vc4: Emit resets of the uniform stream at the starts of blocks.

If a block might be entered from multiple locations, then the uniform
stream will (probably) be at different points, and we need to make sure
that it's pointing where we expect it to be.  The kernel also enforces
that any block reading a uniform resets uniforms, to prevent reading
outside of the uniform stream by using looping.

1 files changed, 101 insertions, 0 deletions

diff --git a/src/gallium/drivers/vc4/vc4_qir_emit_uniform_stream_resets.c b/src/gallium/drivers/vc4/vc4_qir_emit_uniform_stream_resets.c
new file mode 100644
index 0000000..3fd6358
--- /dev/null
+++ b/src/gallium/drivers/vc4/vc4_qir_emit_uniform_stream_resets.c
@@ -0,0 +1,101 @@
+/*
+ * Copyright © 2014 Broadcom
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/**
+ * @file vc4_qir_emit_uniform_stream_resets.c
+ *
+ * Adds updates to the uniform stream address at the start of each basic block
+ * that uses uniforms.
+ *
+ * This will be done just before the translation to QPU instructions, once we
+ * have performed optimization know how many uniforms are used in each block.
+ */
+
+#include "vc4_qir.h"
+#include "util/hash_table.h"
+#include "util/u_math.h"
+
+static bool
+inst_reads_a_uniform(struct qinst *inst)
+{
+        if (qir_is_tex(inst))
+                return true;
+
+        for (int i = 0; i < qir_get_op_nsrc(inst->op); i++) {
+                if (inst->src[i].file == QFILE_UNIF)
+                        return true;
+        }
+
+        return false;
+}
+
+static bool
+block_reads_any_uniform(struct qblock *block)
+{
+        qir_for_each_inst(inst, block) {
+                if (inst_reads_a_uniform(inst))
+                        return true;
+        }
+
+        return false;
+}
+
+void
+qir_emit_uniform_stream_resets(struct vc4_compile *c)
+{
+        uint32_t uniform_count = 0;
+
+        qir_for_each_block(block, c) {
+                if (block != qir_entry_block(c) &&
+                    (block_reads_any_uniform(block) ||
+                     block == qir_exit_block(c))) {
+                        struct qreg t = qir_get_temp(c);
+                        struct qreg uni_addr =
+                                qir_uniform(c, QUNIFORM_UNIFORMS_ADDRESS, 0);
+
+                        /* Load the offset of the next uniform in the stream
+                         * after the one we're generating here.
+                         */
+                        struct qinst *load_imm =
+                                qir_inst(QOP_LOAD_IMM,
+                                         t,
+                                         qir_reg(QFILE_LOAD_IMM,
+                                                 (uniform_count + 1) * 4),
+                                         c->undef);
+                        struct qinst *add =
+                                qir_inst(QOP_UNIFORMS_RESET, c->undef,
+                                         t, uni_addr);
+
+                        /* Pushes to the top of the block, so in reverse
+                         * order.
+                         */
+                        list_add(&add->link, &block->instructions);
+                        list_add(&load_imm->link, &block->instructions);
+                }
+
+                qir_for_each_inst(inst, block) {
+                        if (inst_reads_a_uniform(inst))
+                                uniform_count++;
+                }
+        }
+}