[utils][UpdateLLCTestChecks] Add MIR support to update_llc_test_checks.py

This change enables update_llc_test_checks.py to automatically generate
MIR checks for RUN lines that use -stop-before or -stop-after flags.

This allows tests to verify intermediate compilation stages (e.g., after
instruction selection but before peephole optimizations) alongside the
final assembly output.

Author: vpykhtin

llvm/utils/update_llc_test_checks.py

@@ -13,16 +13,21 @@
 from traceback import print_exc
 import argparse
 import os  # Used to advertise this file's name ("autogenerated_note").
+import re
 import sys
 
 from UpdateTestChecks import common
+import update_mir_test_checks # Reuse MIR parsing code.
 
 # llc is the only llc-like in the LLVM tree but downstream forks can add
 # additional ones here if they have them.
 LLC_LIKE_TOOLS = [
     "llc",
 ]
 
+def has_stop_pass_flag(llc_args):
+    """Check if llc arguments contain -stop-before or -stop-after flag."""
+    return re.search(r'-stop-(?:before|after)=', llc_args) is not None
 
 def update_test(ti: common.TestInfo):
     triple_in_ir = None
@@ -119,6 +124,10 @@ def update_test(ti: common.TestInfo):
         ginfo=ginfo,
     )
 
+    # Dictionary to store MIR function bodies separately
+    mir_func_dict = {}
+    mir_run_list = []
+
     for (
         prefixes,
         llc_tool,
@@ -141,14 +150,31 @@ def update_test(ti: common.TestInfo):
         if not triple:
             triple = common.get_triple_from_march(march_in_cmd)
 
-        scrubber, function_re = output_type.get_run_handler(triple)
-        if 0 == builder.process_run_line(
-            function_re, scrubber, raw_tool_output, prefixes
-        ):
-            common.warn(
-                "Couldn't match any function. Possibly the wrong target triple has been provided"
+        # Check if this run generates MIR output
+        if has_stop_pass_flag(llc_args):
+            common.debug("Detected MIR output mode for prefixes:", str(prefixes))
+            # Initialize MIR func_dict for these prefixes.
+            for prefix in prefixes:
+                if prefix not in mir_func_dict:
+                    mir_func_dict[prefix] = {}
+            
+            # Build MIR function dictionary using imported function.
+            update_mir_test_checks.build_function_info_dictionary(
+                ti.path, raw_tool_output, triple, prefixes, mir_func_dict, ti.args.verbose
             )
-        builder.processed_prefixes(prefixes)
+            
+            # Store this run info for later.
+            mir_run_list.append((prefixes, llc_tool, llc_args, triple_in_cmd, march_in_cmd))
+        else:
+            # Regular assembly output.
+            scrubber, function_re = output_type.get_run_handler(triple)
+            if 0 == builder.process_run_line(
+                function_re, scrubber, raw_tool_output, prefixes
+            ):
+                common.warn(
+                    "Couldn't match any function. Possibly the wrong target triple has been provided"
+                )
+            builder.processed_prefixes(prefixes)
 
     func_dict = builder.finish_and_get_func_dict()
     global_vars_seen_dict = {}
@@ -221,6 +247,21 @@ def update_test(ti: common.TestInfo):
                         is_filtered=builder.is_filtered(),
                     )
                 )
+                
+                # Also add MIR checks if we have them for this function
+                if mir_run_list and func_name:
+                    common.add_mir_checks_for_function(
+                        ti.path,
+                        output_lines,
+                        mir_run_list,
+                        mir_func_dict,
+                        func_name,
+                        single_bb=False, # Don't skip basic block labels.
+                        print_fixed_stack=False, # Don't print fixed stack (ASM tests don't need it).
+                        first_check_is_next=False, # First check is LABEL, not NEXT.
+                        at_the_function_name=False, # Use "name:" not "@name".
+                    )
+                
                 is_in_function_start = False
 
             if is_in_function: