Mesa (master): i965/vs: Copy the live intervals calculation over from the FS.

Eric Anholt anholt at kemper.freedesktop.org
Fri Aug 19 17:14:10 PDT 2011


Module: Mesa
Branch: master
Commit: 3dadc1e3cceac80a1b63cad2e10f0e0f8904531b
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=3dadc1e3cceac80a1b63cad2e10f0e0f8904531b

Author: Eric Anholt <eric at anholt.net>
Date:   Tue Aug 16 15:09:48 2011 -0700

i965/vs: Copy the live intervals calculation over from the FS.

This is a rather pessimistic calculation, since it doesn't distinguish
individual channels of a vec4, or elements of an array, but should be
a minimum start for register allocation.

---

 src/mesa/drivers/dri/i965/Makefile             |    1 +
 src/mesa/drivers/dri/i965/brw_vec4.cpp         |  130 ++++++++++++++++++++++++
 src/mesa/drivers/dri/i965/brw_vec4.h           |    5 +
 src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp |    3 +
 4 files changed, 139 insertions(+), 0 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/Makefile b/src/mesa/drivers/dri/i965/Makefile
index 45a5350..d9c885d 100644
--- a/src/mesa/drivers/dri/i965/Makefile
+++ b/src/mesa/drivers/dri/i965/Makefile
@@ -125,6 +125,7 @@ CXX_SOURCES = \
 	brw_fs_schedule_instructions.cpp \
 	brw_fs_vector_splitting.cpp \
 	brw_shader.cpp \
+	brw_vec4.cpp \
 	brw_vec4_emit.cpp \
 	brw_vec4_reg_allocate.cpp \
 	brw_vec4_visitor.cpp
diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
new file mode 100644
index 0000000..a3ed31a
--- /dev/null
+++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
@@ -0,0 +1,130 @@
+/*
+ * Copyright © 2011 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.
+ */
+
+#include "brw_vec4.h"
+extern "C" {
+#include "main/macros.h"
+#include "program/prog_parameter.h"
+}
+
+#define MAX_INSTRUCTION (1 << 30)
+
+namespace brw {
+
+void
+vec4_visitor::calculate_live_intervals()
+{
+   int *def = ralloc_array(mem_ctx, int, virtual_grf_count);
+   int *use = ralloc_array(mem_ctx, int, virtual_grf_count);
+   int loop_depth = 0;
+   int loop_start = 0;
+
+   if (this->live_intervals_valid)
+      return;
+
+   for (int i = 0; i < virtual_grf_count; i++) {
+      def[i] = MAX_INSTRUCTION;
+      use[i] = -1;
+   }
+
+   int ip = 0;
+   foreach_list(node, &this->instructions) {
+      vec4_instruction *inst = (vec4_instruction *)node;
+
+      if (inst->opcode == BRW_OPCODE_DO) {
+	 if (loop_depth++ == 0)
+	    loop_start = ip;
+      } else if (inst->opcode == BRW_OPCODE_WHILE) {
+	 loop_depth--;
+
+	 if (loop_depth == 0) {
+	    /* Patches up the use of vars marked for being live across
+	     * the whole loop.
+	     */
+	    for (int i = 0; i < virtual_grf_count; i++) {
+	       if (use[i] == loop_start) {
+		  use[i] = ip;
+	       }
+	    }
+	 }
+      } else {
+	 for (unsigned int i = 0; i < 3; i++) {
+	    if (inst->src[i].file == GRF) {
+	       int reg = inst->src[i].reg;
+
+	       if (!loop_depth) {
+		  use[reg] = ip;
+	       } else {
+		  def[reg] = MIN2(loop_start, def[reg]);
+		  use[reg] = loop_start;
+
+		  /* Nobody else is going to go smash our start to
+		   * later in the loop now, because def[reg] now
+		   * points before the bb header.
+		   */
+	       }
+	    }
+	 }
+	 if (inst->dst.file == GRF) {
+	    int reg = inst->dst.reg;
+
+	    if (!loop_depth) {
+	       def[reg] = MIN2(def[reg], ip);
+	    } else {
+	       def[reg] = MIN2(def[reg], loop_start);
+	    }
+	 }
+      }
+
+      ip++;
+   }
+
+   ralloc_free(this->virtual_grf_def);
+   ralloc_free(this->virtual_grf_use);
+   this->virtual_grf_def = def;
+   this->virtual_grf_use = use;
+
+   this->live_intervals_valid = true;
+}
+
+bool
+vec4_visitor::virtual_grf_interferes(int a, int b)
+{
+   int start = MAX2(this->virtual_grf_def[a], this->virtual_grf_def[b]);
+   int end = MIN2(this->virtual_grf_use[a], this->virtual_grf_use[b]);
+
+   /* We can't handle dead register writes here, without iterating
+    * over the whole instruction stream to find every single dead
+    * write to that register to compare to the live interval of the
+    * other register.  Just assert that dead_code_eliminate() has been
+    * called.
+    */
+   assert((this->virtual_grf_use[a] != -1 ||
+	   this->virtual_grf_def[a] == MAX_INSTRUCTION) &&
+	  (this->virtual_grf_use[b] != -1 ||
+	   this->virtual_grf_def[b] == MAX_INSTRUCTION));
+
+   return start < end;
+}
+
+} /* namespace brw */
diff --git a/src/mesa/drivers/dri/i965/brw_vec4.h b/src/mesa/drivers/dri/i965/brw_vec4.h
index 620b055..77a28c7 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.h
+++ b/src/mesa/drivers/dri/i965/brw_vec4.h
@@ -320,6 +320,9 @@ public:
    int virtual_grf_count;
    int virtual_grf_array_size;
    int first_non_payload_grf;
+   int *virtual_grf_def;
+   int *virtual_grf_use;
+   bool live_intervals_valid;
 
    dst_reg *variable_storage(ir_variable *var);
 
@@ -377,6 +380,8 @@ public:
    void reg_allocate_trivial();
    void reg_allocate();
    void move_grf_array_access_to_scratch();
+   void calculate_live_intervals();
+   bool virtual_grf_interferes(int a, int b);
 
    vec4_instruction *emit(enum opcode opcode);
 
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
index a60fc5f..b3a07bd 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
@@ -2109,9 +2109,12 @@ vec4_visitor::vec4_visitor(struct brw_vs_compile *c,
 				       hash_table_pointer_hash,
 				       hash_table_pointer_compare);
 
+   this->virtual_grf_def = NULL;
+   this->virtual_grf_use = NULL;
    this->virtual_grf_sizes = NULL;
    this->virtual_grf_count = 0;
    this->virtual_grf_array_size = 0;
+   this->live_intervals_valid = false;
 
    this->uniforms = 0;
 



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