Reduce allocations

Author: jishnub

src/matmul.jl

@@ -411,15 +411,15 @@ lmul!(A, B)
 _vec_or_mat_str(s::Tuple{Any}) = "vector"
 _vec_or_mat_str(s::Tuple{Any,Any}) = "matrix"
 @noinline function matmul_size_check(sizeA::Tuple{Integer,Vararg{Integer}}, sizeB::Tuple{Integer,Vararg{Integer}})
-    strA = _vec_or_mat_str(sizeA)
-    strB = _vec_or_mat_str(sizeB)
     szA2 = get(sizeA, 2, 1)
-    B_size_len = length(sizeB) == 1 ? sizeB[1] : sizeB
-    size_or_len_str_B = B_size_len isa Integer ? "length" : "size"
-    dim_or_len_str_B = B_size_len isa Integer ? "length" : "first dimension"
-    pos_str_A = (length(sizeA) == length(sizeB) ? "first " : "")*strA
-    pos_str_B = (length(sizeA) == length(sizeB) ? "second " : "")*strB
     if szA2 != sizeB[1]
+        strA = _vec_or_mat_str(sizeA)
+        strB = _vec_or_mat_str(sizeB)
+        B_size_len = length(sizeB) == 1 ? sizeB[1] : sizeB
+        size_or_len_str_B = B_size_len isa Integer ? "length" : "size"
+        dim_or_len_str_B = B_size_len isa Integer ? "length" : "first dimension"
+        pos_str_A = LazyString(length(sizeA) == length(sizeB) ? "first " : "", strA)
+        pos_str_B = LazyString(length(sizeA) == length(sizeB) ? "second " : "", strB)
         throw(DimensionMismatch(
             LazyString(
                 lazy"incompatible dimensions for matrix multiplication: ",
@@ -432,13 +432,13 @@ _vec_or_mat_str(s::Tuple{Any,Any}) = "matrix"
     return nothing
 end
 @noinline function matmul_size_check(sizeC::Tuple{Integer,Vararg{Integer}}, sizeA::Tuple{Integer,Vararg{Integer}}, sizeB::Tuple{Integer,Vararg{Integer}})
-    strA = _vec_or_mat_str(sizeA)
-    strB = _vec_or_mat_str(sizeB)
-    strC = _vec_or_mat_str(sizeC)
+    matmul_size_check(sizeA, sizeB)
     szB2 = get(sizeB, 2, 1)
     szC2 = get(sizeC, 2, 1)
-    matmul_size_check(sizeA, sizeB)
     if sizeC[1] != sizeA[1] || szC2 != szB2
+        strA = _vec_or_mat_str(sizeA)
+        strB = _vec_or_mat_str(sizeB)
+        strC = _vec_or_mat_str(sizeC)
         C_size_len = length(sizeC) == 1 ? sizeC[1] : sizeC
         size_or_len_str_C = C_size_len isa Integer ? "length" : "size"
         B_size_len = length(sizeB) == 1 ? sizeB[1] : sizeB