llvm-project

1b39328d - [CodeGen] Fix MachineInstr::isSafeToMove handling of inline asm. (#126807)

[CodeGen] Fix MachineInstr::isSafeToMove handling of inline asm. (#126807) Even if an inline asm doesn't have memory effects, we can't assume it's safe to speculate: it could trap, or cause undefined behavior. At the LLVM IR level, this is handled correctly: we don't speculate inline asm (unless it's marked "speculatable", but I don't think anyone does that). Codegen also needs to respect this restriction. This change stops Early If Conversion and similar passes from speculating an INLINEASM MachineInstr. Some uses of isSafeToMove probably could be switched to a different API: isSafeToMove assumes you're hoisting, but we could handle some forms of sinking more aggressively. But I'll leave that for a followup, if it turns out to be relevant. See also discussion on gcc bugtracker https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102150 .