nvc0/ir: fix robustness guarantees for constbuf loads on kepler+ compute

Kepler and up unfortunately only support up to 8 constbufs. We work
around this by loading from constbufs as if they were storage buffers.
However we were not consistently applying limits to loads from these
buffers. Make sure to do the same thing we do for storage buffers.

Fixes GL45-CTS.robust_buffer_access_behavior.uniform_buffer

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Cc: mesa-stable@lists.freedesktop.org
(cherry picked from commit 1acdd62847cf0da8a8e9c7915d698208d73a5be8)
diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nvc0.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nvc0.cpp
index ec50578..3ba96c9 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nvc0.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nvc0.cpp
@@ -2279,6 +2279,9 @@
          int8_t fileIndex = i->getSrc(0)->reg.fileIndex - 1;
          Value *ind = i->getIndirect(0, 1);
 
+         if (!ind && fileIndex == -1)
+            return;
+
          if (ind) {
             // Clamp the UBO index when an indirect access is used to avoid
             // loading information from the wrong place in the driver cb.
@@ -2288,32 +2291,26 @@
                              bld.loadImm(NULL, 12));
          }
 
-         if (i->src(0).isIndirect(1)) {
-            Value *offset = bld.loadImm(NULL, i->getSrc(0)->reg.data.offset + typeSizeof(i->sType));
-            Value *ptr = loadUboInfo64(ind, fileIndex * 16);
-            Value *length = loadUboLength32(ind, fileIndex * 16);
-            Value *pred = new_LValue(func, FILE_PREDICATE);
-            if (i->src(0).isIndirect(0)) {
-               bld.mkOp2(OP_ADD, TYPE_U64, ptr, ptr, i->getIndirect(0, 0));
-               bld.mkOp2(OP_ADD, TYPE_U32, offset, offset, i->getIndirect(0, 0));
-            }
-            i->getSrc(0)->reg.file = FILE_MEMORY_GLOBAL;
-            i->setIndirect(0, 1, NULL);
-            i->setIndirect(0, 0, ptr);
-            bld.mkCmp(OP_SET, CC_GT, TYPE_U32, pred, TYPE_U32, offset, length);
-            i->setPredicate(CC_NOT_P, pred);
-            if (i->defExists(0)) {
-               bld.mkMov(i->getDef(0), bld.mkImm(0));
-            }
-         } else if (fileIndex >= 0) {
-            Value *ptr = loadUboInfo64(ind, fileIndex * 16);
-            if (i->src(0).isIndirect(0)) {
-               bld.mkOp2(OP_ADD, TYPE_U64, ptr, ptr, i->getIndirect(0, 0));
-            }
-            i->getSrc(0)->reg.file = FILE_MEMORY_GLOBAL;
-            i->setIndirect(0, 1, NULL);
-            i->setIndirect(0, 0, ptr);
+         Value *offset = bld.loadImm(NULL, i->getSrc(0)->reg.data.offset + typeSizeof(i->sType));
+         Value *ptr = loadUboInfo64(ind, fileIndex * 16);
+         Value *length = loadUboLength32(ind, fileIndex * 16);
+         Value *pred = new_LValue(func, FILE_PREDICATE);
+         if (i->src(0).isIndirect(0)) {
+            bld.mkOp2(OP_ADD, TYPE_U64, ptr, ptr, i->getIndirect(0, 0));
+            bld.mkOp2(OP_ADD, TYPE_U32, offset, offset, i->getIndirect(0, 0));
          }
+         i->getSrc(0)->reg.file = FILE_MEMORY_GLOBAL;
+         i->setIndirect(0, 1, NULL);
+         i->setIndirect(0, 0, ptr);
+         bld.mkCmp(OP_SET, CC_GT, TYPE_U32, pred, TYPE_U32, offset, length);
+         i->setPredicate(CC_NOT_P, pred);
+         Value *zero, *dst = i->getDef(0);
+         i->setDef(0, bld.getSSA());
+
+         bld.setPosition(i, true);
+         bld.mkMov((zero = bld.getSSA()), bld.mkImm(0))
+            ->setPredicate(CC_P, pred);
+         bld.mkOp2(OP_UNION, TYPE_U32, dst, i->getDef(0), zero);
       } else if (i->src(0).isIndirect(1)) {
          Value *ptr;
          if (i->src(0).isIndirect(0))