fix wrong out of memory in edge cases, just try allocate from block for one source of truth

base/runtime/default_temp_allocator_arena.odin

@@ -105,12 +105,14 @@ arena_alloc :: proc(arena: ^Arena, size, alignment: uint, loc := #caller_locatio
 		return
 	}
 
-	needed := align_forward_uint(size, alignment)
+	prev_used := 0 if arena.curr_block == nil else arena.curr_block.used
-	if arena.curr_block == nil || (safe_add(arena.curr_block.used, needed) or_else 0) > arena.curr_block.capacity {
+	data, err = alloc_from_memory_block(arena.curr_block, size, alignment)
+	if err == .Out_Of_Memory {
 		if arena.minimum_block_size == 0 {
 			arena.minimum_block_size = DEFAULT_ARENA_GROWING_MINIMUM_BLOCK_SIZE
 		}
 
+		needed := align_forward_uint(size, alignment)
 		block_size := max(needed, arena.minimum_block_size)
 
 		if arena.backing_allocator.procedure == nil {
@@ -121,10 +123,9 @@ arena_alloc :: proc(arena: ^Arena, size, alignment: uint, loc := #caller_locatio
 		new_block.prev = arena.curr_block
 		arena.curr_block = new_block
 		arena.total_capacity += new_block.capacity
-	}
+		prev_used = 0
-
-	prev_used := arena.curr_block.used
 		data, err = alloc_from_memory_block(arena.curr_block, size, alignment)
+	}
 	arena.total_used += arena.curr_block.used - prev_used
 	return
 }

core/mem/virtual/arena.odin

@@ -107,8 +107,9 @@ arena_alloc :: proc(arena: ^Arena, size: uint, alignment: uint, loc := #caller_l
 
 	switch arena.kind {
 	case .Growing:
-		needed := mem.align_forward_uint(size, alignment)
+		prev_used := 0 if arena.curr_block == nil else arena.curr_block.used
-		if arena.curr_block == nil || (safe_add(arena.curr_block.used, needed) or_else 0) > arena.curr_block.reserved {
+		data, err = alloc_from_memory_block(arena.curr_block, size, alignment, default_commit_size=arena.default_commit_size)
+		if err == .Out_Of_Memory {
 			if arena.minimum_block_size == 0 {
 				arena.minimum_block_size = DEFAULT_ARENA_GROWING_MINIMUM_BLOCK_SIZE
 				arena.minimum_block_size = mem.align_forward_uint(arena.minimum_block_size, DEFAULT_PAGE_SIZE)
@@ -124,6 +125,7 @@ arena_alloc :: proc(arena: ^Arena, size: uint, alignment: uint, loc := #caller_l
 					max(arena.default_commit_size, arena.minimum_block_size)
 			}
 
+			needed := mem.align_forward_uint(size, alignment)
 			needed = max(needed, arena.default_commit_size)
 			block_size := max(needed, arena.minimum_block_size)
 
@@ -131,10 +133,10 @@ arena_alloc :: proc(arena: ^Arena, size: uint, alignment: uint, loc := #caller_l
 			new_block.prev = arena.curr_block
 			arena.curr_block = new_block
 			arena.total_reserved += new_block.reserved
-		}
 
-		prev_used := arena.curr_block.used
+			prev_used = 0
 			data, err = alloc_from_memory_block(arena.curr_block, size, alignment, default_commit_size=arena.default_commit_size)
+		}
 		arena.total_used += arena.curr_block.used - prev_used
 	case .Static:
 		if arena.curr_block == nil {

tests/core/mem/test_core_mem.odin

@@ -1,6 +1,7 @@
 package test_core_mem
 
 import "core:mem/tlsf"
+import "core:mem/virtual"
 import "core:testing"
 
 @test
@@ -39,3 +40,16 @@ test_tlsf_bitscan :: proc(t: ^testing.T) {
 		}
 	}
 }
+
+@(test)
+test_align_bumping_block_limit :: proc(t: ^testing.T) {
+	a: virtual.Arena
+
+	data, err := virtual.arena_alloc(&a, 4193371, 1)
+	testing.expect_value(t, err, nil)
+	testing.expect(t, len(data) == 4193371)
+
+	data, err = virtual.arena_alloc(&a, 896, 64)
+	testing.expect_value(t, err, nil)
+	testing.expect(t, len(data) == 896)
+}

tests/core/runtime/test_core_runtime.odin

@@ -31,6 +31,20 @@ test_temp_allocator_big_alloc_and_alignment :: proc(t: ^testing.T) {
 	testing.expect(t, err == nil)
 }
 
+@(test)
+test_align_bumping_block_limit :: proc(t: ^testing.T) {
+	a: runtime.Arena
+	a.minimum_block_size = 8*mem.Megabyte
+
+	data, err := runtime.arena_alloc(&a, 4193371, 1)
+	testing.expect_value(t, err, nil)
+	testing.expect(t, len(data) == 4193371)
+
+	data, err = runtime.arena_alloc(&a, 896, 64)
+	testing.expect_value(t, err, nil)
+	testing.expect(t, len(data) == 896)
+}
+
 @(test)
 test_temp_allocator_returns_correct_size :: proc(t: ^testing.T) {
 	arena: runtime.Arena