From e67e44522f4f5de4fcde53ad0fb75e396ef31f52 Mon Sep 17 00:00:00 2001
From: Simon Perretta <simon.perretta@imgtec.com>
Date: Thu, 30 May 2024 12:10:06 +0100
Subject: [PATCH] pco: initial validation boilerplate and SSA checks

Signed-off-by: Simon Perretta <simon.perretta@imgtec.com>
Acked-by: Frank Binns <frank.binns@imgtec.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32258>
---
 src/imagination/pco/pco_validate.c | 155 +++++++++++++++++++++++++++++
 1 file changed, 155 insertions(+)

diff --git a/src/imagination/pco/pco_validate.c b/src/imagination/pco/pco_validate.c
index ba70901efd1..ad85be7773a 100644
--- a/src/imagination/pco/pco_validate.c
+++ b/src/imagination/pco/pco_validate.c
@@ -12,7 +12,153 @@
 
 #include "pco.h"
 #include "pco_internal.h"
+#include "util/bitset.h"
 #include "util/macros.h"
+#include "util/ralloc.h"
+
+#include <stdio.h>
+
+enum ref_cursor {
+   REF_CURSOR_NONE,
+   REF_CURSOR_INSTR_DEST,
+   REF_CURSOR_INSTR_SRC,
+   REF_CURSOR_IGRP_SRC,
+   REF_CURSOR_IGRP_ISS,
+   REF_CURSOR_IGRP_DEST,
+};
+
+/** Validation state. */
+struct val_state {
+   const char *when; /** Description of the validation being done. */
+   pco_shader *shader; /** The shader being validated. */
+   pco_func *func; /** Current function being validated. */
+   pco_cf_node *cf_node; /** Current cf node being validated. */
+   pco_igrp *igrp; /** Current instruction group being validated. */
+   enum pco_op_phase phase; /** Phase of the instruction being validated. */
+   pco_instr *instr; /** Current instruction being validated. */
+   pco_ref *ref; /** Current reference being validated. */
+   enum ref_cursor ref_cursor; /** Current reference cursor. */
+};
+
+/**
+ * \brief Asserts a condition, printing an error and aborting on failure.
+ *
+ * \param[in] state Validation state.
+ * \param[in] cond Assertion condition.
+ * \param[in] cond_str Assertion condition string.
+ * \param[in] fmt Format string.
+ */
+static void pco_assert(struct val_state *state,
+                       bool cond,
+                       const char *cond_str,
+                       const char *fmt,
+                       ...)
+{
+   if (cond)
+      return;
+
+   printf("PCO validation failed with assertion \"%s\" - ", cond_str);
+
+   va_list args;
+   va_start(args, fmt);
+   vprintf(fmt, args);
+   va_end(args);
+
+   printf(" - while validating");
+
+   if (state->ref_cursor != REF_CURSOR_NONE) {
+      switch (state->ref_cursor) {
+      case REF_CURSOR_INSTR_DEST:
+         printf(" instr dest #%lu", state->ref - state->instr->dest);
+         break;
+
+      case REF_CURSOR_INSTR_SRC:
+         printf(" instr src #%lu", state->ref - state->instr->src);
+         break;
+
+      default:
+         unreachable();
+      }
+
+      printf(" (");
+      pco_print_ref(state->shader, *state->ref);
+      printf(")");
+   }
+
+   if (state->cf_node) {
+      printf(" ");
+      pco_print_cf_node_name(state->shader, state->cf_node);
+   }
+
+   if (state->igrp) {
+      printf(" igrp ");
+      pco_print_igrp(state->shader, state->igrp);
+   }
+
+   if (state->instr) {
+      printf(" instr ");
+      pco_print_instr(state->shader, state->instr);
+   }
+
+   if (state->func) {
+      printf(" ");
+      pco_print_cf_node_name(state->shader, &state->func->cf_node);
+   }
+
+   printf(".\n");
+
+   pco_print_shader_info(state->shader);
+
+   abort();
+}
+
+#define PCO_ASSERT(state, cond, fmt, ...) \
+   pco_assert(state, cond, #cond, fmt, ##__VA_ARGS__)
+
+/**
+ * \brief Validates SSA assignments and uses.
+ *
+ * \param[in,out] state Validation state.
+ */
+static void pco_validate_ssa(struct val_state *state)
+{
+   BITSET_WORD *ssa_writes;
+   pco_foreach_func_in_shader (func, state->shader) {
+      state->func = func;
+
+      ssa_writes = rzalloc_array_size(NULL,
+                                      sizeof(*ssa_writes),
+                                      BITSET_WORDS(func->next_ssa));
+
+      /* Ensure sources have been defined before they're used. */
+      state->ref_cursor = REF_CURSOR_INSTR_SRC;
+      pco_foreach_instr_in_func (instr, func) {
+         state->cf_node = &instr->parent_block->cf_node;
+         state->instr = instr;
+         pco_foreach_instr_src_ssa (psrc, instr) {
+            state->ref = psrc;
+            PCO_ASSERT(state,
+                       BITSET_TEST(ssa_writes, psrc->val),
+                       "SSA source used before being defined");
+         }
+
+         /* Ensure destinations are only defined once. */
+         state->ref_cursor = REF_CURSOR_INSTR_DEST;
+         pco_foreach_instr_dest_ssa (pdest, instr) {
+            state->ref = pdest;
+            PCO_ASSERT(state,
+                       !BITSET_TEST(ssa_writes, pdest->val),
+                       "SSA destination defined to more than once");
+            BITSET_SET(ssa_writes, pdest->val);
+         }
+      }
+
+      ralloc_free(ssa_writes);
+
+      state->func = NULL;
+      state->ref = NULL;
+   }
+}
 
 /**
  * \brief Validates a PCO shader.
@@ -26,6 +172,15 @@ void pco_validate_shader(UNUSED pco_shader *shader, UNUSED const char *when)
    if (PCO_DEBUG(VAL_SKIP))
       return;
 
+   struct val_state state = {
+      .when = when,
+      .shader = shader,
+      .phase = -1,
+   };
+
+   if (!shader->is_grouped)
+      pco_validate_ssa(&state);
+
    puts("finishme: pco_validate_shader");
 #endif /* NDEBUG */
 }