opt_expr: Fix mul/div/mod by POT patterns to support >= 32 bits.

The previous code, in addition to being needlessly limitted to 32 bits
in the first place, also had UB for the 31th bit (doing 1 << 31).

2 files changed, 35 insertions, 0 deletions

diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index 1d41ba81a..a756218f3 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -363,6 +363,26 @@ bool RTLIL::Const::is_fully_undef() const
 	return true;
 }
 
+bool RTLIL::Const::is_onehot(int *pos) const
+{
+	cover("kernel.rtlil.const.is_onehot");
+
+	bool found = false;
+	for (int i = 0; i < GetSize(*this); i++) {
+		auto &bit = bits[i];
+		if (bit != RTLIL::State::S0 && bit != RTLIL::State::S1)
+			return false;
+		if (bit == RTLIL::State::S1) {
+			if (found)
+				return false;
+			if (pos)
+				*pos = i;
+			found = true;
+		}
+	}
+	return found;
+}
+
 bool RTLIL::AttrObject::has_attribute(RTLIL::IdString id) const
 {
 	return attributes.count(id);
@@ -4211,6 +4231,19 @@ bool RTLIL::SigSpec::has_marked_bits() const
 	return false;
 }
 
+bool RTLIL::SigSpec::is_onehot(int *pos) const
+{
+	cover("kernel.rtlil.sigspec.is_onehot");
+
+	pack();
+	if (!is_fully_const())
+		return false;
+	log_assert(GetSize(chunks_) <= 1);
+	if (width_)
+		return RTLIL::Const(chunks_[0].data).is_onehot(pos);
+	return false;
+}
+
 bool RTLIL::SigSpec::as_bool() const
 {
 	cover("kernel.rtlil.sigspec.as_bool");
diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index 6ecca7370..d876d7831 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -662,6 +662,7 @@ struct RTLIL::Const
 	bool is_fully_ones() const;
 	bool is_fully_def() const;
 	bool is_fully_undef() const;
+	bool is_onehot(int *pos = nullptr) const;
 
 	inline RTLIL::Const extract(int offset, int len = 1, RTLIL::State padding = RTLIL::State::S0) const {
 		RTLIL::Const ret;
@@ -934,6 +935,7 @@ public:
 	bool is_fully_undef() const;
 	bool has_const() const;
 	bool has_marked_bits() const;
+	bool is_onehot(int *pos = nullptr) const;
 
 	bool as_bool() const;
 	int as_int(bool is_signed = false) const;