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ConstPool island bug: watch out for cases where UserMI is the last MI of the BB.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33706 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-01-31 18:19:07 +00:00
parent a88d6ca6f9
commit 934536dab2
1 changed files with 16 additions and 4 deletions
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20
lib/Target/ARM/ARMConstantIslandPass.cpp
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@ -461,6 +461,7 @@ MachineBasicBlock *ARMConstantIslands::SplitBlockBeforeInstr(MachineInstr *MI) {
/// is out-of-range. If so, pick it up the constant pool value and move it some
/// place in-range.
bool ARMConstantIslands::HandleConstantPoolUser(MachineFunction &Fn, CPUser &U){
bool isThumb = AFI->isThumbFunction();
MachineInstr *UserMI = U.MI;
MachineInstr *CPEMI = U.CPEMI;
@ -477,7 +478,7 @@ bool ARMConstantIslands::HandleConstantPoolUser(MachineFunction &Fn, CPUser &U){
// User before the CPE.
if (CPEOffset-UserOffset <= U.MaxDisp)
return false;
} else if (!AFI->isThumbFunction()) {
} else if (!isThumb) {
// Thumb LDR cannot encode negative offset.
if (UserOffset-CPEOffset <= U.MaxDisp)
return false;
@ -487,15 +488,26 @@ bool ARMConstantIslands::HandleConstantPoolUser(MachineFunction &Fn, CPUser &U){
// Solution guaranteed to work: split the user's MBB right after the user and
// insert a clone the CPE into the newly created water.
MachineInstr *NextMI = next(MachineBasicBlock::iterator(UserMI));
MachineBasicBlock *UserMBB = UserMI->getParent();
MachineBasicBlock *NewMBB;
// TODO: Search for the best place to split the code. In practice, using
// loop nesting information to insert these guys outside of loops would be
// sufficient.
MachineBasicBlock *NewBB = SplitBlockBeforeInstr(NextMI);
if (&UserMBB->back() == UserMI) {
assert(BBHasFallthrough(UserMBB) && "Expected a fallthrough BB!");
NewMBB = next(MachineFunction::iterator(UserMBB));
// Add an unconditional branch from UserMBB to fallthrough block.
BuildMI(UserMBB, TII->get(isThumb ? ARM::tB : ARM::B)).addMBB(NewMBB);
BBSizes[UserMBB->getNumber()] += isThumb ? 2 : 4;
} else {
MachineInstr *NextMI = next(MachineBasicBlock::iterator(UserMI));
NewMBB = SplitBlockBeforeInstr(NextMI);
}
// Okay, we know we can put an island before UserMBB now, do it!
MachineBasicBlock *NewIsland = new MachineBasicBlock();
Fn.getBasicBlockList().insert(NewBB, NewIsland);
Fn.getBasicBlockList().insert(NewMBB, NewIsland);
// Update internal data structures to account for the newly inserted MBB.
UpdateForInsertedWaterBlock(NewIsland);