Fix excessive GEBP register spilling for 32-bit NEON.
Clang does a poor job of optimizing the GEBP microkernel on 32-bit ARM,
leading to excessive 16-byte register spills, slowing down basic f32
matrix multiplication by approx 50%.
By specializing `gebp_traits`, we can eliminate the register spills.
Volatile inline ASM both acts as a barrier to prevent reordering and
enforces strict register use. In a simple f32 matrix multiply example,
this modification reduces 16-byte spills from 109 instances to zero,
leading to a 1.5x speed increase (search for `16-byte Spill` in the
assembly in https://godbolt.org/z/chsPbE).
This is a replacement of !379. See there for further discussion.
Also moved `gebp_traits` specializations for NEON to
`Eigen/src/Core/arch/NEON/GeneralBlockPanelKernel.h` to be alongside
other NEON-specific code.
Fixes #2138.
diff --git a/Eigen/Core b/Eigen/Core
index 4d9a330..1a60dcb 100644
--- a/Eigen/Core
+++ b/Eigen/Core
@@ -340,7 +340,9 @@
#include "src/Core/ConditionEstimator.h"
#if defined(EIGEN_VECTORIZE_ALTIVEC) || defined(EIGEN_VECTORIZE_VSX)
-#include "src/Core/arch/AltiVec/MatrixProduct.h"
+ #include "src/Core/arch/AltiVec/MatrixProduct.h"
+#elif defined EIGEN_VECTORIZE_NEON
+ #include "src/Core/arch/NEON/GeneralBlockPanelKernel.h"
#endif
#include "src/Core/BooleanRedux.h"
diff --git a/Eigen/src/Core/arch/NEON/GeneralBlockPanelKernel.h b/Eigen/src/Core/arch/NEON/GeneralBlockPanelKernel.h
new file mode 100644
index 0000000..3481f33
--- /dev/null
+++ b/Eigen/src/Core/arch/NEON/GeneralBlockPanelKernel.h
@@ -0,0 +1,183 @@
+namespace Eigen {
+namespace internal {
+
+#if EIGEN_ARCH_ARM && EIGEN_COMP_CLANG
+
+// Clang seems to excessively spill registers in the GEBP kernel on 32-bit arm.
+// Here we specialize gebp_traits to eliminate these register spills.
+// See #2138.
+template<>
+struct gebp_traits <float,float,false,false,Architecture::NEON,GEBPPacketFull>
+ : gebp_traits<float,float,false,false,Architecture::Generic,GEBPPacketFull>
+{
+ EIGEN_STRONG_INLINE void acc(const AccPacket& c, const ResPacket& alpha, ResPacket& r) const
+ {
+ // This volatile inline ASM both acts as a barrier to prevent reordering,
+ // as well as enforces strict register use.
+ asm volatile(
+ "vmla.f32 %q[r], %q[c], %q[alpha]"
+ : [r] "+w" (r)
+ : [c] "w" (c),
+ [alpha] "w" (alpha)
+ : );
+ }
+
+ template <typename LaneIdType>
+ EIGEN_STRONG_INLINE void madd(const Packet4f& a, const Packet4f& b,
+ Packet4f& c, Packet4f& tmp,
+ const LaneIdType&) const {
+ acc(a, b, c);
+ }
+
+ template <typename LaneIdType>
+ EIGEN_STRONG_INLINE void madd(const Packet4f& a, const QuadPacket<Packet4f>& b,
+ Packet4f& c, Packet4f& tmp,
+ const LaneIdType& lane) const {
+ madd(a, b.get(lane), c, tmp, lane);
+ }
+};
+
+#endif // EIGEN_ARCH_ARM && EIGEN_COMP_CLANG
+
+#if EIGEN_ARCH_ARM64
+
+template<>
+struct gebp_traits <float,float,false,false,Architecture::NEON,GEBPPacketFull>
+ : gebp_traits<float,float,false,false,Architecture::Generic,GEBPPacketFull>
+{
+ typedef float RhsPacket;
+ typedef float32x4_t RhsPacketx4;
+
+ EIGEN_STRONG_INLINE void loadRhs(const RhsScalar* b, RhsPacket& dest) const
+ {
+ dest = *b;
+ }
+
+ EIGEN_STRONG_INLINE void loadRhs(const RhsScalar* b, RhsPacketx4& dest) const
+ {
+ dest = vld1q_f32(b);
+ }
+
+ EIGEN_STRONG_INLINE void updateRhs(const RhsScalar* b, RhsPacket& dest) const
+ {
+ dest = *b;
+ }
+
+ EIGEN_STRONG_INLINE void updateRhs(const RhsScalar*, RhsPacketx4&) const
+ {}
+
+ EIGEN_STRONG_INLINE void loadRhsQuad(const RhsScalar* b, RhsPacket& dest) const
+ {
+ loadRhs(b,dest);
+ }
+
+ EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacket& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<0>&) const
+ {
+ c = vfmaq_n_f32(c, a, b);
+ }
+
+ // NOTE: Template parameter inference failed when compiled with Android NDK:
+ // "candidate template ignored: could not match 'FixedInt<N>' against 'Eigen::internal::FixedInt<0>".
