satrt readme

05/Makefile

@@ -1,4 +1,6 @@
-all: out04 a.out
+TCCDIR=tcc-0.9.27
+TCC=$(TCCDIR)/tcc
+all: out04 a.out test.out README.html
 in04: *.b ../04a/out04
 	../04a/out04 main.b in04
 out04: in04 ../04/out03
@@ -9,5 +11,13 @@ out04: in04 ../04/out03
 	./out04 $< $@
 a.out: main.c *.h out04
 	./out04
+test.out: $(TCC) test.s.o test.c.o
+	$(TCC) -static -nostdlib test.s.o test.c.o -o test.out
+test.s.o: $(TCC) test.s
+	$(TCC) -static -nostdlib -c test.s -o test.s.o
+test.c.o: $(TCC) test.c
+	$(TCC) -static -nostdlib -c test.c -o test.c.o
+$(TCC): $(TCCDIR)/*.c $(TCCDIR)/*.h out04
+	cd $(TCCDIR) && ../out04 tcc.c tcc
 clean:
-	rm -f out* README.html *.out
+	rm -f out* README.html *.out *.o $(TCC)

05/README.md

@@ -0,0 +1,42 @@
+# [bootstrap](../README.md) stage 05
+
+This stage consists of a C compiler capable of compiling TCC (after some modifications
+to TCC's source code).
+Run
+
+```
+make
+```
+
+to build our C compiler and TCC. This will take some time (approx. 25 seconds on my computer).
+A test program, `test.out` will be compiled using `tcc`. If you run
+it, you should get the output
+
+```
+Hello, world!
+```
+
+So now we just compile TCC with itself, and we're done, right?
+Well, not quite...
+
+## the nightmare begins
+
+The issue here is that to compile TCC/GCC with TCC, we need libc, the C standard library functions.
+Our C compiler just includes these functions in the standard header files, but normally
+the code for them is located in a separate library file (called something like
+`/usr/lib/x86_64-linux-gnu/libc-2.31.so`).
+
+This library file is itself compiled from C source files (typically glibc).
+So, can't we just compile glibc with TCC, then compile TCC with itself?
+Well, no. Compiling glibc with TCC is basically impossible; you need to compile
+it with GCC.
+
+Other libc implementations aren't too happy about TCC either -- I tried to compile
+[musl](http://www.musl-libc.org/) for several hours, and had to give up in the end.
+
+It seems that the one option left is to make our own libc, and try to use it along with
+TCC to compile GCC.
+From there, we should be able to compile glibc with GCC. Then, we can compile GCC with GCC and glibc.
+If we do all this, we should get the same libc.so and gcc files as if we had started
+with any GCC and glibc builds. It's all very confusing.
+

05/tcc-0.9.27/.gitignore

@@ -19,7 +19,6 @@ tcc
 *-tcc
 libtcc*.def
 
-config*.h
 config*.mak
 config.texi
 conftest*

05/tcc-0.9.27/config.h

@@ -0,0 +1,8 @@
+#define TCC_VERSION "0.9.27"
+#define CONFIG_TCC_STATIC 1
+#define CONFIG_TCC_ELFINTERP "/XXX"
+#define CONFIG_TCC_CRT_PREFIX "/XXX"
+#define CONFIG_SYSROOT "/XXX"
+#define inline
+#define TCC_TARGET_X86_64 1
+#define ONE_SOURCE 1

05/tcc-0.9.27/x86_64-gen.c

@@ -599,7 +599,7 @@ static void gcall_or_jmp(int is_jmp)
 #ifdef TCC_TARGET_PE
             greloca(cur_text_section, vtop->sym, ind + 1, R_X86_64_PC32, (int)(vtop->c.i-4));
 #else
-            greloca(cur_text_section, vtop->sym, ind + 1, R_X86_64_PLT32, (int)(vtop->c.i-4));
+            greloca(cur_text_section, vtop->sym, ind + 1, R_X86_64_PC32, (int)(vtop->c.i-4)); // tcc's PLT code doesn't seem to work with static builds
 #endif
         } else {
             /* put an empty PC32 relocation */

05/test.c

@@ -1,6 +1,5 @@
-// calling assembly functions from C is not working for some reason.
 extern unsigned long __syscall(int, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long);
-int main(unsigned long (*_syscall)(int, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long)) {
+int main(void) {
 	__syscall(1, 1, (unsigned long)"Hello, world!\n", 14, 0, 0, 0);
 	return 42;
 }

05/test.s

@@ -15,7 +15,6 @@ __syscall:
 	ret
 	
 _start:
-	lea __syscall, %rdi
 	call main
 	mov $60, %eax
 	syscall

README.md

@@ -60,7 +60,7 @@ If you're unfamiliar with x86-64 assembly, you should check out the instruction
 Bootstrapping a compiler is not an easy task, so we're trying to make it as easy
 as possible. We don't even necessarily need a standard-compliant C compiler, we
 only need enough to compile someone else's C compiler, specifically we'll be
-using [TCC](https://bellard.org/tcc/) since it's written in standard C89.
+using [TCC](https://bellard.org/tcc/) since it's written (mostly) in standard C89.
 
 - efficiency is not a concern