fix h2d copy in precompute_barycentric_bases

src/primitives/arith.rs

@@ -56,17 +56,15 @@ pub fn mul_assign_complex(
         assert_eq!(c0_this_ptr.add(domain_size), c1_this.as_ptr());
     }
     let this_ptr = c0_this_ptr as *mut VEF;
-    let mut this_slice: &mut [VEF] =
-        unsafe { slice::from_raw_parts_mut(this_ptr, domain_size) };
+    let mut this_slice: &mut [VEF] = unsafe { slice::from_raw_parts_mut(this_ptr, domain_size) };
     let this_vector = unsafe { DeviceSlice::from_mut_slice(&mut this_slice) };
 
     let c0_other_ptr = c0_other.as_ptr();
     unsafe {
         assert_eq!(c0_other_ptr.add(domain_size), c1_other.as_ptr());
     }
     let other_ptr = c0_other_ptr as *const VEF;
-    let other_slice: &[VEF] =
-        unsafe { slice::from_raw_parts(other_ptr, domain_size) };
+    let other_slice: &[VEF] = unsafe { slice::from_raw_parts(other_ptr, domain_size) };
     let other_vector = unsafe { DeviceSlice::from_slice(&other_slice) };
 
     mul_into_x(this_vector, other_vector, get_stream())
@@ -435,24 +433,34 @@ pub fn precompute_barycentric_bases(
     // (X^N - 1)/ N
     // evaluations are elems of first coset of the lde
     // shift is k*w^0=k where k is multiplicative generator
-    let mut d_point = svec!(1);
-    d_point.copy_from_slice(&[point])?;
+
+    // The following does NOT work ("the trait `SetByVal` is not implemented" for EF)
+    // let mut d_point: DVec<EF, _> = svec!(1);
+    // helpers::set_by_value(d_point.as_mut(), point, get_stream());
+
+    // The following sequence creates a &DeviceVariable<EF> for point.
+    // It's a little ugly but avoids potentially synchronizing copies.
+    let mut coeffs: DVec<F, _> = svec!(2);
+    let [c0, c1] = point.into_coeffs_in_base();
+    helpers::set_by_value(coeffs[..1].as_mut(), c0, get_stream());
+    helpers::set_by_value(coeffs[1..].as_mut(), c1, get_stream());
+    let d_point_ef = unsafe { std::slice::from_raw_parts(coeffs.as_ptr() as *const EF, 1) };
+    let d_point_ef_var = unsafe { DeviceVariable::from_ref(&d_point_ef[0]) };
 
     let mut d_tmp: SVec<EF> = svec!(1);
 
-    let (bases, point, common_factor_storage) = unsafe {
-        let point = &d_point[0];
-        let tmp_point = &mut d_tmp[0];
+    let (bases, common_factor_storage) = unsafe {
         let v_bases = std::slice::from_raw_parts_mut(bases.as_ptr() as *mut _, domain_size);
+        let tmp_point = &mut d_tmp[0];
         (
             DeviceSlice::from_mut_slice(v_bases),
-            DeviceVariable::from_ref(point),
             DeviceVariable::from_mut(tmp_point),
         )
     };
+
     use boojum_cuda::barycentric::PrecomputeAtExt;
     boojum_cuda::barycentric::precompute_lagrange_coeffs::<PrecomputeAtExt>(
-        point,
+        d_point_ef_var,
         common_factor_storage,
         coset,
         bases,

src/prover.rs

@@ -32,7 +32,7 @@ use crate::{
 
 use super::*;
 
-use nvtx::{range_push, range_pop};
+use nvtx::{range_pop, range_push};
 
 pub fn gpu_prove_from_external_witness_data<
     P: boojum::field::traits::field_like::PrimeFieldLikeVectorized<Base = F>,