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Add "nowrshmsk" attribute, fix shift-and-mask bit slice write for signed offset, fixes #1990

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Signed-off-by: Claire Wolf <claire@symbioticeda.com>
This commit is contained in:
Claire Wolf 2020-04-27 17:04:47 +02:00
parent ca3fc3c882
commit bbbce0d1c5
6 changed files with 57 additions and 7 deletions
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50
frontends/ast/simplify.cc
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@ -1786,7 +1786,18 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
result_width = abs(int(left_at_zero_ast->integer - right_at_zero_ast->integer)) + 1;
}
if (0)
bool use_case_method = false;
if (children[0]->id2ast->attributes.count(ID::nowrshmsk)) {
AstNode *node = children[0]->id2ast->attributes.at(ID::nowrshmsk);
while (node->simplify(true, false, false, stage, -1, false, false)) { }
if (node->type != AST_CONSTANT)
log_file_error(filename, location.first_line, "Non-constant value for `nowrshmsk' attribute on `%s'!\n", children[0]->id2ast->str.c_str());
if (node->asAttrConst().as_bool())
use_case_method = true;
}
if (use_case_method)
{
// big case block
@ -1794,10 +1805,10 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
newNode = new AstNode(AST_CASE, shift_expr);
for (int i = 0; i < source_width; i++) {
int start_bit = children[0]->id2ast->range_right + i;
int end_bit = std::min(start_bit+result_width,source_width) - 1;
AstNode *cond = new AstNode(AST_COND, mkconst_int(start_bit, true));
AstNode *lvalue = children[0]->clone();
lvalue->delete_children();
int end_bit = std::min(start_bit+result_width,source_width) - 1;
lvalue->children.push_back(new AstNode(AST_RANGE,
mkconst_int(end_bit, true), mkconst_int(start_bit, true)));
cond->children.push_back(new AstNode(AST_BLOCK, new AstNode(type, lvalue, children[1]->clone())));
@ -1844,11 +1855,36 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
AstNode *shamt = shift_expr;
newNode->children.push_back(new AstNode(AST_ASSIGN_EQ, ref_mask->clone(),
new AstNode(AST_SHIFT_LEFT, mkconst_bits(std::vector<RTLIL::State>(result_width, State::S1), false), shamt->clone())));
newNode->children.push_back(new AstNode(AST_ASSIGN_EQ, ref_data->clone(),
new AstNode(AST_SHIFT_LEFT, new AstNode(AST_BIT_AND, mkconst_bits(std::vector<RTLIL::State>(result_width, State::S1), false), children[1]->clone()), shamt)));
newNode->children.push_back(new AstNode(type, lvalue, new AstNode(AST_BIT_OR, new AstNode(AST_BIT_AND, old_data, new AstNode(AST_BIT_NOT, ref_mask)), ref_data)));
int start_bit = children[0]->id2ast->range_right;
bool use_shift = shamt->is_signed;
if (start_bit != 0) {
shamt = new AstNode(AST_SUB, shamt, mkconst_int(start_bit, true));
use_shift = true;
}
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_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_ASSIGN_EQ, ref_data->clone(), t);
newNode->children.push_back(t);
t = new AstNode(AST_BIT_AND, old_data, new AstNode(AST_BIT_NOT, ref_mask));
t = new AstNode(AST_BIT_OR, t, ref_data);
t = new AstNode(type, lvalue, t);
newNode->children.push_back(t);
}
goto apply_newNode;