[Mono-devel-list] [PATCH] Constant folding signed div

[Paolo Molaro]

On 11/23/04 Torstensson, Patrik wrote:
> +/* divide cfold helper */
> +MINI_OP(OP_DIV_CFOLD, "op_div_cfold")

I don't like the OP_DIV_CFOLD name. Maybe OP_DIV_POWER2_IMM?
Any better suggestions?

> +reg: OP_DIV_CFOLD (reg, OP_ICONST) {
> +	MonoInst *not_signed;
> +	int imm = state->right->tree->inst_c0;
> +	
> +	MONO_NEW_LABEL (s, not_signed);
> +	
> +	MONO_EMIT_NEW_BIALU_IMM (s, OP_COMPARE_IMM, state->left->reg1, state->left->reg1, 0);
> +	MONO_EMIT_NEW_BRANCH_LABEL (s, CEE_BGE, not_signed);
> +	if (imm == 1)
> +		MONO_EMIT_NEW_BIALU_IMM (s, OP_ADC_IMM, state->left->reg1, state->left->reg1, 1);
> +	else
> +		MONO_EMIT_NEW_BIALU_IMM (s, OP_ADD_IMM, state->left->reg1, state->left->reg1, (1 << imm) - 1);
> +	
> +	mono_bblock_add_inst (s->cbb, not_signed);
> +	
> +	MONO_EMIT_NEW_BIALU_IMM (s, OP_SHR_IMM, state->left->reg1, state->left->reg1, imm);
> +	MONO_EMIT_NEW_UNALU (s, OP_MOVE, state->reg1, state->left->reg1);	
> +}

This needs to be forced in its own tree, but there is no good way to do it
when the code in cfold.c runs:-(
Maybe it's better to just introduce the OP_DIV_POWER2_IMM opcode
and let the backend code optionally implement it.

Thanks,
lupus

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