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-rw-r--r--backends/cxxrtl/cxxrtl.h127
1 files changed, 107 insertions, 20 deletions
diff --git a/backends/cxxrtl/cxxrtl.h b/backends/cxxrtl/cxxrtl.h
index 41089a153..0e55c46c2 100644
--- a/backends/cxxrtl/cxxrtl.h
+++ b/backends/cxxrtl/cxxrtl.h
@@ -36,22 +36,48 @@
#include <map>
#include <algorithm>
#include <memory>
+#include <functional>
#include <sstream>
#include <backends/cxxrtl/cxxrtl_capi.h>
+#ifndef __has_attribute
+# define __has_attribute(x) 0
+#endif
+
// CXXRTL essentially uses the C++ compiler as a hygienic macro engine that feeds an instruction selector.
// It generates a lot of specialized template functions with relatively large bodies that, when inlined
// into the caller and (for those with loops) unrolled, often expose many new optimization opportunities.
// Because of this, most of the CXXRTL runtime must be always inlined for best performance.
-#ifndef __has_attribute
-# define __has_attribute(x) 0
-#endif
#if __has_attribute(always_inline)
#define CXXRTL_ALWAYS_INLINE inline __attribute__((__always_inline__))
#else
#define CXXRTL_ALWAYS_INLINE inline
#endif
+// Conversely, some functions in the generated code are extremely large yet very cold, with both of these
+// properties being extreme enough to confuse C++ compilers into spending pathological amounts of time
+// on a futile (the code becomes worse) attempt to optimize the least important parts of code.
+#if __has_attribute(optnone)
+#define CXXRTL_EXTREMELY_COLD __attribute__((__optnone__))
+#elif __has_attribute(optimize)
+#define CXXRTL_EXTREMELY_COLD __attribute__((__optimize__(0)))
+#else
+#define CXXRTL_EXTREMELY_COLD
+#endif
+
+// CXXRTL uses assert() to check for C++ contract violations (which may result in e.g. undefined behavior
+// of the simulation code itself), and CXXRTL_ASSERT to check for RTL contract violations (which may at
+// most result in undefined simulation results).
+//
+// Though by default, CXXRTL_ASSERT() expands to assert(), it may be overridden e.g. when integrating
+// the simulation into another process that should survive violating RTL contracts.
+#ifndef CXXRTL_ASSERT
+#ifndef CXXRTL_NDEBUG
+#define CXXRTL_ASSERT(x) assert(x)
+#else
+#define CXXRTL_ASSERT(x)
+#endif
+#endif
namespace cxxrtl {
@@ -96,9 +122,11 @@ struct value : public expr_base<value<Bits>> {
explicit constexpr value(Init ...init) : data{init...} {}
value(const value<Bits> &) = default;
- value(value<Bits> &&) = default;
value<Bits> &operator=(const value<Bits> &) = default;
+ value(value<Bits> &&) = default;
+ value<Bits> &operator=(value<Bits> &&) = default;
+
// A (no-op) helper that forces the cast to value<>.
CXXRTL_ALWAYS_INLINE
const value<Bits> &val() const {
@@ -289,6 +317,14 @@ struct value : public expr_base<value<Bits>> {
return sext_cast<NewBits>()(*this);
}
+ // Bit replication is far more efficient than the equivalent concatenation.
+ template<size_t Count>
+ CXXRTL_ALWAYS_INLINE
+ value<Bits * Count> repeat() const {
+ static_assert(Bits == 1, "repeat() is implemented only for 1-bit values");
+ return *this ? value<Bits * Count>().bit_not() : value<Bits * Count>();
+ }
+
// Operations with run-time parameters (offsets, amounts, etc).
//
// These operations are used for computations.
