[Mesa-dev] [PATCH 2/3] nv50/ir: optimize slct(b, c, set(a, 0)) to slct(b, c, a)

[Karol Herbst]

From: Karol Herbst <karolherbst at gmail.com>

helps mainly feral ported games

shader-db changes:
total instructions in shared programs     : 7614782 -> 7565661 (-0.65%)
total gprs used in shared programs        : 798045 -> 797213 (-0.10%)
total shared used in shared programs      : 639636 -> 639636 (0.00%)
total local used in shared programs       : 24648 -> 24648 (0.00%)
total bytes used in shared programs       : 81330696 -> 80806160 (-0.64%)

                local     shared        gpr       inst      bytes
    helped          0          0        701       7940       7940
      hurt          0          0         44          4          4

Signed-off-by: Karol Herbst <kherbst at redhat.com>
---
 .../nouveau/codegen/nv50_ir_peephole.cpp      | 47 +++++++++++++++++--
 1 file changed, 44 insertions(+), 3 deletions(-)

diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
index a8bd4f868bf..37e9edc49f4 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
@@ -1763,7 +1763,8 @@ private:
    bool tryADDToMADOrSAD(Instruction *, operation toOp);
    void handleMINMAX(Instruction *);
    void handleRCP(Instruction *);
-   void handleSLCT(Instruction *);
+   void handleSLCT(CmpInstruction *);
+   bool tryMergeSLCTSET(CmpInstruction *slct, CmpInstruction *set);
    void handleLOGOP(Instruction *);
    void handleCVT_NEG(Instruction *);
    void handleCVT_CVT(Instruction *);
@@ -1956,8 +1957,12 @@ AlgebraicOpt::handleRCP(Instruction *rcp)
 }
 
 void
-AlgebraicOpt::handleSLCT(Instruction *slct)
+AlgebraicOpt::handleSLCT(CmpInstruction *slct)
 {
+   Instruction *insn = slct->getSrc(2)->getInsn();
+   while(insn && insn->op == OP_SET && tryMergeSLCTSET(slct, insn->asCmp())) {
+      insn = slct->getSrc(2)->getInsn();
+   }
    if (slct->getSrc(2)->reg.file == FILE_IMMEDIATE) {
       if (slct->getSrc(2)->asImm()->compare(slct->asCmp()->setCond, 0.0f))
          slct->setSrc(0, slct->getSrc(1));
@@ -1970,6 +1975,42 @@ AlgebraicOpt::handleSLCT(Instruction *slct)
    slct->setSrc(2, NULL);
 }
 
+bool
+AlgebraicOpt::tryMergeSLCTSET(CmpInstruction *slct, CmpInstruction *set)
+{
+   assert(slct->op == OP_SLCT && set->op == OP_SET);
+
+   if (typeSizeof(set->sType) != 4)
+      return false;
+
+   CondCode setCC = set->getCondition();
+   CondCode slctCC = slct->getCondition();
+   CondCode newCC = setCC;
+
+   if (slctCC != CC_NE && slctCC != CC_EQ)
+      return false;
+
+   ImmediateValue imm0;
+   int s;
+
+   if (set->src(0).getImmediate(imm0) && imm0.isInteger(0))
+      s = 1;
+   else if (set->src(1).getImmediate(imm0) && imm0.isInteger(0))
+      s = 0;
+   else
+      return false;
+
+   slct->setSrc(2, set->getSrc(s));
+   if (s)
+      newCC = reverseCondCode(newCC);
+   if (slctCC == CC_EQ)
+      newCC = inverseCondCode(newCC);
+
+   slct->sType = set->sType;
+   slct->setCondition(newCC);
+   return true;
+}
+
 void
 AlgebraicOpt::handleLOGOP(Instruction *logop)
 {
@@ -2340,7 +2381,7 @@ AlgebraicOpt::visit(BasicBlock *bb)
          handleMINMAX(i);
          break;
       case OP_SLCT:
-         handleSLCT(i);
+         handleSLCT(i->asCmp());
          break;
       case OP_AND:
       case OP_OR:
-- 
2.19.2