From 9716bc37df435170ad3f4b2954373387d978d67f Mon Sep 17 00:00:00 2001
From: pca006132 <john.lck40@gmail.com>
Date: Sun, 29 Dec 2024 22:31:34 +0800
Subject: [PATCH] update optimizing_tape

---
 src/sdf/affine_value.h    | 42 +++++++++++++++++++++++++++++++++++++++
 src/sdf/context.cpp       | 25 +----------------------
 src/sdf/context.h         |  1 -
 src/sdf/optimizing_tape.h | 14 ++++++-------
 4 files changed, 50 insertions(+), 32 deletions(-)
 create mode 100644 src/sdf/affine_value.h

diff --git a/src/sdf/affine_value.h b/src/sdf/affine_value.h
new file mode 100644
index 000000000..766279f90
--- /dev/null
+++ b/src/sdf/affine_value.h
@@ -0,0 +1,42 @@
+// Copyright 2024 The Manifold Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#pragma once
+
+#include "context.h"
+
+namespace manifold::sdf {
+struct AffineValue {
+  // value = var * a + b
+  Operand var;
+  double a;
+  double b;
+
+  AffineValue(Operand var, double a, double b) : var(var), a(a), b(b) {}
+  AffineValue(double constant) : var(Operand::none()), a(0.0), b(constant) {}
+  bool operator==(const AffineValue &other) const {
+    return var == other.var && a == other.a && b == other.b;
+  }
+  AffineValue operator+(double d) { return AffineValue(var, a, b + d); }
+  AffineValue operator*(double d) { return AffineValue(var, a * d, b * d); }
+};
+}  // namespace manifold::sdf
+
+template <>
+struct std::hash<AffineValue> {
+  size_t operator()(const AffineValue &value) const {
+    size_t h = std::hash<int>()(value.var.id);
+    hash_combine(h, value.a, value.b);
+    return h;
+  }
+};
diff --git a/src/sdf/context.cpp b/src/sdf/context.cpp
index a3b7d8e17..1aa95f6ae 100644
--- a/src/sdf/context.cpp
+++ b/src/sdf/context.cpp
@@ -20,32 +20,9 @@
 #include <iostream>
 #endif
 
+#include "affine_value.h"
 #include "manifold/optional_assert.h"
 
-struct AffineValue {
-  // value = var * a + b
-  Operand var;
-  double a;
-  double b;
-
-  AffineValue(Operand var, double a, double b) : var(var), a(a), b(b) {}
-  AffineValue(double constant) : var(Operand::none()), a(0.0), b(constant) {}
-  bool operator==(const AffineValue &other) const {
-    return var == other.var && a == other.a && b == other.b;
-  }
-  AffineValue operator+(double d) { return AffineValue(var, a, b + d); }
-  AffineValue operator*(double d) { return AffineValue(var, a * d, b * d); }
-};
-
-template <>
-struct std::hash<AffineValue> {
-  size_t operator()(const AffineValue &value) const {
-    size_t h = std::hash<int>()(value.var.id);
-    hash_combine(h, value.a, value.b);
-    return h;
-  }
-};
-
 namespace manifold::sdf {
 void Context::dump() const {
 #ifdef MANIFOLD_DEBUG
diff --git a/src/sdf/context.h b/src/sdf/context.h
index 772366dc2..e0dc20f84 100644
--- a/src/sdf/context.h
+++ b/src/sdf/context.h
@@ -57,7 +57,6 @@ using namespace manifold::sdf;
 
 inline void hash_combine(std::size_t& seed) {}
 
-// note: ankerl hash combine function is too costly
 template <typename T, typename... Rest>
 inline void hash_combine(std::size_t& seed, const T& v, Rest... rest) {
   std::hash<T> hasher;
diff --git a/src/sdf/optimizing_tape.h b/src/sdf/optimizing_tape.h
index d7e0a4ca1..90d80cab7 100644
--- a/src/sdf/optimizing_tape.h
+++ b/src/sdf/optimizing_tape.h
@@ -15,6 +15,7 @@
 
 #include <vector>
 
+#include "affine_value.h"
 #include "interval.h"
 #include "manifold/vec_view.h"
 
@@ -58,7 +59,7 @@ class OptimizerContext {
    * For dependencies, we use relative index to track them.
    *   ID = current ID - value
    * - If value is 0, this means the operand is not being used, i.e. the
-   *   instruction does not have 3 operands.
+   *   instruction does not have that operand.
    * - If value is 255, this means the dependency is too far away, and we
    *   should look it up in far dependencies.
    * Ideally, we should not have too many far dependencies.
@@ -80,10 +81,9 @@ class OptimizerContext {
    * memory operations, we reuse them.
    *
    * - `buffer` is the regular register buffer for tape evaluation.
-   * - `constantOffset` is a constant that adds to a corresponding register.
-   *   This can be constant folded.
-   * - `results` contains instruction id + register id, indicating the
-   *   predetermined branch result for choice/min/max function.
+   * - `affineValue` is the affine value associated with a register.
+   * - `results` contains instruction id + affine value, indicating the
+   *   optimized result for some instruction.
    *   Note that this must be sorted according to instruction id.
    * - `uses` is the temporary use count vector that is mutable in each
    *   evaluation. It is reset before each evaluation.
@@ -91,8 +91,8 @@ class OptimizerContext {
    *   elimination.
    */
   VecView<Interval<double>> buffer;
-  VecView<double> constantOffset;
-  std::vector<std::pair<uint32_t, uint8_t>> results;
+  VecView<AffineValue> affineValues;
+  std::vector<std::pair<uint32_t, AffineValue>> results;
   std::vector<uint8_t> uses;
   std::vector<uint32_t> dead;
 };