[Mesa-dev] [PATCH 08/11] i965/vec4_nir: Use partial SSA form rather than full non-SSA

[Jason Ekstrand]

We made this switch in the FS backend some time ago and it seems to make a
number of things a bit easier.
---
 src/mesa/drivers/dri/i965/brw_nir.c        |  2 +-
 src/mesa/drivers/dri/i965/brw_vec4.h       |  1 +
 src/mesa/drivers/dri/i965/brw_vec4_nir.cpp | 21 ++++++++++++++++++---
 3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_nir.c b/src/mesa/drivers/dri/i965/brw_nir.c
index 8f3edc5..f326b23 100644
--- a/src/mesa/drivers/dri/i965/brw_nir.c
+++ b/src/mesa/drivers/dri/i965/brw_nir.c
@@ -183,7 +183,7 @@ brw_create_nir(struct brw_context *brw,
       nir_print_shader(nir, stderr);
    }
 
-   nir_convert_from_ssa(nir, is_scalar);
+   nir_convert_from_ssa(nir, true);
    nir_validate_shader(nir);
 
    if (!is_scalar) {
diff --git a/src/mesa/drivers/dri/i965/brw_vec4.h b/src/mesa/drivers/dri/i965/brw_vec4.h
index 01c6e84..de74ec9 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.h
+++ b/src/mesa/drivers/dri/i965/brw_vec4.h
@@ -423,6 +423,7 @@ public:
    virtual void nir_emit_alu(nir_alu_instr *instr);
    virtual void nir_emit_jump(nir_jump_instr *instr);
    virtual void nir_emit_texture(nir_tex_instr *instr);
+   virtual void nir_emit_undef(nir_ssa_undef_instr *instr);
 
    dst_reg get_nir_dest(nir_dest dest, enum brw_reg_type type);
    dst_reg get_nir_dest(nir_dest dest, nir_alu_type type);
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp b/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
index 751ec73..87a7941 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
@@ -367,6 +367,10 @@ vec4_visitor::nir_emit_instr(nir_instr *instr)
       nir_emit_texture(nir_instr_as_tex(instr));
       break;
 
+   case nir_instr_type_ssa_undef:
+      nir_emit_undef(nir_instr_as_ssa_undef(instr));
+      break;
+
    default:
       fprintf(stderr, "VS instruction not yet implemented by NIR->vec4\n");
       break;
@@ -393,9 +397,14 @@ dst_reg_for_nir_reg(vec4_visitor *v, nir_register *nir_reg,
 dst_reg
 vec4_visitor::get_nir_dest(nir_dest dest)
 {
-   assert(!dest.is_ssa);
-   return dst_reg_for_nir_reg(this, dest.reg.reg, dest.reg.base_offset,
-                              dest.reg.indirect);
+   if (dest.is_ssa) {
+      dst_reg dst = dst_reg(GRF, alloc.allocate(1));
+      nir_ssa_values[dest.ssa.index] = dst;
+      return dst;
+   } else {
+      return dst_reg_for_nir_reg(this, dest.reg.reg, dest.reg.base_offset,
+                                 dest.reg.indirect);
+   }
 }
 
 dst_reg
@@ -1528,4 +1537,10 @@ vec4_visitor::nir_emit_texture(nir_tex_instr *instr)
                 mcs, is_cube_array, sampler, sampler_reg);
 }
 
+void
+vec4_visitor::nir_emit_undef(nir_ssa_undef_instr *instr)
+{
+   nir_ssa_values[instr->def.index] = dst_reg(GRF, alloc.allocate(1));
+}
+
 }
-- 
2.5.0.400.gff86faf