[Mesa-dev] [PATCH 1/5] glsl: Add conditional-select IR.

[Matt Turner]

It's a ?: that operates per-component on vectors. Will be used in
upcoming lowering pass for ldexp and the implementation of frexp.

 cond_sel(selector, a, b):
   per-component result = selector ? a : b
---
 src/glsl/ir.cpp                            |  2 ++
 src/glsl/ir.h                              | 12 ++++++++++++
 src/glsl/ir_builder.cpp                    |  6 ++++++
 src/glsl/ir_builder.h                      |  1 +
 src/glsl/ir_constant_expression.cpp        |  8 ++++++++
 src/glsl/ir_validate.cpp                   |  7 +++++++
 src/mesa/program/ir_to_mesa.cpp            |  1 +
 src/mesa/state_tracker/st_glsl_to_tgsi.cpp |  1 +
 8 files changed, 38 insertions(+)

diff --git a/src/glsl/ir.cpp b/src/glsl/ir.cpp
index 8769c32..65d9811 100644
--- a/src/glsl/ir.cpp
+++ b/src/glsl/ir.cpp
@@ -435,6 +435,7 @@ ir_expression::ir_expression(int op, ir_rvalue *op0, ir_rvalue *op1,
       break;
 
    case ir_triop_bfi:
+   case ir_triop_cond_sel:
       this->type = op1->type;
       break;
 
@@ -552,6 +553,7 @@ static const char *const operator_strs[] = {
    "vector_extract",
    "fma",
    "lrp",
+   "cond_sel",
    "bfi",
    "bitfield_extract",
    "vector_insert",
diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index bfbb94c..79e4ec8 100644
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -1197,6 +1197,18 @@ enum ir_expression_operation {
    ir_triop_lrp,
 
    /**
+    * \name Conditional Select
+    *
+    * A vector conditional select instruction (like ?:, but operating per-
+    * component on vectors).
+    *
+    * \see lower_instructions_visitor::ldexp_to_arith
+    */
+   /*@{*/
+   ir_triop_cond_sel,
+   /*@}*/
+
+   /**
     * \name Second half of a lowered bitfieldInsert() operation.
     *
     * \see lower_instructions::bitfield_insert_to_bfm_bfi
diff --git a/src/glsl/ir_builder.cpp b/src/glsl/ir_builder.cpp
index 31a457d..d0a8480 100644
--- a/src/glsl/ir_builder.cpp
+++ b/src/glsl/ir_builder.cpp
@@ -479,6 +479,12 @@ lrp(operand a, operand b, operand c)
 }
 
 ir_expression *
+cond_sel(operand a, operand b, operand c)
+{
+   return expr(ir_triop_cond_sel, a, b, c);
+}
+
+ir_expression *
 bitfield_insert(operand a, operand b, operand c, operand d)
 {
    void *mem_ctx = ralloc_parent(a.val);
diff --git a/src/glsl/ir_builder.h b/src/glsl/ir_builder.h
index ce593e2..1414509 100644
--- a/src/glsl/ir_builder.h
+++ b/src/glsl/ir_builder.h
@@ -182,6 +182,7 @@ ir_expression *f2b(operand a);
 ir_expression *b2f(operand a);
 
 ir_expression *lrp(operand a, operand b, operand c);
+ir_expression *cond_sel(operand a, operand b, operand c);
 ir_expression *bitfield_insert(operand a, operand b, operand c, operand d);
 
 ir_swizzle *swizzle(operand a, int swizzle, int components);
diff --git a/src/glsl/ir_constant_expression.cpp b/src/glsl/ir_constant_expression.cpp
index ec338a8..c2b5da5 100644
--- a/src/glsl/ir_constant_expression.cpp
+++ b/src/glsl/ir_constant_expression.cpp
@@ -395,6 +395,7 @@ ir_expression::constant_expression_value(struct hash_table *variable_context)
       case ir_binop_lshift:
       case ir_binop_rshift:
       case ir_binop_vector_extract:
+      case ir_triop_cond_sel:
       case ir_triop_bitfield_extract:
          break;
 
@@ -1399,6 +1400,13 @@ ir_expression::constant_expression_value(struct hash_table *variable_context)
       break;
    }
 
+   case ir_triop_cond_sel:
+      for (unsigned c = 0; c < components; c++) {
+         data.u[c] = op[0]->value.b[c] ? op[1]->value.u[c]
+                                       : op[2]->value.u[c];
+      }
+      break;
+
    case ir_triop_vector_insert: {
       const unsigned idx = op[2]->value.u[0];
 
diff --git a/src/glsl/ir_validate.cpp b/src/glsl/ir_validate.cpp
index 37f26fe..d302dd8 100644
--- a/src/glsl/ir_validate.cpp
+++ b/src/glsl/ir_validate.cpp
@@ -529,6 +529,13 @@ ir_validate::visit_leave(ir_expression *ir)
       assert(ir->operands[2]->type == ir->operands[0]->type || ir->operands[2]->type == glsl_type::float_type);
       break;
 
+   case ir_triop_cond_sel:
+      assert(ir->operands[0]->type->base_type == GLSL_TYPE_BOOL);
+      assert(ir->type->vector_elements == ir->operands[0]->type->vector_elements);
+      assert(ir->type == ir->operands[1]->type);
+      assert(ir->type == ir->operands[2]->type);
+      break;
+
    case ir_triop_bfi:
       assert(ir->operands[0]->type->is_integer());
       assert(ir->operands[1]->type == ir->operands[2]->type);
diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp
index fe9cac0..ded0329 100644
--- a/src/mesa/program/ir_to_mesa.cpp
+++ b/src/mesa/program/ir_to_mesa.cpp
@@ -1497,6 +1497,7 @@ ir_to_mesa_visitor::visit(ir_expression *ir)
    case ir_triop_bitfield_extract:
    case ir_triop_vector_insert:
    case ir_quadop_bitfield_insert:
+   case ir_triop_cond_sel:
       assert(!"not supported");
       break;
 
diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index d4c4260..2e94dac 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -1979,6 +1979,7 @@ glsl_to_tgsi_visitor::visit(ir_expression *ir)
    case ir_quadop_vector:
    case ir_binop_vector_extract:
    case ir_triop_vector_insert:
+   case ir_triop_cond_sel:
       /* This operation is not supported, or should have already been handled.
        */
       assert(!"Invalid ir opcode in glsl_to_tgsi_visitor::visit()");
-- 
1.8.3.2