elf.c: section limit inference for linux, fixes for stb_ds.h hashing, more compilation flags

CMakeLists.txt

@@ -23,6 +23,14 @@ add_subdirectory(third-party/physfs)
 add_subdirectory(third-party/libxm)
 
 
+if(UNIX)
+        set(SYSTEM_SOURCE_FILES
+                src/system/linux/elf.c
+        )
+else()
+        set(SYSTEM_SOURCE_FILES)
+endif()
+
 set(SOURCE_FILES
         third-party/physfs/extras/physfsrwops.c
         third-party/stb/stb_vorbis.c
@@ -49,6 +57,8 @@ set(SOURCE_FILES
         src/game/scenes/scene.c src/game/scenes/scene.h
         src/game/scenes/title.c src/game/scenes/title.h
         src/game/scenes/ingame.c src/game/scenes/ingame.h
+
+        ${SYSTEM_SOURCE_FILES}
 )
 
 # target
@@ -90,19 +100,24 @@ else()
                 # these SHOULDN'T break anything...
                 -fno-math-errno
                 -ffp-contract=fast
-                -fno-signed-zeros
-                -fno-trapping-math
-                -freciprocal-math)
+                -fno-signed-zeros)
         set(BUILD_FLAGS_RELEASE
+                -O3
                 -flto
                 -Wl,-gc-sections
                 -fdata-sections
-                -ffunction-sections)
+                -ffunction-sections
+                -funroll-loops
+                -fomit-frame-pointer
+                -fallow-store-data-races)
         set(BUILD_FLAGS_DEBUG
+                -O0
                 -g3
                 -gdwarf
+                -fno-omit-frame-pointer
+                -fstack-protector-all
                 -fsanitize=undefined
-                -fsanitize-trap=undefined)
+                -fsanitize=address)
         target_compile_options(${PROJECT_NAME} PRIVATE
                                                ${WARNING_FLAGS}
                                                ${BUILD_FLAGS}

src/audio.c

@@ -244,7 +244,7 @@ static void audio_sample_and_mixin_channel(const struct audio_channel *channel,
     static uint8_t buffer[16384];
     const int int16_buffer_frames = sizeof (buffer) / sizeof (int16_t);
     const int float_buffer_frames = sizeof (buffer) / sizeof (float);
-    const int stream_frames = len / sizeof (int16_t);
+    const int stream_frames = len / (int)(sizeof (int16_t));
 
     switch (channel->file_type) {
     case audio_file_type_ogg: {

src/game/scenes/ingame.c

@@ -65,6 +65,7 @@ static void ingame_end(struct state *state) {
     struct scene_ingame *scn = (struct scene_ingame *)state->scene;
     player_destroy(scn->player);
     world_destroy(scn->world);
+    free(state->scene);
 }
 
 

src/game/scenes/title.c

@@ -24,6 +24,7 @@ static void title_end(struct state *state) {
     struct scene_title *scn = (struct scene_title *)state->scene;
     player_destroy(scn->player);
     world_destroy(scn->world);
+    free(state->scene);
 }
 
 

src/private/rendering.h

@@ -95,7 +95,6 @@ union uncolored_space_triangle {
 /* batch of primitives with overlapping properties */
 struct mesh_batch {
     GLuint buffer;          /* server side storage */
-    size_t buffer_len;      /* element count */
     uint8_t *primitives;
 };
 

