Mark all uses as <undef> when joining a copy.
This way, shrinkToUses() will ignore the instruction that is about to be
deleted, and we avoid leaving invalid live ranges that SplitKit doesn't like.
Fix a misunderstanding in MachineVerifier about <def,undef> operands. The
<undef> flag is valid on def operands where it has the same meaning as <undef>
on a use operand. It only applies to sub-register defines which also read the
full register.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128642 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineVerifier.cpp b/lib/CodeGen/MachineVerifier.cpp
index 7351119..e78ca9b 100644
--- a/lib/CodeGen/MachineVerifier.cpp
+++ b/lib/CodeGen/MachineVerifier.cpp
@@ -602,9 +602,7 @@
// Check Live Variables.
if (MI->isDebugValue()) {
// Liveness checks are not valid for debug values.
- } else if (MO->isUndef()) {
- // An <undef> doesn't refer to any register, so just skip it.
- } else if (MO->isUse()) {
+ } else if (MO->isUse() && !MO->isUndef()) {
regsLiveInButUnused.erase(Reg);
bool isKill = false;
@@ -675,8 +673,7 @@
MInfo.vregsLiveIn.insert(std::make_pair(Reg, MI));
}
}
- } else {
- assert(MO->isDef());
+ } else if (MO->isDef()) {
// Register defined.
// TODO: verify that earlyclobber ops are not used.
if (MO->isDead())
diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index 8a10270..8c7eba9 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -104,6 +104,18 @@
MachineFunctionPass::getAnalysisUsage(AU);
}
+void SimpleRegisterCoalescing::markAsJoined(MachineInstr *CopyMI) {
+ /// Joined copies are not deleted immediately, but kept in JoinedCopies.
+ JoinedCopies.insert(CopyMI);
+
+ /// Mark all register operands of CopyMI as <undef> so they won't affect dead
+ /// code elimination.
+ for (MachineInstr::mop_iterator I = CopyMI->operands_begin(),
+ E = CopyMI->operands_end(); I != E; ++I)
+ if (I->isReg())
+ I->setIsUndef(true);
+}
+
/// AdjustCopiesBackFrom - We found a non-trivially-coalescable copy with IntA
/// being the source and IntB being the dest, thus this defines a value number
/// in IntB. If the source value number (in IntA) is defined by a copy from B,
@@ -471,7 +483,7 @@
DEBUG(dbgs() << "\t\tnoop: " << DefIdx << '\t' << *UseMI);
assert(DVNI->def == DefIdx);
BValNo = IntB.MergeValueNumberInto(BValNo, DVNI);
- JoinedCopies.insert(UseMI);
+ markAsJoined(UseMI);
}
// Extend BValNo by merging in IntA live ranges of AValNo. Val# definition
@@ -1070,7 +1082,7 @@
if (!CP.isPartial()) {
if (AdjustCopiesBackFrom(CP, CopyMI) ||
RemoveCopyByCommutingDef(CP, CopyMI)) {
- JoinedCopies.insert(CopyMI);
+ markAsJoined(CopyMI);
DEBUG(dbgs() << "\tTrivial!\n");
return true;
}
@@ -1090,7 +1102,7 @@
}
// Remember to delete the copy instruction.
- JoinedCopies.insert(CopyMI);
+ markAsJoined(CopyMI);
UpdateRegDefsUses(CP);
diff --git a/lib/CodeGen/SimpleRegisterCoalescing.h b/lib/CodeGen/SimpleRegisterCoalescing.h
index 11849df..6e79a40 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.h
+++ b/lib/CodeGen/SimpleRegisterCoalescing.h
@@ -176,6 +176,9 @@
/// cycles Start and End or NULL if there are no uses.
MachineOperand *lastRegisterUse(SlotIndex Start, SlotIndex End,
unsigned Reg, SlotIndex &LastUseIdx) const;
+
+ /// markAsJoined - Remember that CopyMI has already been joined.
+ void markAsJoined(MachineInstr *CopyMI);
};
} // End llvm namespace