest) == SImode
+ && GET_MODE (SUBREG_REG (dest)) == HImode)
+ dest = SUBREG_REG (dest);
+
+ if (GET_MODE_BITSIZE (GET_MODE (dest)) != width)
+ FAIL;
+
+ base_addr = adjust_address (operands[1], HImode,
+ bitpos / BITS_PER_UNIT);
+ emit_insn (gen_unaligned_loadhiu (tmp, base_addr));
+ emit_move_insn (gen_lowpart (SImode, dest), tmp);
+ }
+ DONE;
+ }
+ else if (s_register_operand (operands[1], GET_MODE (operands[1])))
+ {
+ emit_insn (gen_extzv_t2 (operands[0], operands[1], operands[2],
+ operands[3]));
+ DONE;
+ }
+ else
+ FAIL;
}
+
+ if (!s_register_operand (operands[1], GET_MODE (operands[1])))
+ FAIL;
operands[3] = GEN_INT (rshift);
@@ -3729,12 +3813,154 @@
DONE;
}
- operands[2] = GEN_INT (lshift);
- operands[4] = gen_reg_rtx (SImode);
+ emit_insn (gen_extzv_t1 (operands[0], operands[1], GEN_INT (lshift),
+ operands[3], gen_reg_rtx (SImode)));
+ DONE;
}"
)
-(define_insn "extv"
+;; Helper for extzv, for the Thumb-1 register-shifts case.
+
+(define_expand "extzv_t1"
+ [(set (match_operand:SI 4 "s_register_operand" "")
+ (ashift:SI (match_operand:SI 1 "nonimmediate_operand" "")
+ (match_operand:SI 2 "const_int_operand" "")))
+ (set (match_operand:SI 0 "s_register_operand" "")
+ (lshiftrt:SI (match_dup 4)
+ (match_operand:SI 3 "const_int_operand" "")))]
+ "TARGET_THUMB1"
+ "")
+
+(define_expand "extv"
+ [(set (match_operand 0 "s_register_operand" "")
+ (sign_extract (match_operand 1 "nonimmediate_operand" "")
+ (match_operand 2 "const_int_operand" "")
+ (match_operand 3 "const_int_operand" "")))]
+ "arm_arch_thumb2"
+{
+ HOST_WIDE_INT width = INTVAL (operands[2]);
+ HOST_WIDE_INT bitpos = INTVAL (operands[3]);
+
+ if (unaligned_access && MEM_P (operands[1]) && (width == 16 || width == 32)
+ && (bitpos % BITS_PER_UNIT) == 0)
+ {
+ rtx base_addr;
+
+ if (BYTES_BIG_ENDIAN)
+ bitpos = GET_MODE_BITSIZE (GET_MODE (operands[0])) - width - bitpos;
+
+ if (width == 32)
+ {
+ base_addr = adjust_address (operands[1], SImode,
+ bitpos / BITS_PER_UNIT);
+ emit_insn (gen_unaligned_loadsi (operands[0], base_addr));
+ }
+ else
+ {
+ rtx dest = operands[0];
+ rtx tmp = gen_reg_rtx (SImode);
+
+ /* We may get a paradoxical subreg here. Strip it off. */
+ if (GET_CODE (dest) == SUBREG
+ && GET_MODE (dest) == SImode
+ && GET_MODE (SUBREG_REG (dest)) == HImode)
+ dest = SUBREG_REG (dest);
+
+ if (GET_MODE_BITSIZE (GET_MODE (dest)) != width)
+ FAIL;
+
+ base_addr = adjust_address (operands[1], HImode,
+ bitpos / BITS_PER_UNIT);
+ emit_insn (gen_unaligned_loadhis (tmp, base_addr));
+ emit_move_insn (gen_lowpart (SImode, dest), tmp);
+ }
+
+ DONE;
+ }
+ else if (!s_register_operand (operands[1], GET_MODE (operands[1])))
+ FAIL;
+ else if (GET_MODE (operands[0]) == SImode
+ && GET_MODE (operands[1]) == SImode)
+ {
+ emit_insn (gen_extv_regsi (operands[0], operands[1], operands[2],
+ operands[3]));
+ DONE;
+ }
+
+ FAIL;
+})
+
+; Helper to expand register forms of extv with the proper modes.
