优化 Jacobian 确定性复用并补充性能剖析与平台依赖文档

在单次 Jacobian 构建内按完整输入精确复用储气物性、PH 反算、密度和管路求根结果，保持原有求值副作用、差分政策与失败回退。八路模型求解 CPU 中位数减少 19.27%，循环和不循环的完整原始采样均与恢复基线一致。

增加独立的跨平台时间剖析工具，记录互斥阶段耗时、Newton/LU 统计、矩阵复用与内核复用，保存 UD00 两种工况的调查报告和机器可读汇总。

补充 Windows/Linux 运行、测试、原生编译和剖析所需依赖文档及索引，不修改依赖清单、版本锁或安装环境。

验证：8 项新增专项回归通过；2270 次完整 Jacobian 核对零差异；16 次剖析配对及预热运行保持完整数值一致。既有固定样本哈希失败和 Linux 实机验收限制见报告。

native/runtime/cvode_solver.c

@@ -11,11 +11,15 @@
 #include <sunlinsol/sunlinsol_dense.h>
 #include <math.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <sundials/sundials_math.h>
 #ifndef MODEL_JACOBIAN_COLORED
 #define MODEL_JACOBIAN_COLORED 0
 #endif
+#ifndef MODEL_JACOBIAN_GAS_REUSE
+#define MODEL_JACOBIAN_GAS_REUSE 0
+#endif
 
 typedef struct { void *solver; N_Vector scratch; } CvDense;
 static int cv_dense(void *context, double t, double *out) {
@@ -30,6 +34,9 @@ typedef struct {
     N_Vector weights;
     SUNMatrix reference;
     int colored;
+#if MODEL_JACOBIAN_GAS_REUSE
+    ModelJacobianWorkspace *jacobian_workspace;
+#endif
 } CvContext;
 static int cv_rhs(sunrealtype t, N_Vector y, N_Vector dy, void *context) {
     NativeRun *r=((CvContext *)context)->run;
@@ -76,6 +83,28 @@ static int jac_rhs(CvContext *context, sunrealtype t, N_Vector y, N_Vector f) {
 #endif
 }
 
+#if MODEL_JACOBIAN_GAS_REUSE
+_Static_assert(NATIVE_JACOBIAN_STATS_COUNT==NATIVE_JACOBIAN_SCALAR_KINDS,"Jacobian counter layout must match the kernel tags");
+static int jac_rhs_reuse(CvContext *context,sunrealtype t,N_Vector y,N_Vector f) {
+    if(!context->jacobian_workspace)return jac_rhs(context,t,y,f);
+    NativeRun *r=context->run;
+    if(!native_poll(r,r->final_time))return -1;
+    r->jacobian_rhs++;r->nfev++;
+    ModelJacobianWorkspace *workspace=context->jacobian_workspace;
+    NativeJacobianGasStats before=workspace->stats;
+    NativeJacobianScalars scalar_before=workspace->scalars;
+    double outputs[NOUTPUTS];
+    int ok=model_eval_jacobian_reuse(t,N_VGetArrayPointer(y),N_VGetArrayPointer(f),outputs,workspace);
+    r->jacobian_gas_evaluations+=workspace->stats.evaluations-before.evaluations;
+    r->jacobian_gas_reuses+=workspace->stats.reuses-before.reuses;
+    for(int i=0;i<NATIVE_JACOBIAN_SCALAR_KINDS;i++) {
+        r->jacobian_scalar_evaluations[i]+=workspace->scalars.evaluations[i]-scalar_before.evaluations[i];
+        r->jacobian_scalar_reuses[i]+=workspace->scalars.reuses[i]-scalar_before.reuses[i];
+    }
+    return ok?0:1;
+}
+#endif
+
 /* Same perturbation and reciprocal-multiply order as SUNDIALS 7.4 dense DQ.
  * No constraints are set by this runtime. If that changes, carry their vector
  * into this context and apply CVODE's sign rule before enabling coloring. */
@@ -119,7 +148,11 @@ static int colored_difference(CvContext *context, sunrealtype t, N_Vector y, N_V
     for (int color=0;color<MODEL_JACOBIAN_COLOR_COUNT;color++) {
         memcpy(test,state,NSTATES*sizeof(double));
         for (int j=0;j<NSTATES;j++) if (model_jacobian_column_color[j]==color) test[j]+=increments[j];
+#if MODEL_JACOBIAN_GAS_REUSE
+        int flag=jac_rhs_reuse(context,t,trial,ftrial);
+#else
         int flag=jac_rhs(context,t,trial,ftrial);
+#endif
         if (flag) return flag;
         for (int j=0;j<NSTATES;j++) if (model_jacobian_column_color[j]==color) {
             double inverse=1.0/increments[j];
@@ -146,7 +179,16 @@ static int cv_jacobian(sunrealtype t, N_Vector y, N_Vector fy, SUNMatrix matrix,
     /* The CVODE fy belongs to the ordinary RHS cache path. Recompute the
        baseline using the same deterministic path as every perturbed probe;
        mixing the two baselines would amplify cache roundoff by 1/increment. */
+#if MODEL_JACOBIAN_GAS_REUSE
+    /* The baseline belongs only to this refresh. Events, later Newton
+       iterations and another run must never inherit any of these entries. */
+    if(context->colored) {
+        if(context->jacobian_workspace)model_jacobian_begin(context->jacobian_workspace);
+        flag=jac_rhs_reuse(context,t,y,tmp3);
+    } else flag=jac_rhs(context,t,y,tmp3);
+#else
     flag=jac_rhs(context,t,y,tmp3);
+#endif
     if (flag) return flag;
     fy=tmp3;
 #endif
@@ -245,6 +287,11 @@ int native_bdf(NativeRun *r) {
     CV_CHECK(CVodeSetMaxStep(solver,r->options.max_step));
 #if MODEL_JACOBIAN_COLORED
     if (valid_coloring()) {
+#if MODEL_JACOBIAN_GAS_REUSE
+        /* Optional, caller-owned scratch. Allocation failure keeps the
+           original canonical differences; large models do not grow stack. */
+        context.jacobian_workspace=malloc(sizeof(*context.jacobian_workspace));
+#endif
         context.weights=N_VClone(y);
         allocation="N_VClone";
         if (!context.weights) goto allocation_failure;
@@ -339,6 +386,9 @@ int native_bdf(NativeRun *r) {
 allocation_failure:
     native_fail(r,"allocation-failure",allocation,"Cannot allocate native solver resources.");
 cleanup:
+#if MODEL_JACOBIAN_GAS_REUSE
+    free(context.jacobian_workspace);
+#endif
     if (initialized) cv_snapshot(r,solver);
     if (solver) { counters(r,solver); CVodeFree(&solver); }
     if (context.reference) SUNMatDestroy(context.reference);