diff --git a/src/panfrost/bifrost/meson.build b/src/panfrost/bifrost/meson.build
index 15d1b666d28..e66fea341b3 100644
--- a/src/panfrost/bifrost/meson.build
+++ b/src/panfrost/bifrost/meson.build
@@ -172,6 +172,7 @@ if with_tests
         'valhall/test/test-validate-fau.cpp',
         'valhall/test/test-insert-flow.cpp',
         'valhall/test/test-lower-isel.cpp',
+        'valhall/test/test-merge-flow.cpp',
         'valhall/test/test-packing.cpp',
       ),
       c_args : [c_msvc_compat_args, no_override_init_args],
diff --git a/src/panfrost/bifrost/valhall/test/test-merge-flow.cpp b/src/panfrost/bifrost/valhall/test/test-merge-flow.cpp
new file mode 100644
index 00000000000..37d8b3e19dc
--- /dev/null
+++ b/src/panfrost/bifrost/valhall/test/test-merge-flow.cpp
@@ -0,0 +1,294 @@
+/*
+ * Copyright (C) 2022 Collabora, Ltd.
+ *
+ * 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.
+ */
+
+#include "bi_test.h"
+#include "bi_builder.h"
+#include "va_compiler.h"
+#include "valhall_enums.h"
+
+#include <gtest/gtest.h>
+
+#define CASE(test, expected) do { \
+   bi_builder *A = bit_builder(mem_ctx); \
+   bi_builder *B = bit_builder(mem_ctx); \
+   { \
+      bi_builder *b = A; \
+      A->shader->stage = MESA_SHADER_FRAGMENT; \
+      test; \
+   } \
+   va_merge_flow(A->shader); \
+   { \
+      bi_builder *b = B; \
+      B->shader->stage = MESA_SHADER_FRAGMENT; \
+      expected; \
+   } \
+   ASSERT_SHADER_EQUAL(A->shader, B->shader); \
+} while(0)
+
+#define NEGCASE(test) CASE(test, test)
+
+#define flow(f) bi_nop(b)->flow = VA_FLOW_ ## f
+
+class MergeFlow : public testing::Test {
+protected:
+   MergeFlow() {
+      mem_ctx = ralloc_context(NULL);
+   }
+
+   ~MergeFlow() {
+      ralloc_free(mem_ctx);
+   }
+
+   void *mem_ctx;
+   bi_instr *I;
+};
+
+TEST_F(MergeFlow, End) {
+   CASE({
+        bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+        bi_blend_to(b, bi_register(0), bi_register(4), bi_register(5),
+                    bi_register(6), bi_register(7), bi_register(8),
+                    BI_REGISTER_FORMAT_AUTO, 4, 4);
+        flow(END);
+   },
+   {
+        bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+        I = bi_blend_to(b, bi_register(0), bi_register(4), bi_register(5),
+                        bi_register(6), bi_register(7), bi_register(8),
+                        BI_REGISTER_FORMAT_AUTO, 4, 4);
+        I->flow = VA_FLOW_END;
+   });
+}
+
+TEST_F(MergeFlow, Reconverge) {
+   CASE({
+        bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+        bi_blend_to(b, bi_register(0), bi_register(4), bi_register(5),
+                    bi_register(6), bi_register(7), bi_register(8),
+                    BI_REGISTER_FORMAT_AUTO, 4, 4);
+        flow(RECONVERGE);
+   },
+   {
+        bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+        I = bi_blend_to(b, bi_register(0), bi_register(4), bi_register(5),
+                        bi_register(6), bi_register(7), bi_register(8),
+                        BI_REGISTER_FORMAT_AUTO, 4, 4);
+        I->flow = VA_FLOW_RECONVERGE;
+   });
+}
+
+TEST_F(MergeFlow, TrivialWait) {
+   CASE({
+        bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+        flow(WAIT0126);
+        bi_atest_to(b, bi_register(0), bi_register(4), bi_register(5));
+   },
+   {
+        I = bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+        I->flow = VA_FLOW_WAIT0126;
+        bi_atest_to(b, bi_register(0), bi_register(4), bi_register(5));
+   });
+}
+
+TEST_F(MergeFlow, LoadThenUnrelatedThenUse) {
+   CASE({
+         bi_ld_attr_imm_to(b, bi_register(16), bi_register(60), bi_register(61),
+                           BI_REGISTER_FORMAT_F32, BI_VECSIZE_V4, 1);
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         flow(WAIT0);
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(19));
+         flow(END);
+   },
+   {
+         bi_ld_attr_imm_to(b, bi_register(16), bi_register(60), bi_register(61),
+                           BI_REGISTER_FORMAT_F32, BI_VECSIZE_V4, 1);
+         I = bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         I->flow = VA_FLOW_WAIT0;
+         I = bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(19));
+         I->flow = VA_FLOW_END;
+   });
+}
+
+TEST_F(MergeFlow, TrivialDiscard) {
+   CASE({
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         bi_clper_i32_to(b, bi_register(0), bi_register(4), bi_register(8),
+                         BI_INACTIVE_RESULT_ZERO, BI_LANE_OP_NONE,
+                         BI_SUBGROUP_SUBGROUP4);
+         flow(DISCARD);
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         flow(END);
+   },
+   {
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         I = bi_clper_i32_to(b, bi_register(0), bi_register(4), bi_register(8),
+                         BI_INACTIVE_RESULT_ZERO, BI_LANE_OP_NONE,
+                         BI_SUBGROUP_SUBGROUP4);
+         I->flow = VA_FLOW_DISCARD;
+         I = bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         I->flow = VA_FLOW_END;
+   });
+}
+
