Submitter | Richard Sandiford |
---|---|

Date | Oct. 7, 2012, 8:56 a.m. |

Message ID | <874nm6oe2n.fsf@talisman.home> |

Download | mbox | patch |

Permalink | /patch/189795/ |

State | New |

Headers | show |

## Comments

> Yeah, in hindsight, the patch was definitely lacking commentary. > How about the patch below? It also fixes the partial int case > and gets rid of the errant NOT hunk. Tested in the same way as before. > > Richard > > > gcc/ > * machmode.h (GET_MODE_UNIT_PRECISION): New macro. > * simplify-rtx.c (simplify_truncation): New function, > extracted from simplify_subreg and (in small part) from > simplify_unary_operation_1. > (simplify_unary_operation_1) <TRUNCATE>: Use it. Remove sign bit > test for !TRULY_NOOP_TRUNCATION_MODES_P. > (simplify_subreg): Use simplify_truncate for lowpart subregs > where both the inner and outer modes are scalar integers. This looks good to me, thanks.

On Sun, Oct 7, 2012 at 8:56 AM, Richard Sandiford <rdsandiford@googlemail.com> wrote: > Eric Botcazou <ebotcazou@adacore.com> writes: >>> I think modelling it as a TRUNCATE operation is correct for >>> !TRULY_NOOP_TRUNCATION (it's the bug that Andrew pointed out). >>> And we shouldn't generate an actual TRUNCATE rtx for >>> TRULY_NOOP_TRUNCATION (the thing about making >>> simplify_gen_unary (TRUNCATE, ...) no worse than simplify_gen_subreg >>> for those targets). I suppose: >>> >>> /* We can't handle truncation to a partial integer mode here >>> because we don't know the real bitsize of the partial >>> integer mode. */ >>> if (GET_MODE_CLASS (mode) == MODE_PARTIAL_INT) >>> break; >>> >>> might be a problem though; we should still allow a subreg to be >>> generated. Is that what you were thinking of, or something else? >> >> I was thinking of the !TRULY_NOOP_TRUNCATION case, where the two operations >> aren't equivalent. Generating TRUNCATE in simplify_subreg seems suspicious to >> me in this case but, if not doing it is the source of the bug, I guess I need >> to do some homework on this TRULY_NOOP_TRUNCATION stuff. :-) >> >> Maybe add a blurb to the head comment of simplify_truncation, explaining that >> it is valid to call the function both for TRUNCATEs and truncations to the >> lowpart, and why it is correct to generate new TRUNCATEs in the latter case. > > Yeah, in hindsight, the patch was definitely lacking commentary. > How about the patch below? It also fixes the partial int case > and gets rid of the errant NOT hunk. Tested in the same way as before. > > Richard > > > gcc/ > * machmode.h (GET_MODE_UNIT_PRECISION): New macro. > * simplify-rtx.c (simplify_truncation): New function, > extracted from simplify_subreg and (in small part) from > simplify_unary_operation_1. > (simplify_unary_operation_1) <TRUNCATE>: Use it. Remove sign bit > test for !TRULY_NOOP_TRUNCATION_MODES_P. > (simplify_subreg): Use simplify_truncate for lowpart subregs > where both the inner and outer modes are scalar integers. > * config/mips/mips.c (mips_truncated_op_cost): New function. > (mips_rtx_costs): Adjust test for BADDU. > * config/mips/mips.md (*baddu_di<mode>): Push truncates to operands. This triggers PR55052 on ARM.I've attached the .i file and the dumps to the bug report. Thanks, Ramana

