Merge pull request #4834

2c7195d8 bulletproofs: avoid std::vector allocations for slice (moneromooo-monero)

src/ringct/bulletproofs.cc

@@ -31,6 +31,7 @@
 #include <stdlib.h>
 #include <boost/thread/mutex.hpp>
 #include "misc_log_ex.h"
+#include "span.h"
 #include "common/perf_timer.h"
 #include "cryptonote_config.h"
 extern "C"
@@ -218,7 +219,7 @@ static rct::key vector_power_sum(const rct::key &x, size_t n)
 }
 
 /* Given two scalar arrays, construct the inner product */
-static rct::key inner_product(const rct::keyV &a, const rct::keyV &b)
+static rct::key inner_product(const epee::span<const rct::key> &a, const epee::span<const rct::key> &b)
 {
   CHECK_AND_ASSERT_THROW_MES(a.size() == b.size(), "Incompatible sizes of a and b");
   rct::key res = rct::zero();
@@ -229,6 +230,11 @@ static rct::key inner_product(const rct::keyV &a, const rct::keyV &b)
   return res;
 }
 
+static rct::key inner_product(const rct::keyV &a, const rct::keyV &b)
+{
+  return inner_product(epee::span<const rct::key>(a.data(), a.size()), epee::span<const rct::key>(b.data(), b.size()));
+}
+
 /* Given two scalar arrays, construct the Hadamard product */
 static rct::keyV hadamard(const rct::keyV &a, const rct::keyV &b)
 {
@@ -294,7 +300,7 @@ static rct::keyV vector_subtract(const rct::keyV &a, const rct::key &b)
 }
 
 /* Multiply a scalar and a vector */
-static rct::keyV vector_scalar(const rct::keyV &a, const rct::key &x)
+static rct::keyV vector_scalar(const epee::span<const rct::key> &a, const rct::key &x)
 {
   rct::keyV res(a.size());
   for (size_t i = 0; i < a.size(); ++i)
@@ -304,6 +310,11 @@ static rct::keyV vector_scalar(const rct::keyV &a, const rct::key &x)
   return res;
 }
 
+static rct::keyV vector_scalar(const rct::keyV &a, const rct::key &x)
+{
+  return vector_scalar(epee::span<const rct::key>(a.data(), a.size()), x);
+}
+
 /* Create a vector from copies of a single value */
 static rct::keyV vector_dup(const rct::key &x, size_t N)
 {
@@ -401,17 +412,12 @@ static rct::keyV invert(rct::keyV x)
 }
 
 /* Compute the slice of a vector */
-static rct::keyV slice(const rct::keyV &a, size_t start, size_t stop)
+static epee::span<const rct::key> slice(const rct::keyV &a, size_t start, size_t stop)
 {
   CHECK_AND_ASSERT_THROW_MES(start < a.size(), "Invalid start index");
   CHECK_AND_ASSERT_THROW_MES(stop <= a.size(), "Invalid stop index");
   CHECK_AND_ASSERT_THROW_MES(start < stop, "Invalid start/stop indices");
-  rct::keyV res(stop - start);
-  for (size_t i = start; i < stop; ++i)
-  {
-    res[i - start] = a[i];
-  }
-  return res;
+  return epee::span<const rct::key>(&a[start], stop - start);
 }
 
 static rct::key hash_cache_mash(rct::key &hash_cache, const rct::key &mash0, const rct::key &mash1)