Checking different cases for abc

Makefile

@@ -783,12 +783,24 @@ $(PROGRAM_PREFIX)yosys-config: misc/yosys-config.in
 .PHONY: check-git-abc
 
 check-git-abc:
-	@if [ -f "$(YOSYS_SRC)/abc/.git" ]; then \
-	    echo "abc/.git exists"; \
-		  exit 0; \
-	else \
-	    echo "abc/.git does not exist. Please execute git submodule update --init"; \
+	@if [ ! -d "$(YOSYS_SRC)/abc" ]; then \
+	    echo "Error: The 'abc' directory does not exist."; \
+			echo "Initialize the submodule: Run 'git submodule update --init' to set up 'abc' as a submodule."; \
+	    exit 1; \
+	elif git -C "$(YOSYS_SRC)" submodule status abc 2>/dev/null | grep -q '^ '; then \
+	    echo "'abc' is a git submodule. Continuing."; \
+	    exit 0; \
+	elif [ -f "$(YOSYS_SRC)/abc/.gitcommit" ] && grep -q '\$$Format:%h\$$' "$(YOSYS_SRC)/abc/.gitcommit"; then \
+	    echo "Error: 'abc' is not configured as a git submodule."; \
+	    echo "To resolve this:"; \
+	    echo "1. Back up your changes: Save any modifications from the 'abc' directory to another location."; \
+	    echo "2. Remove the existing 'abc' directory: Delete the 'abc' directory and all its contents."; \
+	    echo "3. Initialize the submodule: Run 'git submodule update --init' to set up 'abc' as a submodule."; \
+	    echo "4. Reapply your changes: Move your saved changes back to the 'abc' directory, if necessary."; \
 	    exit 1; \
+	else \
+	    echo "'abc' comes from a tarball. Continuing."; \
+	    exit 0; \
 	fi
 
 ABC_SOURCES := $(wildcard $(YOSYS_SRC)/abc/*)