<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Apr 22, 2016 at 3:13 PM, Jason Ekstrand <span dir="ltr"><<a href="mailto:jason@jlekstrand.net" target="_blank">jason@jlekstrand.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote"><span class="">On Tue, Apr 12, 2016 at 1:05 AM, Samuel Iglesias Gonsálvez <span dir="ltr"><<a href="mailto:siglesias@igalia.com" target="_blank">siglesias@igalia.com</a>></span> wrote:<br></span><div><div class="h5"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">From: Iago Toral Quiroga <<a href="mailto:itoral@igalia.com" target="_blank">itoral@igalia.com</a>><br>
<br>
At least i965 hardware does not have native support for floor on doubles.<br>
---<br>
src/compiler/nir/nir.h | 1 +<br>
src/compiler/nir/nir_lower_double_ops.c | 29 +++++++++++++++++++++++++++++<br>
2 files changed, 30 insertions(+)<br>
<br>
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h<br>
index f83b2e0..b7231a7 100644<br>
--- a/src/compiler/nir/nir.h<br>
+++ b/src/compiler/nir/nir.h<br>
@@ -2287,6 +2287,7 @@ typedef enum {<br>
nir_lower_dsqrt = (1 << 1),<br>
nir_lower_drsq = (1 << 2),<br>
nir_lower_dtrunc = (1 << 3),<br>
+ nir_lower_dfloor = (1 << 4),<br>
} nir_lower_doubles_options;<br>
<br>
void nir_lower_doubles(nir_shader *shader, nir_lower_doubles_options options);<br>
diff --git a/src/compiler/nir/nir_lower_double_ops.c b/src/compiler/nir/nir_lower_double_ops.c<br>
index 9eec858..e1ec6da 100644<br>
--- a/src/compiler/nir/nir_lower_double_ops.c<br>
+++ b/src/compiler/nir/nir_lower_double_ops.c<br>
@@ -377,6 +377,27 @@ lower_trunc(nir_builder *b, nir_ssa_def *src)<br>
return nir_pack_double_2x32_split(b, new_src_lo, new_src_hi);<br>
}<br>
<br>
+static nir_ssa_def *<br>
+lower_floor(nir_builder *b, nir_ssa_def *src)<br>
+{<br>
+ /*<br>
+ * For x >= 0, floor(x) = trunc(x)<br>
+ * For x < 0,<br>
+ * - if x is integer, floor(x) = x<br>
+ * - otherwise, floor(x) = trunc(x) - 1<br>
+ */<br>
+ nir_ssa_def *tr = nir_ftrunc(b, src);<br>
+ return nir_bcsel(b,<br>
+ nir_fge(b, src, nir_imm_double(b, 0.0)),<br>
+ tr,<br>
+ nir_bcsel(b,<br>
+ nir_fne(b,<br>
+ nir_fsub(b, src, tr),<br>
+ nir_imm_double(b, 0.0)),<br></blockquote><div><br></div></div></div><div>As an aside, you can just as easily check "x is integer" by "x == truc(x)". That might be simpler. Same goes for ceil().<br></div></div></div></div></blockquote><div><br></div><div>One more thought (Sorry for all the e-mails): It might be better to implement this as<br><br></div><div>floor(x) = (x >= 0 || x == trunc(x)) ? trunc(x) : trunc(x) - 1;<br><br></div><div>That way you only have one bcsel and fewer 64-bit values floating around. It *might* reduce register pressure (not sure if it actually will).<br></div><div>--Jason<br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><div></div><div><div class="h5"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
+ nir_fsub(b, tr, nir_imm_double(b, 1.0)),<br>
+ src));<br>
+}<br>
+<br>
static void<br>
lower_doubles_instr(nir_alu_instr *instr, nir_lower_doubles_options options)<br>
{<br>
@@ -405,6 +426,11 @@ lower_doubles_instr(nir_alu_instr *instr, nir_lower_doubles_options options)<br>
return;<br>
break;<br>
<br>
+ case nir_op_ffloor:<br>
+ if (!(options & nir_lower_dfloor))<br>
+ return;<br>
+ break;<br>
+<br>
default:<br>
return;<br>
}<br>
@@ -431,6 +457,9 @@ lower_doubles_instr(nir_alu_instr *instr, nir_lower_doubles_options options)<br>
case nir_op_ftrunc:<br>
result = lower_trunc(&bld, src);<br>
break;<br>
+ case nir_op_ffloor:<br>
+ result = lower_floor(&bld, src);<br>
+ break;<br>
default:<br>
unreachable("unhandled opcode");<br>
}<br>
<span><font color="#888888">--<br>
2.5.0<br>
<br>
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