src/system/linux/elf.c

@@ -0,0 +1,68 @@
+#include "elf.h"
+
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/auxv.h>
+#include <elf.h>
+#include <linux/limits.h>
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+bool infer_elf_section_bounds(const char *const restrict name,
+							  const char **restrict vm_start,
+							  const char **restrict vm_end)
+{
+	bool result = false;
+	char buf[PATH_MAX];
+	ssize_t l = readlink("/proc/self/exe", buf, PATH_MAX);
+	if (l == -1)
+		goto ERR_CANT_READLINK;
+	buf[l] = 0; /* readlink() doesn't write a terminator */
+
+	int elf = open(buf, O_RDONLY);
+	if (elf == -1)
+		goto ERR_CANT_OPEN_SELF;
+
+	/* elf header */
+	Elf64_Ehdr ehdr;
+	read(elf, &ehdr, sizeof ehdr);
+	if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
+			ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
+			ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
+			ehdr.e_ident[EI_MAG3] != ELFMAG3)
+		goto ERR_NOT_ELF;
+
+	/* section header string table */
+	Elf64_Shdr shstrdr;
+	lseek(elf, ehdr.e_shoff + ehdr.e_shstrndx * sizeof (Elf64_Shdr), SEEK_SET);
+	read(elf, &shstrdr, sizeof shstrdr);
+	char *sh = malloc(shstrdr.sh_size);
+	lseek(elf, shstrdr.sh_offset, SEEK_SET);
+	read(elf, sh, shstrdr.sh_size);
+
+	/* walk sections searching for needed name */
+	lseek(elf, ehdr.e_shoff, SEEK_SET);
+	for (size_t s = 0; s < ehdr.e_shnum; ++s) {
+		Elf64_Shdr shdr;
+		read(elf, &shdr, sizeof shdr);
+
+		if (strcmp(&sh[shdr.sh_name], name) == 0) {
+			result = true;
+			*vm_start = getauxval(AT_ENTRY) - ehdr.e_entry + (char *)shdr.sh_addr;
+			*vm_end   = getauxval(AT_ENTRY) - ehdr.e_entry + (char *)shdr.sh_addr + shdr.sh_size;
+			break;
+		}
+	}
+
+	free(sh);
+
+ERR_NOT_ELF:
+	close(elf);
+
+ERR_CANT_OPEN_SELF:
+ERR_CANT_READLINK:
+	return result;
+}

src/system/linux/elf.h

@@ -0,0 +1,10 @@
+#ifndef ELF_H
+#define ELF_H
+
+#include <stdbool.h>
+
+bool infer_elf_section_bounds(const char *restrict name,
+							  const char **restrict vm_start,
+							  const char **restrict vm_end);
+
+#endif

src/textures.c

@@ -295,8 +295,9 @@ void textures_dump_atlases(struct texture_cache *cache) {
 
 static t_texture_key textures_load(struct texture_cache *cache, const char *path) {
     /* no need to do anything if it was loaded already */
-    if (shgeti(cache->hash, path) >= 0)
-        return (t_texture_key){0};
+    const ptrdiff_t i = shgeti(cache->hash, path);
+    if (i >= 0)
+        return (t_texture_key){ (uint16_t)i };
 
     SDL_Surface *surface = image_to_surface(path);
     struct texture new_texture = {0};
@@ -308,12 +309,12 @@ static t_texture_key textures_load(struct texture_cache *cache, const char *path
         upload_texture_from_surface(new_texture.loner_texture, surface); 
         new_texture.srcrect = (t_rect) { .w = surface->w, .h = surface->h };
         shput(cache->hash, path, new_texture);
-        return (t_texture_key){ shgeti(cache->hash, path) };
+        return (t_texture_key){ (uint16_t)shgeti(cache->hash, path) };
     } else {
         new_texture.atlas_index = cache->atlas_index;
         shput(cache->hash, path, new_texture);
         cache->is_dirty = true;
-        return (t_texture_key){ shgeti(cache->hash, path) };
+        return (t_texture_key){ (uint16_t)shgeti(cache->hash, path) };
     }
 }
 
@@ -363,35 +364,44 @@ void textures_update_atlas(struct texture_cache *cache) {
 }
 
 /* EXPERIMANTAL: LIKELY TO BE REMOVED! */
-/* todo: If it's proven to be useful: add runtime checking for .rodata > .data */
-#ifdef __unix__ /* use rodata elf section for fast lookups of repeating textures */
+#ifdef __linux__ /* use rodata elf section for fast lookups of repeating textures */
 
-extern const char start_rodata_address[];
-extern const char stop_rodata_heuristic[];
+#include "system/linux/elf.h"
 