## Patch

Index: gcc/machmode.h =================================================================== --- gcc/machmode.h 2012-10-06 11:22:55.888609330 +0100 +++ gcc/machmode.h 2012-10-06 11:24:42.459603393 +0100 @@ -217,6 +217,11 @@ #define GET_MODE_UNIT_SIZE(MODE) \ #define GET_MODE_UNIT_BITSIZE(MODE) \ ((unsigned short) (GET_MODE_UNIT_SIZE (MODE) * BITS_PER_UNIT)) +#define GET_MODE_UNIT_PRECISION(MODE) \ + (GET_MODE_INNER (MODE) == VOIDmode \ + ? GET_MODE_PRECISION (MODE) \ + : GET_MODE_PRECISION (GET_MODE_INNER (MODE))) + /* Get the number of units in the object. */ extern const unsigned char mode_nunits[NUM_MACHINE_MODES]; Index: gcc/simplify-rtx.c =================================================================== --- gcc/simplify-rtx.c 2012-10-06 11:23:57.005605924 +0100 +++ gcc/simplify-rtx.c 2012-10-06 17:14:40.018658588 +0100 @@ -564,6 +564,212 @@ simplify_replace_rtx (rtx x, const_rtx o return simplify_replace_fn_rtx (x, old_rtx, 0, new_rtx); } +/* Try to simplify a MODE truncation of OP, which has OP_MODE. + Only handle cases where the truncated value is inherently an rvalue. + + RTL provides two ways of truncating a value: + + 1. a lowpart subreg. This form is only a truncation when both + the outer and inner modes (here MODE and OP_MODE respectively) + are scalar integers, and only then when the subreg is used as + an rvalue. + + It is only valid to form such truncating subregs if the + truncation requires no action by the target. The onus for + proving this is on the creator of the subreg -- e.g. the + caller to simplify_subreg or simplify_gen_subreg -- and typically + involves either TRULY_NOOP_TRUNCATION_MODES_P or truncated_to_mode. + + 2. a TRUNCATE. This form handles both scalar and compound integers. + + The first form is preferred where valid. However, the TRUNCATE + handling in simplify_unary_operation turns the second form into the + first form when TRULY_NOOP_TRUNCATION_MODES_P or truncated_to_mode allow, + so it is generally safe to form rvalue truncations using: + + simplify_gen_unary (TRUNCATE, ...) + + and leave simplify_unary_operation to work out which representation + should be used. + + Because of the proof requirements on (1), simplify_truncation must + also use simplify_gen_unary (TRUNCATE, ...) to truncate parts of OP, + regardless of whether the outer truncation came from a SUBREG or a + TRUNCATE. For example, if the caller has proven that an SImode + truncation of: + + (and:DI X Y) + + is a no-op and can be represented as a subreg, it does not follow + that SImode truncations of X and Y are also no-ops. On a target + like 64-bit MIPS that requires SImode values to be stored in + sign-extended form, an SImode truncation of: + + (and:DI (reg:DI X) (const_int 63)) + + is trivially a no-op because only the lower 6 bits can be set. + However, X is still an arbitrary 64-bit number and so we cannot + assume that truncating it too is a no-op. */ + +static rtx +simplify_truncation (enum machine_mode mode, rtx op, + enum machine_mode op_mode) +{ + unsigned int precision = GET_MODE_UNIT_PRECISION (mode); + unsigned int op_precision = GET_MODE_UNIT_PRECISION (op_mode); + gcc_assert (precision <= op_precision); + + /* Optimize truncations of zero and sign extended values. */ + if (GET_CODE (op) == ZERO_EXTEND + || GET_CODE (op) == SIGN_EXTEND) + { + /* There are three possibilities. If MODE is the same as the + origmode, we can omit both the extension and the subreg. + If MODE is not larger than the origmode, we can apply the + truncation without the extension. Finally, if the outermode + is larger than the origmode, we can just extend to the appropriate + mode. */ + enum machine_mode origmode = GET_MODE (XEXP (op, 0)); + if (mode == origmode) + return XEXP (op, 0); + else if (precision <= GET_MODE_UNIT_PRECISION (origmode)) + return simplify_gen_unary (TRUNCATE, mode, + XEXP (op, 0), origmode); + else + return simplify_gen_unary (GET_CODE (op), mode, + XEXP (op, 0), origmode); + } + + /* Simplify (truncate:SI (op:DI (x:DI) (y:DI))) + to (op:SI (truncate:SI (x:DI)) (truncate:SI (x:DI))). */ + if (GET_CODE (op) == PLUS + || GET_CODE (op) == MINUS + || GET_CODE (op) == MULT) + { + rtx op0 = simplify_gen_unary (TRUNCATE, mode, XEXP (op, 0), op_mode); + if (op0) + { + rtx op1 = simplify_gen_unary (TRUNCATE, mode, XEXP (op, 1), op_mode); + if (op1) + return simplify_gen_binary (GET_CODE (op), mode, op0, op1); + } + } + + /* Simplify (truncate:QI (lshiftrt:SI (sign_extend:SI (x:QI)) C)) into + to (ashiftrt:QI (x:QI) C), where C is a suitable small constant and + the outer subreg is effectively a truncation to the original mode. */ + if ((GET_CODE (op) == LSHIFTRT + || GET_CODE (op) == ASHIFTRT) + /* Ensure that OP_MODE is at least twice as wide as MODE + to avoid the possibility that an outer LSHIFTRT shifts by more + than the sign extension's sign_bit_copies and introduces zeros + into the high bits of the result. */ + && 2 * precision <= op_precision + && CONST_INT_P (XEXP (op, 1)) + && GET_CODE (XEXP (op, 0)) == SIGN_EXTEND + && GET_MODE (XEXP (XEXP (op, 0), 0)) == mode + && INTVAL (XEXP (op, 1)) < precision) + return simplify_gen_binary (ASHIFTRT, mode, + XEXP (XEXP (op, 0), 0), XEXP (op, 1)); + + /* Likewise (truncate:QI (lshiftrt:SI (zero_extend:SI (x:QI)) C)) into + to (lshiftrt:QI (x:QI) C), where C is a suitable small constant and + the outer subreg is effectively a truncation to the original mode. */ + if ((GET_CODE (op) == LSHIFTRT + || GET_CODE (op) == ASHIFTRT) + && CONST_INT_P (XEXP (op, 1)) + && GET_CODE (XEXP (op, 0)) == ZERO_EXTEND + && GET_MODE (XEXP (XEXP (op, 0), 0)) == mode + && INTVAL (XEXP (op, 1)) < precision) + return simplify_gen_binary (LSHIFTRT, mode, + XEXP (XEXP (op, 0), 0), XEXP (op, 1)); + + /* Likewise (truncate:QI (ashift:SI (zero_extend:SI (x:QI)) C)) into + to (ashift:QI (x:QI) C), where C is a suitable small constant and + the outer subreg is effectively a truncation to the