Tweak build rules for WebAssembly

The "emcc --version" command displays information about the version of
emcc, which contains the "gcc" or "clang" string. As a result, the build
rule should only match one compiler and stop checking anymore.  If not,
the build could be failed by a mix of different compiler's CFLAGS. For
example, -flto from clang and -flto=thin from emcc.

After refactoring the riscv.[ch] public APIs in commit 820cd9b, it is
now possible to adjust the memory size to accommodate varying runtime
requirements. The memory size must align to a 4KB page size for the
WASM runtime and I set 1GB as default memory size for WASM runtime.

The LTO is not supported to build emscripten-port SDL library,
so disable it when both ENABLE_LTO=1 and ENABLE_SDL=1 are set.

Related to: #75
Close #375

Makefile

@@ -10,6 +10,7 @@ CONFIG_FILE := $(OUT)/.config
 CFLAGS = -std=gnu99 -O2 -Wall -Wextra
 CFLAGS += -Wno-unused-label
 CFLAGS += -include src/common.h
+CFLAGS_emcc ?=
 
 # Enable link-time optimization (LTO)
 ENABLE_LTO ?= 1
@@ -21,7 +22,14 @@ endif
 endif
 $(call set-feature, LTO)
 ifeq ($(call has, LTO), 1)
-ifeq ("$(CC_IS_GCC)$(CC_IS_EMCC)", "1")
+ifeq ("$(CC_IS_EMCC)", "1")
+ifeq ($(call has, SDL), 1)
+$(warning LTO is not supported to build emscripten-port SDL using emcc.)
+else
+CFLAGS += -flto
+endif
+endif
+ifeq ("$(CC_IS_GCC)", "1")
 CFLAGS += -flto
 endif
 ifeq ("$(CC_IS_CLANG)", "1")
@@ -136,6 +144,13 @@ ifeq ("$(CC_IS_EMCC)", "1")
 CFLAGS += -mtail-call
 endif
 
+# Build emscripten-port SDL
+ifeq ("$(CC_IS_EMCC)", "1")
+ifeq ($(call has, SDL), 1)
+CFLAGS_emcc += -sUSE_SDL=2 -sSDL2_MIXER_FORMATS=wav,mid -sUSE_SDL_MIXER=2
+endif
+endif
+
 ENABLE_UBSAN ?= 0
 ifeq ("$(ENABLE_UBSAN)", "1")
 CFLAGS += -fsanitize=undefined -fno-sanitize=alignment -fno-sanitize-recover=all
@@ -148,6 +163,13 @@ $(OUT)/emulate.o: CFLAGS += -foptimize-sibling-calls -fomit-frame-pointer -fno-s
 # to the first target after .DEFAULT_GOAL is not set.
 .DEFAULT_GOAL :=
 
+WEB_FILES += $(BIN).js \
+	     $(BIN).wasm \
+	     $(BIN).worker.js
+ifeq ("$(CC_IS_EMCC)", "1")
+BIN := $(BIN).js
+endif
+
 all: config $(BIN)
 
 OBJS := \
@@ -167,13 +189,23 @@ OBJS := \
 OBJS := $(addprefix $(OUT)/, $(OBJS))
 deps := $(OBJS:%.o=%.o.d)
 
+EXPORTED_FUNCS := _main
+ifeq ("$(CC_IS_EMCC)", "1")
+CFLAGS_emcc += -sINITIAL_MEMORY=2GB \
+	       -sALLOW_MEMORY_GROWTH \
+	       -s"EXPORTED_FUNCTIONS=$(EXPORTED_FUNCS)" \
+	       --embed-file build \
+	       -DMEM_SIZE=0x40000000 \
+	       -w
+endif
+
 $(OUT)/%.o: src/%.c
 	$(VECHO) "  CC\t$@\n"
-	$(Q)$(CC) -o $@ $(CFLAGS) -c -MMD -MF $@.d $<
+	$(Q)$(CC) -o $@ $(CFLAGS) $(CFLAGS_emcc) -c -MMD -MF $@.d $<
 