-asm(".set start_rodata_address, .rodata");
-asm(".set stop_rodata_heuristic, .data"); /* there's nothing in default linker script to know the size of .rodata */
+static const char *rodata_start;
+static const char *rodata_stop;
 
-/* TODO: it might be better to contruct a new table that hashes pointers, not strings, to texture keys */
-/*       this way every used texture will benefit, no matter the order of commission */
 t_texture_key textures_get_key(struct texture_cache *cache, const char *path) {
     static const char *last_path = NULL;
     static t_texture_key last_texture;
+    static struct ptr_to_texture {
+        const void *key;
+        t_texture_key value;
+    } *ptr_to_texture;
 
-    /* fast path */
+    if (rodata_stop == NULL)
+        if (!infer_elf_section_bounds(".rodata", &rodata_start, &rodata_stop))
+            CRY("Section inference", ".rodata section lookup failed");
+
+    /* the fastest path */
     if (path == last_path)
         return last_texture;
+    else {
+        /* moderately fast path, by pointer hashing */
+        const ptrdiff_t texture = hmgeti(ptr_to_texture, path);
+        if (texture != -1) {
+            if (path >= rodata_start && path < rodata_stop)
+                last_path = path;
+            last_texture = ptr_to_texture[texture].value;
+            return last_texture;
+        }
+    }
 
-    /* hash tables are assumed to be stable, so we just return indices */
-    ptrdiff_t texture = shgeti(cache->hash, path);
+    /* try loading */
+    last_texture = textures_load(cache, path);
+    hmput(ptr_to_texture, path, last_texture);
 
-    /* load it if it isn't */
-    if (texture == -1) {
-        last_texture = textures_load(cache, path);
-    } else
-        last_texture = (t_texture_key){ (uint16_t)texture };
-
-    if (path >= start_rodata_address && path < stop_rodata_heuristic)
+    if (path >= rodata_start && path < rodata_stop)
         last_path = path;
 
     return last_texture;
@@ -400,7 +410,7 @@ t_texture_key textures_get_key(struct texture_cache *cache, const char *path) {
 #else
 t_texture_key textures_get_key(struct texture_cache *cache, const char *path) {
     /* hash tables are assumed to be stable, so we just return indices */
-    ptrdiff_t texture = shgeti(cache->hash, path);
+    const ptrdiff_t texture = shgeti(cache->hash, path);
 
     /* load it if it isn't */
     if (texture == -1) {

third-party/stb/stb_ds.h

@@ -1121,7 +1121,7 @@ size_t stbds_hash_bytes(void *p, size_t len, size_t seed)
   unsigned char *d = (unsigned char *) p;
 
   if (len == 4) {
-    unsigned int hash = d[0] | (d[1] << 8) | (d[2] << 16) | (d[3] << 24);
+    uint32_t hash = (uint32_t)d[0] | ((uint32_t)d[1] << 8) | ((uint32_t)d[2] << 16) | ((uint32_t)d[3] << 24);
     #if 0
     // HASH32-A  Bob Jenkin's hash function w/o large constants
     hash ^= seed;
@@ -1177,8 +1177,8 @@ size_t stbds_hash_bytes(void *p, size_t len, size_t seed)
 
     return (((size_t) hash << 16 << 16) | hash) ^ seed;
   } else if (len == 8 && sizeof(size_t) == 8) {
-    size_t hash = d[0] | (d[1] << 8) | (d[2] << 16) | (d[3] << 24);
-    hash |= (size_t) (d[4] | (d[5] << 8) | (d[6] << 16) | (d[7] << 24)) << 16 << 16; // avoid warning if size_t == 4
+    size_t hash = (size_t)d[0] | ((size_t)d[1] << 8) | ((size_t)d[2] << 16) | ((size_t)d[3] << 24);
+    hash |= ((size_t)d[4] | ((size_t)d[5] << 8) | ((size_t)d[6] << 16) | ((size_t)d[7] << 24)) << 16 << 16;
     hash ^= seed;
     hash = (~hash) + (hash << 21);
     hash ^= STBDS_ROTATE_RIGHT(hash,24);