llvm-project

dc34d163 - Re-apply "[AMDGPU][Scheduler] Use MIR-level rematerializer in rematerialization stage (#189491)" (#192443)

Re-apply "[AMDGPU][Scheduler] Use MIR-level rematerializer in rematerialization stage (#189491)" (#192443) This fixes compilation errors in EXPENSIVE_CHECKS introduced by [be62f27](https://github.com/llvm/llvm-project/commit/be62f270fd01e8c526f1e37df74ff1061e360dab). This is solved by moving the EXPENSIVE_CHECKS block at its original caller's site so that the data it reads is available. Original PR description below. --- This makes the scheduler's rematerialization stage use the target-independent rematerializer. Previosuly duplicate logic is deleted, and restrictions are put in place in the stage so that the same cosntraints as before apply on rematerializable registers (as the rematerializer is able to expose many more rematerialization opportunities than what the stage can track at the moment). Consequently it is not expected that this change improves performance overall, but it is a first step toward being able to use the rematerializer's more advanced capabilities during scheduling. This is *not* a NFC for 2 reasons. - Score equalities between two rematerialization candidates with otherwise equivalent score are decided by their corresponding register's index handle in the rematerializer (previously the pointer to their state object's value). This is determined by the rematerializer's register collection order, which is different from the stage's old register collection order. This is the cause of all test changes but one, and should not be detrimental to performance in real cases. - To support rollback, the stage now uses the rematerializer's rollback listener instead of its previous ad-hoc method (setting the opcode of rematerialized MIs to a DBG_VALUE, and their registers to the sentinel). This is the source of test changes in `machine-scheduler-sink-trivial-remats-debug.mir`. The new rollback mechanism completely removes the behavior tested by `misched-remat-revert.ll` so the test is deleted.