 $(BIN): $(OBJS)
 	$(VECHO) "  LD\t$@\n"
-	$(Q)$(CC) -o $@ $^ $(LDFLAGS)
+	$(Q)$(CC) -o $@ $(CFLAGS_emcc) $^ $(LDFLAGS)
 
 config: $(CONFIG_FILE)
 $(CONFIG_FILE):
@@ -236,7 +268,7 @@ endif
 endif
 
 clean:
-	$(RM) $(BIN) $(OBJS) $(HIST_BIN) $(HIST_OBJS) $(deps) $(CACHE_OUT) src/rv32_jit.c
+	$(RM) $(BIN) $(OBJS) $(HIST_BIN) $(HIST_OBJS) $(deps) $(WEB_FILES) $(CACHE_OUT) src/rv32_jit.c
 distclean: clean
 	-$(RM) $(DOOM_DATA) $(QUAKE_DATA)
 	$(RM) -r $(OUT)/id1

mk/toolchain.mk

@@ -3,12 +3,33 @@ CC_IS_CLANG :=
 CC_IS_GCC :=
 ifneq ($(shell $(CC) --version | head -n 1 | grep emcc),)
     CC_IS_EMCC := 1
-endif
-ifneq ($(shell $(CC) --version | head -n 1 | grep clang),)
-    CC_IS_CLANG := 1
-endif
-ifneq ($(shell $(CC) --version | grep "Free Software Foundation"),)
-    CC_IS_GCC := 1
+
+    # see commit 165c1a3 of emscripten
+    MIMALLOC_SUPPORT_SINCE_MAJOR := 3
+    MIMALLOC_SUPPORT_SINCE_MINOR := 1
+    MIMALLOC_SUPPORT_SINCE_PATCH := 50
+    MIMALLOC_UNSUPPORTED_WARNING := mimalloc is supported after version $(MIMALLOC_SUPPORT_SINCE_MAJOR).$(MIMALLOC_SUPPORT_SINCE_MINOR).$(MIMALLOC_SUPPORT_SINCE_PATCH)
+    EMCC_VERSION := $(shell $(CC) --version | head -n 1 | cut -f10 -d ' ')
+    EMCC_MAJOR := $(shell echo $(EMCC_VERSION) | cut -f1 -d.)
+    EMCC_MINOR := $(shell echo $(EMCC_VERSION) | cut -f2 -d.)
+    EMCC_PATCH := $(shell echo $(EMCC_VERSION) | cut -f3 -d.)
+    ifeq ($(shell echo $(EMCC_MAJOR)\>=$(MIMALLOC_SUPPORT_SINCE_MAJOR) | bc), 1)
+        ifeq ($(shell echo $(EMCC_MINOR)\>=$(MIMALLOC_SUPPORT_SINCE_MINOR) | bc), 1)
+            ifeq ($(shell echo $(EMCC_PATCH)\>=$(MIMALLOC_SUPPORT_SINCE_PATCH) | bc), 1)
+                CFLAGS_emcc += -sMALLOC=mimalloc
+            else
+                $(warning $(MIMALLOC_UNSUPPORTED_WARNING))
+            endif
+        else
+            $(warning $(MIMALLOC_UNSUPPORTED_WARNING))
+        endif
+    else
+        $(warning $(MIMALLOC_UNSUPPORTED_WARNING))
+    endif
+else ifneq ($(shell $(CC) --version | head -n 1 | grep clang),)
+     CC_IS_CLANG := 1
+else ifneq ($(shell $(CC) --version | grep "Free Software Foundation"),)
+     CC_IS_GCC := 1
 endif
 
 CFLAGS_NO_CET :=

src/main.c

@@ -168,7 +168,10 @@ static void dump_test_signature(const char *prog_name)
     elf_delete(elf);
 }
 
-#define MEM_SIZE 0xFFFFFFFFULL  /* 2^32 - 1 */
+/* MEM_SIZE shall be defined on different runtime */
+#ifndef MEM_SIZE
+#define MEM_SIZE 0xFFFFFFFFULL /* 2^32 - 1 */
+#endif
 #define STACK_SIZE 0x1000       /* 4096 */
 #define ARGS_OFFSET_SIZE 0x1000 /* 4096 */