gallium: fix tgsi SAMPLE_L opcode to use separate source for explicit lod

It looks like using coord.w as explicit lod value is a mistake, most likely
because some dx10 docs had it specified that way. Seems this was changed though:
http://msdn.microsoft.com/en-us/library/windows/desktop/hh447229%28v=vs.85%29.aspx
- let's just hope it doesn't depend on runtime build version or something.
Not only would this need translation (so go against the stated goal these
opcodes should be close to dx10 semantics) but it would prevent usage of this
opcode with cube arrays, which is apparently possible:
http://msdn.microsoft.com/en-us/library/windows/desktop/bb509699%28v=vs.85%29.aspx
(Note not only does this show cube arrays using explicit lod, but also the
confusion with this opcode: it lists an explicit lod parameter value, but then
states last component of location is used as lod).
(For "true" hw drivers, only nv50 had code to handle it, and it appears the
code was already right for the new semantics, though fix up the seemingly
wrong c/d arguments while there.)

v2: fix comment, separate out other changes.

Reviewed-by: Jose Fonseca <jfonseca@vmware.com>

7 files changed, 10 insertions, 20 deletions

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_tgsi_info.c b/src/gallium/auxiliary/gallivm/lp_bld_tgsi_info.c
index cb6564ad079..3a19fe2a64f 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_tgsi_info.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_tgsi_info.c
@@ -241,13 +241,10 @@ analyse_sample(struct analysis_context *ctx,
       tex_info->sampler_unit = inst->Src[2].Register.Index;
 
       if (modifier == LP_BLD_TEX_MODIFIER_EXPLICIT_DERIV ||
+          modifier == LP_BLD_TEX_MODIFIER_EXPLICIT_LOD ||
           modifier == LP_BLD_TEX_MODIFIER_LOD_BIAS || shadow) {
          /* We don't track insts with additional regs, although we could */
          indirect = TRUE;
-      }  else {
-         if (modifier == LP_BLD_TEX_MODIFIER_EXPLICIT_LOD) {
-            readmask |= TGSI_WRITEMASK_W;
-         }
       }
 
       for (chan = 0; chan < 4; ++chan) {
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_tgsi_soa.c b/src/gallium/auxiliary/gallivm/lp_bld_tgsi_soa.c
index 52a60dd43b6..808e8168824 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_tgsi_soa.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_tgsi_soa.c
@@ -1428,9 +1428,8 @@ emit_sample(struct lp_build_tgsi_soa_context *bld,
       explicit_lod = NULL;
    }
    else if (modifier == LP_BLD_TEX_MODIFIER_EXPLICIT_LOD) {
-      /* lod bias comes from src 3.r but explicit lod from 0.a */
       lod_bias = NULL;
-      explicit_lod = lp_build_emit_fetch( &bld->bld_base, inst, 0, 3 );
+      explicit_lod = lp_build_emit_fetch( &bld->bld_base, inst, 3, 0 );
    }
    else if (modifier == LP_BLD_TEX_MODIFIER_LOD_ZERO) {
       lod_bias = NULL;
diff --git a/src/gallium/auxiliary/tgsi/tgsi_exec.c b/src/gallium/auxiliary/tgsi/tgsi_exec.c
index 6da7d42455c..03f19420986 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_exec.c
+++ b/src/gallium/auxiliary/tgsi/tgsi_exec.c
@@ -2154,7 +2154,7 @@ exec_sample(struct tgsi_exec_machine *mach,
          control = tgsi_sampler_lod_bias;
       }
       else if (modifier == TEX_MODIFIER_EXPLICIT_LOD) {
-         FETCH(&c1, 0, TGSI_CHAN_W);
+         FETCH(&c1, 3, TGSI_CHAN_X);
          lod = &c1;
          control = tgsi_sampler_lod_explicit;
       }
diff --git a/src/gallium/auxiliary/tgsi/tgsi_info.c b/src/gallium/auxiliary/tgsi/tgsi_info.c
index f8a3cb665f9..f289ebcda5a 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_info.c
+++ b/src/gallium/auxiliary/tgsi/tgsi_info.c
@@ -190,7 +190,7 @@ static const struct tgsi_opcode_info opcode_info[TGSI_OPCODE_LAST] =
    { 1, 4, 0, 0, 0, 0, OTHR, "SAMPLE_C",    TGSI_OPCODE_SAMPLE_C },
    { 1, 4, 0, 0, 0, 0, OTHR, "SAMPLE_C_LZ", TGSI_OPCODE_SAMPLE_C_LZ },
    { 1, 5, 0, 0, 0, 0, OTHR, "SAMPLE_D",    TGSI_OPCODE_SAMPLE_D },
-   { 1, 3, 0, 0, 0, 0, OTHR, "SAMPLE_L",    TGSI_OPCODE_SAMPLE_L },
+   { 1, 4, 0, 0, 0, 0, OTHR, "SAMPLE_L",    TGSI_OPCODE_SAMPLE_L },
    { 1, 3, 0, 0, 0, 0, OTHR, "GATHER4",     TGSI_OPCODE_GATHER4 },
    { 1, 2, 0, 0, 0, 0, OTHR, "SVIEWINFO",   TGSI_OPCODE_SVIEWINFO },
    { 1, 2, 0, 0, 0, 0, OTHR, "SAMPLE_POS",  TGSI_OPCODE_SAMPLE_POS },
diff --git a/src/gallium/auxiliary/tgsi/tgsi_opcode_tmp.h b/src/gallium/auxiliary/tgsi/tgsi_opcode_tmp.h
index 75e27a666f1..4a1b811b30b 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_opcode_tmp.h
+++ b/src/gallium/auxiliary/tgsi/tgsi_opcode_tmp.h
@@ -176,7 +176,7 @@ OP14(SAMPLE_B)
 OP14(SAMPLE_C)
 OP14(SAMPLE_C_LZ)
 OP15(SAMPLE_D)
-OP13(SAMPLE_L)
+OP14(SAMPLE_L)
 OP13(GATHER4)
 OP12(SVIEWINFO)
 OP13(SAMPLE_POS)
diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst
index 31b679621da..f13dd8fdffa 100644
--- a/src/gallium/docs/source/tgsi.rst
+++ b/src/gallium/docs/source/tgsi.rst
@@ -1423,11 +1423,10 @@ instructions. If in doubt double check Direct3D documentation.
 
