[HashRecognize] Fix excess.tc coverage

Author: artagnon

llvm/test/Analysis/HashRecognize/cyclic-redundancy-check.ll

@@ -696,7 +696,7 @@ exit:                                              ; preds = %loop
   ret i16 %crc.next
 }
 
-define i16 @not.crc.excess.tc(i16 %msg, i16 %checksum) {
+define i16 @not.crc.excess.tc(i8 %msg, i16 %checksum) {
 ; CHECK-LABEL: 'not.crc.excess.tc'
 ; CHECK-NEXT:  Did not find a hash algorithm
 ; CHECK-NEXT:  Reason: Loop iterations exceed bitwidth of data
@@ -707,16 +707,17 @@ entry:
 loop:                                              ; preds = %loop, %entry
   %iv = phi i8 [ 0, %entry ], [ %iv.next, %loop ]
   %crc = phi i16 [ %checksum, %entry ], [ %crc.next, %loop ]
-  %data = phi i16 [ %msg, %entry ], [ %data.next, %loop ]
-  %xor.crc.data = xor i16 %crc, %data
-  %and.crc.data = and i16 %xor.crc.data, 1
-  %data.next = lshr i16 %data, 1
-  %check.sb = icmp eq i16 %and.crc.data, 0
+  %data = phi i8 [ %msg, %entry ], [ %data.next, %loop ]
+  %crc.trunc = trunc i16 %crc to i8
+  %xor.crc.data = xor i8 %crc.trunc, %data
+  %and.crc.data = and i8 %xor.crc.data, 1
+  %data.next = lshr i8 %data, 1
+  %check.sb = icmp eq i8 %and.crc.data, 0
   %crc.lshr = lshr i16 %crc, 1
   %crc.xor = xor i16 %crc.lshr, -24575
   %crc.next = select i1 %check.sb, i16 %crc.lshr, i16 %crc.xor
   %iv.next = add nuw nsw i8 %iv, 1
-  %exit.cond = icmp samesign ult i8 %iv, 31
+  %exit.cond = icmp samesign ult i8 %iv, 15
   br i1 %exit.cond, label %loop, label %exit
 
 exit:                                              ; preds = %loop