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mem2reg: tolerate out of bounds constant accesses

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This brings the mem2reg behavior in line with the nomem2reg behavior.
This commit is contained in:
Zachary Snow 2021-05-26 18:22:31 -04:00 • committed by Zachary Snow
parent d9f11bb7a6
commit c79fbfe0a1
4 changed files with 94 additions and 5 deletions
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47
frontends/ast/simplify.cc
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@ -1762,7 +1762,7 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
}
// split memory access with bit select to individual statements
if (type == AST_IDENTIFIER && children.size() == 2 && children[0]->type == AST_RANGE && children[1]->type == AST_RANGE && !in_lvalue)
if (type == AST_IDENTIFIER && children.size() == 2 && children[0]->type == AST_RANGE && children[1]->type == AST_RANGE && !in_lvalue && stage == 2)
{
if (id2ast == NULL || id2ast->type != AST_MEMORY || children[0]->children.size() != 1)
log_file_error(filename, location.first_line, "Invalid bit-select on memory access!\n");
@ -4501,11 +4501,48 @@ bool AstNode::mem2reg_as_needed_pass2(pool<AstNode*> &mem2reg_set, AstNode *mod,
if (children[0]->children[0]->type == AST_CONSTANT)
{
int id = children[0]->children[0]->integer;
str = stringf("%s[%d]", str.c_str(), id);
int left = id2ast->children[1]->children[0]->integer;
int right = id2ast->children[1]->children[1]->integer;
bool valid_const_access =
(left <= id && id <= right) ||
(right <= id && id <= left);
if (valid_const_access)
{
str = stringf("%s[%d]", str.c_str(), id);
delete_children();
range_valid = false;
id2ast = NULL;
}
else
{
int width;
if (bit_part_sel)
{
bit_part_sel->dumpAst(nullptr, "? ");
if (bit_part_sel->children.size() == 1)
width = 0;
else
width = bit_part_sel->children[0]->integer -
bit_part_sel->children[1]->integer;
delete bit_part_sel;
bit_part_sel = nullptr;
}
else
{
width = id2ast->children[0]->children[0]->integer -
id2ast->children[0]->children[1]->integer;
}
width = abs(width) + 1;
delete_children();
range_valid = false;
id2ast = NULL;
delete_children();
std::vector<RTLIL::State> x_bits;
for (int i = 0; i < width; i++)
x_bits.push_back(RTLIL::State::Sx);
AstNode *constant = AstNode::mkconst_bits(x_bits, false);
constant->cloneInto(this);
delete constant;
}
}
else
{