fix an issue in update_mc_script that the not case is not handle

properly

Author: broxigarchen

llvm/test/tools/UpdateTestChecks/update_mc_test_checks/Inputs/amdgpu_asm_err.s

@@ -1,3 +1,5 @@
 // RUN: not llvm-mc -triple=amdgcn -show-encoding %s 2>&1 | FileCheck --check-prefixes=CHECK %s
 
 v_bfrev_b32 v5, v299
+
+v_bfrev_b32 v5, v1

llvm/test/tools/UpdateTestChecks/update_mc_test_checks/Inputs/amdgpu_asm_err.s.expected

@@ -3,3 +3,6 @@
 
 v_bfrev_b32 v5, v299
 // CHECK: :[[@LINE-1]]:17: error: register index is out of range
+
+v_bfrev_b32 v5, v1
+// CHECK: v_bfrev_b32_e32 v5, v1                  ; encoding: [0x01,0x71,0x0a,0x7e]

llvm/utils/update_mc_test_checks.py

@@ -15,15 +15,14 @@
 
 mc_LIKE_TOOLS = [
     "llvm-mc",
-    "not llvm-mc",
 ]
 ERROR_RE = re.compile(r":\d+: (warning|error): .*")
 ERROR_CHECK_RE = re.compile(r"# COM: .*")
 OUTPUT_SKIPPED_RE = re.compile(r"(.text)")
 COMMENT = {"asm": "//", "dasm": "#"}
 
 
-def invoke_tool(exe, cmd_args, testline, verbose=False):
+def invoke_tool(exe, prefix_not, cmd_args, testline, verbose=False):
     if isinstance(cmd_args, list):
         args = [applySubstitutions(a, substitutions) for a in cmd_args]
     else:
@@ -32,7 +31,20 @@ def invoke_tool(exe, cmd_args, testline, verbose=False):
     cmd = 'echo "' + testline + '" | ' + exe + " " + args
     if verbose:
         print("Command: ", cmd)
-    out = subprocess.check_output(cmd, shell=True)
+
+    # if not is used in runline, the command might or might not
+    # return non-zero code on a single line run
+    try:
+        out = subprocess.check_output(cmd, shell=True)
+    except:
+        if prefix_not:
+            cmd = 'echo "' + testline + '" | ' + "not " + exe + " " + args
+            if verbose:
+                print("Command: ", cmd)
+            out = subprocess.check_output(cmd, shell=True)
+        else:
+            raise Exception("Command '{}' return non-zero value".format(cmd))
+
     # Fix line endings to unix CR style.
     return out.decode().replace("\r\n", "\n")
 
@@ -151,11 +163,16 @@ def main():
             assert len(commands) >= 2
             mc_cmd = " | ".join(commands[:-1])
             filecheck_cmd = commands[-1]
-            mc_tool = mc_cmd.split(" ")[0]
 
             # special handling for negating exit status
-            if mc_tool == "not":
-                mc_tool = mc_tool + " " + mc_cmd.split(" ")[1]
+            prefix_not = ""
+            mc_cmd_args = mc_cmd.split(" ")
+            if mc_cmd_args[0] == "not":
+                prefix_not = mc_cmd_args[0]
+                mc_tool = mc_cmd_args[1]
+                mc_cmd = mc_cmd[len(mc_cmd_args[0]) :].strip()
+            else:
+                mc_tool = mc_cmd_args[0]
 
             triple_in_cmd = None
             m = common.TRIPLE_ARG_RE.search(mc_cmd)
@@ -188,6 +205,7 @@ def main():
                 (
                     check_prefixes,
                     mc_tool,
+                    prefix_not,
                     mc_cmd_args,
                     triple_in_cmd,
                     march_in_cmd,
@@ -204,6 +222,7 @@ def main():
         for (
             prefixes,
             mc_tool,
+            prefix_not,
             mc_args,
             triple_in_cmd,
             march_in_cmd,
@@ -222,6 +241,7 @@ def main():
                 # get output for each testline
                 out = invoke_tool(
                     ti.args.llvm_mc_binary or mc_tool,
+                    prefix_not,
                     mc_args,
                     line,
                     verbose=ti.args.verbose,