Modify nginx compile script for dynamic compilation

[rishabhBudhouliya]

Branch: dylink_impl_multi_process in lind-wasm introduces dynamic compilation.

Changes made to script:

1. LIND_DYLINK env var toggle (default 0)
2. CFLAGS: adds -fPIC when LIND_DYLINK=1
3. LDFLAGS (dynamic mode):
   - -nostartfiles + 3 custom CRT objects (set_stack_pointer.o, crt1_shared.o, lind_utils.o)
   - -Wl,-pie --import-table --allow-undefined --unresolved-symbols=import-dynamic
   - Exports: __wasm_call_ctors, __wasm_init_tls (if-defined), __tls_base
   - Validates CRT objects exist at startup with helpful error messages
4. wasm-opt (dynamic mode):
   - Uses --enable-bulk-memory --enable-threads
   - --epoch-injection --pass-arg=epoch-import --pass-arg=epoch-main-module
   - --asyncify --pass-arg=asyncify-import-globals
   - No --fpcast-emu, no -O2 (matches lmbench pattern)
5. add-export-tool post-link step (dynamic only):
   - __wasm_apply_tls_relocs (func, optional)
   - __wasm_apply_global_relocs (func, optional)
   - __stack_pointer (global, required)
6. Cache signature includes dylink=$LIND_DYLINK so switching modes triggers reconfigure

[vidyalakshmir]

@rishabhBudhouliya Regarding lmbench, I had some questions.

• Shouldn't the compiler flag add -fPIC while compiling?
• Is libtirpc a library, if so its .so file should be produced and it be not statically compiled with lmbench

[vidyalakshmir]

Also noticed that there is no --fpcast-emu flag for the dynamic build.

[rishabhBudhouliya]

Yeah, I missed that. I also didn't test the network lmbench tests also so didn't notice a failure.

[rishabhBudhouliya]

@vidyalakshmir The -fPIC flag is present under the DYLINK=1 section here:

lind-wasm-apps/lmbench/src/compile_lmbench.sh

Lines 198 to 201 in 668ef5e

	if [[ "$LIND_DYLINK" == "1" ]]; then
	echo "[lmbench] Dynamic linking mode enabled (LIND_DYLINK=1)"
	CFLAGS+=" -fPIC"
	# add-export-tool is used after linking to export relocation and stack symbols

[vidyalakshmir]

@vidyalakshmir The -fPIC flag is present under the DYLINK=1 section here:

lind-wasm-apps/lmbench/src/compile_lmbench.sh

Lines 198 to 201 in 668ef5e

	if [[ "$LIND_DYLINK" == "1" ]]; then
	echo "[lmbench] Dynamic linking mode enabled (LIND_DYLINK=1)"
	CFLAGS+=" -fPIC"
	# add-export-tool is used after linking to export relocation and stack symbols

Thanks!

[rishabhBudhouliya]

@vidyalakshmir libtirpc perhaps should be dynamically linked but it is being statically compiled as before. I am unsure whether linking multiple dependencies dynamically is supported by lind-boot currently and if so, what are the steps to do so.

[vidyalakshmir]

@rishabhBudhouliya
Nginx seems to work. The only thing which we need to look into is it depends on any other library other than libc. I did not have to pass any other library explicitly for the tests and since build script disables libraries like openssl, I assume we do not, but worth checking.

For lmbench, I got the following errors. Are these expected failures similar to the static build?

[FAIL] lat_sig (exit 134)
[FAIL] lat_fifo (exit 124)
[FAIL] lat_unix (exit 124)
[FAIL] memsize (exit 134)
[FAIL] par_mem (exit 124)
[FAIL] tlb (exit 124)
[lmbench-test] 29/35 tests passed, 6 failed