original mode. */ + if (GET_CODE (op) == ASHIFT + && CONST_INT_P (XEXP (op, 1)) + && (GET_CODE (XEXP (op, 0)) == ZERO_EXTEND + || GET_CODE (XEXP (op, 0)) == SIGN_EXTEND) + && GET_MODE (XEXP (XEXP (op, 0), 0)) == mode + && INTVAL (XEXP (op, 1)) < precision) + return simplify_gen_binary (ASHIFT, mode, + XEXP (XEXP (op, 0), 0), XEXP (op, 1)); + + /* Recognize a word extraction from a multi-word subreg. */ + if ((GET_CODE (op) == LSHIFTRT + || GET_CODE (op) == ASHIFTRT) + && SCALAR_INT_MODE_P (mode) + && SCALAR_INT_MODE_P (op_mode) + && precision >= BITS_PER_WORD + && 2 * precision <= op_precision + && CONST_INT_P (XEXP (op, 1)) + && (INTVAL (XEXP (op, 1)) & (precision - 1)) == 0 + && INTVAL (XEXP (op, 1)) >= 0 + && INTVAL (XEXP (op, 1)) < op_precision) + { + int byte = subreg_lowpart_offset (mode, op_mode); + int shifted_bytes = INTVAL (XEXP (op, 1)) / BITS_PER_UNIT; + return simplify_gen_subreg (mode, XEXP (op, 0), op_mode, + (WORDS_BIG_ENDIAN + ? byte - shifted_bytes + : byte + shifted_bytes)); + } + + /* If we have a TRUNCATE of a right shift of MEM, make a new MEM + and try replacing the TRUNCATE and shift with it. Don't do this + if the MEM has a mode-dependent address. */ + if ((GET_CODE (op) == LSHIFTRT + || GET_CODE (op) == ASHIFTRT) + && SCALAR_INT_MODE_P (op_mode) + && MEM_P (XEXP (op, 0)) + && CONST_INT_P (XEXP (op, 1)) + && (INTVAL (XEXP (op, 1)) % GET_MODE_BITSIZE (mode)) == 0 + && INTVAL (XEXP (op, 1)) > 0 + && INTVAL (XEXP (op, 1)) < GET_MODE_BITSIZE (op_mode) + && ! mode_dependent_address_p (XEXP (XEXP (op, 0), 0), + MEM_ADDR_SPACE (XEXP (op, 0))) + && ! MEM_VOLATILE_P (XEXP (op, 0)) + && (GET_MODE_SIZE (mode) >= UNITS_PER_WORD + || WORDS_BIG_ENDIAN == BYTES_BIG_ENDIAN)) + { + int byte = subreg_lowpart_offset (mode, op_mode); + int shifted_bytes = INTVAL (XEXP (op, 1)) / BITS_PER_UNIT; + return adjust_address_nv (XEXP (op, 0), mode, + (WORDS_BIG_ENDIAN + ? byte - shifted_bytes + : byte + shifted_bytes)); + } + + /* (truncate:SI (OP:DI ({sign,zero}_extend:DI foo:SI))) is + (OP:SI foo:SI) if OP is NEG or ABS. */ + if ((GET_CODE (op) == ABS + || GET_CODE (op) == NEG) + && (GET_CODE (XEXP (op, 0)) == SIGN_EXTEND + || GET_CODE (XEXP (op, 0)) == ZERO_EXTEND) + && GET_MODE (XEXP (XEXP (op, 0), 0)) == mode) + return simplify_gen_unary (GET_CODE (op), mode, + XEXP (XEXP (op, 0), 0), mode); + + /* (truncate:A (subreg:B (truncate:C X) 0)) is + (truncate:A X). */ + if (GET_CODE (op) == SUBREG + && SCALAR_INT_MODE_P (mode) + && SCALAR_INT_MODE_P (op_mode) + && SCALAR_INT_MODE_P (GET_MODE (SUBREG_REG (op))) + && GET_CODE (SUBREG_REG (op)) == TRUNCATE + && subreg_lowpart_p (op)) + return simplify_gen_unary (TRUNCATE, mode, XEXP (SUBREG_REG (op), 0), + GET_MODE (XEXP (SUBREG_REG (op), 0))); + + /* (truncate:A (truncate:B X)) is (truncate:A X). */ + if (GET_CODE (op) == TRUNCATE) + return simplify_gen_unary (TRUNCATE, mode, XEXP (op, 0), + GET_MODE (XEXP (op, 0))); + + return NULL_RTX; +} + /* Try to simplify a unary operation CODE whose output mode is to be MODE with input operand OP whose mode was originally