[Mesa-dev] [PATCH 2/8] i965: Add support for saturating immediates.

[Matt Turner]

I don't feel great about unreachable("unimplemented: ...") but these
cases do only seem possible under some currently impossible circumstances.
---
 src/mesa/drivers/dri/i965/brw_fs.cpp     | 16 +++++++++++
 src/mesa/drivers/dri/i965/brw_shader.cpp | 47 ++++++++++++++++++++++++++++++++
 src/mesa/drivers/dri/i965/brw_shader.h   |  1 +
 src/mesa/drivers/dri/i965/brw_vec4.cpp   | 16 +++++++++++
 4 files changed, 80 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 2837fc0..789f967 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -2292,6 +2292,22 @@ fs_visitor::opt_algebraic()
 
    foreach_block_and_inst(block, fs_inst, inst, cfg) {
       switch (inst->opcode) {
+      case BRW_OPCODE_MOV:
+         if (inst->src[0].file != IMM)
+            break;
+
+         if (inst->saturate) {
+            if (inst->dst.type != inst->src[0].type)
+               unreachable("unimplemented: saturate mixed types");
+
+            if (brw_saturate_immediate(inst->dst.type,
+                                       &inst->src[0].fixed_hw_reg)) {
+               inst->saturate = false;
+               progress = true;
+            }
+         }
+         break;
+
       case BRW_OPCODE_MUL:
 	 if (inst->src[1].file != IMM)
 	    continue;
diff --git a/src/mesa/drivers/dri/i965/brw_shader.cpp b/src/mesa/drivers/dri/i965/brw_shader.cpp
index 1e5227c..a2fc471 100644
--- a/src/mesa/drivers/dri/i965/brw_shader.cpp
+++ b/src/mesa/drivers/dri/i965/brw_shader.cpp
@@ -575,6 +575,53 @@ brw_instruction_name(enum opcode op)
    unreachable("not reached");
 }
 
+bool
+brw_saturate_immediate(enum brw_reg_type type, struct brw_reg *reg)
+{
+   union {
+      unsigned ud;
+      int d;
+      float f;
+   } imm = { reg->dw1.ud }, sat_imm;
+
+   switch (type) {
+   case BRW_REGISTER_TYPE_UD:
+   case BRW_REGISTER_TYPE_D:
+   case BRW_REGISTER_TYPE_UQ:
+   case BRW_REGISTER_TYPE_Q:
+      /* Nothing to do. */
+      return false;
+   case BRW_REGISTER_TYPE_UW:
+      sat_imm.ud = CLAMP(imm.ud, 0, USHRT_MAX);
+      break;
+   case BRW_REGISTER_TYPE_W:
+      sat_imm.d = CLAMP(imm.d, SHRT_MIN, SHRT_MAX);
+      break;
+   case BRW_REGISTER_TYPE_F:
+      sat_imm.f = CLAMP(imm.f, 0.0f, 1.0f);
+      break;
+   case BRW_REGISTER_TYPE_UB:
+      sat_imm.ud = CLAMP(imm.ud, 0, UCHAR_MAX);
+      break;
+   case BRW_REGISTER_TYPE_B:
+      sat_imm.d = CLAMP(imm.d, CHAR_MIN, CHAR_MAX);
+      break;
+   case BRW_REGISTER_TYPE_V:
+   case BRW_REGISTER_TYPE_UV:
+   case BRW_REGISTER_TYPE_VF:
+      unreachable("unimplemented: saturate vector immediate");
+   case BRW_REGISTER_TYPE_DF:
+   case BRW_REGISTER_TYPE_HF:
+      unreachable("unimplemented: saturate DF/HF immediate");
+   }
+
+   if (imm.ud != sat_imm.ud) {
+      reg->dw1.ud = sat_imm.ud;
+      return true;
+   }
+   return false;
+}
+
 backend_visitor::backend_visitor(struct brw_context *brw,
                                  struct gl_shader_program *shader_prog,
                                  struct gl_program *prog,
diff --git a/src/mesa/drivers/dri/i965/brw_shader.h b/src/mesa/drivers/dri/i965/brw_shader.h
index 05434a7..233e224 100644
--- a/src/mesa/drivers/dri/i965/brw_shader.h
+++ b/src/mesa/drivers/dri/i965/brw_shader.h
@@ -192,6 +192,7 @@ enum brw_reg_type brw_type_for_base_type(const struct glsl_type *type);
 enum brw_conditional_mod brw_conditional_for_comparison(unsigned int op);
 uint32_t brw_math_function(enum opcode op);
 const char *brw_instruction_name(enum opcode op);
+bool brw_saturate_immediate(enum brw_reg_type type, struct brw_reg *reg);
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
index b303eb6..7619eb6 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
@@ -572,6 +572,22 @@ vec4_visitor::opt_algebraic()
 
    foreach_block_and_inst(block, vec4_instruction, inst, cfg) {
       switch (inst->opcode) {
+      case BRW_OPCODE_MOV:
+         if (inst->src[0].file != IMM)
+            break;
+
+         if (inst->saturate) {
+            if (inst->dst.type != inst->src[0].type)
+               unreachable("unimplemented: saturate mixed types");
+
+            if (brw_saturate_immediate(inst->dst.type,
+                                       &inst->src[0].fixed_hw_reg)) {
+               inst->saturate = false;
+               progress = true;
+            }
+         }
+         break;
+
       case VEC4_OPCODE_UNPACK_UNIFORM:
          if (inst->src[0].file != UNIFORM) {
             inst->opcode = BRW_OPCODE_MOV;
-- 
2.0.4