Demand paging on Windows

qemu/tcg/tcg.c

@@ -23,6 +23,8 @@
  */
 
 /* define it to use liveness analysis (better code) */
+#include "tcg/tcg.h"
+#include <stdio.h>
 #define USE_TCG_OPTIMIZATIONS
 
 #include "qemu/osdep.h"
@@ -406,6 +408,13 @@ static void tcg_region_assign(TCGContext *s, size_t curr_region)
     s->code_gen_buffer = start;
     s->code_gen_ptr = start;
     s->code_gen_buffer_size = (char *)end - (char *)start;
+#if defined(WIN32) && !defined(USE_STATIC_CODE_GEN_BUFFER)
+    VirtualAlloc(
+        s->code_gen_buffer, 
+        ROUND_UP(s->code_gen_buffer_size, s->uc->qemu_real_host_page_size), 
+        MEM_COMMIT, 
+        PAGE_EXECUTE_READWRITE);
+#endif
     memset(s->code_gen_buffer, 0x00, s->code_gen_buffer_size);
     s->code_gen_highwater = (char *)end - TCG_HIGHWATER;
 }
@@ -500,7 +509,11 @@ void tcg_region_init(TCGContext *tcg_ctx)
     size_t n_regions;
     size_t i;
 
+#if defined(WIN32) && !defined(USE_STATIC_CODE_GEN_BUFFER)
+    n_regions = size / (tcg_ctx->uc->qemu_real_host_page_size * UC_TCG_REGION_PAGES_COUNT);
+#else
     n_regions = 1;
+#endif
 
     /* The first region will be 'aligned - buf' bytes larger than the others */
     aligned = (void *)QEMU_ALIGN_PTR_UP(buf, page_size);
@@ -537,6 +550,11 @@ void tcg_region_init(TCGContext *tcg_ctx)
     }
 
     tcg_ctx->tree = g_tree_new(tb_tc_cmp);
+
+#if defined(WIN32) && !defined(USE_STATIC_CODE_GEN_BUFFER)
+    // Allocate a region immediately, or the highwater is not set correctly.
+    tcg_region_alloc(tcg_ctx);
+#endif
 }
 
 /*