diff options
Diffstat (limited to 'gcc/rtlanal.c')
| -rw-r--r-- | gcc/rtlanal.c | 312 |
1 files changed, 312 insertions, 0 deletions
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c index d61df8902bf..8ada3974c1b 100644 --- a/gcc/rtlanal.c +++ b/gcc/rtlanal.c @@ -4333,3 +4333,315 @@ insn_rtx_cost (rtx pat) cost = rtx_cost (SET_SRC (set), SET); return cost > 0 ? cost : COSTS_N_INSNS (1); } + +/* Given an insn INSN and condition COND, return the condition in a + canonical form to simplify testing by callers. Specifically: + + (1) The code will always be a comparison operation (EQ, NE, GT, etc.). + (2) Both operands will be machine operands; (cc0) will have been replaced. + (3) If an operand is a constant, it will be the second operand. + (4) (LE x const) will be replaced with (LT x <const+1>) and similarly + for GE, GEU, and LEU. + + If the condition cannot be understood, or is an inequality floating-point + comparison which needs to be reversed, 0 will be returned. + + If REVERSE is nonzero, then reverse the condition prior to canonizing it. + + If EARLIEST is nonzero, it is a pointer to a place where the earliest + insn used in locating the condition was found. If a replacement test + of the condition is desired, it should be placed in front of that + insn and we will be sure that the inputs are still valid. + + If WANT_REG is nonzero, we wish the condition to be relative to that + register, if possible. Therefore, do not canonicalize the condition + further. If ALLOW_CC_MODE is nonzero, allow the condition returned + to be a compare to a CC mode register. + + If VALID_AT_INSN_P, the condition must be valid at both *EARLIEST + and at INSN. */ + +rtx +canonicalize_condition (rtx insn, rtx cond, int reverse, rtx *earliest, + rtx want_reg, int allow_cc_mode, int valid_at_insn_p) +{ + enum rtx_code code; + rtx prev = insn; + rtx set; + rtx tem; + rtx op0, op1; + int reverse_code = 0; + enum machine_mode mode; + + code = GET_CODE (cond); + mode = GET_MODE (cond); + op0 = XEXP (cond, 0); + op1 = XEXP (cond, 1); + + if (reverse) + code = reversed_comparison_code (cond, insn); + if (code == UNKNOWN) + return 0; + + if (earliest) + *earliest = insn; + + /* If we are comparing a register with zero, see if the register is set + in the previous insn to a COMPARE or a comparison operation. Perform + the same tests as a function of STORE_FLAG_VALUE as find_comparison_args + in cse.c */ + + while ((GET_RTX_CLASS (code) == RTX_COMPARE + || GET_RTX_CLASS (code) == RTX_COMM_COMPARE) + && op1 == CONST0_RTX (GET_MODE (op0)) + && op0 != want_reg) + { + /* Set nonzero when we find something of interest. */ + rtx x = 0; + +#ifdef HAVE_cc0 + /* If comparison with cc0, import actual comparison from compare + insn. */ + if (op0 == cc0_rtx) + { + if ((prev = prev_nonnote_insn (prev)) == 0 + || !NONJUMP_INSN_P (prev) + || (set = single_set (prev)) == 0 + || SET_DEST (set) != cc0_rtx) + return 0; + + op0 = SET_SRC (set); + op1 = CONST0_RTX (GET_MODE (op0)); + if (earliest) + *earliest = prev; + } +#endif + + /* If this is a COMPARE, pick up the two things being compared. */ + if (GET_CODE (op0) == COMPARE) + { + op1 = XEXP (op0, 1); + op0 = XEXP (op0, 0); + continue; + } + else if (!REG_P (op0)) + break; + + /* Go back to the previous insn. Stop if it is not an INSN. We also + stop if it isn't a single set or if it has a REG_INC note because + we don't want to bother dealing with it. */ + + if ((prev = prev_nonnote_insn (prev)) == 0 + || !NONJUMP_INSN_P (prev) + || FIND_REG_INC_NOTE (prev, NULL_RTX)) + break; + + set = set_of (op0, prev); + + if (set + && (GET_CODE (set) != SET + || !rtx_equal_p (SET_DEST (set), op0))) + break; + + /* If this is setting OP0, get what it sets it to if it looks + relevant. */ + if (set) + { + enum machine_mode inner_mode = GET_MODE (SET_DEST (set)); +#ifdef FLOAT_STORE_FLAG_VALUE + REAL_VALUE_TYPE fsfv; +#endif + + /* ??? We may not combine comparisons done in a CCmode with + comparisons not done in a CCmode. This is to aid targets + like Alpha that have an IEEE compliant EQ instruction, and + a non-IEEE compliant BEQ instruction. The use of CCmode is + actually artificial, simply to prevent the combination, but + should not affect other platforms. + + However, we must allow VOIDmode comparisons to match either + CCmode or non-CCmode comparison, because some ports have + modeless comparisons inside branch patterns. + + ??? This mode check should perhaps look more like the mode check + in simplify_comparison in combine. */ + + if ((GET_CODE (SET_SRC (set)) == COMPARE + || (((code == NE + || (code == LT + && GET_MODE_CLASS (inner_mode) == MODE_INT + && (GET_MODE_BITSIZE (inner_mode) + <= HOST_BITS_PER_WIDE_INT) + && (STORE_FLAG_VALUE + & ((HOST_WIDE_INT) 1 + << (GET_MODE_BITSIZE (inner_mode) - 