gallivm: add a version of log2 which handles edge cases

That means that if input is:
 * - less than zero (to and including -inf) then NaN will be returned
 * - equal to zero (-denorm, -0, +0 or +denorm), then -inf will be returned
 * - +infinity, then +infinity will be returned
 * - NaN, then NaN will be returned
It's a separate function because the checks are a little bit costly
and in most cases are likely unnecessary.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_tgsi_action.c b/src/gallium/auxiliary/gallivm/lp_bld_tgsi_action.c
index f23e08b..d16ccae 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_tgsi_action.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_tgsi_action.c
@@ -1236,8 +1236,8 @@ lg2_emit_cpu(
    struct lp_build_tgsi_context * bld_base,
    struct lp_build_emit_data * emit_data)
 {
-   emit_data->output[emit_data->chan] = lp_build_log2(&bld_base->base,
-                                                        emit_data->args[0]);
+   emit_data->output[emit_data->chan] = lp_build_log2_safe(&bld_base->base,
+                                                           emit_data->args[0]);
 }
 
 /* TGSI_OPCODE_LOG (CPU Only) */
@@ -1253,7 +1253,7 @@ log_emit_cpu(
    LLVMValueRef src0 = emit_data->args[0];
 
    lp_build_log2_approx(&bld_base->base, src0,
-                        &p_exp, &p_floor_log2, &p_log2);
+                        &p_exp, &p_floor_log2, &p_log2, FALSE);
 
    emit_data->output[TGSI_CHAN_X] = p_floor_log2;