1 //===-- PPCCTRLoops.cpp - Generate CTR loops ------------------------------===//
9 // This pass generates machine instructions for the CTR loops related pseudos:
13 // If a CTR loop can be generated:
18 // If a CTR loop can not be generated due to clobber of CTR:
24 // register allocator to allocate register for DecreaseCTRloop if a CTR can be
25 // generated or if a CTR loop can not be generated, we don't have any condition
54 STATISTIC(NumCTRLoops, "Number of CTR loops generated");
87 INITIALIZE_PASS_BEGIN(PPCCTRLoops, DEBUG_TYPE, "PowerPC CTR loops generation",
90 INITIALIZE_PASS_END(PPCCTRLoops, DEBUG_TYPE, "PowerPC CTR loops generation",  in INITIALIZE_PASS_DEPENDENCY()
112              "CTR loop pseudo is not expanded!");  in runOnMachineFunction()
123     // CTR defination inside the callee of a call instruction will not impact  in isCTRClobber()
126     return MI->definesRegister(PPC::CTR, /*TRI=*/nullptr) ||  in isCTRClobber()
130   if (MI->modifiesRegister(PPC::CTR, /*TRI=*/nullptr) ||  in isCTRClobber()
137   // We define the CTR in the loop preheader, so if there is any CTR reader in  in isCTRClobber()
138   // the loop, we also can not use CTR loop form.  in isCTRClobber()
139   if (MI->readsRegister(PPC::CTR, /*TRI=*/nullptr) ||  in isCTRClobber()
183   // This is not a CTR loop candidate.  in processLoop()
187   // If CTR is live to the preheader, we can not redefine the CTR register.  in processLoop()
188   if (Preheader->isLiveIn(PPC::CTR) || Preheader->isLiveIn(PPC::CTR8))  in processLoop()
191   // Make sure there is also no CTR clobber in the block preheader between the  in processLoop()
196     // Only check the definitions of CTR. If there is non-dead definition for  in processLoop()
197     // the CTR, we conservatively don't generate a CTR loop.  in processLoop()
203   // Make sure there is also no CTR clobber/user in the block preheader between  in processLoop()
212   // Find the CTR loop components and decide whether or not to fall back to a  in processLoop()
220         // If any instruction clobber CTR, then we can not generate a CTR loop.  in processLoop()
227   assert(Dec && "CTR loop is not complete!");  in processLoop()
248          "Preheader and exiting should exist for CTR loop!");  in expandNormalLoops()
297                "CTR loop should not be generated for irreducible loop!");  in expandNormalLoops()
327          "Preheader and exiting should exist for CTR loop!");  in expandCTRLoops()
343            "Invalid ctr loop!");  in expandCTRLoops()
348            "Invalid ctr loop!");  in expandCTRLoops()