+
+(define_expand "extv_regsi"
+ [(set (match_operand:SI 0 "s_register_operand" "")
+ (sign_extract:SI (match_operand:SI 1 "s_register_operand" "")
+ (match_operand 2 "const_int_operand" "")
+ (match_operand 3 "const_int_operand" "")))]
+ ""
+{
+})
+
+; ARMv6+ unaligned load/store instructions (used for packed structure accesses).
+
+(define_insn "unaligned_loadsi"
+ [(set (match_operand:SI 0 "s_register_operand" "=l,r")
+ (unspec:SI [(match_operand:SI 1 "memory_operand" "Uw,m")]
+ UNSPEC_UNALIGNED_LOAD))]
+ "unaligned_access && TARGET_32BIT"
+ "ldr%?\t%0, %1\t@ unaligned"
+ [(set_attr "arch" "t2,any")
+ (set_attr "length" "2,4")
+ (set_attr "predicable" "yes")
+ (set_attr "type" "load1")])
+
+(define_insn "unaligned_loadhis"
+ [(set (match_operand:SI 0 "s_register_operand" "=l,r")
+ (sign_extend:SI
+ (unspec:HI [(match_operand:HI 1 "memory_operand" "Uw,m")]
+ UNSPEC_UNALIGNED_LOAD)))]
+ "unaligned_access && TARGET_32BIT"
+ "ldr%(sh%)\t%0, %1\t@ unaligned"
+ [(set_attr "arch" "t2,any")
+ (set_attr "length" "2,4")
+ (set_attr "predicable" "yes")
+ (set_attr "type" "load_byte")])
+
+(define_insn "unaligned_loadhiu"
+ [(set (match_operand:SI 0 "s_register_operand" "=l,r")
+ (zero_extend:SI
+ (unspec:HI [(match_operand:HI 1 "memory_operand" "Uw,m")]
+ UNSPEC_UNALIGNED_LOAD)))]
+ "unaligned_access && TARGET_32BIT"
+ "ldr%(h%)\t%0, %1\t@ unaligned"
+ [(set_attr "arch" "t2,any")
+ (set_attr "length" "2,4")
+ (set_attr "predicable" "yes")
+ (set_attr "type" "load_byte")])
+
+(define_insn "unaligned_storesi"
+ [(set (match_operand:SI 0 "memory_operand" "=Uw,m")
+ (unspec:SI [(match_operand:SI 1 "s_register_operand" "l,r")]
+ UNSPEC_UNALIGNED_STORE))]
+ "unaligned_access && TARGET_32BIT"
+ "str%?\t%1, %0\t@ unaligned"
+ [(set_attr "arch" "t2,any")
+ (set_attr "length" "2,4")
+ (set_attr "predicable" "yes")
+ (set_attr "type" "store1")])
+
+(define_insn "unaligned_storehi"
+ [(set (match_operand:HI 0 "memory_operand" "=Uw,m")
+ (unspec:HI [(match_operand:HI 1 "s_register_operand" "l,r")]
+ UNSPEC_UNALIGNED_STORE))]
+ "unaligned_access && TARGET_32BIT"
+ "str%(h%)\t%1, %0\t@ unaligned"
+ [(set_attr "arch" "t2,any")
+ (set_attr "length" "2,4")
+ (set_attr "predicable" "yes")
+ (set_attr "type" "store1")])
+
+(define_insn "*extv_reg"
[(set (match_operand:SI 0 "s_register_operand" "=r")
(sign_extract:SI (match_operand:SI 1 "s_register_operand" "r")
(match_operand:SI 2 "const_int_operand" "M")
diff --git a/gcc/config/arm/arm.opt b/gcc/config/arm/arm.opt
index be5fd3c..98eace3 100644
--- a/gcc/config/arm/arm.opt
+++ b/gcc/config/arm/arm.opt
@@ -249,3 +249,7 @@ mfix-cortex-m3-ldrd
Target Report Var(fix_cm3_ldrd) Init(2)
Avoid overlapping destination and address registers on LDRD instructions
that may trigger Cortex-M3 errata.
+
+munaligned-access
+Target Report Var(unaligned_access) Init(2)
+Enable unaligned word and halfword accesses to packed data.
diff --git a/gcc/config/arm/constraints.md b/gcc/config/arm/constraints.md
index f5b8521..53c358e 100644
--- a/gcc/config/arm/constraints.md
+++ b/gcc/config/arm/constraints.md
@@ -36,7 +36,7 @@
;; The following memory constraints have been used:
;; in ARM/Thumb-2 state: Q, Ut, Uv, Uy, Un, Um, Us
;; in ARM state: Uq
-;; in Thumb state: Uu
+;; in Thumb state: Uu, Uw
(define_register_constraint "f" "TARGET_ARM ? FPA_REGS : NO_REGS"
@@ -341,6 +341,19 @@
&& thumb1_legitimate_address_p (GET_MODE (op), XEXP (op, 0),
0)")))
+; The 16-bit post-increment LDR/STR accepted by thumb1_legitimate_address_p
+; are actually LDM/STM instructions, so cannot be used to access unaligned
+; data.
