diff options
Diffstat (limited to 'llvm/lib/Target')
| -rw-r--r-- | llvm/lib/Target/X86/X86InstrInfo.cpp | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp index 11c532c7d71..acf042f242f 100644 --- a/llvm/lib/Target/X86/X86InstrInfo.cpp +++ b/llvm/lib/Target/X86/X86InstrInfo.cpp @@ -3927,17 +3927,21 @@ bool X86InstrInfo::isUnpredicatedTerminator(const MachineInstr &MI) const { return !isPredicated(MI); } -// Given a MBB and its TBB, find the FBB which was a fallthrough MBB (it may not -// be a fallthorough MBB now due to layout changes). Return nullptr if the -// fallthough MBB cannot be identified. +// Given a MBB and its TBB, find the FBB which was a fallthrough MBB (it may +// not be a fallthrough MBB now due to layout changes). Return nullptr if the +// fallthrough MBB cannot be identified. static MachineBasicBlock *getFallThroughMBB(MachineBasicBlock *MBB, MachineBasicBlock *TBB) { + // Look for non-EHPad successors other than TBB. If we find exactly one, it + // is the fallthrough MBB. If we find zero, then TBB is both the target MBB + // and fallthrough MBB. If we find more than one, we cannot identify the + // fallthrough MBB and should return nullptr. MachineBasicBlock *FallthroughBB = nullptr; for (auto SI = MBB->succ_begin(), SE = MBB->succ_end(); SI != SE; ++SI) { - if ((*SI)->isEHPad() || *SI == TBB) + if ((*SI)->isEHPad() || (*SI == TBB && FallthroughBB)) continue; // Return a nullptr if we found more than one fallthrough successor. - if (FallthroughBB) + if (FallthroughBB && FallthroughBB != TBB) return nullptr; FallthroughBB = *SI; } |
