From 528649b2f207d0595210e92fbb312c78bdebca15 Mon Sep 17 00:00:00 2001
From: OBattler <oubattler@gmail.com>
Date: Wed, 17 Dec 2025 19:33:29 +0100
Subject: [PATCH] Bring back RichardG's recompiler changes.

---
 src/86box.c               |  3 +++
 src/cpu/386_dynarec.c     | 32 +++++++++++++++++++++++---------
 src/include/86box/86box.h |  1 +
 src/include/86box/mem.h   |  6 ++++++
 4 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/src/86box.c b/src/86box.c
index fe5dcf5b7..ad79e391b 100644
--- a/src/86box.c
+++ b/src/86box.c
@@ -331,6 +331,7 @@ int   scrnsz_y = SCREEN_RES_Y; /* current screen size, Y */
 int config_changed; /* config has changed */
 int title_update;
 int framecountx        = 0;
+int seconds_elapsed    = 0;
 int hard_reset_pending = 0;
 
 #if 0
@@ -1974,6 +1975,8 @@ pc_onesec(void)
     framecount = 0;
 
     title_update = 1;
+
+    seconds_elapsed++;
 }
 
 void
diff --git a/src/cpu/386_dynarec.c b/src/cpu/386_dynarec.c
index 852c25427..260346572 100644
--- a/src/cpu/386_dynarec.c
+++ b/src/cpu/386_dynarec.c
@@ -392,10 +392,9 @@ static inline void __attribute__((optimize("O2")))
 #else
 static __inline void
 #endif
-exec386_dynarec_dyn(void)
+exec386_dynarec_dyn(uint32_t phys_addr, page_t *page)
 {
     uint32_t start_pc  = 0;
-    uint32_t phys_addr = get_phys(cs + cpu_state.pc);
     int      hash      = HASH(phys_addr);
 #    ifdef USE_NEW_DYNAREC
     codeblock_t *block = &codeblock[codeblock_hash[hash]];
@@ -410,8 +409,6 @@ exec386_dynarec_dyn(void)
     if (block && !cpu_state.abrt)
 #    endif
     {
-        page_t *page = &pages[phys_addr >> 12];
-
         /* Block must match current CS, PC, code segment size,
            and physical address. The physical address check will
            also catch any page faults at this stage */
@@ -445,16 +442,30 @@ exec386_dynarec_dyn(void)
         if (valid_block && (block->page_mask & *block->dirty_mask)) {
 #    ifdef USE_NEW_DYNAREC
             codegen_check_flush(page, page->dirty_mask, phys_addr);
-            if (block->pc == BLOCK_PC_INVALID)
+            if (block->pc == BLOCK_PC_INVALID) {
                 valid_block = 0;
-            else if (block->flags & CODEBLOCK_IN_DIRTY_LIST)
+                goto invalid_block;
+            } else if (block->flags & CODEBLOCK_IN_DIRTY_LIST) {
                 block->flags &= ~CODEBLOCK_WAS_RECOMPILED;
+invalid_block:
 #    else
             codegen_check_flush(page, page->dirty_mask[(phys_addr >> 10) & 3], phys_addr);
             page->dirty_mask[(phys_addr >> 10) & 3] = 0;
-            if (!block->valid)
+            if (!block->valid) {
                 valid_block = 0;
 #    endif
+                if (page->inv_timestamp != seconds_elapsed) {
+                    page->inv_timestamp = seconds_elapsed;
+                    page->inv_count = 1;
+                } else {
+                    page->inv_count++;
+#    define INVALIDATION_LIMIT 100 /* amount of invalidations *per second* to kick a page to the interpreter */
+#    ifdef ENABLE_386_DYNAREC_LOG
+                    if (page->inv_count >= INVALIDATION_LIMIT)
+                        x386_dynarec_log("Forcing interpreter on page %08X\n", phys_addr & 0xfffff000);
+#    endif
+                }
+            }
         }
         if (valid_block && block->page_mask2) {
             /* We don't want the second page to cause a page
@@ -779,11 +790,14 @@ exec386_dynarec(int32_t cycs)
             cycles_old       = cycles;
             oldtsc           = tsc;
             tsc_old          = tsc;
-            if (cpu_force_interpreter || cpu_override_dynarec ||  (!CACHE_ON())) /*Interpret block*/
+
+            uint32_t phys_addr = get_phys(cs + cpu_state.pc);
+            page_t *page = &pages[phys_addr >> 12];
+            if (cpu_force_interpreter || cpu_override_dynarec || (page->inv_count >= INVALIDATION_LIMIT) || (!CACHE_ON())) /*Interpret block*/
             {
                 exec386_dynarec_int();
             } else {
-                exec386_dynarec_dyn();
+                exec386_dynarec_dyn(phys_addr, page);
             }
 
             if (cpu_init) {
diff --git a/src/include/86box/86box.h b/src/include/86box/86box.h
index d9c105546..f8765aecb 100644
--- a/src/include/86box/86box.h
+++ b/src/include/86box/86box.h
@@ -321,6 +321,7 @@ extern void do_pause(int p);
 extern double isa_timing;
 extern int    io_delay;
 extern int    framecountx;
+extern int    seconds_elapsed;
 
 extern volatile int     cpu_thread_run;
 extern          uint8_t postcard_codes[POSTCARDS_NUM];
diff --git a/src/include/86box/mem.h b/src/include/86box/mem.h
index 9051189a6..215dca438 100644
--- a/src/include/86box/mem.h
+++ b/src/include/86box/mem.h
@@ -224,6 +224,9 @@ typedef struct page_t {
 
     uint64_t *byte_dirty_mask;
     uint64_t *byte_code_present_mask;
+
+    uint32_t inv_count;
+    uint32_t inv_timestamp;
 } page_t;
 
 extern uint32_t purgable_page_list_head;
@@ -250,6 +253,9 @@ typedef struct _page_ {
 
     /*Head of codeblock tree associated with this page*/
     struct codeblock_t *head;
+
+    uint32_t inv_count;
+    uint32_t inv_timestamp;
 } page_t;
 #endif