pan/mdg: Replace writeout booleans with a single value

A single value is easier to deal with than three separate booleans.

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5065>

src/panfrost/midgard/compiler.h

@@ -70,6 +70,10 @@ typedef struct midgard_branch {
         };
 } midgard_branch;
 
+#define PAN_WRITEOUT_C 1
+#define PAN_WRITEOUT_Z 2
+#define PAN_WRITEOUT_S 4
+
 /* Generic in-memory data type repesenting a single logical instruction, rather
  * than a single instruction group. This is the preferred form for code gen.
  * Multiple midgard_insturctions will later be combined during scheduling,
@@ -142,9 +146,7 @@ typedef struct midgard_instruction {
         bool has_inline_constant;
 
         bool compact_branch;
-        bool writeout;
-        bool writeout_depth;
-        bool writeout_stencil;
+        uint8_t writeout;
         bool last_writeout;
 
         /* Masks in a saneish format. One bit per channel, not packed fancy.

src/panfrost/midgard/midgard_compile.c

@@ -1307,13 +1307,14 @@ emit_fragment_store(compiler_context *ctx, unsigned src, enum midgard_rt_id rt)
         struct midgard_instruction ins =
                 v_branch(false, false);
 
-        ins.writeout = true;
+        bool depth_only = (rt == MIDGARD_ZS_RT);
+
+        ins.writeout = depth_only ? PAN_WRITEOUT_Z : PAN_WRITEOUT_C;
 
         /* Add dependencies */
         ins.src[0] = src;
         ins.src_types[0] = nir_type_uint32;
-        ins.constants.u32[0] = rt == MIDGARD_ZS_RT ?
-                               0xFF : (rt - MIDGARD_COLOR_RT0) * 0x100;
+        ins.constants.u32[0] = depth_only ? 0xFF : (rt - MIDGARD_COLOR_RT0) * 0x100;
         for (int i = 0; i < 4; ++i)
                 ins.swizzle[0][i] = i;
 
@@ -2233,9 +2234,7 @@ emit_fragment_epilogue(compiler_context *ctx, unsigned rt)
         /* Loop to ourselves */
         midgard_instruction *br = ctx->writeout_branch[rt];
         struct midgard_instruction ins = v_branch(false, false);
-        ins.writeout = true;
-        ins.writeout_depth = br->writeout_depth;
-        ins.writeout_stencil = br->writeout_stencil;
+        ins.writeout = br->writeout;
         ins.branch.target_block = ctx->block_count - 1;
         ins.constants.u32[0] = br->constants.u32[0];
         memcpy(&ins.src_types, &br->src_types, sizeof(ins.src_types));