nv50/ir: avoid messing up arg1 of PFETCH

There can be scenarios where the "indirect" arg of a PFETCH becomes
known, and so the code will attempt to propagate it. Use this
opportunity to just fold it into the first argument, and prevent the
load propagation pass from touching PFETCH further.

This fixes gs-input-array-vec4-index-rd.shader_test and
vs-output-array-vec4-index-wr-before-gs.shader_test on nvc0 at least.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Tobias Klausmann <tobias.johannes.klausmann@mni.thm.de>
Cc: "10.5 10.6" <mesa-stable@lists.freedesktop.org>
(cherry picked from commit fa7f9f123b70f313d3c073b52c9c16b4b8df28f8)

1 files changed, 18 insertions, 2 deletions

diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
index 14446b6b53f..e1b2d075fb3 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
@@ -236,6 +236,9 @@ LoadPropagation::visit(BasicBlock *bb)
       if (i->op == OP_CALL) // calls have args as sources, they must be in regs
          continue;
 
+      if (i->op == OP_PFETCH) // pfetch expects arg1 to be a reg
+         continue;
+
       if (i->srcExists(1))
          checkSwapSrc01(i);
 
@@ -574,6 +577,11 @@ ConstantFolding::expr(Instruction *i,
    case OP_POPCNT:
       res.data.u32 = util_bitcount(a->data.u32 & b->data.u32);
       break;
+   case OP_PFETCH:
+      // The two arguments to pfetch are logically added together. Normally
+      // the second argument will not be constant, but that can happen.
+      res.data.u32 = a->data.u32 + b->data.u32;
+      break;
    default:
       return;
    }
@@ -588,7 +596,9 @@ ConstantFolding::expr(Instruction *i,
 
    i->getSrc(0)->reg.data = res.data;
 
-   if (i->op == OP_MAD || i->op == OP_FMA) {
+   switch (i->op) {
+   case OP_MAD:
+   case OP_FMA: {
       i->op = OP_ADD;
 
       i->setSrc(1, i->getSrc(0));
@@ -603,8 +613,14 @@ ConstantFolding::expr(Instruction *i,
          bld.setPosition(i, false);
          i->setSrc(1, bld.loadImm(NULL, res.data.u32));
       }
-   } else {
+      break;
+   }
+   case OP_PFETCH:
+      // Leave PFETCH alone... we just folded its 2 args into 1.
+      break;
+   default:
       i->op = i->saturate ? OP_SAT : OP_MOV; /* SAT handled by unary() */
+      break;
    }
    i->subOp = 0;
 }