+(define_memory_constraint "Uw"
+ "@internal
+ In Thumb state an address that is valid in 16bit encoding, and that can be
+ used for unaligned accesses."
+ (and (match_code "mem")
+ (match_test "TARGET_THUMB
+ && thumb1_legitimate_address_p (GET_MODE (op), XEXP (op, 0),
+ 0)
+ && GET_CODE (XEXP (op, 0)) != POST_INC")))
+
;; We used to have constraint letters for S and R in ARM state, but
;; all uses of these now appear to have been removed.
diff --git a/gcc/expmed.c b/gcc/expmed.c
index 0047cd0..3c63750 100644
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -620,6 +620,10 @@ store_bit_field_1 (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
&& GET_MODE (value) != BLKmode
&& bitsize > 0
&& GET_MODE_BITSIZE (op_mode) >= bitsize
+ /* Do not use insv for volatile bitfields when
+ -fstrict-volatile-bitfields is in effect. */
+ && !(MEM_P (op0) && MEM_VOLATILE_P (op0)
+ && flag_strict_volatile_bitfields > 0)
&& ! ((REG_P (op0) || GET_CODE (op0) == SUBREG)
&& (bitsize + bitpos > GET_MODE_BITSIZE (op_mode))))
{
@@ -659,19 +663,19 @@ store_bit_field_1 (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
copy_back = true;
}
- /* On big-endian machines, we count bits from the most significant.
- If the bit field insn does not, we must invert. */
-
- if (BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN)
- xbitpos = unit - bitsize - xbitpos;
-
/* We have been counting XBITPOS within UNIT.
Count instead within the size of the register. */
- if (BITS_BIG_ENDIAN && !MEM_P (xop0))
+ if (BYTES_BIG_ENDIAN && !MEM_P (xop0))
xbitpos += GET_MODE_BITSIZE (op_mode) - unit;
unit = GET_MODE_BITSIZE (op_mode);
+ /* On big-endian machines, we count bits from the most significant.
+ If the bit field insn does not, we must invert. */
+
+ if (BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN)
+ xbitpos = unit - bitsize - xbitpos;
+
/* Convert VALUE to op_mode (which insv insn wants) in VALUE1. */
value1 = value;
if (GET_MODE (value) != op_mode)
@@ -1507,6 +1511,10 @@ extract_bit_field_1 (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
if (ext_mode != MAX_MACHINE_MODE
&& bitsize > 0
&& GET_MODE_BITSIZE (ext_mode) >= bitsize
+ /* Do not use extv/extzv for volatile bitfields when
+ -fstrict-volatile-bitfields is in effect. */
+ && !(MEM_P (op0) && MEM_VOLATILE_P (op0)
+ && flag_strict_volatile_bitfields > 0)
/* If op0 is a register, we need it in EXT_MODE to make it
acceptable to the format of ext(z)v. */
&& !(GET_CODE (op0) == SUBREG && GET_MODE (op0) != ext_mode)
@@ -1528,17 +1536,17 @@ extract_bit_field_1 (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
/* Get ref to first byte containing part of the field. */
xop0 = adjust_address (xop0, byte_mode, xoffset);
- /* On big-endian machines, we count bits from the most significant.
- If the bit field insn does not, we must invert. */
- if (BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN)
- xbitpos = unit - bitsize - xbitpos;
-
/* Now convert from counting within UNIT to counting in EXT_MODE. */
- if (BITS_BIG_ENDIAN && !MEM_P (xop0))
+ if (BYTES_BIG_ENDIAN && !MEM_P (xop0))
xbitpos += GET_MODE_BITSIZE (ext_mode) - unit;
unit = GET_MODE_BITSIZE (ext_mode);
+ /* On big-endian machines, we count bits from the most significant.
+ If the bit field insn does not, we must invert. */
+ if (BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN)
+ xbitpos = unit - bitsize - xbitpos;
+
if (xtarget == 0)
xtarget = xspec_target = gen_reg_rtx (tmode);
