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verilog: fix dynamic dynamic range asgn elab

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Zachary Snow 2022-01-17 23:18:12 -07:00 • committed by Zachary Snow
parent 90bb47d181
commit 15eb66b99d
4 changed files with 144 additions and 17 deletions
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51
frontends/ast/simplify.cc
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@ -2704,6 +2704,18 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
while (wire_data->simplify(true, false, false, 1, -1, false, false)) { }
current_ast_mod->children.push_back(wire_data);
int shamt_width_hint = -1;
bool shamt_sign_hint = true;
shift_expr->detectSignWidth(shamt_width_hint, shamt_sign_hint);
AstNode *wire_sel = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(shamt_width_hint-1, true), mkconst_int(0, true)));
wire_sel->str = stringf("$bitselwrite$sel$%s:%d$%d", filename.c_str(), location.first_line, autoidx++);
wire_sel->attributes[ID::nosync] = AstNode::mkconst_int(1, false);
wire_sel->is_logic = true;
wire_sel->is_signed = shamt_sign_hint;
while (wire_sel->simplify(true, false, false, 1, -1, false, false)) { }
current_ast_mod->children.push_back(wire_sel);
did_something = true;
newNode = new AstNode(AST_BLOCK);
@ -2720,39 +2732,44 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
ref_data->id2ast = wire_data;
ref_data->was_checked = true;
AstNode *ref_sel = new AstNode(AST_IDENTIFIER);
ref_sel->str = wire_sel->str;
ref_sel->id2ast = wire_sel;
ref_sel->was_checked = true;
AstNode *old_data = lvalue->clone();
if (type == AST_ASSIGN_LE)
old_data->lookahead = true;
AstNode *shamt = shift_expr;
AstNode *s = new AstNode(AST_ASSIGN_EQ, ref_sel->clone(), shift_expr);
newNode->children.push_back(s);
int shamt_width_hint = 0;
bool shamt_sign_hint = true;
shamt->detectSignWidth(shamt_width_hint, shamt_sign_hint);
AstNode *shamt = ref_sel;
// convert to signed while preserving the sign and value
shamt = new AstNode(AST_CAST_SIZE, mkconst_int(shamt_width_hint + 1, true), shamt);
shamt = new AstNode(AST_TO_SIGNED, shamt);
// offset the shift amount by the lower bound of the dimension
int start_bit = children[0]->id2ast->range_right;
bool use_shift = shamt_sign_hint;
shamt = new AstNode(AST_SUB, shamt, mkconst_int(start_bit, true));
if (start_bit != 0) {
shamt = new AstNode(AST_SUB, shamt, mkconst_int(start_bit, true));
use_shift = true;
}
// reflect the shift amount if the dimension is swapped
if (children[0]->id2ast->range_swapped)
shamt = new AstNode(AST_SUB, mkconst_int(source_width - result_width, true), shamt);
// AST_SHIFT uses negative amounts for shifting left
shamt = new AstNode(AST_NEG, shamt);
AstNode *t;
t = mkconst_bits(std::vector<RTLIL::State>(result_width, State::S1), false);
if (use_shift)
t = new AstNode(AST_SHIFT, t, new AstNode(AST_NEG, shamt->clone()));
else
t = new AstNode(AST_SHIFT_LEFT, t, shamt->clone());
t = new AstNode(AST_SHIFT, t, shamt->clone());
t = new AstNode(AST_ASSIGN_EQ, ref_mask->clone(), t);
newNode->children.push_back(t);
t = new AstNode(AST_BIT_AND, mkconst_bits(std::vector<RTLIL::State>(result_width, State::S1), false), children[1]->clone());
if (use_shift)
t = new AstNode(AST_SHIFT, t, new AstNode(AST_NEG, shamt));
else
t = new AstNode(AST_SHIFT_LEFT, t, shamt);
t = new AstNode(AST_SHIFT, t, shamt);
t = new AstNode(AST_ASSIGN_EQ, ref_data->clone(), t);
newNode->children.push_back(t);