Allocate heap with mmap and advise the OS that the unused part of the heap is...

Allocate heap with mmap and advise the OS that the unused part of the heap is not needed after garbage collection on x64 Linux

astartup.asm

@@ -128,6 +128,11 @@ heap_mbp	dq	0
 heap_p		dq	0
 stack_mbp	dq	0
 
+ ifdef LINUX
+page_size_m1	dq	0
+page_size_m1_neg	dq	0
+ endif
+
 bit_counter	label ptr
 	dq	0
 bit_vector_p	label ptr
@@ -866,11 +871,28 @@ init_clean:
 	mov	rbp,rsp
 	and	rsp,-16
  ifdef LINUX
-	mov	rdi,rax
+	mov	rbx,rax
+	mov	rdi,30
+  ifdef PIC
+	call	sysconf@PLT
+  else
+	call	sysconf
+  endif
+	sub	rax,1
+	mov	qword ptr page_size_m1,rax
+	not	rax
+	mov	qword ptr page_size_m1_neg,rax
+
+	xor	rdi,rdi
+	mov	rsi,rbx
+	mov	rdx,0x3
+	mov	rcx,0x22
+	mov	r8,-1
+	xor	r9,r9
   ifdef PIC
-	call	malloc@PLT
+	call	mmap@PLT
   else
-	call	malloc
+	call	mmap
   endif
  else
 	mov	rcx,rax
@@ -1044,11 +1066,12 @@ no_memory_3:
 	mov	qword ptr execution_aborted+0,1
  
  ifdef LINUX
+	mov	rsi,qword ptr heap_size+0
 	mov	rdi,heap_mbp+0
   ifdef PIC
-	call	free@PLT
+	call	munmap@PLT
   else
-	call	free
+	call	munmap
   endif
  else
 	mov	rcx,heap_mbp
@@ -1296,11 +1319,12 @@ no_print_execution_time:
 	call	free
   endif
 
+	mov	rsi,qword ptr heap_size+0
 	mov	rdi,heap_mbp+0
   ifdef PIC
-	call	free@PLT
+	call	munmap@PLT
   else
-	call	free
+	call	munmap
   endif
  else
 	mov	rcx,stack_mbp
@@ -2611,6 +2635,30 @@ end_zero_bit_vector:
 
 	include	acopy.asm
 
+ ifdef LINUX
+	push	rdi
+	push	rsi
+	mov	rdi,qword ptr heap_p1
+	mov	rsi,qword ptr heap_mbp
+	cmp	rdi,rsi
+	mov	rsi,qword ptr heap_copied_vector
+	je	advise_after_copy_1
+	mov	rsi,qword ptr heap_mbp
+	add	rsi,qword ptr heap_size
+advise_after_copy_1:
+	add	rdi,qword ptr page_size_m1
+	and	rdi,qword ptr page_size_m1_neg
+	sub	rsi,rdi
+	mov	rdx,4
+  ifdef PIC
+	call	madvise@PLT
+  else
+	call	madvise
+  endif
+	pop	rsi
+	pop	rdi
+ endif
+
 	mov	qword ptr heap2_begin_and_end+0,rsi 
 
 	mov	r15,rsi
@@ -3295,6 +3343,27 @@ no_mark_6:
 no_copy_garbage_collection:
 	call	add_compact_garbage_collect_time
 
+ ifdef LINUX
+	push	rdi
+	push	rsi
+	mov	rsi,r15
+	shl	rsi,3
+	add	rdi,rsi
+	add	rdi,qword ptr page_size_m1
+	and	rdi,qword ptr page_size_m1_neg
+	mov	rsi,qword ptr heap_mbp
+	add	rsi,qword ptr heap_size
+	sub	rsi,rdi
+	mov	rdx,4
+  ifdef PIC
+	call	madvise@PLT
+  else
+	call	madvise
+  endif
+	pop	rsi
+	pop	rdi
+ endif
+
 	mov	rax,rdi
 	sub	rax,qword ptr heap_p3+0