Fix static shift operands, neg result type, minor formatting

Static shift operands must be constants.
The result of FIRRTL's neg operator is signed.
Fix poor indentation for gen_read().

diff --git a/backends/firrtl/firrtl.cc b/backends/firrtl/firrtl.cc
index fe6bdb8f60c0e18f653af0d5f1ff08d67bace3ec..1c7a7351fba0157fbefb7445159fe2d718d006c5 100644 (file)
--- a/backends/firrtl/firrtl.cc
+++ b/backends/firrtl/firrtl.cc
@@ -146,7 +146,7 @@ struct FirrtlWorker
                        if (!mask.is_fully_def())
                                this->ena = SigSpec(RTLIL::Const(1));
                }
-         string gen_read(const char * /* indent */) {
+               string gen_read(const char * /* indent */) {
                        log_error("gen_read called on write_port: %s\n", name.c_str());
                        return stringf("gen_read called on write_port: %s\n", name.c_str());
                }
@@ -449,8 +449,10 @@ struct FirrtlWorker
                                string primop;
                                bool always_uint = false;
                                if (cell->type == "$not") primop = "not";
-                               else if (cell->type == "$neg") primop = "neg";
-                               else if (cell->type == "$logic_not") {
+                               else if (cell->type == "$neg") {
+                                       primop = "neg";
+                                       is_signed = true;       // Result of "neg" is signed (an SInt).
+                               } else if (cell->type == "$logic_not") {
                                         primop = "eq";
                                         a_expr = stringf("%s, UInt(0)", a_expr.c_str());
                                 }
@@ -562,6 +564,7 @@ struct FirrtlWorker
                                        auto b_sig = cell->getPort("\\B");
                                        if (b_sig.is_fully_const()) {
                                                primop = "shl";
+                                               b_expr = std::to_string(b_sig.as_int());
                                        } else {
                                                primop = "dshl";
                                                // Convert from FIRRTL left shift semantics.
@@ -575,6 +578,7 @@ struct FirrtlWorker
                                        auto b_sig = cell->getPort("\\B");
                                        if (b_sig.is_fully_const()) {
                                                primop = "shr";
+                                               b_expr = std::to_string(b_sig.as_int());
                                        } else {
                                                primop = "dshr";
                                        }