From: whitequark <whitequark@whitequark.org>
Date: Tue, 9 Jun 2020 07:26:13 +0000 (+0000)
Subject: cxxrtl: ignore cell input signedness when it is irrelevant.
X-Git-Tag: working-ls180~488^2
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=ef4e1594470b46eab6f311998511a5eee22a96d3;p=yosys.git

cxxrtl: ignore cell input signedness when it is irrelevant.

Before this commit, Verilog expressions like `x && 1` would result in
references to `logic_and_us` in generated CXXRTL code, which would
not compile. After this commit, since cells like that actually behave
the same regardless of signedness attributes, the signedness is
ignored, which also reduces the template instantiation pressure.
---

diff --git a/backends/cxxrtl/cxxrtl.h b/backends/cxxrtl/cxxrtl.h
index 30f4667c5..c988c9e80 100644
--- a/backends/cxxrtl/cxxrtl.h
+++ b/backends/cxxrtl/cxxrtl.h
@@ -829,73 +829,55 @@ constexpr T max(const T &a, const T &b) {
 
 // Logic operations
 template<size_t BitsY, size_t BitsA>
-value<BitsY> not_u(const value<BitsA> &a) {
-	return a.template zcast<BitsY>().bit_not();
-}
-
-template<size_t BitsY, size_t BitsA>
-value<BitsY> not_s(const value<BitsA> &a) {
-	return a.template scast<BitsY>().bit_not();
-}
-
-template<size_t BitsY, size_t BitsA>
-value<BitsY> logic_not_u(const value<BitsA> &a) {
+value<BitsY> logic_not(const value<BitsA> &a) {
 	return value<BitsY> { a ? 0u : 1u };
 }
 
-template<size_t BitsY, size_t BitsA>
-value<BitsY> logic_not_s(const value<BitsA> &a) {
-	return value<BitsY> { a ? 0u : 1u };
+template<size_t BitsY, size_t BitsA, size_t BitsB>
+value<BitsY> logic_and(const value<BitsA> &a, const value<BitsB> &b) {
+	return value<BitsY> { (bool(a) & bool(b)) ? 1u : 0u };
 }
 
-template<size_t BitsY, size_t BitsA>
-value<BitsY> reduce_and_u(const value<BitsA> &a) {
-	return value<BitsY> { a.bit_not().is_zero() ? 1u : 0u };
+template<size_t BitsY, size_t BitsA, size_t BitsB>
+value<BitsY> logic_or(const value<BitsA> &a, const value<BitsB> &b) {
+	return value<BitsY> { (bool(a) | bool(b)) ? 1u : 0u };
 }
 
+// Reduction operations
 template<size_t BitsY, size_t BitsA>
-value<BitsY> reduce_and_s(const value<BitsA> &a) {
+value<BitsY> reduce_and(const value<BitsA> &a) {
 	return value<BitsY> { a.bit_not().is_zero() ? 1u : 0u };
 }
 
 template<size_t BitsY, size_t BitsA>
-value<BitsY> reduce_or_u(const value<BitsA> &a) {
-	return value<BitsY> { a ? 1u : 0u };
-}
-
-template<size_t BitsY, size_t BitsA>
-value<BitsY> reduce_or_s(const value<BitsA> &a) {
+value<BitsY> reduce_or(const value<BitsA> &a) {
 	return value<BitsY> { a ? 1u : 0u };
 }
 
 template<size_t BitsY, size_t BitsA>
-value<BitsY> reduce_xor_u(const value<BitsA> &a) {
-	return value<BitsY> { (a.ctpop() % 2) ? 1u : 0u };
-}
-
-template<size_t BitsY, size_t BitsA>
-value<BitsY> reduce_xor_s(const value<BitsA> &a) {
+value<BitsY> reduce_xor(const value<BitsA> &a) {
 	return value<BitsY> { (a.ctpop() % 2) ? 1u : 0u };
 }
 
 template<size_t BitsY, size_t BitsA>
-value<BitsY> reduce_xnor_u(const value<BitsA> &a) {
+value<BitsY> reduce_xnor(const value<BitsA> &a) {
 	return value<BitsY> { (a.ctpop() % 2) ? 0u : 1u };
 }
 
 template<size_t BitsY, size_t BitsA>
-value<BitsY> reduce_xnor_s(const value<BitsA> &a) {
-	return value<BitsY> { (a.ctpop() % 2) ? 0u : 1u };
+value<BitsY> reduce_bool(const value<BitsA> &a) {
+	return value<BitsY> { a ? 1u : 0u };
 }
 
