nv50/ir: allow to swap sources for OP_SUB

This allows the load-propagation pass to swap the sources in presence
of immediate values.

Maxwell (GM107):

total instructions in shared programs :1928187 -> 1927634 (-0.03%)
total gprs used in shared programs    :330741 -> 330154 (-0.18%)
total local used in shared programs   :28032 -> 28032 (0.00%)

                local        gpr       inst      bytes
    helped           0         271         425         425
      hurt           0           0         194         194

Fermi (GF114):

total instructions in shared programs :2334474 -> 2333829 (-0.03%)
total gprs used in shared programs    :380934 -> 380215 (-0.19%)
total local used in shared programs   :33304 -> 33264 (-0.12%)

                local        gpr       inst      bytes
    helped           5         314         521         521
      hurt           0           4         195         195

No regressions on GM107 and GF114 with full piglit.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>

diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
index 3fc1abf18cdd0c894082d4f1ae477863809009e3..a9172f834b25daa05a1a6ab31e19687a7e2eb9a7 100644 (file)
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
@@ -192,7 +192,7 @@ LoadPropagation::checkSwapSrc01(Instruction *insn)
 {
    const Target *targ = prog->getTarget();
    if (!targ->getOpInfo(insn).commutative)
-      if (insn->op != OP_SET && insn->op != OP_SLCT)
+      if (insn->op != OP_SET && insn->op != OP_SLCT && insn->op != OP_SUB)
          return;
    if (insn->src(1).getFile() != FILE_GPR)
       return;
@@ -232,6 +232,11 @@ LoadPropagation::checkSwapSrc01(Instruction *insn)
    else
    if (insn->op == OP_SLCT)
       insn->asCmp()->setCond = inverseCondCode(insn->asCmp()->setCond);
+   else
+   if (insn->op == OP_SUB) {
+      insn->src(0).mod = insn->src(0).mod ^ Modifier(NV50_IR_MOD_NEG);
+      insn->src(1).mod = insn->src(1).mod ^ Modifier(NV50_IR_MOD_NEG);
+   }
 }
 
 bool