1)))) +#ifdef FLOAT_STORE_FLAG_VALUE + || (code == LT + && GET_MODE_CLASS (inner_mode) == MODE_FLOAT + && (fsfv = FLOAT_STORE_FLAG_VALUE (inner_mode), + REAL_VALUE_NEGATIVE (fsfv))) +#endif + )) + && COMPARISON_P (SET_SRC (set)))) + && (((GET_MODE_CLASS (mode) == MODE_CC) + == (GET_MODE_CLASS (inner_mode) == MODE_CC)) + || mode == VOIDmode || inner_mode == VOIDmode)) + x = SET_SRC (set); + else if (((code == EQ + || (code == GE + && (GET_MODE_BITSIZE (inner_mode) + <= HOST_BITS_PER_WIDE_INT) + && GET_MODE_CLASS (inner_mode) == MODE_INT + && (STORE_FLAG_VALUE + & ((HOST_WIDE_INT) 1 + << (GET_MODE_BITSIZE (inner_mode) - 1)))) +#ifdef FLOAT_STORE_FLAG_VALUE + || (code == GE + && GET_MODE_CLASS (inner_mode) == MODE_FLOAT + && (fsfv = FLOAT_STORE_FLAG_VALUE (inner_mode), + REAL_VALUE_NEGATIVE (fsfv))) +#endif + )) + && COMPARISON_P (SET_SRC (set)) + && (((GET_MODE_CLASS (mode) == MODE_CC) + == (GET_MODE_CLASS (inner_mode) == MODE_CC)) + || mode == VOIDmode || inner_mode == VOIDmode)) + + { + reverse_code = 1; + x = SET_SRC (set); + } + else + break; + } + + else if (reg_set_p (op0, prev)) + /* If this sets OP0, but not directly, we have to give up. */ + break; + + if (x) + { + /* If the caller is expecting the condition to be valid at INSN, + make sure X doesn't change before INSN. */ + if (valid_at_insn_p) + if (modified_in_p (x, prev) || modified_between_p (x, prev, insn)) + break; + if (COMPARISON_P (x)) + code = GET_CODE (x); + if (reverse_code) + { + code = reversed_comparison_code (x, prev); + if (code == UNKNOWN) + return 0; + reverse_code = 0; + } + + op0 = XEXP (x, 0), op1 = XEXP (x, 1); + if (earliest) + *earliest = prev; + } + } + + /* If constant is first, put it last. */ + if (CONSTANT_P (op0)) + code = swap_condition (code), tem = op0, op0 = op1, op1 = tem; + + /* If OP0 is the result of a comparison, we weren't able to find what + was really being compared, so fail. */ + if (!allow_cc_mode + && GET_MODE_CLASS (GET_MODE (op0)) == MODE_CC) + return 0; + + /* Canonicalize any ordered comparison with integers involving equality + if we can do computations in the relevant mode and we do not + overflow. */ + + if (GET_MODE_CLASS (GET_MODE (op0)) != MODE_CC + && GET_CODE (op1) == CONST_INT + && GET_MODE (op0) != VOIDmode + && GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT) + { + HOST_WIDE_INT const_val = INTVAL (op1); + unsigned HOST_WIDE_INT uconst_val = const_val; + unsigned HOST_WIDE_INT max_val + = (unsigned HOST_WIDE_INT) GET_MODE_MASK (GET_MODE (op0)); + + switch (code) + { + case LE: + if ((unsigned HOST_WIDE_INT) const_val != max_val >> 1) + code = LT, op1 = gen_int_mode (const_val + 1, GET_MODE (op0)); + break; + + /* When cross-compiling, const_val might be sign-extended from + BITS_PER_WORD to HOST_BITS_PER_WIDE_INT */ + case GE: + if ((HOST_WIDE_INT) (const_val & max_val) + != (((HOST_WIDE_INT) 1 + << (GET_MODE_BITSIZE (GET_MODE (op0)) - 1)))) + code = GT, op1 = gen_int_mode (const_val - 1, GET_MODE (op0)); + break; + + case LEU: + if (uconst_val < max_val) + code = LTU, op1 = gen_int_mode (uconst_val + 1, GET_MODE (op0)); + break; + + case GEU: + if (uconst_val != 0) + code = GTU, op1 = gen_int_mode (uconst_val - 1, GET_MODE (op0)); + break; + + default: + break; + } + } + + /* Never return CC0; return zero instead. */ + if (CC0_P (op0)) + return 0; + + return gen_rtx_fmt_ee (code, VOIDmode, op0, op1); +} + +/* Given a jump insn JUMP, return the condition that will cause it to branch + to its JUMP_LABEL. If the condition cannot be understood, or is an + inequality floating-point comparison which needs to be reversed, 0 will + be returned. + + If EARLIEST is nonzero, it is a pointer to a place where the earliest + insn used in locating the condition was found. If a replacement test + of the condition is desired, it should be placed in front of that + insn and we will be sure that the inputs are still valid. If EARLIEST + is null, the returned condition will be valid at INSN. + + If ALLOW_CC_MODE is nonzero, allow the condition returned to be a + compare CC mode register. + + VALID_AT_INSN_P is the same as for canonicalize_condition. */ + +rtx +get_condition (rtx jump, rtx *earliest, int allow_cc_mode, int valid_at_insn_p) +{ + rtx cond; + int reverse; + rtx set; + + /* If this is not a standard conditional jump, we can't parse it. */ + if (!JUMP_P (jump) + || ! any_condjump_p (jump)) + return 0; + set = pc_set (jump); + + cond = XEXP (SET_SRC (set), 0); + + /* If this branches to JUMP_LABEL when the condition is false, reverse + the condition. */ + reverse + = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF + && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump); + + return canonicalize_condition (jump, cond, reverse, earliest, NULL_RTX, + allow_cc_mode, valid_at_insn_p); +} + |