https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89752
--- Comment #3 from Wilco <wilco at gcc dot gnu.org> --- Full instruction: (insn 531 530 532 19 (parallel [ (set (mem/c:BLK (reg:DI 3842) [29 A0+0 S2 A64]) (asm_operands:BLK ("") ("=rm") 0 [ (mem/c:BLK (reg:DI 3846) [29 A0+0 S2 A64]) (mem/c:BLK (reg:DI 3848) [29 A1+0 S2 A128]) ] [ (asm_input:BLK ("0") external/eigen_archive/unsupported/Eigen/CXX11/../../../Eigen/src/Core/products/GeneralBlockPanelKernel.h:1418) (asm_input:BLK ("1") external/eigen_archive/unsupported/Eigen/CXX11/../../../Eigen/src/Core/products/GeneralBlockPanelKernel.h:1418) ] [] external/eigen_archive/unsupported/Eigen/CXX11/../../../Eigen/src/Core/products/GeneralBlockPanelKernel.h:1418)) (set (mem/c:BLK (reg:DI 3844) [29 A1+0 S2 A128]) (asm_operands:BLK ("") ("=rm") 1 [ (mem/c:BLK (reg:DI 3846) [29 A0+0 S2 A64]) (mem/c:BLK (reg:DI 3848) [29 A1+0 S2 A128]) ] [ (asm_input:BLK ("0") external/eigen_archive/unsupported/Eigen/CXX11/../../../Eigen/src/Core/products/GeneralBlockPanelKernel.h:1418) (asm_input:BLK ("1") external/eigen_archive/unsupported/Eigen/CXX11/../../../Eigen/src/Core/products/GeneralBlockPanelKernel.h:1418) ] [] external/eigen_archive/unsupported/Eigen/CXX11/../../../Eigen/src/Core/products/GeneralBlockPanelKernel.h:1418)) ]) "external/eigen_archive/unsupported/Eigen/CXX11/../../../Eigen/src/Core/products/GeneralBlockPanelKernel.h":1418:511 -1 (nil)) I guess this comes from the source like this with some of the arguments being immediates due to template substitution: __asm__ ("" : [a0] "+rm" (A0),[a1] "+rm" (A1)); It's not obvious what this is supposed to achieve, let alone whether it is valid...