From 10660f5adfeed943fdc653554dcaf661f0adacb6 Mon Sep 17 00:00:00 2001
From: Caio Oliveira <caio.oliveira@intel.com>
Date: Fri, 7 Mar 2025 23:05:43 -0800
Subject: [PATCH] brw: Add analysis for block IP ranges

Calculate the IP ranges of the shader as an analysis pass.  This will
later replace the existing tracking of start_ip/end_ip as the blocks are
changed (and the defer/adjust scheme to avoid too much churn when that
happen).

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34012>
---
 src/intel/compiler/brw_analysis.cpp | 43 +++++++++++++++++++++++++++++
 src/intel/compiler/brw_analysis.h   | 32 +++++++++++++++++++++
 src/intel/compiler/brw_shader.cpp   |  3 ++
 src/intel/compiler/brw_shader.h     |  1 +
 4 files changed, 79 insertions(+)

diff --git a/src/intel/compiler/brw_analysis.cpp b/src/intel/compiler/brw_analysis.cpp
index 2b2a866c997..fb05e242bd8 100644
--- a/src/intel/compiler/brw_analysis.cpp
+++ b/src/intel/compiler/brw_analysis.cpp
@@ -77,6 +77,49 @@ brw_idom_tree::dump(FILE *file) const
    fprintf(file, "}\n");
 }
 
+brw_ip_ranges::brw_ip_ranges(const brw_shader *shader)
+{
+   num_blocks = shader->cfg->num_blocks;
+   start_ip   = new int[num_blocks];
+
+   unsigned next_ip = 0;
+   for (int i = 0; i < num_blocks; i++) {
+      start_ip[i] = next_ip;
+
+      bblock_t *block = shader->cfg->blocks[i];
+      next_ip += block->num_instructions;
+   }
+}
+
+brw_ip_ranges::~brw_ip_ranges()
+{
+   delete[] start_ip;
+}
+
+bool
+brw_ip_ranges::validate(const brw_shader *s) const
+{
+   if (s->cfg->num_blocks != num_blocks)
+      return false;
+
+   int ip = 0;
+   for (int i = 0; i < num_blocks; i++) {
+      bblock_t *block = s->cfg->blocks[i];
+      if (start_ip[i] != ip)
+         return false;
+      ip += block->num_instructions;
+   }
+
+   if (num_blocks) {
+      bblock_t *last_block = s->cfg->blocks[num_blocks - 1];
+      unsigned last_ip = end(last_block);
+      if (last_ip + 1 != s->cfg->total_instructions)
+         return false;
+   }
+
+   return true;
+}
+
 brw_register_pressure::brw_register_pressure(const brw_shader *v)
 {
    const brw_live_variables &live = v->live_analysis.require();
diff --git a/src/intel/compiler/brw_analysis.h b/src/intel/compiler/brw_analysis.h
index 8200858c03b..c127efbce22 100644
--- a/src/intel/compiler/brw_analysis.h
+++ b/src/intel/compiler/brw_analysis.h
@@ -232,6 +232,38 @@ private:
    bblock_t **parents;
 };
 
+struct brw_ip_ranges {
+   brw_ip_ranges(const brw_shader *s);
+   ~brw_ip_ranges();
+
+   bool validate(const brw_shader *) const;
+
+   brw_analysis_dependency_class
+   dependency_class() const
+   {
+      return BRW_DEPENDENCY_INSTRUCTION_IDENTITY |
+             BRW_DEPENDENCY_BLOCKS;
+   }
+
+   int
+   start(const bblock_t *block) const
+   {
+      assert(block->num < num_blocks);
+      return start_ip[block->num];
+   }
+
+   int
+   end(const bblock_t *block) const
+   {
+      assert(block->num < num_blocks);
+      return start_ip[block->num] + block->num_instructions - 1;
+   }
+
+private:
+   int num_blocks;
+   int *start_ip;
+};
+
 /**
  * Register pressure analysis of a shader.  Estimates how many registers
  * are live at any point of the program in GRF units.
diff --git a/src/intel/compiler/brw_shader.cpp b/src/intel/compiler/brw_shader.cpp
index 74ed1f4f2e6..4e9141b08c8 100644
--- a/src/intel/compiler/brw_shader.cpp
+++ b/src/intel/compiler/brw_shader.cpp
@@ -409,6 +409,7 @@ brw_shader::brw_shader(const struct brw_compiler *compiler,
      key(key), prog_data(prog_data),
      live_analysis(this), regpressure_analysis(this),
      performance_analysis(this), idom_analysis(this), def_analysis(this),
+     ip_ranges_analysis(this),
      needs_register_pressure(needs_register_pressure),
      dispatch_width(dispatch_width),
      max_polygons(0),
@@ -433,6 +434,7 @@ brw_shader::brw_shader(const struct brw_compiler *compiler,
      key(&key->base), prog_data(&prog_data->base),
      live_analysis(this), regpressure_analysis(this),
      performance_analysis(this), idom_analysis(this), def_analysis(this),
+     ip_ranges_analysis(this),
      needs_register_pressure(needs_register_pressure),
      dispatch_width(dispatch_width),
      max_polygons(max_polygons),
@@ -957,6 +959,7 @@ brw_shader::invalidate_analysis(brw_analysis_dependency_class c)
    performance_analysis.invalidate(c);
    idom_analysis.invalidate(c);
    def_analysis.invalidate(c);
+   ip_ranges_analysis.invalidate(c);
 }
 
 void
diff --git a/src/intel/compiler/brw_shader.h b/src/intel/compiler/brw_shader.h
index 6a4ab528540..ebe55bd9dbf 100644
--- a/src/intel/compiler/brw_shader.h
+++ b/src/intel/compiler/brw_shader.h
@@ -139,6 +139,7 @@ public:
    brw_analysis<brw_performance, brw_shader> performance_analysis;
    brw_analysis<brw_idom_tree, brw_shader> idom_analysis;
    brw_analysis<brw_def_analysis, brw_shader> def_analysis;
+   brw_analysis<brw_ip_ranges, brw_shader> ip_ranges_analysis;
 
    /** Number of uniform variable components visited. */
    unsigned uniforms;