OP_MODE. Return zero if no simplification can be made. */ @@ -815,50 +1021,34 @@ simplify_unary_operation_1 (enum rtx_cod break; case TRUNCATE: - /* We can't handle truncation to a partial integer mode here - because we don't know the real bitsize of the partial - integer mode. */ - if (GET_MODE_CLASS (mode) == MODE_PARTIAL_INT) - break; - - /* (truncate:SI ({sign,zero}_extend:DI foo:SI)) == foo:SI. */ - if ((GET_CODE (op) == SIGN_EXTEND - || GET_CODE (op) == ZERO_EXTEND) - && GET_MODE (XEXP (op, 0)) == mode) - return XEXP (op, 0); + /* Don't optimize (lshiftrt (mult ...)) as it would interfere + with the umulXi3_highpart patterns. */ + if (GET_CODE (op) == LSHIFTRT + && GET_CODE (XEXP (op, 0)) == MULT) + break; - /* (truncate:SI (OP:DI ({sign,zero}_extend:DI foo:SI))) is - (OP:SI foo:SI) if OP is NEG or ABS. */ - if ((GET_CODE (op) == ABS - || GET_CODE (op) == NEG) - && (GET_CODE (XEXP (op, 0)) == SIGN_EXTEND - || GET_CODE (XEXP (op, 0)) == ZERO_EXTEND) - && GET_MODE (XEXP (XEXP (op, 0), 0)) == mode) - return simplify_gen_unary (GET_CODE (op), mode, - XEXP (XEXP (op, 0), 0), mode); + if (GET_MODE_CLASS (mode) == MODE_PARTIAL_INT) + { + if (TRULY_NOOP_TRUNCATION_MODES_P (mode, GET_MODE (op))) + return rtl_hooks.gen_lowpart_no_emit (mode, op); + /* We can't handle truncation to a partial integer mode here + because we don't know the real bitsize of the partial + integer mode. */ + break; + } - /* (truncate:A (subreg:B (truncate:C X) 0)) is - (truncate:A X). */ - if (GET_CODE (op) == SUBREG - && GET_CODE (SUBREG_REG (op)) == TRUNCATE - && subreg_lowpart_p (op)) - return simplify_gen_unary (TRUNCATE, mode, XEXP (SUBREG_REG (op), 0), - GET_MODE (XEXP (SUBREG_REG (op), 0))); + if (GET_MODE (op) != VOIDmode) + { + temp = simplify_truncation (mode, op, GET_MODE (op)); + if (temp) + return temp; + } /* If we know that the value is already truncated, we can - replace the TRUNCATE with a SUBREG. Note that this is also - valid if TRULY_NOOP_TRUNCATION is false for the corresponding - modes we just have to apply a different definition for - truncation. But don't do this for an (LSHIFTRT (MULT ...)) - since this will cause problems with the umulXi3_highpart - patterns. */ - if ((TRULY_NOOP_TRUNCATION_MODES_P (mode, GET_MODE (op)) - ? (num_sign_bit_copies (op, GET_MODE (op)) - > (unsigned int) (GET_MODE_PRECISION (GET_MODE (op)) - - GET_MODE_PRECISION (mode))) - : truncated_to_mode (mode, op)) - && ! (GET_CODE (op) == LSHIFTRT - && GET_CODE (XEXP (op, 0)) == MULT)) + replace the TRUNCATE with a SUBREG. */ + if (GET_MODE_NUNITS (mode) == 1 + && (TRULY_NOOP_TRUNCATION_MODES_P (mode, GET_MODE (op)) + || truncated_to_mode (mode, op))) return rtl_hooks.gen_lowpart_no_emit (mode, op); /* A truncate of a comparison can be replaced with a subreg if @@ -5596,14 +5786,6 @@ simplify_subreg (enum machine_mode outer return NULL_RTX; } - /* Merge implicit and explicit truncations. */ - - if (GET_CODE (op) == TRUNCATE - && GET_MODE_SIZE (outermode) < GET_MODE_SIZE (innermode) - && subreg_lowpart_offset (outermode, innermode) == byte) - return