[Mesa-dev] [PATCH 1/2] nv50/ir: flip shl(add, imm) into add(shl, imm)

[Ilia Mirkin]

This works when the add also has an immediate. This often happens in
address calculations. These addresses can then be inlined as well.

On code targeted to SM35:

total instructions in shared programs : 6223346 -> 6206257 (-0.27%)
total gprs used in shared programs    : 911075 -> 911045 (-0.00%)
total local used in shared programs   : 39072 -> 39072 (0.00%)

                local        gpr       inst      bytes
    helped           0         119        3664        3664
      hurt           0          74          15          15

Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
---
 .../drivers/nouveau/codegen/nv50_ir_peephole.cpp   | 38 +++++++++++++++++++---
 1 file changed, 34 insertions(+), 4 deletions(-)

diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
index 5f47887..539edaf 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
@@ -1132,13 +1132,43 @@ ConstantFolding::opnd(Instruction *i, ImmediateValue &imm0, int s)
          break;
       // try to concatenate shifts
       Instruction *si = i->getSrc(0)->getInsn();
-      if (!si || si->op != OP_SHL)
+      if (!si)
          break;
       ImmediateValue imm1;
-      if (si->src(1).getImmediate(imm1)) {
+      switch (si->op) {
+      case OP_SHL:
+         if (si->src(1).getImmediate(imm1)) {
+            bld.setPosition(i, false);
+            i->setSrc(0, si->getSrc(0));
+            i->setSrc(1, bld.loadImm(NULL, imm0.reg.data.u32 + imm1.reg.data.u32));
+         }
+         break;
+      case OP_SUB:
+      case OP_ADD:
+         int adds;
+         if (isFloatType(si->dType))
+            return;
+         if (si->op != OP_SUB && si->src(0).getImmediate(imm1))
+            adds = 0;
+         else if (si->src(1).getImmediate(imm1))
+            adds = 1;
+         else
+            return;
+         // SHL(ADD(x, y), z) = ADD(SHL(x, z), SHL(y, z))
+
+         // This is more operations, but if one of x, y is an immediate, then
+         // we can get a situation where (a) we can use ISCADD, or (b)
+         // propagate the add bit into an indirect load.
          bld.setPosition(i, false);
-         i->setSrc(0, si->getSrc(0));
-         i->setSrc(1, bld.loadImm(NULL, imm0.reg.data.u32 + imm1.reg.data.u32));
+         i->op = si->op;
+         i->setSrc(adds, bld.loadImm(NULL, imm1.reg.data.u32 << imm0.reg.data.u32));
+         i->setSrc(!adds, bld.mkOp2v(OP_SHL, i->dType,
+                                     bld.getSSA(i->def(0).getSize(), i->def(0).getFile()),
+                                     si->getSrc(!adds),
+                                     bld.mkImm(imm0.reg.data.u32)));
+         break;
+      default:
+         return;
       }
    }
       break;
-- 
2.4.10