diff options
| -rw-r--r-- | lib/CodeGen/RegisterCoalescer.cpp | 25 | ||||
| -rw-r--r-- | test/CodeGen/X86/coalescer-identity.ll | 82 |
2 files changed, 100 insertions, 7 deletions
diff --git a/lib/CodeGen/RegisterCoalescer.cpp b/lib/CodeGen/RegisterCoalescer.cpp index 30997c24ba..db117ed1a0 100644 --- a/lib/CodeGen/RegisterCoalescer.cpp +++ b/lib/CodeGen/RegisterCoalescer.cpp @@ -988,20 +988,31 @@ bool RegisterCoalescer::joinCopy(MachineInstr *CopyMI, bool &Again) { return true; } - // If they are already joined we continue. - if (CP.getSrcReg() == CP.getDstReg()) { - DEBUG(dbgs() << "\tCopy already coalesced.\n"); + // Eliminate undefs. + if (!CP.isPhys() && eliminateUndefCopy(CopyMI, CP)) { + DEBUG(dbgs() << "\tEliminated copy of <undef> value.\n"); LIS->RemoveMachineInstrFromMaps(CopyMI); CopyMI->eraseFromParent(); return false; // Not coalescable. } - // Eliminate undefs. - if (!CP.isPhys() && eliminateUndefCopy(CopyMI, CP)) { - DEBUG(dbgs() << "\tEliminated copy of <undef> value.\n"); + // Coalesced copies are normally removed immediately, but transformations + // like removeCopyByCommutingDef() can inadvertently create identity copies. + // When that happens, just join the values and remove the copy. + if (CP.getSrcReg() == CP.getDstReg()) { + LiveInterval &LI = LIS->getInterval(CP.getSrcReg()); + DEBUG(dbgs() << "\tCopy already coalesced: " << LI << '\n'); + LiveRangeQuery LRQ(LI, LIS->getInstructionIndex(CopyMI)); + if (VNInfo *DefVNI = LRQ.valueDefined()) { + VNInfo *ReadVNI = LRQ.valueIn(); + assert(ReadVNI && "No value before copy and no <undef> flag."); + assert(ReadVNI != DefVNI && "Cannot read and define the same value."); + LI.MergeValueNumberInto(DefVNI, ReadVNI); + DEBUG(dbgs() << "\tMerged values: " << LI << '\n'); + } LIS->RemoveMachineInstrFromMaps(CopyMI); CopyMI->eraseFromParent(); - return false; // Not coalescable. + return true; } // Enforce policies. diff --git a/test/CodeGen/X86/coalescer-identity.ll b/test/CodeGen/X86/coalescer-identity.ll new file mode 100644 index 0000000000..9c72ee6296 --- /dev/null +++ b/test/CodeGen/X86/coalescer-identity.ll @@ -0,0 +1,82 @@ +; RUN: llc < %s -verify-coalescing +; PR12927 +target triple = "x86_64-apple-macosx10.8.0" + +; This is a case where removeCopyByCommutingDef() creates an identity copy that +; joinCopy must then deal with correctly. + +@s = common global i16 0, align 2 +@g1 = common global i32 0, align 4 +@g2 = common global i32 0, align 4 +@g0 = common global i32 0, align 4 + +define void @func() nounwind uwtable ssp { +for.body.lr.ph: + %0 = load i32* @g2, align 4, !tbaa !0 + %tobool6 = icmp eq i32 %0, 0 + %s.promoted = load i16* @s, align 2 + %.pre = load i32* @g1, align 4, !tbaa !0 + br i1 %tobool6, label %for.body.us, label %for.body + +for.body.us: ; preds = %for.body.lr.ph, %for.inc.us + %1 = phi i32 [ %3, %for.inc.us ], [ %.pre, %for.body.lr.ph ] + %dec13.us = phi i16 [ %dec12.us, %for.inc.us ], [ %s.promoted, %for.body.lr.ph ] + %i.011.us = phi i32 [ %inc.us, %for.inc.us ], [ undef, %for.body.lr.ph ] + %v.010.us = phi i32 [ %phitmp.us, %for.inc.us ], [ 1, %for.body.lr.ph ] + %tobool1.us = icmp ne i32 %v.010.us, 0 + %2 = zext i1 %tobool1.us to i16 + %lnot.ext.us = xor i16 %2, 1 + %add.us = add i16 %dec13.us, %lnot.ext.us + %conv3.us = zext i16 %add.us to i32 + %add4.us = sub i32 0, %1 + %tobool5.us = icmp eq i32 %conv3.us, %add4.us + br i1 %tobool5.us, label %for.inc.us, label %if.then7.us + +for.inc.us: ; preds = %cond.end.us, %for.body.us + %3 = phi i32 [ %1, %for.body.us ], [ %4, %cond.end.us ] + %dec12.us = phi i16 [ %add.us, %for.body.us ], [ %dec.us, %cond.end.us ] + %inc.us = add i32 %i.011.us, 1 + %phitmp.us = udiv i32 %v.010.us, 12 + %tobool.us = icmp eq i32 %inc.us, 0 + br i1 %tobool.us, label %for.end, label %for.body.us + +cond.end.us: ; preds = %if.then7.us, %cond.false.us + %4 = phi i32 [ 0, %cond.false.us ], [ %1, %if.then7.us ] + %cond.us = phi i32 [ 0, %cond.false.us ], [ %v.010.us, %if.then7.us ] + store i32 %cond.us, i32* @g0, align 4, !tbaa !0 + br label %for.inc.us + +cond.false.us: ; preds = %if.then7.us + store i32 0, i32* @g1, align 4, !tbaa !0 + br label %cond.end.us + +if.then7.us: ; preds = %for.body.us + %dec.us = add i16 %add.us, -1 + br i1 %tobool1.us, label %cond.end.us, label %cond.false.us + +for.body: ; preds = %for.body.lr.ph, %for.body + %dec13 = phi i16 [ %dec12, %for.body ], [ %s.promoted, %for.body.lr.ph ] + %i.011 = phi i32 [ %inc, %for.body ], [ undef, %for.body.lr.ph ] + %v.010 = phi i32 [ %phitmp, %for.body ], [ 1, %for.body.lr.ph ] + %tobool1 = icmp eq i32 %v.010, 0 + %lnot.ext = zext i1 %tobool1 to i16 + %add = add i16 %dec13, %lnot.ext + %conv3 = zext i16 %add to i32 + %add4 = sub i32 0, %.pre + %not.tobool5 = icmp ne i32 %conv3, %add4 + %dec = sext i1 %not.tobool5 to i16 + %dec12 = add i16 %add, %dec + %inc = add i32 %i.011, 1 + %phitmp = udiv i32 %v.010, 12 + %tobool = icmp eq i32 %inc, 0 + br i1 %tobool, label %for.end, label %for.body + +for.end: ; preds = %for.inc.us, %for.body + %dec12.lcssa = phi i16 [ %dec12.us, %for.inc.us ], [ %dec12, %for.body ] + store i16 %dec12.lcssa, i16* @s, align 2 + ret void +} + +!0 = metadata !{metadata !"int", metadata !1} +!1 = metadata !{metadata !"omnipotent char", metadata !2} +!2 = metadata !{metadata !"Simple C/C++ TBAA"} |