testsuite: Add testcase for #14754

testsuite/tests/codeGen/should_run/T14754.hs

+module Main where
+
+import Debug.Trace
+
+main :: IO ()
+main = print (alg 3 1)
+
+alg :: Word -> Word -> Word
+alg a b
+  | traceShow (a, b) False = undefined
+  | c < b = alg b c
+  | c > b = alg c b
+  | otherwise = c
+  where
+    c = a - b

testsuite/tests/codeGen/should_run/T14754.stderr

+(3,1)
+(2,1)

testsuite/tests/codeGen/should_run/T14754.stdout

+1

testsuite/tests/codeGen/should_run/all.T

@@ -166,3 +166,4 @@ test('T13825-unit',
      compile_and_run,
      ['-package ghc'])
 test('T14619', normal, compile_and_run, [''])
+test('T14754', normal, compile_and_run, [''])