simplify_gen_unary (TRUNCATE, outermode, XEXP (op, 0), - GET_MODE (XEXP (op, 0))); - /* SUBREG of a hard register => just change the register number and/or mode. If the hard register is not valid in that mode, suppress this simplification. If the hard register is the stack, @@ -5689,160 +5871,23 @@ simplify_subreg (enum machine_mode outer return NULL_RTX; } - /* Optimize SUBREG truncations of zero and sign extended values. */ - if ((GET_CODE (op) == ZERO_EXTEND - || GET_CODE (op) == SIGN_EXTEND) - && SCALAR_INT_MODE_P (innermode) - && GET_MODE_PRECISION (outermode) < GET_MODE_PRECISION (innermode)) + /* A SUBREG resulting from a zero extension may fold to zero if + it extracts higher bits that the ZERO_EXTEND's source bits. */ + if (GET_CODE (op) == ZERO_EXTEND) { unsigned int bitpos = subreg_lsb_1 (outermode, innermode, byte); - - /* If we're requesting the lowpart of a zero or sign extension, - there are three possibilities. If the outermode is the same - as the origmode, we can omit both the extension and the subreg. - If the outermode is not larger than the origmode, we can apply - the truncation without the extension. Finally, if the outermode - is larger than the origmode, but both are integer modes, we - can just extend to the appropriate mode. */ - if (bitpos == 0) - { - enum machine_mode origmode = GET_MODE (XEXP (op, 0)); - if (outermode == origmode) - return XEXP (op, 0); - if (GET_MODE_PRECISION (outermode) <= GET_MODE_PRECISION (origmode)) - return simplify_gen_subreg (outermode, XEXP (op, 0), origmode, - subreg_lowpart_offset (outermode, - origmode)); - if (SCALAR_INT_MODE_P (outermode)) - return simplify_gen_unary (GET_CODE (op), outermode, - XEXP (op, 0), origmode); - } - - /* A SUBREG resulting from a zero extension may fold to zero if - it extracts higher bits that the ZERO_EXTEND's source bits. */ - if (GET_CODE (op) == ZERO_EXTEND - && bitpos >= GET_MODE_PRECISION (GET_MODE (XEXP (op, 0)))) + if (bitpos >= GET_MODE_PRECISION (GET_MODE (XEXP (op, 0)))) return CONST0_RTX (outermode); } - /* Simplify (subreg:SI (op:DI ((x:DI) (y:DI)), 0) - to (op:SI (subreg:SI (x:DI) 0) (subreg:SI (x:DI) 0)), where - the outer subreg is effectively a truncation to the original mode. */ - if ((GET_CODE (op) == PLUS - || GET_CODE (op) == MINUS - || GET_CODE (op) == MULT) - && SCALAR_INT_MODE_P (outermode) - && SCALAR_INT_MODE_P (innermode) - && GET_MODE_PRECISION (outermode) < GET_MODE_PRECISION (innermode) - && byte == subreg_lowpart_offset (outermode, innermode)) - { - rtx op0 = simplify_gen_subreg (outermode, XEXP (op, 0), - innermode, byte); - if (op0) - { - rtx op1 = simplify_gen_subreg (outermode, XEXP (op, 1), - innermode, byte); - if (op1) - return simplify_gen_binary (GET_CODE (op), outermode, op0, op1); - } - } - - /* Simplify (subreg:QI (lshiftrt:SI (sign_extend:SI (x:QI)) C), 0) into - to (ashiftrt:QI (x:QI) C), where C is a suitable small constant and - the outer subreg is effectively a truncation to the original mode. */ - if ((GET_CODE (op) == LSHIFTRT - || GET_CODE (op) == ASHIFTRT) - && SCALAR_INT_MODE_P (outermode) - && SCALAR_INT_MODE_P (innermode) - /* Ensure that OUTERMODE is at least twice as wide as the INNERMODE - to avoid the possibility that an outer LSHIFTRT shifts by more - than the sign extension's sign_bit_copies and introduces zeros - into the high bits of the result. */ - && (2 * GET_MODE_PRECISION (outermode)) <= GET_MODE_PRECISION (innermode) - && CONST_INT_P (XEXP (op, 1)) - && GET_CODE (XEXP (op, 0)) == SIGN_EXTEND - && GET_MODE (XEXP (XEXP (op, 0), 0)) == outermode - && INTVAL (XEXP (op, 1)) < GET_MODE_PRECISION (outermode) - && subreg_lsb_1 (outermode, innermode, byte) == 0) - return simplify_gen_binary (ASHIFTRT, outermode, - XEXP (XEXP (op, 0), 0), XEXP (op, 1)); - - /* Likewise (subreg:QI (lshiftrt:SI (zero_extend:SI (x:QI)) C), 0) into - to (lshiftrt:QI (x:QI) C), where C is a suitable small constant and - the outer subreg is effectively a truncation to the original mode. */ - if ((GET_CODE (op) == LSHIFTRT - || GET_CODE (op) == ASHIFTRT) - && SCALAR_INT_MODE_P (outermode) - && SCALAR_INT_MODE_P (innermode) - && GET_MODE_PRECISION (outermode) < GET_MODE_PRECISION (innermode) - && CONST_INT_P (XEXP (op, 1)) - && GET_CODE (XEXP (op, 0)) == ZERO_EXTEND - && GET_MODE (XEXP (XEXP (op, 0), 0)) == outermode - && INTVAL (XEXP (op, 1)) < GET_MODE_PRECISION (outermode) - && subreg_lsb_1 (outermode, innermode, byte) == 0) - return simplify_gen_binary (LSHIFTRT, outermode, - XEXP (XEXP (op, 0), 0), XEXP (op, 1)); - - /* Likewise (subreg:QI (ashift:SI (zero_extend:SI (x:QI)) C), 0) into - to (ashift:QI (x:QI) C), where C is a suitable small constant and - the outer subreg is effectively a truncation to the original mode. */ - if (GET_CODE (op) == ASHIFT - && SCALAR_INT_MODE_P (outermode) + if (SCALAR_INT_MODE_P (outermode) && SCALAR_INT_MODE_P (innermode) && GET_MODE_PRECISION (outermode) < GET_MODE_PRECISION (innermode) - && CONST_INT_P (XEXP (op, 1)) - && (GET_CODE (XEXP (op, 0)) == ZERO_EXTEND - || GET_CODE (XEXP (op, 0)) == SIGN_EXTEND) - && GET_MODE (XEXP (XEXP (op, 0), 0)) == outermode - && INTVAL (XEXP (op, 1)) < GET_MODE_PRECISION (outermode) - && subreg_lsb_1 (outermode, innermode, byte) == 0) - return simplify_gen_binary (ASHIFT, outermode, - XEXP (XEXP (op, 0), 0), XEXP (op, 1)); - - /* Recognize a word extraction from a multi-word subreg. */ - if ((GET_CODE (op) == LSHIFTRT - || GET_CODE (op) == ASHIFTRT) - && SCALAR_INT_MODE_P (innermode) - && GET_MODE_PRECISION (outermode) >= BITS_PER_WORD - && GET_MODE_PRECISION (innermode) >= (2 * GET_MODE_PRECISION (outermode)) - && CONST_INT_P (XEXP (op, 1)) - && (INTVAL (XEXP (op, 1)) & (GET_MODE_PRECISION (outermode) - 1)) == 0 - && INTVAL (XEXP (op, 1)) >= 0 - && INTVAL (XEXP (op, 1)) < GET_MODE_PRECISION (innermode) && byte == subreg_lowpart_offset (outermode, innermode)) { - int shifted_bytes = INTVAL (XEXP (op, 1)) / BITS_PER_UNIT; - return simplify_gen_subreg (outermode, XEXP (op, 0), innermode, - (WORDS_BIG_ENDIAN - ? byte - shifted_bytes - : byte + shifted_bytes)); - } - - /* If we have a lowpart SUBREG of