GCC optimizes hard register set iteration by replacing `TEST_HARD_REG_BIT`.
GCC improves the efficiency of iterating over hard register sets by replacing `TEST_HARD_REG_BIT` with `hard_reg_set_iterator` and `hard_reg_set_popcount`.
This GCC commit refactors internal loops that check individual bits in hard register sets, replacing inefficient TEST_HARD_REG_BIT calls within loops with the more efficient EXECUTE_IF_SET_IN_HARD_REG_SET macro. Additionally, direct calls to hard_reg_set_size are replaced with hard_reg_set_popcount, as the latter more accurately reflects the intended operation of counting set bits. These changes improve compiler performance by streamlining register set manipulations, primarily in architecture-specific code generation and optimization passes.
In Details
This change focuses on optimizing hard register set manipulation within GCC's backend. Previously, iterating through a hard_reg_set to check for individual bits often involved a for loop with TEST_HARD_REG_BIT. This has been replaced with EXECUTE_IF_SET_IN_HARD_REG_SET, which leverages hard_reg_set_iterator for more efficient iteration over the set bits. Similarly, instances of hard_reg_set_size, which internally used such a loop to count set bits, are replaced with hard_reg_set_popcount, which is a more direct and efficient way to achieve the population count. These changes pri…
For Context
Compilers work with 'registers,' which are tiny storage locations inside the computer's processor. To make your programs fast, the compiler carefully manages which data goes into which registers. Sometimes, the compiler needs to check many registers at once to see which ones are available or in use. This commit improves how GCC, the compiler, does these checks. Instead of checking each register individually in a slow loop, it now uses more specialized and faster techniques that can quickly find all the registers that meet a certain condition. This makes the compiler faster at its job, which can indirectly lead to faster compilation times for your programs.