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AnalyzeBranch doesn't change which successors a bb has, just the order

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we try to branch to them.

Before we were creating successor lists with duplicated entries. Fixing that
found a bug in isBlockOnlyReachableByFallthrough that would causes it to
return the wrong answer for

-----------
...
jne foo
jmp bar

foo:
----------

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132882 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola 2011-06-12 03:20:32 +00:00
parent 026dc223ae
commit 4509ec42b8
3 changed files with 13 additions and 7 deletions
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15
lib/CodeGen/AsmPrinter/AsmPrinter.cpp
View File

@ -1925,7 +1925,7 @@ isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const {
return false;
// The predecessor has to be immediately before this block.
const MachineBasicBlock *Pred = *PI;
MachineBasicBlock *Pred = *PI;
if (!Pred->isLayoutSuccessor(MBB))
return false;
@ -1934,9 +1934,16 @@ isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const {
if (Pred->empty())
return true;
// Otherwise, check the last instruction.
const MachineInstr &LastInst = Pred->back();
return !LastInst.getDesc().isBarrier();
// Otherwise, ask the backend.
const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
MachineBasicBlock *PredTBB = NULL, *PredFBB = NULL;
SmallVector<MachineOperand, 4> PredCond;
if (TII->AnalyzeBranch(*Pred, PredTBB, PredFBB, PredCond))
return false;
if (PredCond.empty())
return true;
return !PredFBB || PredFBB == MBB;
}

1
lib/Target/X86/X86InstrInfo.cpp
View File

@ -1789,7 +1789,6 @@ bool X86InstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
.addMBB(UnCondBrIter->getOperand(0).getMBB());
BuildMI(MBB, UnCondBrIter, MBB.findDebugLoc(I), get(X86::JMP_4))
.addMBB(TargetBB);
MBB.addSuccessor(TargetBB);
OldInst->eraseFromParent();
UnCondBrIter->eraseFromParent();

4
test/CodeGen/Thumb2/machine-licm.ll
View File

@ -13,7 +13,7 @@ entry:
br i1 %0, label %return, label %bb.nph
bb.nph: ; preds = %entry
; CHECK: BB#1
; CHECK: LBB0_1:
; CHECK: movw r[[R2:[0-9]+]], :lower16:L_GV$non_lazy_ptr
; CHECK: movt r[[R2]], :upper16:L_GV$non_lazy_ptr
; CHECK: ldr{{(.w)?}} r[[R2b:[0-9]+]], [r[[R2]]
@ -21,7 +21,7 @@ bb.nph: ; preds = %entry
; CHECK: LBB0_2
; CHECK-NOT: LCPI0_0:
; PIC: BB#1
; PIC: LBB0_1:
; PIC: movw r[[R2:[0-9]+]], :lower16:(L_GV$non_lazy_ptr-(LPC0_0+4))
; PIC: movt r[[R2]], :upper16:(L_GV$non_lazy_ptr-(LPC0_0+4))
; PIC: add r[[R2]], pc