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| author | Richard Kenner <kenner@gcc.gnu.org> | 1994-09-22 18:56:08 -0400 |
|---|---|---|
| committer | Richard Kenner <kenner@gcc.gnu.org> | 1994-09-22 18:56:08 -0400 |
| commit | 73f277280f8f89979f1ecea9de0ef8a385f7f0f8 (patch) | |
| tree | 6601134e565e4a1b6059231cbac42e3df26e9154 /gcc/expmed.c | |
| parent | eeed1288b804a77aa2914567bb7bf06463076b3a (diff) | |
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(expand_divmod): Special case for signed CEIL_DIV_EXPR when divisor is
power of 2.
From-SVN: r8123
Diffstat (limited to 'gcc/expmed.c')
| -rw-r--r-- | gcc/expmed.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/gcc/expmed.c b/gcc/expmed.c index 715aedf..c5860a0 100644 --- a/gcc/expmed.c +++ b/gcc/expmed.c @@ -3247,6 +3247,44 @@ expand_divmod (rem_flag, code, mode, op0, op1, target, unsignedp) } else /* signed */ { + if (op1_is_constant && EXACT_POWER_OF_2_OR_ZERO_P (INTVAL (op1)) + && INTVAL (op1) >= 0) + { + /* This is extremely similar to the code for the unsigned case + above. For 2.7 we should merge these variants, but for + 2.6.1 I don't want to touch the code for unsigned since that + get used in C. The signed case will only be used by other + languages (Ada). */ + + rtx t1, t2, t3; + unsigned HOST_WIDE_INT d = INTVAL (op1); + t1 = expand_shift (RSHIFT_EXPR, compute_mode, op0, + build_int_2 (floor_log2 (d), 0), + tquotient, 0); + t2 = expand_binop (compute_mode, and_optab, op0, + GEN_INT (d - 1), + NULL_RTX, 1, OPTAB_LIB_WIDEN); + t3 = gen_reg_rtx (compute_mode); + t3 = emit_store_flag (t3, NE, t2, const0_rtx, + compute_mode, 1, 1); + if (t3 == 0) + { + rtx lab; + lab = gen_label_rtx (); + emit_cmp_insn (t2, const0_rtx, EQ, NULL_RTX, + compute_mode, 0, 0); + emit_jump_insn (gen_beq (lab)); + expand_inc (t1, const1_rtx); + emit_label (lab); + quotient = t1; + } + else + quotient = force_operand (gen_rtx (PLUS, compute_mode, + t1, t3), + tquotient); + break; + } + /* Try using an instruction that produces both the quotient and remainder, using truncation. We can easily compensate the quotient or remainder to get ceiling rounding, once we have the |