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Add some checks for MachineCFG consistency. Use AnalyzeBranch and

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do extra checking when it succeeds, as those are cases where
CodeGen will be doing particularly interesting CFG modifications.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80196 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2009-08-27 02:43:49 +00:00
parent 7008087b8c
commit 27920594b9
1 changed files with 133 additions and 0 deletions
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133
lib/CodeGen/MachineVerifier.cpp
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@ -300,6 +300,139 @@ MachineVerifier::visitMachineFunctionBefore()
void
MachineVerifier::visitMachineBasicBlockBefore(const MachineBasicBlock *MBB)
{
const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
// Start with minimal CFG sanity checks.
MachineFunction::const_iterator MBBI = MBB;
++MBBI;
if (MBBI != MF->end()) {
// Block is not last in function.
if (!MBB->isSuccessor(MBBI)) {
// Block does not fall through.
if (MBB->empty()) {
report("MBB doesn't fall through but is empty!", MBB);
}
} else {
// Block falls through.
if (!MBB->empty() && MBB->back().getDesc().isBarrier()) {
report("MBB falls through but ends with a barrier instruction!", MBB);
}
if (TII->BlockHasNoFallThrough(*MBB)) {
report("TargetInstrInfo says the block has no fall through, but the "
"CFG has a fall-through edge!", MBB);
}
}
} else {
// Block is last in function.
if (MBB->empty()) {
report("MBB is last in function but is empty!", MBB);
}
}
// Call AnalyzeBranch. If it succeeds, there several more conditions to check.
MachineBasicBlock *TBB = 0, *FBB = 0;
SmallVector<MachineOperand, 4> Cond;
if (!TII->AnalyzeBranch(*const_cast<MachineBasicBlock *>(MBB),
TBB, FBB, Cond)) {
// Ok, AnalyzeBranch thinks it knows what's going on with this block. Let's
// check whether its answers match up with reality.
if (!TBB && !FBB) {
// Block falls through to its successor.
MachineFunction::const_iterator MBBI = MBB;
++MBBI;
if (MBBI == MF->end()) {
// TODO: This condition is sometimes reached for functions which
// make noreturn calls or contain unreachable. Should AnalyzeBranch
// be changed to handle such cases differently?
report("MBB falls through out of function!", MBB);
} else if (MBB->succ_size() != 1) {
report("MBB exits via unconditional fall-through but doesn't have "
"exactly one CFG successor!", MBB);
} else if (MBB->succ_begin()[0] != MBBI) {
report("MBB exits via unconditional fall-through but its successor "
"differs from its CFG successor!", MBB);
}
if (!MBB->empty() && MBB->back().getDesc().isBarrier()) {
report("MBB exits via unconditional fall-through but ends with a "
"barrier instruction!", MBB);
}
if (!Cond.empty()) {
report("MBB exits via unconditional fall-through but has a condition!",
MBB);
}
} else if (TBB && !FBB && Cond.empty()) {
// Block unconditionally branches somewhere.
if (MBB->succ_size() != 1) {
report("MBB exits via unconditional branch but doesn't have "
"exactly one CFG successor!", MBB);
} else if (MBB->succ_begin()[0] != TBB) {
report("MBB exits via unconditional branch but the CFG "
"successor doesn't match the actual successor!", MBB);
}
if (MBB->empty()) {
report("MBB exits via unconditional branch but doesn't contain "
"any instructions!", MBB);
} else if (!MBB->back().getDesc().isBarrier()) {
report("MBB exits via unconditional branch but doesn't end with a "
"barrier instruction!", MBB);
} else if (!MBB->back().getDesc().isTerminator()) {
report("MBB exits via unconditional branch but the branch isn't a "
"terminator instruction!", MBB);
}
} else if (TBB && !FBB && !Cond.empty()) {
// Block conditionally branches somewhere, otherwise falls through.
MachineFunction::const_iterator MBBI = MBB;
++MBBI;
if (MBBI == MF->end()) {
report("MBB conditionally falls through out of function!", MBB);
} if (MBB->succ_size() != 2) {
report("MBB exits via conditional branch/fall-through but doesn't have "
"exactly two CFG successors!", MBB);
} else if ((MBB->succ_begin()[0] == TBB && MBB->succ_end()[1] == MBBI) ||
(MBB->succ_begin()[1] == TBB && MBB->succ_end()[0] == MBBI)) {
report("MBB exits via conditional branch/fall-through but the CFG "
"successors don't match the actual successors!", MBB);
}
if (MBB->empty()) {
report("MBB exits via conditional branch/fall-through but doesn't "
"contain any instructions!", MBB);
} else if (MBB->back().getDesc().isBarrier()) {
report("MBB exits via conditional branch/fall-through but ends with a "
"barrier instruction!", MBB);
} else if (!MBB->back().getDesc().isTerminator()) {
report("MBB exits via conditional branch/fall-through but the branch "
"isn't a terminator instruction!", MBB);
}
} else if (TBB && FBB) {
// Block conditionally branches somewhere, otherwise branches
// somewhere else.
if (MBB->succ_size() != 2) {
report("MBB exits via conditional branch/branch but doesn't have "
"exactly two CFG successors!", MBB);
} else if ((MBB->succ_begin()[0] == TBB && MBB->succ_end()[1] == FBB) ||
(MBB->succ_begin()[1] == TBB && MBB->succ_end()[0] == FBB)) {
report("MBB exits via conditional branch/branch but the CFG "
"successors don't match the actual successors!", MBB);
}
if (MBB->empty()) {
report("MBB exits via conditional branch/branch but doesn't "
"contain any instructions!", MBB);
} else if (!MBB->back().getDesc().isBarrier()) {
report("MBB exits via conditional branch/branch but doesn't end with a "
"barrier instruction!", MBB);
} else if (!MBB->back().getDesc().isTerminator()) {
report("MBB exits via conditional branch/branch but the branch "
"isn't a terminator instruction!", MBB);
}
if (Cond.empty()) {
report("MBB exits via conditinal branch/branch but there's no "
"condition!", MBB);
}
} else {
report("AnalyzeBranch returned invalid data!", MBB);
}
}
regsLive.clear();
for (MachineBasicBlock::const_livein_iterator I = MBB->livein_begin(),
E = MBB->livein_end(); I != E; ++I) {