[Mesa-dev] [PATCH 1/3] i965/fs: Add and use get_nir_src_imm().

[Matt Turner]

Terrible name. Suggest something else, or even a better way to do this.

Basically, the next patch wants to inspect the LOD argument and do
something different if it's 0.0f. But at that point we've emitted a MOV
for it and we just have a register to look at.
---
This is an alternative approach to the 4 patch series I sent ast night.

 src/mesa/drivers/dri/i965/brw_fs.h       |  1 +
 src/mesa/drivers/dri/i965/brw_fs_nir.cpp | 36 +++++++++++++++++++++++++++-----
 2 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.h b/src/mesa/drivers/dri/i965/brw_fs.h
index ba6bd3f..29fa593 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.h
+++ b/src/mesa/drivers/dri/i965/brw_fs.h
@@ -273,6 +273,7 @@ public:
    void nir_emit_jump(const brw::fs_builder &bld,
                       nir_jump_instr *instr);
    fs_reg get_nir_src(nir_src src);
+   fs_reg get_nir_src_imm(nir_src src);
    fs_reg get_nir_dest(nir_dest dest);
    fs_reg get_nir_image_deref(const nir_deref_var *deref);
    fs_reg get_indirect_offset(nir_intrinsic_instr *instr);
diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
index 4d14fda..fb59800 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
@@ -1245,6 +1245,32 @@ fs_visitor::get_nir_src(nir_src src)
 }
 
 fs_reg
+fs_visitor::get_nir_src_imm(nir_src src)
+{
+   fs_reg reg;
+   if (src.is_ssa) {
+      if (src.ssa->parent_instr->type == nir_instr_type_load_const) {
+         nir_load_const_instr *load_const =
+            nir_instr_as_load_const(src.ssa->parent_instr);
+         return brw_imm_ud(load_const->value.u32[0]);
+      }
+
+      reg = nir_ssa_values[src.ssa->index];
+   } else {
+      /* We don't handle indirects on locals */
+      assert(src.reg.indirect == NULL);
+      reg = offset(nir_locals[src.reg.reg->index], bld,
+                   src.reg.base_offset * src.reg.reg->num_components);
+   }
+
+   /* to avoid floating-point denorm flushing problems, set the type by
+    * default to D - instructions that need floating point semantics will set
+    * this to F if they need to
+    */
+   return retype(reg, BRW_REGISTER_TYPE_D);
+}
+
+fs_reg
 fs_visitor::get_nir_dest(nir_dest dest)
 {
    if (dest.is_ssa) {
@@ -3444,7 +3470,7 @@ fs_visitor::nir_emit_texture(const fs_builder &bld, nir_tex_instr *instr)
       fs_reg src = get_nir_src(instr->src[i].src);
       switch (instr->src[i].src_type) {
       case nir_tex_src_bias:
-         lod = retype(src, BRW_REGISTER_TYPE_F);
+         lod = retype(get_nir_src_imm(instr->src[i].src), BRW_REGISTER_TYPE_F);
          break;
       case nir_tex_src_comparitor:
          shadow_comparitor = retype(src, BRW_REGISTER_TYPE_F);
@@ -3462,7 +3488,7 @@ fs_visitor::nir_emit_texture(const fs_builder &bld, nir_tex_instr *instr)
          }
          break;
       case nir_tex_src_ddx:
-         lod = retype(src, BRW_REGISTER_TYPE_F);
+         lod = retype(get_nir_src_imm(instr->src[i].src), BRW_REGISTER_TYPE_F);
          lod_components = nir_tex_instr_src_size(instr, i);
          break;
       case nir_tex_src_ddy:
@@ -3471,13 +3497,13 @@ fs_visitor::nir_emit_texture(const fs_builder &bld, nir_tex_instr *instr)
       case nir_tex_src_lod:
          switch (instr->op) {
          case nir_texop_txs:
-            lod = retype(src, BRW_REGISTER_TYPE_UD);
+            lod = retype(get_nir_src_imm(instr->src[i].src), BRW_REGISTER_TYPE_UD);
             break;
          case nir_texop_txf:
-            lod = retype(src, BRW_REGISTER_TYPE_D);
+            lod = retype(get_nir_src_imm(instr->src[i].src), BRW_REGISTER_TYPE_D);
             break;
          default:
-            lod = retype(src, BRW_REGISTER_TYPE_F);
+            lod = retype(get_nir_src_imm(instr->src[i].src), BRW_REGISTER_TYPE_F);
             break;
          }
          break;
-- 
2.7.3