From 512b74aaa19fa12a05774dd30205d2c97e8bdef9 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Mon, 18 Feb 2019 11:47:54 +0100
Subject: GEMM: catch all scalar-multiple variants when falling-back to a
 coeff-based product. Before only s*A*B was caught which was both inconsistent
 with GEMM, sub-optimal, and could even lead to compilation-errors
 (https://stackoverflow.com/questions/54738495).

---
 test/product_notemporary.cpp | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

(limited to 'test/product_notemporary.cpp')

diff --git a/test/product_notemporary.cpp b/test/product_notemporary.cpp
index dffb07608..7f169e6ae 100644
--- a/test/product_notemporary.cpp
+++ b/test/product_notemporary.cpp
@@ -11,6 +11,35 @@
 
 #include "main.h"
 
+template<typename Dst, typename Lhs, typename Rhs>
+void check_scalar_multiple3(Dst &dst, const Lhs& A, const Rhs& B)
+{
+  VERIFY_EVALUATION_COUNT( (dst.noalias()  = A * B), 0);
+  VERIFY_IS_APPROX( dst, (A.eval() * B.eval()).eval() );
+  VERIFY_EVALUATION_COUNT( (dst.noalias() += A * B), 0);
+  VERIFY_IS_APPROX( dst, 2*(A.eval() * B.eval()).eval() );
+  VERIFY_EVALUATION_COUNT( (dst.noalias() -= A * B), 0);
+  VERIFY_IS_APPROX( dst, (A.eval() * B.eval()).eval() );
+}
+
+template<typename Dst, typename Lhs, typename Rhs, typename S2>
+void check_scalar_multiple2(Dst &dst, const Lhs& A, const Rhs& B, S2 s2)
+{
+  CALL_SUBTEST( check_scalar_multiple3(dst, A,    B) );
+  CALL_SUBTEST( check_scalar_multiple3(dst, A,   -B) );
+  CALL_SUBTEST( check_scalar_multiple3(dst, A, s2*B) );
+  CALL_SUBTEST( check_scalar_multiple3(dst, A, B*s2) );
+}
+
+template<typename Dst, typename Lhs, typename Rhs, typename S1, typename S2>
+void check_scalar_multiple1(Dst &dst, const Lhs& A, const Rhs& B, S1 s1, S2 s2)
+{
+  CALL_SUBTEST( check_scalar_multiple2(dst,    A, B, s2) );
+  CALL_SUBTEST( check_scalar_multiple2(dst,   -A, B, s2) );
+  CALL_SUBTEST( check_scalar_multiple2(dst, s1*A, B, s2) );
+  CALL_SUBTEST( check_scalar_multiple2(dst, A*s1, B, s2) );
+}
+
 template<typename MatrixType> void product_notemporary(const MatrixType& m)
 {
   /* This test checks the number of temporaries created
@@ -148,6 +177,15 @@ template<typename MatrixType> void product_notemporary(const MatrixType& m)
   // Check nested products
   VERIFY_EVALUATION_COUNT( cvres.noalias() = m1.adjoint() * m1 * cv1, 1 );
   VERIFY_EVALUATION_COUNT( rvres.noalias() = rv1 * (m1 * m2.adjoint()), 1 );
+
+  // exhaustively check all scalar multiple combinations:
+  {
+    // Generic path:
+    check_scalar_multiple1(m3, m1, m2, s1, s2);
+    // Force fall back to coeff-based:
+    typename ColMajorMatrixType::BlockXpr m3_blck = m3.block(r0,r0,1,1);
+    check_scalar_multiple1(m3_blck, m1.block(r0,c0,1,1), m2.block(c0,r0,1,1), s1, s2);
+  }
 }
 
 EIGEN_DECLARE_TEST(product_notemporary)
-- 
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