On Mon, Feb 16, 2015 at 22:08:12 +0100, Jakub Jelinek wrote: > Anyway, the question is if for offloading we use wpa stage at all these days > or not at all, if there is a way for ACCEL_COMPILER to differentiate > somehow between LTO sections written by the host compiler and LTO sections > perhaps created by the offloading compiler when trying to LTO the thing (if > it does it at all). Because obviously the host compiler written LTO > (in .gnu.offload_lto_*) would need the machine modes translated, while > LTO streamed already by the ACCEL_COMPILER (if any) generally would already > use the offloading target machine modes and therefore should be treated as > native lto (.gnu.lto_*).
Currently both intelmic and nvptx offloading compilers are executed in non-partitioned LTO mode. I don't know whether we need to support WHOPR (WPA+LTRANS) mode. Maybe it would be useful for programs with large number of target regions? But I think this is not needed for GCC 5. > > If we don't try to write .gnu.offload_lto_* again, I think following patch > with additionally not calling lto_write_mode_table for !lto_stream_offload_p > and not calling lto_input_mode_table for !ACCEL_COMPILER - instead build > a single shared identity table - might actually work. > > Thoughts on this? Probably the ACCEL_COMPILER in WPA mode (flag_wpa) can read .gnu.offload_lto_* sections and produce temporary partitions with .gnu.lto_* sections. And the ACCEL_COMPILER in LTRANS mode (flag_ltrans) will read .gnu.lto_* sections? -- Ilya
