Allow lefshift by zero.

git-svn-id: https://stp-fast-prover.svn.sourceforge.net/svnroot/stp-fast-prover/trunk/stp@633 e59a4935-1847-0410-ae03-e826735625c1

diff --git a/src/parser/CVC.y b/src/parser/CVC.y
index 97dedeadfe5b2a6feabc3f57f31f56cda9951e42..eeb4a1dc3b91ff4ef0308b95b0b83a0087692f44 100644 (file)
--- a/src/parser/CVC.y
+++ b/src/parser/CVC.y
@@ -911,6 +911,12 @@ Expr            :      TERMID_TOK { $$ = new ASTNode(ParserBM->GetLetMgr()->Reso
 }
 |      Expr BVLEFTSHIFT_TOK NUMERAL_TOK 
 {
+  if (0 == $3)
+       {
+       $$ = $1;
+       }
+  else
+  {
   ASTNode zero_bits = ParserBM->CreateZeroConst($3);
   ASTNode * n = 
     new ASTNode(ParserBM->CreateTerm(BVCONCAT,
@@ -918,6 +924,7 @@ Expr            :      TERMID_TOK { $$ = new ASTNode(ParserBM->GetLetMgr()->Reso
   BVTypeCheck(*n);
   $$ = n;
   delete $1;
+  }
 }
 /* |      Expr BVLEFTSHIFT_TOK Expr */
 /* { */