 .. opcode:: SAMPLE_L - SAMPLE_L is identical to the SAMPLE opcode except
                that the LOD is provided directly as a scalar value,
-               representing no anisotropy. Source addresses A channel
-               is used as the LOD.
-               SAMPLE_L dst, address, sampler_view, sampler
+               representing no anisotropy.
+               SAMPLE_L dst, address, sampler_view, sampler, explicit_lod
                e.g.
-               SAMPLE_L TEMP[0], TEMP[1], SVIEW[0], SAMP[0]
+               SAMPLE_L TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2].x
 
 .. opcode:: GATHER4 - Gathers the four texels to be used in a bi-linear
                filtering operation and packs them into a single register.
diff --git a/src/gallium/state_trackers/d3d1x/gd3d1x/sm4_to_tgsi.cpp b/src/gallium/state_trackers/d3d1x/gd3d1x/sm4_to_tgsi.cpp
index aaa46f19e8c..ed1f8dac948 100644
--- a/src/gallium/state_trackers/d3d1x/gd3d1x/sm4_to_tgsi.cpp
+++ b/src/gallium/state_trackers/d3d1x/gd3d1x/sm4_to_tgsi.cpp
@@ -470,14 +470,9 @@ struct sm4_to_tgsi_converter
 			case SM4_OPCODE_SAMPLE_D: // dst, coord, res, samp, ddx, ddy
 				ureg_SAMPLE_D(ureg, _dst(), _src(1), resources[_idx(SM4_FILE_RESOURCE, 2)], samplers[_idx(SM4_FILE_SAMPLER, 3)], _src(4), _src(5));
 				break;
-			case SM4_OPCODE_SAMPLE_L: // dst, coord, res, samp, bias.x
-			{
-				struct ureg_dst tmp = _tmp();
-				ureg_MOV(ureg, ureg_writemask(tmp, TGSI_WRITEMASK_XYZ), _src(1));
-				ureg_MOV(ureg, ureg_writemask(tmp, TGSI_WRITEMASK_W), ureg_swizzle(_src(4), 0, 0, 0, 0));
-				ureg_SAMPLE_L(ureg, _dst(), ureg_src(tmp), resources[_idx(SM4_FILE_RESOURCE, 2)], samplers[_idx(SM4_FILE_SAMPLER, 3)]);
+			case SM4_OPCODE_SAMPLE_L: // dst, coord, res, samp, lod.x
+				ureg_SAMPLE_L(ureg, _dst(), _src(1), resources[_idx(SM4_FILE_RESOURCE, 2)], samplers[_idx(SM4_FILE_SAMPLER, 3)], _src(4));
 				break;
-			}
 			default:
 				ok = false;
 				break;