#16333: Implement Loop-invariant code motion / Hoisting for Cmm -------------------------------------+------------------------------------- Reporter: AndreasK | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #12808 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Currently we don't but we should. An example from nofib: This is the innermost loop of fannkuch-redux. {{{ #!C ca12: _s9D0::I64 = %MO_UU_Conv_W8_W64(I8[_s9zN::I64]); if (_s9D0::I64 != 0) goto ca1f; else goto ca1i; ca1f: I64[Sp - 16] = ca1d; R3 = _s9zN::I64 + _s9D0::I64; R2 = _s9zN::I64; I64[Sp - 8] = _s9CV::I64; I64[Sp] = _s9Cd::I64; I64[Sp + 40] = _s9Cc::I64; I64[Sp + 48] = _s9Cb::I64; I64[Sp + 56] = _s9zN::I64; Sp = Sp - 16; call $wflopp_r9x0_info(R3, R2) returns to ca1d, args: 8, res: 8, upd: 8; ca1d: Sp = Sp + 16; _s9CV::I64 = I64[Sp - 8] + 1; _s9Cd::I64 = I64[Sp + 0]; 16 _s9z5::I64 = I64[Sp + 8]; //24 _s9zv::I64 = I64[Sp + 16]; 32 _s9zx::I64 = I64[Sp + 24]; 40 _s9zz::I64 = I64[Sp + 32]; 48 _s9Cc::I64 = I64[Sp + 40]; 56 _s9Cb::I64 = I64[Sp + 48]; 64 _s9zN::I64 = I64[Sp + 56]; 72 goto ca12; }}} We should try to move the loads NOT used in the loop out of the loop at least. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16333 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler