i965: Add initial assembly validation pass.

Initially just checks that sources are non-NULL, which would have
alerted us to the problem fixed by commit 6c846dc5.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/mesa/drivers/dri/i965/Makefile.sources

@@ -14,6 +14,7 @@ i965_compiler_FILES = \
 	brw_eu_emit.c \
 	brw_eu.h \
 	brw_eu_util.c \
+	brw_eu_validate.c \
 	brw_fs_builder.h \
 	brw_fs_channel_expressions.cpp \
 	brw_fs_cmod_propagation.cpp \

src/mesa/drivers/dri/i965/brw_eu.h

@@ -522,6 +522,10 @@ bool brw_try_compact_instruction(const struct brw_device_info *devinfo,
 void brw_debug_compact_uncompact(const struct brw_device_info *devinfo,
                                  brw_inst *orig, brw_inst *uncompacted);
 
+/* brw_eu_validate.c */
+bool brw_validate_instructions(const struct brw_codegen *p, int start_offset,
+                               struct annotation_info *annotation);
+
 static inline int
 next_offset(const struct brw_device_info *devinfo, void *store, int offset)
 {

src/mesa/drivers/dri/i965/brw_eu_validate.c

@@ -0,0 +1,153 @@
+/*
+ * Copyright © 2015 Intel Corporation
+ *
+ * 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.
+ */
+
+/** @file brw_eu_validate.c
+ *
+ * This file implements a pass that validates shader assembly.
+ */
+
+#include "brw_eu.h"
+
+/* We're going to do lots of string concatenation, so this should help. */
+struct string {
+   char *str;
+   size_t len;
+};
+
+static void
+cat(struct string *dest, const struct string src)
+{
+   dest->str = realloc(dest->str, dest->len + src.len + 1);
+   memcpy(dest->str + dest->len, src.str, src.len);
+   dest->str[dest->len + src.len + 1] = '\0';
+   dest->len = dest->len + src.len;
+}
+#define CAT(dest, src) cat(&dest, (struct string){src, strlen(src)})
+
+#define error(str) "\tERROR: " str "\n"
+
+#define ERROR_IF(cond, msg)          \
+   do {                              \
+      if (cond) {                    \
+         CAT(error_msg, error(msg)); \
+         valid = false;              \
+      }                              \
+   } while(0)
+
+static bool
+src0_is_null(const struct brw_device_info *devinfo, const brw_inst *inst)
+{
+   return brw_inst_src0_reg_file(devinfo, inst) == BRW_ARCHITECTURE_REGISTER_FILE &&
+          brw_inst_src0_da_reg_nr(devinfo, inst) == BRW_ARF_NULL;
+}
+
+static bool
+src1_is_null(const struct brw_device_info *devinfo, const brw_inst *inst)
+{
+   return brw_inst_src1_reg_file(devinfo, inst) == BRW_ARCHITECTURE_REGISTER_FILE &&
+          brw_inst_src1_da_reg_nr(devinfo, inst) == BRW_ARF_NULL;
+}
+
+static unsigned
+num_sources_from_inst(const struct brw_device_info *devinfo,
+                      const brw_inst *inst)
+{
+   unsigned math_function;
+
+   if (brw_inst_opcode(devinfo, inst) == BRW_OPCODE_MATH) {
+      math_function = brw_inst_math_function(devinfo, inst);
+   } else if (devinfo->gen < 6 &&
+              brw_inst_opcode(devinfo, inst) == BRW_OPCODE_SEND) {
+      if (brw_inst_sfid(devinfo, inst) == BRW_SFID_MATH) {
+         math_function = brw_inst_math_msg_function(devinfo, inst);
+      } else {
+         /* Send instructions are allowed to have null sources since they use
+          * the base_mrf field to specify which message register source.
+          */
+         return 0;
+      }
+   } else {
+      return opcode_descs[brw_inst_opcode(devinfo, inst)].nsrc;
+   }
+
+   switch (math_function) {
+   case BRW_MATH_FUNCTION_INV:
+   case BRW_MATH_FUNCTION_LOG:
+   case BRW_MATH_FUNCTION_EXP:
+   case BRW_MATH_FUNCTION_SQRT:
+   case BRW_MATH_FUNCTION_RSQ:
+   case BRW_MATH_FUNCTION_SIN:
+   case BRW_MATH_FUNCTION_COS:
+   case BRW_MATH_FUNCTION_SINCOS:
+   case GEN8_MATH_FUNCTION_INVM:
+   case GEN8_MATH_FUNCTION_RSQRTM:
+      return 1;
+   case BRW_MATH_FUNCTION_FDIV:
+   case BRW_MATH_FUNCTION_POW:
+   case BRW_MATH_FUNCTION_INT_DIV_QUOTIENT_AND_REMAINDER:
+   case BRW_MATH_FUNCTION_INT_DIV_QUOTIENT:
+   case BRW_MATH_FUNCTION_INT_DIV_REMAINDER:
+      return 2;
+   default:
+      unreachable("not reached");
+   }
+}
+
+bool
+brw_validate_instructions(const struct brw_codegen *p, int start_offset,
+                          struct annotation_info *annotation)
+{
+   const struct brw_device_info *devinfo = p->devinfo;
+   const void *store = p->store + start_offset / 16;
+   bool valid = true;
+
+   for (int src_offset = 0; src_offset < p->next_insn_offset - start_offset;
+        src_offset += sizeof(brw_inst)) {
+      struct string error_msg = { .str = NULL, .len = 0 };
+      const brw_inst *inst = store + src_offset;
+
+      switch (num_sources_from_inst(devinfo, inst)) {
+      case 3:
+         /* Nothing to test. 3-src instructions can only have GRF sources, and
+          * there's no bit to control the file.
+          */
+         break;
+      case 2:
+         ERROR_IF(src1_is_null(devinfo, inst), "src1 is null");
+         /* fallthrough */
+      case 1:
+         ERROR_IF(src0_is_null(devinfo, inst), "src0 is null");
+         break;
+      case 0:
+      default:
+         break;
+      }
+
+      if (error_msg.str && annotation) {
+         annotation_insert_error(annotation, src_offset, error_msg.str);
+      }
+      free(error_msg.str);
+   }
+
+   return valid;
+}

