Determine correct signedness and expression width in for loop unrolling, fixes #370

Signed-off-by: Clifford Wolf <clifford@clifford.at>

diff --git a/frontends/ast/simplify.cc b/frontends/ast/simplify.cc
index 76da5a97cfcc955c9e14f66784f536455a8e53a0..3e453bd7f367555f786e432028aaf6db13d9a01c 100644 (file)
--- a/frontends/ast/simplify.cc
+++ b/frontends/ast/simplify.cc
@@ -1085,7 +1085,12 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
 
                // eval 1st expression
                AstNode *varbuf = init_ast->children[1]->clone();
-               while (varbuf->simplify(true, false, false, stage, 32, true, false)) { }
+               {
+                       int expr_width_hint = -1;
+                       bool expr_sign_hint = true;
+                       varbuf->detectSignWidth(expr_width_hint, expr_sign_hint);
+                       while (varbuf->simplify(true, false, false, stage, 32, true, false)) { }
+               }
 
                if (varbuf->type != AST_CONSTANT)
                        log_file_error(filename, linenum, "Right hand side of 1st expression of generate for-loop is not constant!\n");
@@ -1107,7 +1112,12 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
                {
                        // eval 2nd expression
                        AstNode *buf = while_ast->clone();
-                       while (buf->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
+                       {
+                               int expr_width_hint = -1;
+                               bool expr_sign_hint = true;
+                               buf->detectSignWidth(expr_width_hint, expr_sign_hint);
+                               while (buf->simplify(true, false, false, stage, expr_width_hint, expr_sign_hint, false)) { }
+                       }
 
                        if (buf->type != AST_CONSTANT)
                                log_file_error(filename, linenum, "2nd expression of generate for-loop is not constant!\n");
@@ -1148,7 +1158,12 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
 
                        // eval 3rd expression
                        buf = next_ast->children[1]->clone();
-                       while (buf->simplify(true, false, false, stage, 32, true, false)) { }
+                       {
+                               int expr_width_hint = -1;
+                               bool expr_sign_hint = true;
+                               buf->detectSignWidth(expr_width_hint, expr_sign_hint);
+                               while (buf->simplify(true, false, false, stage, expr_width_hint, expr_sign_hint, true)) { }
+                       }
 
                        if (buf->type != AST_CONSTANT)
                                log_file_error(filename, linenum, "Right hand side of 3rd expression of generate for-loop is not constant!\n");