@@ -643,14 +679,20 @@ struct wire {
value<Bits> next;
wire() = default;
- constexpr wire(const value<Bits> &init) : curr(init), next(init) {}
+ explicit constexpr wire(const value<Bits> &init) : curr(init), next(init) {}
template<typename... Init>
explicit constexpr wire(Init ...init) : curr{init...}, next{init...} {}
+ // Copying and copy-assigning values is natural. If, however, a value is replaced with a wire,
+ // e.g. because a module is built with a different optimization level, then existing code could
+ // unintentionally copy a wire instead, which would create a subtle but serious bug. To make sure
+ // this doesn't happen, prohibit copying and copy-assigning wires.
wire(const wire<Bits> &) = delete;
- wire(wire<Bits> &&) = default;
wire<Bits> &operator=(const wire<Bits> &) = delete;
+ wire(wire<Bits> &&) = default;
+ wire<Bits> &operator=(wire<Bits> &&) = default;
+
template<class IntegerT>
CXXRTL_ALWAYS_INLINE
IntegerT get() const {
@@ -692,6 +734,9 @@ struct memory {
memory(const memory<Width> &) = delete;
memory<Width> &operator=(const memory<Width> &) = delete;
+ memory(memory<Width> &&) = default;
+ memory<Width> &operator=(memory<Width> &&) = default;
+
// The only way to get the compiler to put the initializer in .rodata and do not copy it on stack is to stuff it
// into a plain array. You'd think an std::initializer_list would work here, but it doesn't, because you can't
// construct an initializer_list in a constexpr (or something) and so if you try to do that the whole thing is
@@ -815,9 +860,12 @@ struct metadata {
typedef std::map<std::string, metadata> metadata_map;
-// Helper class to disambiguate values/wires and their aliases.
+// Tag class to disambiguate values/wires and their aliases.
struct debug_alias {};
+// Tag declaration to disambiguate values and debug outlines.
+using debug_outline = ::_cxxrtl_outline;
+
// This structure is intended for consumption via foreign function interfaces, like Python's ctypes.
// Because of this it uses a C-style layout that is easy to parse rather than more idiomatic C++.
//
@@ -826,10 +874,11 @@ struct debug_alias {};
struct debug_item : ::cxxrtl_object {
// Object types.
enum : uint32_t {
- VALUE = CXXRTL_VALUE,
- WIRE = CXXRTL_WIRE,
- MEMORY = CXXRTL_MEMORY,
- ALIAS = CXXRTL_ALIAS,
+ VALUE = CXXRTL_VALUE,
+ WIRE = CXXRTL_WIRE,
+ MEMORY = CXXRTL_MEMORY,
+ ALIAS = CXXRTL_ALIAS,
+ OUTLINE = CXXRTL_OUTLINE,
};
// Object flags.
@@ -856,6 +905,7 @@ struct debug_item : ::cxxrtl_object {
zero_at = 0;
curr = item.data;
next = item.data;
+ outline = nullptr;
}
template<size_t Bits>
@@ -870,6 +920,7 @@ struct debug_item : ::cxxrtl_object {
zero_at = 0;
curr = const_cast<chunk_t*>(item.data);
next = nullptr;
+ outline = nullptr;
}
template<size_t Bits>
@@ -885,6 +936,7 @@ struct debug_item : ::cxxrtl_object {
zero_at = 0;
curr = item.curr.data;
next = item.next.data;
+ outline = nullptr;
}
template<size_t Width>
@@ -899,6 +951,7 @@ struct debug_item : ::cxxrtl_object {
zero_at = zero_offset;
curr = item.data.empty() ? nullptr : item.data[0].data;
next = nullptr;
+ outline = nullptr;
}
template<size_t Bits>
@@ -913,6 +966,7 @@ struct debug_item : ::cxxrtl_object {
zero_at = 0;
curr = const_cast<chunk_t*>(item.data);
next = nullptr;
+ outline = nullptr;
}
template<size_t Bits>
@@ -928,6 +982,22 @@ struct debug_item : ::cxxrtl_object {
zero_at = 0;
curr = const_cast<chunk_t*>(item.curr.data);
next = nullptr;
+ outline = nullptr;
+ }
+
+ template<size_t Bits>
+ debug_item(debug_outline &group, const value<Bits> &item, size_t lsb_offset = 0) {
+ static_assert(sizeof(item) == value<Bits>::chunks * sizeof(chunk_t),
+ "value<Bits> is not compatible with C layout");
+ type = OUTLINE;
+ flags = DRIVEN_COMB;
+ width = Bits;
+ lsb_at = lsb_offset;
+ depth = 1;
+ zero_at = 0;
+ curr = const_cast<chunk_t*>(item.data);
+ next = nullptr;
+ outline = &group;
}
};
static_assert(std::is_standard_layout<debug_item>::value, "debug_item is not compatible with C layout");
@@ -965,13 +1035,25 @@ struct debug_items {
}
};
+// Tag class to disambiguate module move constructor and module constructor that takes black boxes
+// out of another instance of the module.