src/mesa/drivers/dri/i965/brw_fs_generator.cpp

@@ -2252,6 +2252,13 @@ fs_generator::generate_code(const cfg_t *cfg, int dispatch_width)
    brw_set_uip_jip(p);
    annotation_finalize(&annotation, p->next_insn_offset);
 
+#ifndef NDEBUG
+   bool validated = brw_validate_instructions(p, start_offset, &annotation);
+#else
+   if (unlikely(debug_flag))
+      brw_validate_instructions(p, start_offset, &annotation);
+#endif
+
    int before_size = p->next_insn_offset - start_offset;
    brw_compact_instructions(p, start_offset, annotation.ann_count,
                             annotation.ann);
@@ -2269,6 +2276,7 @@ fs_generator::generate_code(const cfg_t *cfg, int dispatch_width)
                     p->devinfo);
       ralloc_free(annotation.mem_ctx);
    }
+   assert(validated);
 
    compiler->shader_debug_log(log_data,
                               "%s SIMD%d shader: %d inst, %d loops, %u cycles, "

src/mesa/drivers/dri/i965/brw_vec4_generator.cpp

@@ -1543,6 +1543,13 @@ generate_code(struct brw_codegen *p,
    brw_set_uip_jip(p);
    annotation_finalize(&annotation, p->next_insn_offset);
 
+#ifndef NDEBUG
+   bool validated = brw_validate_instructions(p, 0, &annotation);
+#else
+   if (unlikely(debug_flag))
+      brw_validate_instructions(p, 0, &annotation);
+#endif
+
    int before_size = p->next_insn_offset;
    brw_compact_instructions(p, 0, annotation.ann_count, annotation.ann);
    int after_size = p->next_insn_offset;
@@ -1562,6 +1569,7 @@ generate_code(struct brw_codegen *p,
                     p->devinfo);
       ralloc_free(annotation.mem_ctx);
    }
+   assert(validated);
 
    compiler->shader_debug_log(log_data,
                               "%s vec4 shader: %d inst, %d loops, %u cycles, "