ir3: add debug option to expand rpt instructions

Signed-off-by: Job Noorman <jnoorman@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28341>

src/freedreno/ir3/ir3_compiler.c

@@ -51,6 +51,7 @@ static const struct debug_named_value shader_debug_options[] = {
    {"fullnop",    IR3_DBG_FULLNOP,    "Add nops before each instruction"},
    {"noearlypreamble", IR3_DBG_NOEARLYPREAMBLE, "Disable early preambles"},
    {"nodescprefetch", IR3_DBG_NODESCPREFETCH, "Disable descriptor prefetch optimization"},
+   {"expandrpt",  IR3_DBG_EXPANDRPT,  "Expand rptN instructions"},
 #if MESA_DEBUG
    /* MESA_DEBUG-only options: */
    {"schedmsgs",  IR3_DBG_SCHEDMSGS,  "Enable scheduler debug messages"},

src/freedreno/ir3/ir3_compiler.h

@@ -345,6 +345,7 @@ enum ir3_shader_debug {
    IR3_DBG_FULLNOP = BITFIELD_BIT(16),
    IR3_DBG_NOEARLYPREAMBLE = BITFIELD_BIT(17),
    IR3_DBG_NODESCPREFETCH = BITFIELD_BIT(18),
+   IR3_DBG_EXPANDRPT = BITFIELD_BIT(19),
 
    /* MESA_DEBUG-only options: */
    IR3_DBG_SCHEDMSGS = BITFIELD_BIT(20),

src/freedreno/ir3/ir3_legalize.c

@@ -1369,6 +1369,42 @@ dbg_nop_sched(struct ir3 *ir, struct ir3_shader_variant *so)
    }
 }
 
+static void
+dbg_expand_rpt(struct ir3 *ir)
+{
+   foreach_block (block, &ir->block_list) {
+      foreach_instr_safe (instr, &block->instr_list) {
+         if (instr->repeat == 0 || instr->opc == OPC_NOP ||
+             instr->opc == OPC_SWZ || instr->opc == OPC_GAT ||
+             instr->opc == OPC_SCT) {
+            continue;
+         }
+
+         for (unsigned i = 0; i <= instr->repeat; ++i) {
+            struct ir3_instruction *rpt = ir3_instr_clone(instr);
+            ir3_instr_move_before(rpt, instr);
+            rpt->repeat = 0;
+
+            foreach_dst (dst, rpt) {
+               dst->num += i;
+               dst->wrmask = 1;
+            }
+
+            foreach_src (src, rpt) {
+               if (!(src->flags & IR3_REG_R))
+                  continue;
+
+               src->num += i;
+               src->wrmask = 1;
+               src->flags &= ~IR3_REG_R;
+            }
+         }
+
+         list_delinit(&instr->node);
+      }
+   }
+}
+
 struct ir3_helper_block_data {
    /* Whether helper invocations may be used on any path starting at the
     * beginning of the block.
@@ -1695,6 +1731,10 @@ ir3_legalize(struct ir3 *ir, struct ir3_shader_variant *so, int *max_bary)
 
    assert(ctx->early_input_release || ctx->compiler->gen >= 5);
 
+   if (ir3_shader_debug & IR3_DBG_EXPANDRPT) {
+      dbg_expand_rpt(ir);
+   }
+
    /* process each block: */
    do {
       progress = false;