a right shift of MEM, make a new MEM - and try replacing the SUBREG and shift with it. Don't do this if - the MEM has a mode-dependent address or if we would be widening it. */ - - if ((GET_CODE (op) == LSHIFTRT - || GET_CODE (op) == ASHIFTRT) - && SCALAR_INT_MODE_P (innermode) - && MEM_P (XEXP (op, 0)) - && CONST_INT_P (XEXP (op, 1)) - && GET_MODE_SIZE (outermode) < GET_MODE_SIZE (GET_MODE (op)) - && (INTVAL (XEXP (op, 1)) % GET_MODE_BITSIZE (outermode)) == 0 - && INTVAL (XEXP (op, 1)) > 0 - && INTVAL (XEXP (op, 1)) < GET_MODE_BITSIZE (innermode) - && ! mode_dependent_address_p (XEXP (XEXP (op, 0), 0), - MEM_ADDR_SPACE (XEXP (op, 0))) - && ! MEM_VOLATILE_P (XEXP (op, 0)) - && byte == subreg_lowpart_offset (outermode, innermode) - && (GET_MODE_SIZE (outermode) >= UNITS_PER_WORD - || WORDS_BIG_ENDIAN == BYTES_BIG_ENDIAN)) - { - int shifted_bytes = INTVAL (XEXP (op, 1)) / BITS_PER_UNIT; - return adjust_address_nv (XEXP (op, 0), outermode, - (WORDS_BIG_ENDIAN - ? byte - shifted_bytes - : byte + shifted_bytes)); + rtx tem = simplify_truncation (outermode, op, innermode); + if (tem) + return tem; } return NULL_RTX; Index: gcc/config/mips/mips.c =================================================================== --- gcc/config/mips/mips.c 2012-10-06 11:22:55.888609330 +0100 +++ gcc/config/mips/mips.c 2012-10-06 16:32:25.240799783 +0100 @@ -3527,6 +3527,17 @@ mips_set_reg_reg_cost (enum machine_mode } } +/* Return the cost of an operand X that can be trucated for free. + SPEED says whether we're optimizing for size or speed. */ + +static int +mips_truncated_op_cost (rtx x, bool speed) +{ + if (GET_CODE (x) == TRUNCATE) + x = XEXP (x, 0); + return set_src_cost (x, speed); +} + /* Implement TARGET_RTX_COSTS. */ static bool @@ -3907,12 +3918,13 @@ mips_rtx_costs (rtx x, int code, int out case ZERO_EXTEND: if (outer_code == SET && ISA_HAS_BADDU - && (GET_CODE (XEXP (x, 0)) == TRUNCATE - || GET_CODE (XEXP (x, 0)) == SUBREG) && GET_MODE (XEXP (x, 0)) == QImode - && GET_CODE (XEXP (XEXP (x, 0), 0)) == PLUS) + && GET_CODE (XEXP (x, 0)) == PLUS) { - *total = set_src_cost (XEXP (XEXP (x, 0), 0), speed); + rtx plus = XEXP (x, 0); + *total = (COSTS_N_INSNS (1) + + mips_truncated_op_cost (XEXP (plus, 0), speed) + + mips_truncated_op_cost (XEXP (plus, 1), speed)); return true; } *total = mips_zero_extend_cost (mode, XEXP (x, 0)); Index: gcc/config/mips/mips.md =================================================================== --- gcc/config/mips/mips.md 2012-10-06 11:22:55.888609330 +0100 +++ gcc/config/mips/mips.md 2012-10-06 16:32:21.168800012 +0100 @@ -1305,9 +1305,8 @@ (define_insn "*baddu_si" (define_insn "*baddu_di<mode>" [(set (match_operand:GPR 0 "register_operand" "=d") (zero_extend:GPR - (truncate:QI - (plus:DI (match_operand:DI 1 "register_operand" "d") - (match_operand:DI 2 "register_operand" "d")))))] + (plus:QI (truncate:QI (match_operand:DI 1 "register_operand" "d")) + (truncate:QI (match_operand:DI 2 "register_operand" "d")))))] "ISA_HAS_BADDU && TARGET_64BIT" "baddu\\t%0,%1,%2" [(set_attr "alu_type" "add")])