On Tue, Jun 11, 2019 at 1:32 AM Alex Hill <hardest2005@xxxxxxx> wrote: > BUT! In case we using IF loop GCC wont emit minmax AGAIN! It looks like the memory accesses are the problem, not the control flow. However, the control flow may be affecting exactly how the compiler optimizes the memory references. If you create a temporary variable, store the result in the temporary variable, and then write the temporary variable to memory at the end, it should be optimized regardless of control flow. > what`s the difference between > (reg:DI 113 [ ivtmp.29 ]) [1 MEM[base: _39, offset: 0B]+0 S8 A64]) > and > (reg/f:DI 89 [ _48 ]) [1 *_48+0 S8 A64]) _ivtmp.29 and _48 are variable names. In both cases, these are variable names created by high level optimization passes. See the -fdump-tree-all output, and look at the last one before the conversion to RTL. The MEM is giving alias analysis info. A is the alignment, S is the size. The first number is the alias set, where alias set 0 aliases everything, and other numbers only alias values in the same alias set. The MEM is the original base and offset for this address, where _39 is again a compiler generated variable. You can find the code that prints this stuff in print-rtl.c, and then you probably need to look at the alias analysis code if you want to know more. See also the noce_try_minmax function I pointed at earlier, to see why it works in one case but not in another case. Jim