+
+ EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<0>&) const
+ { madd_helper<0>(a, b, c); }
+ EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<1>&) const
+ { madd_helper<1>(a, b, c); }
+ EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<2>&) const
+ { madd_helper<2>(a, b, c); }
+ EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<3>&) const
+ { madd_helper<3>(a, b, c); }
+
+ private:
+ template<int LaneID>
+ EIGEN_STRONG_INLINE void madd_helper(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c) const
+ {
+ #if EIGEN_COMP_GNUC_STRICT && !(EIGEN_GNUC_AT_LEAST(9,0))
+ // workaround gcc issue https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89101
+ // vfmaq_laneq_f32 is implemented through a costly dup
+ if(LaneID==0) asm("fmla %0.4s, %1.4s, %2.s[0]\n" : "+w" (c) : "w" (a), "w" (b) : );
+ else if(LaneID==1) asm("fmla %0.4s, %1.4s, %2.s[1]\n" : "+w" (c) : "w" (a), "w" (b) : );
+ else if(LaneID==2) asm("fmla %0.4s, %1.4s, %2.s[2]\n" : "+w" (c) : "w" (a), "w" (b) : );
+ else if(LaneID==3) asm("fmla %0.4s, %1.4s, %2.s[3]\n" : "+w" (c) : "w" (a), "w" (b) : );
+ #else
+ c = vfmaq_laneq_f32(c, a, b, LaneID);
+ #endif
+ }
+};
+
+
+template<>
+struct gebp_traits <double,double,false,false,Architecture::NEON>
+ : gebp_traits<double,double,false,false,Architecture::Generic>
+{
+ typedef double RhsPacket;
+
+ struct RhsPacketx4 {
+ float64x2_t B_0, B_1;
+ };
+
+ EIGEN_STRONG_INLINE void loadRhs(const RhsScalar* b, RhsPacket& dest) const
+ {
+ dest = *b;
+ }
+
+ EIGEN_STRONG_INLINE void loadRhs(const RhsScalar* b, RhsPacketx4& dest) const
+ {
+ dest.B_0 = vld1q_f64(b);
+ dest.B_1 = vld1q_f64(b+2);
+ }
+
+ EIGEN_STRONG_INLINE void updateRhs(const RhsScalar* b, RhsPacket& dest) const
+ {
+ loadRhs(b,dest);
+ }
+
+ EIGEN_STRONG_INLINE void updateRhs(const RhsScalar*, RhsPacketx4&) const
+ {}
+
+ EIGEN_STRONG_INLINE void loadRhsQuad(const RhsScalar* b, RhsPacket& dest) const
+ {
+ loadRhs(b,dest);
+ }
+
+ EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacket& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<0>&) const
+ {
+ c = vfmaq_n_f64(c, a, b);
+ }
+
+ // NOTE: Template parameter inference failed when compiled with Android NDK:
+ // "candidate template ignored: could not match 'FixedInt<N>' against 'Eigen::internal::FixedInt<0>".
+
+ EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<0>&) const
+ { madd_helper<0>(a, b, c); }
+ EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<1>&) const
+ { madd_helper<1>(a, b, c); }
+ EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<2>&) const
+ { madd_helper<2>(a, b, c); }
+ EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<3>&) const
+ { madd_helper<3>(a, b, c); }
+
+ private:
+ template <int LaneID>
+ EIGEN_STRONG_INLINE void madd_helper(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c) const
+ {
+ #if EIGEN_COMP_GNUC_STRICT && !(EIGEN_GNUC_AT_LEAST(9,0))
+ // workaround gcc issue https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89101
+ // vfmaq_laneq_f64 is implemented through a costly dup
+ if(LaneID==0) asm("fmla %0.2d, %1.2d, %2.d[0]\n" : "+w" (c) : "w" (a), "w" (b.B_0) : );
+ else if(LaneID==1) asm("fmla %0.2d, %1.2d, %2.d[1]\n" : "+w" (c) : "w" (a), "w" (b.B_0) : );
+ else if(LaneID==2) asm("fmla %0.2d, %1.2d, %2.d[0]\n" : "+w" (c) : "w" (a), "w" (b.B_1) : );
+ else if(LaneID==3) asm("fmla %0.2d, %1.2d, %2.d[1]\n" : "+w" (c) : "w" (a), "w" (b.B_1) : );
+ #else
+ if(LaneID==0) c = vfmaq_laneq_f64(c, a, b.B_0, 0);
+ else if(LaneID==1) c = vfmaq_laneq_f64(c, a, b.B_0, 1);
+ else if(LaneID==2) c = vfmaq_laneq_f64(c, a, b.B_1, 0);
+ else if(LaneID==3) c = vfmaq_laneq_f64(c, a, b.B_1, 1);
+ #endif
+ }
+};
+
+#endif // EIGEN_ARCH_ARM64
+
+} // namespace internal
+} // namespace Eigen
diff --git a/Eigen/src/Core/products/GeneralBlockPanelKernel.h b/Eigen/src/Core/products/GeneralBlockPanelKernel.h
index 216d1ad..79367f1 100644
--- a/Eigen/src/Core/products/GeneralBlockPanelKernel.h
+++ b/Eigen/src/Core/products/GeneralBlockPanelKernel.h
@@ -1076,148 +1076,6 @@
};
-
-#if EIGEN_ARCH_ARM64 && defined EIGEN_VECTORIZE_NEON
-
-template<>
-struct gebp_traits <float, float, false, false,Architecture::NEON,GEBPPacketFull>
- : gebp_traits<float,float,false,false,Architecture::Generic,GEBPPacketFull>
-{
- typedef float RhsPacket;
-
- typedef float32x4_t RhsPacketx4;
-
- EIGEN_STRONG_INLINE void loadRhs(const RhsScalar* b, RhsPacket& dest) const
- {
- dest = *b;
- }
-
- EIGEN_STRONG_INLINE void loadRhs(const RhsScalar* b, RhsPacketx4& dest) const
- {
- dest = vld1q_f32(b);
- }
-
- EIGEN_STRONG_INLINE void updateRhs(const RhsScalar* b, RhsPacket& dest) const
- {
- dest = *b;
- }
-
- EIGEN_STRONG_INLINE void updateRhs(const RhsScalar*, RhsPacketx4&) const
- {}
-
- EIGEN_STRONG_INLINE void loadRhsQuad(const RhsScalar* b, RhsPacket& dest) const
- {
- loadRhs(b,dest);
- }
-
- EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacket& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<0>&) const
- {
- c = vfmaq_n_f32(c, a, b);
- }
-
- // NOTE: Template parameter inference failed when compiled with Android NDK:
- // "candidate template ignored: could not match 'FixedInt<N>' against 'Eigen::internal::FixedInt<0>".