+TEST_F(MergeFlow, TrivialDiscardAtTheStart) {
+   CASE({
+         flow(DISCARD);
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+   },
+   {
+         I = bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         I->flow = VA_FLOW_DISCARD;
+   });
+}
+
+TEST_F(MergeFlow, MoveDiscardPastWait) {
+   CASE({
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         bi_clper_i32_to(b, bi_register(0), bi_register(4), bi_register(8),
+                         BI_INACTIVE_RESULT_ZERO, BI_LANE_OP_NONE,
+                         BI_SUBGROUP_SUBGROUP4);
+         flow(DISCARD);
+         flow(WAIT0);
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+   },
+   {
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         I = bi_clper_i32_to(b, bi_register(0), bi_register(4), bi_register(8),
+                         BI_INACTIVE_RESULT_ZERO, BI_LANE_OP_NONE,
+                         BI_SUBGROUP_SUBGROUP4);
+         I->flow = VA_FLOW_WAIT0;
+         I = bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         I->flow = VA_FLOW_DISCARD;
+   });
+}
+
+TEST_F(MergeFlow, OccludedWaitsAndDiscard) {
+   CASE({
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         bi_clper_i32_to(b, bi_register(0), bi_register(4), bi_register(8),
+                         BI_INACTIVE_RESULT_ZERO, BI_LANE_OP_NONE,
+                         BI_SUBGROUP_SUBGROUP4);
+         flow(WAIT0);
+         flow(DISCARD);
+         flow(WAIT2);
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+   },
+   {
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         I = bi_clper_i32_to(b, bi_register(0), bi_register(4), bi_register(8),
+                         BI_INACTIVE_RESULT_ZERO, BI_LANE_OP_NONE,
+                         BI_SUBGROUP_SUBGROUP4);
+         I->flow = VA_FLOW_WAIT02;
+         I = bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         I->flow = VA_FLOW_DISCARD;
+   });
+}
+
+TEST_F(MergeFlow, DeleteUselessWaits) {
+   CASE({
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         flow(WAIT0);
+         flow(WAIT2);
+         flow(END);
+   },
+   {
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         I = bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         I->flow = VA_FLOW_END;
+   });
+}
+
+TEST_F(MergeFlow, BlockFullOfUselessWaits) {
+   CASE({
+         flow(WAIT0);
+         flow(WAIT2);
+         flow(DISCARD);
+         flow(END);
+   },
+   {
+         flow(END);
+   });
+}
+
+TEST_F(MergeFlow, WaitWithMessage) {
+   CASE({
+         bi_ld_attr_imm_to(b, bi_register(16), bi_register(60), bi_register(61),
+                           BI_REGISTER_FORMAT_F32, BI_VECSIZE_V4, 1);
+         flow(WAIT0);
+   },
+   {
+         I = bi_ld_attr_imm_to(b, bi_register(16), bi_register(60), bi_register(61),
+                               BI_REGISTER_FORMAT_F32, BI_VECSIZE_V4, 1);
+         I->flow = VA_FLOW_WAIT0;
+   });
+}
+
+TEST_F(MergeFlow, CantMoveWaitPastMessage) {
+   NEGCASE({
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         I = bi_ld_attr_imm_to(b, bi_register(16), bi_register(60), bi_register(61),
+                           BI_REGISTER_FORMAT_F32, BI_VECSIZE_V4, 1);
+
+         /* Pretend it's blocked for some reason. This doesn't actually happen
+          * with the current algorithm, but it's good to handle the special
+          * cases correctly in case we change later on.
+          */
+         I->flow = VA_FLOW_DISCARD;
+         flow(WAIT0);
+   });
+}
+
+TEST_F(MergeFlow, DeletePointlessDiscard) {
+   CASE({
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         bi_tex_single_to(b, bi_register(0), bi_register(4), bi_register(8),
+                          bi_register(12), false, BI_DIMENSION_2D,
+                          BI_REGISTER_FORMAT_F32, false, false,
+                          BI_VA_LOD_MODE_COMPUTED_LOD, BI_WRITE_MASK_RGBA, 4);
+         flow(DISCARD);
+         flow(WAIT0);
+         flow(WAIT0126);
+         bi_atest_to(b, bi_register(0), bi_register(4), bi_register(5));
+         flow(WAIT);
+         bi_blend_to(b, bi_register(0), bi_register(4), bi_register(5),
+                     bi_register(6), bi_register(7), bi_register(8),
+                     BI_REGISTER_FORMAT_AUTO, 4, 4);
+         flow(END);
+   },
+   {
+         bi_fadd_f32_to(b, bi_register(0), bi_register(0), bi_register(0));
+         I = bi_tex_single_to(b, bi_register(0), bi_register(4), bi_register(8),
+                          bi_register(12), false, BI_DIMENSION_2D,
+                          BI_REGISTER_FORMAT_F32, false, false,
+                          BI_VA_LOD_MODE_COMPUTED_LOD, BI_WRITE_MASK_RGBA, 4);
+         I->flow = VA_FLOW_WAIT0126;
+         I = bi_atest_to(b, bi_register(0), bi_register(4), bi_register(5));
+         I->flow = VA_FLOW_WAIT;
+         I = bi_blend_to(b, bi_register(0), bi_register(4), bi_register(5),
+                         bi_register(6), bi_register(7), bi_register(8),
+                         BI_REGISTER_FORMAT_AUTO, 4, 4);
+         I->flow = VA_FLOW_END;
+   });
+}
+