+struct adopt {};
+
struct module {
module() {}
virtual ~module() {}
+ // Modules with black boxes cannot be copied. Although not all designs include black boxes,
+ // delete the copy constructor and copy assignment operator to make sure that any downstream
+ // code that manipulates modules doesn't accidentally depend on their availability.
module(const module &) = delete;
module &operator=(const module &) = delete;
+ module(module &&) = default;
+ module &operator=(module &&) = default;
+
+ virtual void reset() = 0;
+
virtual bool eval() = 0;
virtual bool commit() = 0;
@@ -992,11 +1074,16 @@ struct module {
} // namespace cxxrtl
-// Internal structure used to communicate with the implementation of the C interface.
+// Internal structures used to communicate with the implementation of the C interface.
+
typedef struct _cxxrtl_toplevel {
std::unique_ptr<cxxrtl::module> module;
} *cxxrtl_toplevel;
+typedef struct _cxxrtl_outline {
+ std::function<void()> eval;
+} *cxxrtl_outline;
+
// Definitions of internal Yosys cells. Other than the functions in this namespace, CXXRTL is fully generic
// and indepenent of Yosys implementation details.
//
@@ -1130,49 +1217,49 @@ value<BitsY> xnor_ss(const value<BitsA> &a, const value<BitsB> &b) {
template<size_t BitsY, size_t BitsA, size_t BitsB>
CXXRTL_ALWAYS_INLINE
value<BitsY> shl_uu(const value<BitsA> &a, const value<BitsB> &b) {
- return a.template zcast<BitsY>().template shl(b);
+ return a.template zcast<BitsY>().shl(b);
}
template<size_t BitsY, size_t BitsA, size_t BitsB>
CXXRTL_ALWAYS_INLINE
value<BitsY> shl_su(const value<BitsA> &a, const value<BitsB> &b) {
- return a.template scast<BitsY>().template shl(b);
+ return a.template scast<BitsY>().shl(b);
}
template<size_t BitsY, size_t BitsA, size_t BitsB>
CXXRTL_ALWAYS_INLINE
value<BitsY> sshl_uu(const value<BitsA> &a, const value<BitsB> &b) {
- return a.template zcast<BitsY>().template shl(b);
+ return a.template zcast<BitsY>().shl(b);
}
template<size_t BitsY, size_t BitsA, size_t BitsB>
CXXRTL_ALWAYS_INLINE
value<BitsY> sshl_su(const value<BitsA> &a, const value<BitsB> &b) {
- return a.template scast<BitsY>().template shl(b);
+ return a.template scast<BitsY>().shl(b);
}
template<size_t BitsY, size_t BitsA, size_t BitsB>
CXXRTL_ALWAYS_INLINE
value<BitsY> shr_uu(const value<BitsA> &a, const value<BitsB> &b) {
- return a.template shr(b).template zcast<BitsY>();
+ return a.shr(b).template zcast<BitsY>();
}
template<size_t BitsY, size_t BitsA, size_t BitsB>
CXXRTL_ALWAYS_INLINE
value<BitsY> shr_su(const value<BitsA> &a, const value<BitsB> &b) {
- return a.template shr(b).template scast<BitsY>();
+ return a.shr(b).template scast<BitsY>();
}
template<size_t BitsY, size_t BitsA, size_t BitsB>
CXXRTL_ALWAYS_INLINE
value<BitsY> sshr_uu(const value<BitsA> &a, const value<BitsB> &b) {
- return a.template shr(b).template zcast<BitsY>();
+ return a.shr(b).template zcast<BitsY>();
}
template<size_t BitsY, size_t BitsA, size_t BitsB>
CXXRTL_ALWAYS_INLINE
value<BitsY> sshr_su(const value<BitsA> &a, const value<BitsB> &b) {
- return a.template sshr(b).template scast<BitsY>();
+ return a.sshr(b).template scast<BitsY>();
}
template<size_t BitsY, size_t BitsA, size_t BitsB>
generated by cgit v1.2.3 (git 2.25.1) at 2025-04-03 05:39:59 +0000