mirror of
https://github.com/llvm/llvm-project.git
synced 2025-04-27 05:16:06 +00:00
4e545bdb35
SimplifyCFG implements basic jump threading, if a branch is performed on a phi node with constant operands. However, InstCombine canonicalizes such phis to the condition value of a previous branch, if possible. SimplifyCFG does support this as well, but only in the very limited case where the same condition is used in a direct predecessor -- notably, this does not include the common diamond pattern (i.e. two consecutive if/elses on the same condition). This patch extends the code to look back a limited number of blocks to find a branch on the same value, rather than only looking at the direct predecessor. Fixes https://github.com/llvm/llvm-project/issues/54980. Differential Revision: https://reviews.llvm.org/D124159