From ee28cae1ef1cf0d965e7cafe3fc3be1e83736bfb Mon Sep 17 00:00:00 2001
From: Ilia Mirkin <imirkin@alum.mit.edu>
Date: Mon, 15 Feb 2021 12:22:02 -0500
Subject: [PATCH] nv50/ir: fix emission of RED

When the atomic result is unused, the opcode form needs to be a bit
different.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Acked-by: Pierre Moreau <dev@pmoreau.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9299>
---
 .../nouveau/codegen/nv50_ir_emit_nv50.cpp     | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_nv50.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_nv50.cpp
index 8c5646cd168..5143950f430 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_nv50.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_emit_nv50.cpp
@@ -1824,19 +1824,28 @@ CodeEmitterNV50::emitATOM(const Instruction *i)
       return;
    }
    code[0] = 0xd0000001;
-   code[1] = 0xe0c00000 | (subOp << 2);
+   code[1] = 0xc0c00000 | (subOp << 2);
    if (isSignedType(i->dType))
       code[1] |= 1 << 21;
 
    // args
    emitFlagsRd(i);
-   setDst(i, 0);
-   setSrc(i, 1, 1);
+   if (i->subOp == NV50_IR_SUBOP_ATOM_EXCH ||
+       i->subOp == NV50_IR_SUBOP_ATOM_CAS ||
+       i->defExists(0)) {
+      code[1] |= 0x20000000;
+      setDst(i, 0);
+      setSrc(i, 1, 1);
+      // g[] pointer
+      code[0] |= i->getSrc(0)->reg.fileIndex << 23;
+   } else {
+      srcId(i->src(1), 2);
+      // g[] pointer
+      code[0] |= i->getSrc(0)->reg.fileIndex << 16;
+   }
    if (i->subOp == NV50_IR_SUBOP_ATOM_CAS)
       setSrc(i, 2, 2);
 
-   // g[] pointer
-   code[0] |= i->getSrc(0)->reg.fileIndex << 23;
    srcId(i->getIndirect(0, 0), 9);
 }