[Mesa-dev] [PATCH] gm107/ir: use CS2R for SV_CLOCK

[Rhys Perry]

This instruction seems to be faster than S2R and requires no barrier,
though the range of special registers it can read from is limited.

Signed-off-by: Rhys Perry <pendingchaos02 at gmail.com>
---
 src/gallium/drivers/nouveau/codegen/nv50_ir_emit_gm107.cpp | 14 +++++++++++++-
 .../drivers/nouveau/codegen/nv50_ir_target_gm107.cpp       |  4 +++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_gm107.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_gm107.cpp
index 694d1b10a3..c306a4680b 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_gm107.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_gm107.cpp
@@ -124,6 +124,7 @@ private:
 
    void emitMOV();
    void emitS2R();
+   void emitCS2R();
    void emitF2F();
    void emitF2I();
    void emitI2F();
@@ -749,6 +750,14 @@ CodeEmitterGM107::emitS2R()
    emitGPR (0x00, insn->def(0));
 }
 
+void
+CodeEmitterGM107::emitCS2R()
+{
+   emitInsn(0x50c80000);
+   emitSYS (0x14, insn->src(0));
+   emitGPR (0x00, insn->def(0));
+}
+
 void
 CodeEmitterGM107::emitF2F()
 {
@@ -3192,7 +3201,10 @@ CodeEmitterGM107::emitInstruction(Instruction *i)
       emitMOV();
       break;
    case OP_RDSV:
-      emitS2R();
+      if (insn->getSrc(0)->reg.data.id == SV_CLOCK)
+         emitCS2R();
+      else
+         emitS2R();
       break;
    case OP_ABS:
    case OP_NEG:
diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_target_gm107.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_target_gm107.cpp
index 04cbd402a1..009470fb93 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_target_gm107.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_target_gm107.cpp
@@ -153,9 +153,10 @@ TargetGM107::isBarrierRequired(const Instruction *insn) const
       case OP_AFETCH:
       case OP_PFETCH:
       case OP_PIXLD:
-      case OP_RDSV:
       case OP_SHFL:
          return true;
+      case OP_RDSV:
+         return insn->getSrc(0)->reg.data.id != SV_CLOCK;
       default:
          break;
       }
@@ -229,6 +230,7 @@ TargetGM107::getLatency(const Instruction *insn) const
    case OP_SUB:
    case OP_VOTE:
    case OP_XOR:
+   case OP_RDSV:
       if (insn->dType != TYPE_F64)
          return 6;
       break;
-- 
2.14.4