From df2881381ac67c42aa8ec9e0ed28f21a1d253785 Mon Sep 17 00:00:00 2001
From: Ilia Mirkin <imirkin@alum.mit.edu>
Date: Wed, 25 May 2016 22:41:06 -0400
Subject: [PATCH] nvc0/ir: handle a load's reg result not being used for locked
 variants

For a load locked, we might not use the first result but the second
result is the predicate result of the locking. In that case the load
splitting logic doesn't apply (which is designed for splitting 128-bit
loads). Instead we take the predicate and move it into the first
position (as having a dead result in first def's position upsets all
sorts of things including RA). Update the emitters to deal with this as
well.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Tested-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
---
 .../nouveau/codegen/nv50_ir_emit_gk110.cpp    | 20 +++++++++++---
 .../nouveau/codegen/nv50_ir_emit_nvc0.cpp     | 26 ++++++++++++++-----
 .../nouveau/codegen/nv50_ir_peephole.cpp      | 10 +++++--
 3 files changed, 45 insertions(+), 11 deletions(-)

diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_gk110.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_gk110.cpp
index 6a5981daadf..27d9b8e1689 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_gk110.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_gk110.cpp
@@ -2080,15 +2080,29 @@ CodeEmitterGK110::emitLOAD(const Instruction *i)
    code[1] |= offset >> 9;
 
    // Locked store on shared memory can fail.
+   int r = 0, p = -1;
    if (i->src(0).getFile() == FILE_MEMORY_SHARED &&
        i->subOp == NV50_IR_SUBOP_LOAD_LOCKED) {
-      assert(i->defExists(1));
-      defId(i->def(1), 32 + 16);
+      if (i->def(0).getFile() == FILE_PREDICATE) { // p, #
+         r = -1;
+         p = 0;
+      } else if (i->defExists(1)) { // r, p
+         p = 1;
+      } else {
+         assert(!"Expected predicate dest for load locked");
+      }
    }
 
    emitPredicate(i);
 
-   defId(i->def(0), 2);
+   if (r >= 0)
+      defId(i->def(r), 2);
+   else
+      code[0] |= 255 << 2;
+
+   if (p >= 0)
+      defId(i->def(p), 32 + 16);
+
    if (i->getIndirect(0, 0)) {
       srcId(i->src(0).getIndirect(0), 10);
       if (i->getIndirect(0, 0)->reg.size == 8)
diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_nvc0.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_nvc0.cpp
index 596293ed2df..1bb962f9e26 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_nvc0.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_nvc0.cpp
@@ -1874,17 +1874,31 @@ CodeEmitterNVC0::emitLOAD(const Instruction *i)
    }
    code[1] = opc;
 
+   int r = 0, p = -1;
    if (i->src(0).getFile() == FILE_MEMORY_SHARED) {
       if (i->subOp == NV50_IR_SUBOP_LOAD_LOCKED) {
-         assert(i->defExists(1));
-         if (targ->getChipset() >= NVISA_GK104_CHIPSET)
-            defId(i->def(1), 8);
-         else
-            defId(i->def(1), 32 + 18);
+         if (i->def(0).getFile() == FILE_PREDICATE) { // p, #
+            r = -1;
+            p = 0;
+         } else if (i->defExists(1)) { // r, p
+            p = 1;
+         } else {
+            assert(!"Expected predicate dest for load locked");
+         }
       }
    }
 
-   defId(i->def(0), 14);
+   if (r >= 0)
+      defId(i->def(r), 14);
+   else
+      code[0] |= 63 << 14;
+
+   if (p >= 0) {
+      if (targ->getChipset() >= NVISA_GK104_CHIPSET)
+         defId(i->def(p), 8);
+      else
+         defId(i->def(p), 32 + 18);
+   }
 
    setAddressByFile(i->src(0));
    srcId(i->src(0).getIndirect(0), 20);
diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
index cd801f342dd..32131884c5f 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
@@ -3265,14 +3265,20 @@ DeadCodeElim::visit(BasicBlock *bb)
          ++deadCount;
          delete_Instruction(prog, i);
       } else
-      if (i->defExists(1) && (i->op == OP_VFETCH || i->op == OP_LOAD)) {
+      if (i->defExists(1) &&
+          i->subOp == 0 &&
+          (i->op == OP_VFETCH || i->op == OP_LOAD)) {
          checkSplitLoad(i);
       } else
       if (i->defExists(0) && !i->getDef(0)->refCount()) {
          if (i->op == OP_ATOM ||
              i->op == OP_SUREDP ||
-             i->op == OP_SUREDB)
+             i->op == OP_SUREDB) {
             i->setDef(0, NULL);
+         } else if (i->op == OP_LOAD && i->subOp == NV50_IR_SUBOP_LOAD_LOCKED) {
+            i->setDef(0, i->getDef(1));
+            i->setDef(1, NULL);
+         }
       }
    }
    return true;