pan/bi: Unwrap BRANCH into CONDITIONAL class

We can simplify the IR considerably and unify more conditions, which
gives conditional discard for free.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4883>

4 files changed, 26 insertions, 46 deletions

diff --git a/src/panfrost/bifrost/bi_print.c b/src/panfrost/bifrost/bi_print.c
index 26a5ff7f198..151e2fe6c2d 100644
--- a/src/panfrost/bifrost/bi_print.c
+++ b/src/panfrost/bifrost/bi_print.c
@@ -315,12 +315,6 @@ bi_cond_name(enum bi_cond cond)
 }
 
 static void
-bi_print_branch(struct bi_branch *branch, FILE *fp)
-{
-        fprintf(fp, ".%s", bi_cond_name(branch->cond));
-}
-
-static void
 bi_print_texture(struct bi_texture *tex, FILE *fp)
 {
         fprintf(fp, " - texture %u, sampler %u",
@@ -352,10 +346,6 @@ bi_print_instruction(bi_instruction *ins, FILE *fp)
                 fprintf(fp, "%s", bi_minmax_mode_name(ins->minmax));
         else if (ins->type == BI_LOAD_VAR)
                 bi_print_load_vary(&ins->load_vary, fp);
-        else if (ins->type == BI_BRANCH)
-                bi_print_branch(&ins->branch, fp);
-        else if (ins->type == BI_CSEL || ins->type == BI_CMP)
-                fprintf(fp, ".%s", bi_cond_name(ins->cond));
         else if (ins->type == BI_BLEND)
                 fprintf(fp, ".loc%u", ins->blend_location);
         else if (ins->type == BI_TEX) {
@@ -363,6 +353,9 @@ bi_print_instruction(bi_instruction *ins, FILE *fp)
         } else if (ins->type == BI_BITWISE)
                 fprintf(fp, ".%cshift", ins->bitwise.rshift ? 'r' : 'l');
 
+        if (bi_class_props[ins->type] & BI_CONDITIONAL)
+                fprintf(fp, ".%s", bi_cond_name(ins->cond));
+
         if (ins->vector_channels)
                 fprintf(fp, ".v%u", ins->vector_channels);
 
@@ -397,10 +390,8 @@ bi_print_instruction(bi_instruction *ins, FILE *fp)
         }
 
         if (ins->type == BI_BRANCH) {
-                if (ins->branch.target)
-                        fprintf(fp, "-> block%u", ins->branch.target->base.name);
-                else
-                        fprintf(fp, "-> blockhole");
+                assert(ins->branch_target);
+                fprintf(fp, "-> block%u", ins->branch_target->base.name);
         } else if (ins->type == BI_TEX) {
                 bi_print_texture(&ins->texture, fp);
         }
diff --git a/src/panfrost/bifrost/bi_tables.c b/src/panfrost/bifrost/bi_tables.c
index 4bae5216e2d..bfa8c3bdae1 100644
--- a/src/panfrost/bifrost/bi_tables.c
+++ b/src/panfrost/bifrost/bi_tables.c
@@ -29,14 +29,14 @@
 unsigned bi_class_props[BI_NUM_CLASSES] = {
         [BI_ADD] 		= BI_MODS | BI_SCHED_ALL | BI_NO_ABS_ABS_FP16_FMA,
         [BI_ATEST] 		= BI_SCHED_HI_LATENCY | BI_SCHED_ADD,
-        [BI_BRANCH] 		= BI_SCHED_HI_LATENCY | BI_SCHED_ADD,
-        [BI_CMP] 		= BI_MODS | BI_SCHED_ALL,
+        [BI_BRANCH] 		= BI_SCHED_HI_LATENCY | BI_SCHED_ADD | BI_CONDITIONAL,
+        [BI_CMP] 		= BI_MODS | BI_SCHED_ALL | BI_CONDITIONAL,
         [BI_BLEND] 		= BI_SCHED_HI_LATENCY | BI_SCHED_ADD | BI_VECTOR | BI_DATA_REG_SRC,
         [BI_BITWISE] 		= BI_SCHED_ALL,
         [BI_COMBINE] 		= 0,
         [BI_CONVERT] 		= BI_SCHED_ADD | BI_SWIZZLABLE | BI_ROUNDMODE, /* +FMA on G71 */
-        [BI_CSEL] 		= BI_SCHED_FMA,
-        [BI_DISCARD] 		= BI_SCHED_HI_LATENCY | BI_SCHED_ADD,
+        [BI_CSEL] 		= BI_SCHED_FMA | BI_CONDITIONAL,
+        [BI_DISCARD] 		= BI_SCHED_HI_LATENCY | BI_SCHED_ADD | BI_CONDITIONAL,
         [BI_FMA] 		= BI_ROUNDMODE | BI_SCHED_FMA | BI_MODS,
         [BI_FREXP] 		= BI_SCHED_ALL,
         [BI_ISUB] 		= BI_SCHED_ALL,
diff --git a/src/panfrost/bifrost/bifrost_compile.c b/src/panfrost/bifrost/bifrost_compile.c
index 945d0190762..e656eeb49ce 100644
--- a/src/panfrost/bifrost/bifrost_compile.c
+++ b/src/panfrost/bifrost/bifrost_compile.c
@@ -63,16 +63,16 @@ emit_jump(bi_context *ctx, nir_jump_instr *instr)
 
         switch (instr->type) {
         case nir_jump_break:
-                branch->branch.target = ctx->break_block;
+                branch->branch_target = ctx->break_block;
                 break;
         case nir_jump_continue:
-                branch->branch.target = ctx->continue_block;
+                branch->branch_target = ctx->continue_block;
                 break;
         default:
                 unreachable("Unhandled jump type");
         }
 
