wasm2c tests fail on 32-bit due to assumption that pointers are 64-bit

[rathann]

The spectest_make_externref() in test/spec-wasm2c-prefix.c:203 assumes that u64 (uint64_t) can be converted to wasm_rt_externref_t (void *). This is not the case on 32-bit platforms:

- test/regress/regress-2039.txt
  expected error code 0, got 1.
  STDERR MISMATCH:
  --- expected
  +++ actual
  @@ -0,0 +1,19 @@
  +out/test/regress/regress-2039/regress-2039-main.c: In function ‘spectest_make_externref’:
  +out/test/regress/regress-2039/regress-2039-main.c:205:10: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
  +  205 |   return (wasm_rt_externref_t)(x + 1);  // externref(0) is not null
  +      |          ^
  +At top level:
  +cc1: note: unrecognized command-line option ‘-Wno-tautological-constant-out-of-range-compare’ may have been intended to silence earlier diagnostics
  +cc1: note: unrecognized command-line option ‘-Wno-ignored-optimization-argument’ may have been intended to silence earlier diagnostics
  +cc1: all warnings being treated as errors
  +Traceback (most recent call last):
  +  File "/builddir/build/BUILD/wabt-1.0.31/test/run-spec-wasm2c.py", line 554, in <module>
  +    sys.exit(main(sys.argv[1:]))
  +  File "/builddir/build/BUILD/wabt-1.0.31/test/run-spec-wasm2c.py", line 536, in main
  +    o_filenames.append(Compile(cc, main_filename, out_dir, includes))
  +  File "/builddir/build/BUILD/wabt-1.0.31/test/run-spec-wasm2c.py", line 408, in Compile
  +    cc.RunWithArgsForStdout(*args)
  +  File "/builddir/build/BUILD/wabt-1.0.31/test/utils.py", line 88, in RunWithArgsForStdout
  +    raise error
  +utils.Error: Error running "gcc -I/builddir/build/BUILD/wabt-1.0.31/wasm2c -c out/test/regress/regress-2039/regress-2039-main.c -o out/test/regress/regress-2039/regress-2039-main.o -O2 -Wall -Werror -Wno-unused -Wno-ignored-optimization-argument -Wno-tautological-constant-out-of-range-compare -Wno-infinite-recursion -Wno-array-bounds -Wbidi-chars=none -fno-optimize-sibling-calls -frounding-math -fsignaling-nans -std=c99 -D_DEFAULT_SOURCE" (1):
  +None
  STDOUT MISMATCH:
  --- expected
  +++ actual
  @@ -1 +0,0 @@
  -0/0 tests passed.

The same error occurs with all wasm2c tests. This can be fixed with a trivial patch:

diff -up wabt-1.0.31/test/spec-wasm2c-prefix.c.32bit wabt-1.0.31/test/spec-wasm2c-prefix.c
--- wabt-1.0.31/test/spec-wasm2c-prefix.c.32bit 2022-11-14 05:43:40.000000000 +0100
+++ wabt-1.0.31/test/spec-wasm2c-prefix.c       2022-12-11 22:17:36.181299604 +0100
@@ -200,7 +200,7 @@ static bool is_equal_wasm_rt_funcref_t(w
          (x.module_instance == y.module_instance);
 }

-wasm_rt_externref_t spectest_make_externref(u64 x) {
+wasm_rt_externref_t spectest_make_externref(uintptr_t x) {
   return (wasm_rt_externref_t)(x + 1);  // externref(0) is not null
 }

Additionally, the example code in wasm2c/examples/fac/fac.c makes assumptions that memory addresses are 64-bit, too, for example in lines 71, 81, 97 and 106. The code should use uintptr_t instead in the above lines, too.

[keithw]

Thanks -- if you have cycles to submit this as a PR, happy to take it.

Ideally we would pass the tests on i386 in general and run them in CI. I think #1044 and #1973 are tracking this. My understanding was that the interpreter and wasm2c both currently have problems on i386.

[keithw]

Also btw if this is helpful: fac.c isn't example code itself; it's the C version of fac.wat after running it through wasm2c. (Rebuilt with make update-wasm2c-fac). The code is coming from the source in the src/template directory.

[rathann]

@keithw I've submitted a PR with just the test failure fix for now. fac.c (or, actually, wasm2c.declarations.c) seems to have more pointer width issues than just the above.