[UpdateTestChecks] Sync flags in update_mir_test_checks.py with MIFlags

[asi-sc]

Summary

Some instructions are not matched by update_mir_test_checks.py because MIFlags and
regex in the script are not synchronized.

[anton-afanasyev]

This should be covered itself by new test in test/tools/UpdateTestChecks/update_mir_test_checks/.

[asi-sc]

Add tests

[asi-sc]

I added a test to check nofpexcept flag. I didn't find a way to add a test for nomerge flag as for now we do not have instructions that may have this flag and return a result simultaneously. @zequanwu may correct me.

[nhaehnle]

LGTM

[asi-sc]

Rebase after precommit test is merged.

llvm/utils/update_mir_test_checks.py

 from UpdateTestChecks import common
 
 MIR_FUNC_NAME_RE = re.compile(r' *name: *(?P<func>[A-Za-z0-9_.-]+)')
 MIR_BODY_BEGIN_RE = re.compile(r' *body: *\|')
 MIR_BASIC_BLOCK_RE = re.compile(r' *bb\.[0-9]+.*:$')
 VREG_RE = re.compile(r'(%[0-9]+)(?::[a-z0-9_]+)?(?:\([<>a-z0-9 ]+\))?')
 MI_FLAGS_STR= (
     r'(frame-setup |frame-destroy |nnan |ninf |nsz |arcp |contract |afn '
-    r'|reassoc |nuw |nsw |exact |fpexcept )*')
+    r'|reassoc |nuw |nsw |exact |nofpexcept |nomerge )*')
 VREG_DEF_RE = re.compile(
     r'^ *(?P<vregs>{0}(?:, {0})*) = '
     r'{1}(?P<opcode>[A-Zt][A-Za-z0-9_]+)'.format(VREG_RE.pattern, MI_FLAGS_STR))
 MIR_PREFIX_DATA_RE = re.compile(r'^ *(;|bb.[0-9].*: *$|[a-z]+:( |$)|$)')
 
 IR_FUNC_NAME_RE = re.compile(
     r'^\s*define\s+(?:internal\s+)?[^@]*@(?P<func>[A-Za-z0-9_.]+)\s*\(')
 IR_PREFIX_DATA_RE = re.compile(r'^ *(;|$)')