-
- EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<0>&) const
- { madd_helper<0>(a, b, c); }
- EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<1>&) const
- { madd_helper<1>(a, b, c); }
- EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<2>&) const
- { madd_helper<2>(a, b, c); }
- EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<3>&) const
- { madd_helper<3>(a, b, c); }
-
- private:
- template<int LaneID>
- EIGEN_STRONG_INLINE void madd_helper(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c) const
- {
- #if EIGEN_COMP_GNUC_STRICT && !(EIGEN_GNUC_AT_LEAST(9,0))
- // workaround gcc issue https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89101
- // vfmaq_laneq_f32 is implemented through a costly dup
- if(LaneID==0) asm("fmla %0.4s, %1.4s, %2.s[0]\n" : "+w" (c) : "w" (a), "w" (b) : );
- else if(LaneID==1) asm("fmla %0.4s, %1.4s, %2.s[1]\n" : "+w" (c) : "w" (a), "w" (b) : );
- else if(LaneID==2) asm("fmla %0.4s, %1.4s, %2.s[2]\n" : "+w" (c) : "w" (a), "w" (b) : );
- else if(LaneID==3) asm("fmla %0.4s, %1.4s, %2.s[3]\n" : "+w" (c) : "w" (a), "w" (b) : );
- #else
- c = vfmaq_laneq_f32(c, a, b, LaneID);
- #endif
- }
-};
-
-
-template<>
-struct gebp_traits <double, double, false, false,Architecture::NEON>
- : gebp_traits<double,double,false,false,Architecture::Generic>
-{
- typedef double RhsPacket;
-
- struct RhsPacketx4 {
- float64x2_t B_0, B_1;
- };
-
- EIGEN_STRONG_INLINE void loadRhs(const RhsScalar* b, RhsPacket& dest) const
- {
- dest = *b;
- }
-
- EIGEN_STRONG_INLINE void loadRhs(const RhsScalar* b, RhsPacketx4& dest) const
- {
- dest.B_0 = vld1q_f64(b);
- dest.B_1 = vld1q_f64(b+2);
- }
-
- EIGEN_STRONG_INLINE void updateRhs(const RhsScalar* b, RhsPacket& dest) const
- {
- loadRhs(b,dest);
- }
-
- EIGEN_STRONG_INLINE void updateRhs(const RhsScalar*, RhsPacketx4&) const
- {}
-
- EIGEN_STRONG_INLINE void loadRhsQuad(const RhsScalar* b, RhsPacket& dest) const
- {
- loadRhs(b,dest);
- }
-
- EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacket& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<0>&) const
- {
- c = vfmaq_n_f64(c, a, b);
- }
-
- // NOTE: Template parameter inference failed when compiled with Android NDK:
- // "candidate template ignored: could not match 'FixedInt<N>' against 'Eigen::internal::FixedInt<0>".
-
- EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<0>&) const
- { madd_helper<0>(a, b, c); }
- EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<1>&) const
- { madd_helper<1>(a, b, c); }
- EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<2>&) const
- { madd_helper<2>(a, b, c); }
- EIGEN_STRONG_INLINE void madd(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c, RhsPacket& /*tmp*/, const FixedInt<3>&) const
- { madd_helper<3>(a, b, c); }
-
- private:
- template <int LaneID>
- EIGEN_STRONG_INLINE void madd_helper(const LhsPacket& a, const RhsPacketx4& b, AccPacket& c) const
- {
- #if EIGEN_COMP_GNUC_STRICT && !(EIGEN_GNUC_AT_LEAST(9,0))
- // workaround gcc issue https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89101
- // vfmaq_laneq_f64 is implemented through a costly dup
- if(LaneID==0) asm("fmla %0.2d, %1.2d, %2.d[0]\n" : "+w" (c) : "w" (a), "w" (b.B_0) : );
- else if(LaneID==1) asm("fmla %0.2d, %1.2d, %2.d[1]\n" : "+w" (c) : "w" (a), "w" (b.B_0) : );
- else if(LaneID==2) asm("fmla %0.2d, %1.2d, %2.d[0]\n" : "+w" (c) : "w" (a), "w" (b.B_1) : );
- else if(LaneID==3) asm("fmla %0.2d, %1.2d, %2.d[1]\n" : "+w" (c) : "w" (a), "w" (b.B_1) : );
- #else
- if(LaneID==0) c = vfmaq_laneq_f64(c, a, b.B_0, 0);
- else if(LaneID==1) c = vfmaq_laneq_f64(c, a, b.B_0, 1);
- else if(LaneID==2) c = vfmaq_laneq_f64(c, a, b.B_1, 0);
- else if(LaneID==3) c = vfmaq_laneq_f64(c, a, b.B_1, 1);
- #endif
- }
-};
-
-#endif
-
/* optimized General packed Block * packed Panel product kernel
*
* Mixing type logic: C += A * B
