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Added support for constant bit- or part-select for memory writes

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This commit is contained in:
Clifford Wolf 2014-07-17 13:13:21 +02:00
parent 1b00861d0a
commit 6d69d4aaa8
2 changed files with 56 additions and 9 deletions
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45
frontends/ast/simplify.cc
View file

@ -607,9 +607,9 @@ 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)
if (type == AST_IDENTIFIER && children.size() == 2 && children[0]->type == AST_RANGE && children[1]->type == AST_RANGE && !in_lvalue)
{
if (id2ast == NULL || id2ast->type != AST_MEMORY || children[0]->children.size() != 1 || in_lvalue)
if (id2ast == NULL || id2ast->type != AST_MEMORY || children[0]->children.size() != 1)
log_error("Invalid bit-select on memory access at %s:%d!\n", filename.c_str(), linenum);
int mem_width, mem_size, addr_bits;
@ -1150,9 +1150,9 @@ skip_dynamic_range_lvalue_expansion:;
// assignment with memory in left-hand side expression -> replace with memory write port
if (stage > 1 && (type == AST_ASSIGN_EQ || type == AST_ASSIGN_LE) && children[0]->type == AST_IDENTIFIER &&
children[0]->children.size() == 1 && children[0]->id2ast && children[0]->id2ast->type == AST_MEMORY &&
children[0]->id2ast->children.size() >= 2 && children[0]->id2ast->children[0]->range_valid &&
children[0]->id2ast->children[1]->range_valid)
children[0]->id2ast && children[0]->id2ast->type == AST_MEMORY && children[0]->id2ast->children.size() >= 2 &&
children[0]->id2ast->children[0]->range_valid && children[0]->id2ast->children[1]->range_valid &&
(children[0]->children.size() == 1 || children[0]->children.size() == 2))
{
std::stringstream sstr;
sstr << "$memwr$" << children[0]->str << "$" << filename << ":" << linenum << "$" << (RTLIL::autoidx++);
@ -1209,11 +1209,38 @@ skip_dynamic_range_lvalue_expansion:;
assign_addr = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), children[0]->children[0]->children[0]->clone());
assign_addr->children[0]->str = id_addr;
assign_data = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), children[1]->clone());
assign_data->children[0]->str = id_data;
if (children[0]->children.size() == 2)
{
if (children[0]->children[1]->range_valid)
{
int offset = children[0]->children[1]->range_right;
int width = children[0]->children[1]->range_left - offset + 1;
assign_en = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), mkconst_bits(set_bits_en, false));
assign_en->children[0]->str = id_en;
std::vector<RTLIL::State> padding_x(offset, RTLIL::State::Sx);
for (int i = 0; i < mem_width; i++)
set_bits_en[i] = offset <= i && i < offset+width ? RTLIL::State::S1 : RTLIL::State::S0;
assign_data = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER),
new AstNode(AST_CONCAT, mkconst_bits(padding_x, false), children[1]->clone()));
assign_data->children[0]->str = id_data;
assign_en = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), mkconst_bits(set_bits_en, false));
assign_en->children[0]->str = id_en;
}
else
{
log_error("Writing to memories with dynamic bit- or part-select is not supported yet at %s:%d.\n", filename.c_str(), linenum);
}
}
else
{
assign_data = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), children[1]->clone());
assign_data->children[0]->str = id_data;
assign_en = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), mkconst_bits(set_bits_en, false));
assign_en->children[0]->str = id_en;
}
newNode = new AstNode(AST_BLOCK);
newNode->children.push_back(assign_addr);

20
tests/simple/memory.v
View file

@ -114,3 +114,23 @@ assign rd_data = memory[rd_addr_buf];
endmodule
// ----------------------------------------------------------
module test05(clk, addr, wdata, rdata, wen);
input clk;
input [1:0] addr;
input [7:0] wdata;
output reg [7:0] rdata;
input [3:0] wen;
reg [7:0] mem [0:3];
integer i;
always @(posedge clk) begin
for (i = 0; i < 4; i = i+1)
if (wen[i]) mem[addr][i*2 +: 2] <= wdata[i*2 +: 2];
rdata <= mem[addr];
end
endmodule