Move struct and upfront tests to separate library

code/speed_demo/struct/Makefile

@@ -1,2 +1,14 @@
-main.exe: main.c
-	gcc $< -o $@
+test: main.exe
+	time -p ./main.exe
+
+main.exe: main.o libincrement.so
+	gcc -Wl,-rpath,$(CURDIR) -o $@ $< -L. -lincrement
+
+libincrement.so: libincrement.o
+	gcc -shared -o $@ $<
+
+%.o: %.c
+	gcc -fPIC -Wall -c $< -o $@
+
+clean:
+	rm -f *.exe *.o *.so

code/speed_demo/struct/libincrement.c

@@ -0,0 +1,10 @@
+// Use this incrementer algorithm if AVX2 is available.
+int fancy_incrementer(int x) {
+	return x + 1;
+}
+
+// Use this if AVX2 is not available. It's the same as above, because we don't
+// actually rely on AVX2. 
+int normal_incrementer(int x) {
+	return x + 1;
+}

code/speed_demo/struct/main.c

@@ -4,25 +4,15 @@
 #include <stdio.h>
 #include <sys/mman.h>
 #include <unistd.h>
-static int counter = 0;
-
 struct myfuncs {
-	void (*increment_counter)();
+	int (*increment)(int);
 };
 
 static struct myfuncs *page;
 
 
-// Use this incrementer algorithm if AVX2 is available.
-void fancy_incrementer() {
-	counter += 1;
-}
-
-// Use this if AVX2 is not available. It's the same as above, because we don't
-// actually rely on AVX2. 
-void normal_incrementer() {
-	counter += 1;
-}
+int fancy_incrementer(int);
+int normal_incrementer(int);
 
 void initfuncs(void) {
 	int pagesize = getpagesize();
@@ -34,9 +24,9 @@ void initfuncs(void) {
 
 	__builtin_cpu_init();
 	if (__builtin_cpu_supports("avx2")) {
-		page->increment_counter = fancy_incrementer;
+		page->increment = fancy_incrementer;
 	} else {
-		page->increment_counter = normal_incrementer;
+		page->increment = normal_incrementer;
 	}
 
 	if(mprotect(page, pagesize, PROT_READ))
@@ -48,8 +38,9 @@ void initfuncs(void) {
 int main(void) {
 	initfuncs();
 
+        int counter = 0;
 	while (counter < INT_MAX) {
-		page->increment_counter();
+		counter = page->increment(counter);
 	}
 
 	return 0;

code/speed_demo/upfront/Makefile

@@ -1,2 +1,14 @@
-main.exe: main.c
-	gcc $< -o $@
+test: main.exe
+	time -p ./main.exe
+
+main.exe: main.o libincrement.so
+	gcc -Wl,-rpath,$(CURDIR) -o $@ $< -L. -lincrement
+
+libincrement.so: libincrement.o
+	gcc -shared -o $@ $<
+
+%.o: %.c
+	gcc -fPIC -Wall -c $< -o $@
+
+clean:
+	rm -f *.exe *.o *.so

code/speed_demo/upfront/libincrement.c

@@ -0,0 +1,10 @@
+// Use this incrementer algorithm if AVX2 is available.
+int fancy_incrementer(int x) {
+	return x + 1;
+}
+
+// Use this if AVX2 is not available. It's the same as above, because we don't
+// actually rely on AVX2. 
+int normal_incrementer(int x) {
+	return x + 1;
+}

code/speed_demo/upfront/main.c

@@ -10,27 +10,18 @@
 #include <limits.h>
 #include <stddef.h>
 #include <stdbool.h>
-static int counter = 0;
 static bool cpu_has_avx2 = false;
 
-// Use this incrementer algorithm if AVX2 is available.
-void avx2_incrementer() {
-	counter += 1;
-}
-
-// Use this if AVX2 is not available. It's the same as above, because we don't
-// actually rely on AVX2. 
-void normal_incrementer() {
-	counter += 1;
-}
+int fancy_incrementer(int);
+int normal_incrementer(int);
 
 // Select an "appropriate" incrementer based on CPU features. The actual choice
 // doesn't matter in this case, we just need something for the resolver to do.
-void increment_counter() {
+int increment(int x) {
 	if (cpu_has_avx2) {
-		avx2_incrementer();
+		return fancy_incrementer(x);
 	} else {
-		normal_incrementer();
+		return normal_incrementer(x);
 	}
 }
 
@@ -43,8 +34,9 @@ int main() {
 	detect_cpu_features();
 
 	// Count to ~ 2 Billion by calling a dynamically-resolved incrementer
+        int counter = 0;
 	while (counter < INT_MAX) {
-		increment_counter();
+		counter = increment(counter);
 	}
 	return 0;
 }