5 Commits

Author SHA1 Message Date
Arthur Eubanks
5c31b8b94f Revert "Use uint64_t for branch weights instead of uint32_t"
This reverts commit 10f2a0d662d8d72eaac48d3e9b31ca8dc90df5a4.

More uint64_t overflows.
2020-10-31 00:25:32 -07:00
Arthur Eubanks
10f2a0d662 Use uint64_t for branch weights instead of uint32_t
CallInst::updateProfWeight() creates branch_weights with i64 instead of i32.
To be more consistent everywhere and remove lots of casts from uint64_t
to uint32_t, use i64 for branch_weights.

Reviewed By: davidxl

Differential Revision: https://reviews.llvm.org/D88609
2020-10-30 10:03:46 -07:00
Nico Weber
2a4e704c92 Revert "Use uint64_t for branch weights instead of uint32_t"
This reverts commit e5766f25c62c185632e3a75bf45b313eadab774b.
Makes clang assert when building Chromium, see https://crbug.com/1142813
for a repro.
2020-10-27 09:26:21 -04:00
Arthur Eubanks
e5766f25c6 Use uint64_t for branch weights instead of uint32_t
CallInst::updateProfWeight() creates branch_weights with i64 instead of i32.
To be more consistent everywhere and remove lots of casts from uint64_t
to uint32_t, use i64 for branch_weights.

Reviewed By: davidxl

Differential Revision: https://reviews.llvm.org/D88609
2020-10-26 20:24:04 -07:00
Hongtao Yu
f3731d34fa [LoopUnroll] Update branch weight for remainder loop
Unrolling a loop with compile-time unknown trip count results in a remainder loop. The remainder loop executes the remaining iterations of the original loop when the original trip count is not a multiple of the unroll factor. For better profile counts maintenance throughout the optimization pipeline, I'm assigning an artificial weight to the latch branch of the remainder loop.

A remainder loop runs up to as many times as the unroll factor subtracted by 1. Therefore I'm assigning the maximum possible trip count as the back edge weight. This should be more accurate than the default non-profile weight, which assumes the back edge runs much more frequently than the exit edge.

Differential Revision: https://reviews.llvm.org/D83187
2020-07-15 12:33:29 -07:00