[Mesa-dev] [PATCH] nv50/ir: optimmize shl(a, 0) to a

[Karol Herbst]

helps two alien isolation shaders

shader-db:
total instructions in shared programs : 4251497 -> 4251494 (-0.00%)
total gprs used in shared programs    : 513962 -> 513962 (0.00%)
total local used in shared programs   : 29797 -> 29797 (0.00%)
total bytes used in shared programs   : 38960264 -> 38960232 (-0.00%)

                local        gpr       inst      bytes
    helped           0           0           2           2
      hurt           0           0           0           0

Signed-off-by: Karol Herbst <karolherbst at gmail.com>
---
 src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
index 015def0391..a2446e4df8 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
@@ -1284,6 +1284,11 @@ ConstantFolding::opnd(Instruction *i, ImmediateValue &imm0, int s)
 
    case OP_SHL:
    {
+      if (s == 1 && imm0.isInteger(0)) {
+         i->op = OP_MOV;
+         i->setSrc(1, NULL);
+         break;
+      }
       if (s != 1 || i->src(0).mod != Modifier(0))
          break;
       // try to concatenate shifts
-- 
2.12.2