PC-Relative addressing introduces a fair bit of complexity for correctly
eliminating TOC accesses. FastISel does not include any of that handling so we
miscompile code with -mcpu=pwr10 -O0 if it includes an external call that
FastISel does not handle followed by any of the following:
Floating point constant materialization
Materialization of a GlobalValue
Call that FastISel does handle
This patch switches to SDISel for any of the above.
Differential revision: https://reviews.llvm.org/D86343
Our handling of PC-Relative addressing is currently broken with
Fast ISel in 3 ways:
- FISel emits calls without handling all the PC-Rel intricacies
- FISel materializes FP constants through the TOC
- FISel materializes GV's through the TOC
As it would be unnecessarily tedious to implement all the handling
for PC-Rel in Fast ISel, we will turn off FISel for anything that
generates references to the TOC.
Nemanja Ivanovic