Progress in SMV back-end

diff --git a/backends/smv/smv.cc b/backends/smv/smv.cc
index 6ff336a33853374b746bce6883c7db92ef1c0c17..941495726dd3ffa4f7e457b36dc9c3caad31a0df 100644 (file)
--- a/backends/smv/smv.cc
+++ b/backends/smv/smv.cc
@@ -115,7 +115,9 @@ struct SmvWorker
                        sigmap.apply(sig);
 
                string s;
+               int count_chunks = 0;
                for (auto &c : sig.chunks()) {
+                       count_chunks++;
                        if (!s.empty())
                                s = " :: " + s;
                        if (c.wire) {
@@ -141,6 +143,8 @@ struct SmvWorker
                                s = stringf("resize(%s, %d)", s.c_str(), width);
                } else if (is_signed)
                        s = stringf("signed(%s)", s.c_str());
+               else if (count_chunks > 1)
+                       s = stringf("(%s)", s.c_str());
 
                strbuf.push_back(s);
                return strbuf.back().c_str();
@@ -224,26 +228,68 @@ struct SmvWorker
 
                        if (cell->type.in("$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx"))
                        {
+                               SigSpec sig_a = cell->getPort("\\A");
+                               SigSpec sig_b = cell->getPort("\\B");
+
                                int width_y = GetSize(cell->getPort("\\Y"));
-                               int width = std::max(GetSize(cell->getPort("\\A")), width_y);
+                               int shift_b_width = GetSize(sig_b);
+                               int width_ay = std::max(GetSize(sig_a), width_y);
+                               int width = width_ay;
+
+                               for (int i = 1, j = 0;; i <<= 1, j++)
+                                       if (width_ay < i) {
+                                               width = i-1;
+                                               shift_b_width = std::min(shift_b_width, j);
+                                               break;
+                                       }
+
                                bool signed_a = cell->getParam("\\A_SIGNED").as_bool();
+                               bool signed_b = cell->getParam("\\B_SIGNED").as_bool();
                                string op = cell->type.in("$shl", "$sshl") ? "<<" : ">>";
                                string expr, expr_a;
 
-                               if (signed_a) {
-                                       expr_a = stringf("resize(signed(%s), %d)", rvalue(cell->getPort("\\A")), width);
-                               } else
-                                       expr_a = stringf("resize(%s, %d)", rvalue(cell->getPort("\\A")), width);
+                               if (cell->type == "$sshr" && signed_a)
+                               {
+                                       expr_a = rvalue_s(sig_a, width);
+                                       expr = stringf("resize(unsigned(%s %s %s), %d)", expr_a.c_str(), op.c_str(), rvalue(sig_b.extract(0, shift_b_width)), width_y);
+                                       if (shift_b_width < GetSize(sig_b))
+                                               expr = stringf("%s != 0ud%d_0 ? (bool(%s) ? !0ud%d_0 : 0ud%d_0) : %s",
+                                                               rvalue(sig_b.extract(shift_b_width, GetSize(sig_b) - shift_b_width)), GetSize(sig_b) - shift_b_width,
+                                                               rvalue(sig_a[GetSize(sig_a)-1]), width_y, width_y, expr.c_str());
+                               }
+                               else if (cell->type.in("$shift", "$shiftx") && signed_b)
+                               {
+                                       expr_a = rvalue_u(sig_a, width);
+
+                                       const char *b_shr = rvalue_u(sig_b);
+                                       const char *b_shl = cid();
+
+                                       f << stringf("    %s : unsigned word[%d]; -- neg(%s)\n", b_shl, GetSize(sig_b), log_signal(sig_b));
+                                       assignments.push_back(stringf("%s := unsigned(-%s);", b_shl, rvalue_s(sig_b)));
+
+                                       string expr_shl = stringf("resize(%s << %s[%d:0], %d)", expr_a.c_str(), b_shl, shift_b_width-1, width_y);
+                                       string expr_shr = stringf("resize(%s >> %s[%d:0], %d)", expr_a.c_str(), b_shr, shift_b_width-1, width_y);
+
+                                       if (shift_b_width < GetSize(sig_b)) {
+                                               expr_shl = stringf("%s[%d:%d] != 0ud%d_0 ? 0ud%d_0 : %s", b_shl, GetSize(sig_b)-1, shift_b_width,
+                                                               GetSize(sig_b)-shift_b_width, width_y, expr_shl.c_str());
+                                               expr_shr = stringf("%s[%d:%d] != 0ud%d_0 ? 0ud%d_0 : %s", b_shr, GetSize(sig_b)-1, shift_b_width,
+                                                               GetSize(sig_b)-shift_b_width, width_y, expr_shr.c_str());
+                                       }
 
-                               if (cell->type == "$sshr" && signed_a) {
-                                       expr = stringf("resize(%s %s %s, %d)", expr_a.c_str(), op.c_str(), rvalue(cell->getPort("\\B")), width_y);
-                               } else {
-                                       if (signed_a)
-                                               expr_a = "unsigned(" + expr_a + ")";
-                                       if (cell->type.in("$shift", "$shiftx") && cell->getParam("\\B_SIGNED").as_bool())
-                                               expr = stringf("resize(%s %s signed(%s), %d)", expr_a.c_str(), op.c_str(), rvalue(cell->getPort("\\B")), width_y);
+                                       expr = stringf("bool(%s) ? %s : %s", rvalue(sig_b[GetSize(sig_b)-1]), expr_shl.c_str(), expr_shr.c_str());
+                               }
+                               else
+                               {
+                                       if (cell->type.in("$shift", "$shiftx") || !signed_a)
+                                               expr_a = rvalue_u(sig_a, width);
                                        else
-                                               expr = stringf("resize(%s %s %s, %d)", expr_a.c_str(), op.c_str(), rvalue(cell->getPort("\\B")), width_y);
+                                               expr_a = stringf("resize(unsigned(%s), %d)", rvalue_s(sig_a, width_ay), width);
+
+                                       expr = stringf("resize(%s %s %s[%d:0], %d)", expr_a.c_str(), op.c_str(), rvalue_u(sig_b), shift_b_width-1, width_y);
+                                       if (shift_b_width < GetSize(sig_b))
+                                               expr = stringf("%s[%d:%d] != 0ud%d_0 ? 0ud%d_0 : %s", rvalue_u(sig_b), GetSize(sig_b)-1, shift_b_width,
+                                                               GetSize(sig_b)-shift_b_width, width_y, expr.c_str());
                                }
 
                                assignments.push_back(stringf("%s := %s;", lvalue(cell->getPort("\\Y")), expr.c_str()));

diff --git a/tests/smv/run-test.sh b/tests/smv/run-test.sh
index c61f67d307b1687dcc52f084e59021766d0b9523..74a54486d95eee5f9f6b1a46d0c05ad620b68ae0 100755 (executable)
--- a/tests/smv/run-test.sh
+++ b/tests/smv/run-test.sh
@@ -6,7 +6,7 @@ rm -rf temp
 mkdir -p temp
 
 ../../yosys -p 'test_cell -muxdiv -w temp/test all'
-rm -f temp/test_{alu,fa,lcu,lut,macc}_*
+rm -f temp/test_{alu,fa,lcu,lut,macc,shiftx}_*
 
 cat > temp/makefile << "EOT"
 all: $(addsuffix .ok,$(basename $(wildcard temp/test_*.il)))