Am 15.01.2016 um 20:13 schrieb Jeff Muizelaar:
> This adds code that is basically the same as the code in smod, div and idiv.
That would be umod, not smod, above (and udiv).
> However, unlike idiv we return -1.
>
> diff --git a/src/gallium/auxiliary/gallivm/lp_bld_tgsi_action.c
> b/src/gallium/auxiliary/gallivm/lp_bld_tgsi_action.c
> index 0ad78b0..d17ef31 100644
> --- a/src/gallium/auxiliary/gallivm/lp_bld_tgsi_action.c
> +++ b/src/gallium/auxiliary/gallivm/lp_bld_tgsi_action.c
> @@ -1524,18 +1524,32 @@ min_emit_cpu(
>
> /* TGSI_OPCODE_MOD (CPU Only) */
> static void
> mod_emit_cpu(
> const struct lp_build_tgsi_action * action,
> struct lp_build_tgsi_context * bld_base,
> struct lp_build_emit_data * emit_data)
> {
> - emit_data->output[emit_data->chan] = lp_build_mod(&bld_base->int_bld,
> - emit_data->args[0], emit_data->args[1]);
> + LLVMBuilderRef builder = bld_base->base.gallivm->builder;
> + LLVMValueRef div_mask = lp_build_cmp(&bld_base->uint_bld,
> + PIPE_FUNC_EQUAL, emit_data->args[1],
> + bld_base->uint_bld.zero);
> + /* We want to make sure that we never divide/mod by zero to not
> + * generate sigfpe. We don't want to crash just because the
> + * shader is doing something weird. */
> + LLVMValueRef divisor = LLVMBuildOr(builder,
> + div_mask,
> + emit_data->args[1], "");
> + LLVMValueRef result = lp_build_mod(&bld_base->int_bld,
> + emit_data->args[0], divisor);
> + /* umod by zero is guaranteed to return 0xffffffff */
I think this should use language along the lines of what idiv does, i.e.
no guaranteed value, pick -1. Because we don't say anything about that
in the gallium tgsi docs section about that (unlike udiv/umod).
(AFAIK we only really care for udiv/umod due to d3d10, which doesn't
have the signed versions - glsl doesn't care either way.)
> + emit_data->output[emit_data->chan] = LLVMBuildOr(builder,
> + div_mask,
> + result, "");
> }
>
> /* TGSI_OPCODE_NOT */
> static void
> not_emit_cpu(
> const struct lp_build_tgsi_action * action,
> struct lp_build_tgsi_context * bld_base,
> struct lp_build_emit_data * emit_data)
Subject should probably say: gallivm: ...
With that fixed: Reviewed-by: Roland Scheidegger <srol...@vmware.com>
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