change c-file test structure

tests/c-form/Makefile

@@ -1,19 +1,22 @@
 BPF_CLANG := clang
-CFLAGS := -O0 -emit-llvm -target bpf -c
+CFLAGS := -emit-llvm -target bpf -c
 
 SRC := $(wildcard *.bpf.c)
 LL := $(SRC:.bpf.c=.bpf.ll)
 OBJ := $(SRC:.bpf.c=.bpf.o)
-
+LL0 := $(SRC:.bpf.c=.bpf.o0.ll)
 .PHONY: all clean
 
-all: $(LL) $(OBJ)
+all: $(LL) $(OBJ) $(LL0)
 
 %.bpf.o: %.bpf.c
 	$(BPF_CLANG) -O2 -g -target bpf -c $< -o $@
 
 %.bpf.ll: %.bpf.c
-	$(BPF_CLANG) $(CFLAGS) -g -S $< -o $@
+	$(BPF_CLANG) $(CFLAGS) -O2 -g -S $< -o $@
+
+%.bpf.o0.ll: %.bpf.c
+	$(BPF_CLANG) $(CFLAGS) -O0 -g -S $< -o $@
 
 clean:
-	rm -f $(LL) $(OBJ)
+	rm -f $(LL) $(OBJ) $(LL0)

tests/c-form/requests.bpf.c

@@ -0,0 +1,15 @@
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char LICENSE[] SEC("license") = "GPL";
+
+SEC("kprobe/blk_mq_start_request")
+int example(struct pt_regs *ctx)
+{
+    struct request *req = (struct request *)(ctx->di);
+    u32 data_len = req->__data_len;
+    bpf_printk("data length %u\n", data_len);
+
+    return 0;
+}