-        pan_block_add_successor(&ctx->current_block->base, &branch->branch.target->base);
+        pan_block_add_successor(&ctx->current_block->base, &branch->branch_target->base);
 }
 
 static bi_instruction
@@ -937,9 +937,7 @@ bi_emit_branch(bi_context *ctx)
 {
         bi_instruction branch = {
                 .type = BI_BRANCH,
-                .branch = {
-                        .cond = BI_COND_ALWAYS
-                }
+                .cond = BI_COND_ALWAYS
         };
 
         return bi_emit(ctx, branch);
@@ -959,7 +957,7 @@ bi_set_branch_cond(bi_instruction *branch, nir_src *cond, bool invert)
         branch->src[0] = pan_src_index(cond);
         branch->src[1] = BIR_INDEX_ZERO;
         branch->src_types[0] = branch->src_types[1] = nir_type_uint16;
-        branch->branch.cond = invert ? BI_COND_EQ : BI_COND_NE;
+        branch->cond = invert ? BI_COND_EQ : BI_COND_NE;
 }
 
 static void
@@ -993,16 +991,16 @@ emit_if(bi_context *ctx, nir_if *nif)
         if (ctx->instruction_count == count_in) {
                 /* The else block is empty, so don't emit an exit jump */
                 bi_remove_instruction(then_exit);
-                then_branch->branch.target = ctx->after_block;
+                then_branch->branch_target = ctx->after_block;
         } else {
-                then_branch->branch.target = else_block;
-                then_exit->branch.target = ctx->after_block;
-                pan_block_add_successor(&end_then_block->base, &then_exit->branch.target->base);
+                then_branch->branch_target = else_block;
+                then_exit->branch_target = ctx->after_block;
+                pan_block_add_successor(&end_then_block->base, &then_exit->branch_target->base);
         }
 
         /* Wire up the successors */
 
-        pan_block_add_successor(&before_block->base, &then_branch->branch.target->base); /* then_branch */
+        pan_block_add_successor(&before_block->base, &then_branch->branch_target->base); /* then_branch */
 
         pan_block_add_successor(&before_block->base, &then_block->base); /* fallthrough */
         pan_block_add_successor(&end_else_block->base, &ctx->after_block->base); /* fallthrough */
@@ -1026,7 +1024,7 @@ emit_loop(bi_context *ctx, nir_loop *nloop)
 
         /* Branch back to loop back */
         bi_instruction *br_back = bi_emit_branch(ctx);
-        br_back->branch.target = ctx->continue_block;
+        br_back->branch_target = ctx->continue_block;
         pan_block_add_successor(&start_block->base, &ctx->continue_block->base);
         pan_block_add_successor(&ctx->current_block->base, &ctx->continue_block->base);
 
diff --git a/src/panfrost/bifrost/compiler.h b/src/panfrost/bifrost/compiler.h
index e438a58845e..16f44ff0103 100644
--- a/src/panfrost/bifrost/compiler.h
+++ b/src/panfrost/bifrost/compiler.h
@@ -86,7 +86,8 @@ extern unsigned bi_class_props[BI_NUM_CLASSES];
 /* abs/neg/outmod valid for a float op */
 #define BI_MODS (1 << 0)
 
-/* bit 1 unused */
+/* Accepts a bi_cond */
+#define BI_CONDITIONAL (1 << 1)
 
 /* Accepts a bifrost_roundmode */
 #define BI_ROUNDMODE (1 << 2)
@@ -154,15 +155,6 @@ enum bi_cond {
         BI_COND_NE,
 };
 
-struct bi_branch {
-        /* Types are specified in src_types and must be compatible (either both
-         * int, or both float, 16/32, and same size or 32/16 if float. Types
-         * ignored if BI_COND_ALWAYS is set for an unconditional branch. */
-
-        enum bi_cond cond;
-        struct bi_block *target;
-};
-
 /* Opcodes within a class */
 enum bi_minmax_op {
         BI_MINMAX_MIN,
@@ -270,6 +262,9 @@ typedef struct {
         /* For VECTOR ops, how many channels are written? */
         unsigned vector_channels;
 
+        /* The comparison op. BI_COND_ALWAYS may not be valid. */
+        enum bi_cond cond;
+
         /* A class-specific op from which the actual opcode can be derived
          * (along with the above information) */
 
@@ -290,11 +285,7 @@ typedef struct {
         union {
                 enum bifrost_minmax_mode minmax;
                 struct bi_load_vary load_vary;
-                struct bi_branch branch;
-
-                /* For CSEL, the comparison op. BI_COND_ALWAYS doesn't make
-                 * sense here but you can always just use a move for that */
-                enum bi_cond cond;
+                struct bi_block *branch_target;
 
                 /* For BLEND -- the location 0-7 */
                 unsigned blend_location;