Integrate SSA-based middle-end and snapshot tests

[vacantron]

The current cfront and IR generation are high coupling that making the flow analysis harder. To introduce the further optimizations, the static single assignment (SSA) is imperative. This patch introduces the minimal changes for it, and also keeps the old first phase IR (ph1_ir) for the compatibility to the upcoming works.

The current unit test only covers the end to end case. It is hard the classify which part went wrong in the compilation. The new middle end can dump the IR with the dot file as a snapshot. We can also use the tool like graphviz to check the flow during the compilation.

Use make check-snapshots to invoke the snapshot test, and use tests/update-snapshots.sh to update the snapshots if there's any change for the cfont.

Notice: The snapshots should be updated under the ARM configure.

[vacantron]

The GitHub Action reports the broken pipe if the snapshot testing failed. It works fine on my local PC and only reports Files /dev/fd/63 and /dev/fd/62 differ. Do I mess up something?

https://github.com/vacantron/shecc/actions/runs/6834732304/job/18587784272#step:3:467

[jserv]

It is a bit confusing that there are 'check' and 'test' targets which deal with the test suite. Can you clarify?

[jserv]

Rename src/SSA.c to src/ssa.c (lowercase).
Don't check in JSON files which are generated by snapshot.

[jserv]

The GitHub Action reports the broken pipe if the snapshot testing failed. It works fine on my local PC and only reports Files /dev/fd/63 and /dev/fd/62 differ. Do I mess up something?

I got the following messages from CI:

int main(int argc, int argv) { int i; int j; i=0; j=0; while (i<10) { j=j+i; i=i+1; } return j; }
exit code => 45
output => 
tests/driver.sh: line 16:  3327 Segmentation fault      (core dumped) "$SHECC" -o "$tmp_exe" "$tmp_in"
int main(int argc, int argv) { int x; x=0; do {x = x + 1; break;} while (1); return x; }
exit code => 1
output => 
tests/driver.sh: line 16:  3334 Aborted                 (core dumped) "$SHECC" -o "$tmp_exe" "$tmp_in"
int main(int argc, int argv) { int x; x=0; do {x++; continue; abort();} while (x < 2); return x; } => 2 expected, but got 1
input: /tmp/tmp.gUdRxRqzMl.c
make: *** [Makefile:54: test] Error 1

[vacantron]

https://github.com/vacantron/shecc/actions/runs/6834732304/job/18587784272#step:3:467

I forgot to provide the error messages from GitHub Action:

tests/check-snapshots.sh
Files /dev/fd/63 and /dev/fd/62 differ
Error: writing output failed: Broken pipe
cat: write error: Broken pipe
Files /dev/fd/63 and /dev/fd/62 differ
make: *** [Makefile:54: check] Error 1
Error: writing output failed: Broken pipe
cat: write error: Broken pipe
Error: Process completed with exit code 1.

I got the following messages from CI:

That message was caused by the mentioned control-flow change. The snapshot testing had been passed. I edited lib/c.c and tried to cause the test failed and received the above messages.

[jserv]

Drop the generated JSON file and update .gitignore.

[vacantron]

Drop the generated JSON file and update .gitignore.

We need some JSON files as the baseline of tests in tests/snapshots, right? The other snapshots that generated by mktemp when running check-snapshots are already not in the work directory.

[vacantron]

shecc now passes all the unit tests before, but the cfront lacks the support for some syntax, likes structure declaration without typedef. So the self-hosting still fails now.

The instructions which loads/stores with a huge offset also need to be modified when self-hosting.

[jserv]

Let's unify our terminology. From now on, use insn as the abbreviation for "Instruction," rather than "inst."

[jserv]

Thank @vacantron for contributing!