bool SIInsertSkips::shouldSkip(const MachineBasicBlock &From, const MachineBasicBlock &To) const { if (From.succ_empty()) return false; unsigned NumInstr = 0; const MachineFunction *MF = From.getParent(); for (MachineFunction::const_iterator MBBI(&From), ToI(&To), End = MF->end(); MBBI != End && MBBI != ToI; ++MBBI) { const MachineBasicBlock &MBB = *MBBI; for (MachineBasicBlock::const_iterator I = MBB.begin(), E = MBB.end(); NumInstr < SkipThreshold && I != E; ++I) { if (opcodeEmitsNoInsts(I->getOpcode())) continue; // FIXME: Since this is required for correctness, this should be inserted // during SILowerControlFlow. // When a uniform loop is inside non-uniform control flow, the branch // leaving the loop might be an S_CBRANCH_VCCNZ, which is never taken // when EXEC = 0. We should skip the loop lest it becomes infinite. if (I->getOpcode() == AMDGPU::S_CBRANCH_VCCNZ || I->getOpcode() == AMDGPU::S_CBRANCH_VCCZ) return true; if (I->isInlineAsm()) { const MCAsmInfo *MAI = MF->getTarget().getMCAsmInfo(); const char *AsmStr = I->getOperand(0).getSymbolName(); // inlineasm length estimate is number of bytes assuming the longest // instruction. uint64_t MaxAsmSize = TII->getInlineAsmLength(AsmStr, *MAI); NumInstr += MaxAsmSize / MAI->getMaxInstLength(); } else { ++NumInstr; } if (NumInstr >= SkipThreshold) return true; } } return false; }