https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71627
--- Comment #4 from Senthil Kumar Selvaraj <saaadhu at gcc dot gnu.org> --- Author: saaadhu Date: Fri Oct 21 11:48:19 2016 New Revision: 241400 URL: https://gcc.gnu.org/viewcvs?rev=241400&root=gcc&view=rev Log: Fix PR 71627 - unable to find a register to spill Tweak find_valid_class_1 to consider a reg class if atleast one regno in that class is ok. Previously, even if no regno was in_hard_reg_set_p, the code goes ahead and considers rclass as valid. bad was set only if a regno was in the reg class *and* HARD_REGNO_MODE_OK was false - if both were false, bad wasn't set and the reload got a wrong rclass. If that happened to be the best one, this eventually lead to find_reg running out of registers to spill, because the chosen rclass wouldn't have enough regs. Also, it expected every regno in rclass to be valid for mode i.e., if any regno fails HARD_REGNO_MODE_OK, it rejected the rclass. The comments in the original commit for find_valid_class_1 say atleast one regno is ok. This was updated to say "class which contains only registers" when in_hard_reg_set_p was introduced in place of just TEST_HARD_REG_BIT. This commit fixes both of the above problems by not breaking out of the loop on first unavailable regno. Instead, it computes the rclass size consisting of all regnos in that class valid for the current mode. If that computed size is zero, the rclass would be skipped, as it won't beat best_size. Otherwise, the computed size is used to choose the best rclass, instead of the static size from reg_class_size. gcc/ 2016-10-21 Senthil Kumar Selvaraj <senthil_kumar.selva...@atmel.com> PR target/71627 * reload.c (find_valid_class_1): Allow regclass if atleast one regno in regclass is ok. Compute and use rclass size based on actually available regnos for mode in rclass. gcc/testsuite/ 2016-10-21 Senthil Kumar Selvaraj <senthil_kumar.selva...@atmel.com> PR target/71627 * gcc.target/avr/pr71627.c: New test Added: trunk/gcc/testsuite/gcc.target/avr/pr71627.c Modified: trunk/gcc/ChangeLog trunk/gcc/reload.c trunk/gcc/testsuite/ChangeLog