+// Bitwise operations
 template<size_t BitsY, size_t BitsA>
-value<BitsY> reduce_bool_u(const value<BitsA> &a) {
-	return value<BitsY> { a ? 1u : 0u };
+value<BitsY> not_u(const value<BitsA> &a) {
+	return a.template zcast<BitsY>().bit_not();
 }
 
 template<size_t BitsY, size_t BitsA>
-value<BitsY> reduce_bool_s(const value<BitsA> &a) {
-	return value<BitsY> { a ? 1u : 0u };
+value<BitsY> not_s(const value<BitsA> &a) {
+	return a.template scast<BitsY>().bit_not();
 }
 
 template<size_t BitsY, size_t BitsA, size_t BitsB>
@@ -938,26 +920,6 @@ value<BitsY> xnor_ss(const value<BitsA> &a, const value<BitsB> &b) {
 	return a.template scast<BitsY>().bit_xor(b.template scast<BitsY>()).bit_not();
 }
 
-template<size_t BitsY, size_t BitsA, size_t BitsB>
-value<BitsY> logic_and_uu(const value<BitsA> &a, const value<BitsB> &b) {
-	return value<BitsY> { (bool(a) & bool(b)) ? 1u : 0u };
-}
-
-template<size_t BitsY, size_t BitsA, size_t BitsB>
-value<BitsY> logic_and_ss(const value<BitsA> &a, const value<BitsB> &b) {
-	return value<BitsY> { (bool(a) & bool(b)) ? 1u : 0u };
-}
-
-template<size_t BitsY, size_t BitsA, size_t BitsB>
-value<BitsY> logic_or_uu(const value<BitsA> &a, const value<BitsB> &b) {
-	return value<BitsY> { (bool(a) | bool(b)) ? 1u : 0u };
-}
-
-template<size_t BitsY, size_t BitsA, size_t BitsB>
-value<BitsY> logic_or_ss(const value<BitsA> &a, const value<BitsB> &b) {
-	return value<BitsY> { (bool(a) | bool(b)) ? 1u : 0u };
-}
-
 template<size_t BitsY, size_t BitsA, size_t BitsB>
 value<BitsY> shl_uu(const value<BitsA> &a, const value<BitsB> &b) {
 	return a.template zcast<BitsY>().template shl(b);
diff --git a/backends/cxxrtl/cxxrtl_backend.cc b/backends/cxxrtl/cxxrtl_backend.cc
index bf01b263a..2646f9371 100644
--- a/backends/cxxrtl/cxxrtl_backend.cc
+++ b/backends/cxxrtl/cxxrtl_backend.cc
@@ -192,6 +192,13 @@ bool is_binary_cell(RTLIL::IdString type)
 		ID($add), ID($sub), ID($mul), ID($div), ID($mod));
 }
 
+bool is_extending_cell(RTLIL::IdString type)
+{
+	return !type.in(
+		ID($logic_not), ID($logic_and), ID($logic_or),
+		ID($reduce_and), ID($reduce_or), ID($reduce_xor), ID($reduce_xnor), ID($reduce_bool));
+}
+
 bool is_elidable_cell(RTLIL::IdString type)
 {
 	return is_unary_cell(type) || is_binary_cell(type) || type.in(
@@ -907,17 +914,19 @@ struct CxxrtlWorker {
 	{
 		// Unary cells
 		if (is_unary_cell(cell->type)) {
-			f << cell->type.substr(1) << '_' <<
-			     (cell->getParam(ID::A_SIGNED).as_bool() ? 's' : 'u') <<
-			     "<" << cell->getParam(ID::Y_WIDTH).as_int() << ">(";
+			f << cell->type.substr(1);
+			if (is_extending_cell(cell->type))
+				f << '_' << (cell->getParam(ID::A_SIGNED).as_bool() ? 's' : 'u');
+			f << "<" << cell->getParam(ID::Y_WIDTH).as_int() << ">(";
 			dump_sigspec_rhs(cell->getPort(ID::A));
 			f << ")";
 		// Binary cells
 		} else if (is_binary_cell(cell->type)) {
-			f << cell->type.substr(1) << '_' <<
-			     (cell->getParam(ID::A_SIGNED).as_bool() ? 's' : 'u') <<
-			     (cell->getParam(ID::B_SIGNED).as_bool() ? 's' : 'u') <<
-			     "<" << cell->getParam(ID::Y_WIDTH).as_int() << ">(";
+			f << cell->type.substr(1);
+			if (is_extending_cell(cell->type))
+				f << '_' << (cell->getParam(ID::A_SIGNED).as_bool() ? 's' : 'u') <<
+				            (cell->getParam(ID::B_SIGNED).as_bool() ? 's' : 'u');
+			f << "<" << cell->getParam(ID::Y_WIDTH).as_int() << ">(";
 			dump_sigspec_rhs(cell->getPort(ID::A));
 			f << ", ";
 			dump_sigspec_rhs(cell->getPort(ID::B));