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It's possible to sink a def if its local uses are PHI's.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111537 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2010-08-19 18:33:29 +00:00
parent 6715be20e2
commit e5e7946018
2 changed files with 44 additions and 5 deletions
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10
lib/CodeGen/MachineSink.cpp
View File

@ -103,15 +103,14 @@ bool MachineSinking::AllUsesDominatedByBlock(unsigned Reg,
// Determine the block of the use.
MachineInstr *UseInst = &*I;
MachineBasicBlock *UseBlock = UseInst->getParent();
if (UseBlock == DefMBB) {
LocalUse = true;
return false;
}
if (UseInst->isPHI()) {
// PHI nodes use the operand in the predecessor block, not the block with
// the PHI.
UseBlock = UseInst->getOperand(I.getOperandNo()+1).getMBB();
} else if (UseBlock == DefMBB) {
LocalUse = true;
return false;
}
// Check that it dominates.
@ -270,7 +269,6 @@ bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
// decide.
MachineBasicBlock *SuccToSinkTo = 0;
bool LocalUse = false;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
const MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg()) continue; // Ignore non-register operands.
@ -328,6 +326,7 @@ bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
if (SuccToSinkTo) {
// If a previous operand picked a block to sink to, then this operand
// must be sinkable to the same block.
bool LocalUse = false;
if (!AllUsesDominatedByBlock(Reg, SuccToSinkTo, ParentBlock, LocalUse))
return false;
@ -338,6 +337,7 @@ bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
// we should sink to.
for (MachineBasicBlock::succ_iterator SI = ParentBlock->succ_begin(),
E = ParentBlock->succ_end(); SI != E; ++SI) {
bool LocalUse = false;
if (AllUsesDominatedByBlock(Reg, *SI, ParentBlock, LocalUse)) {
SuccToSinkTo = *SI;
break;

39
test/CodeGen/X86/MachineSink-PHIUse.ll Normal file
View File

@ -0,0 +1,39 @@
; RUN: llc < %s -mtriple=x86_64-appel-darwin -stats |& grep {machine-sink}
define fastcc void @t() nounwind ssp {
entry:
br i1 undef, label %bb, label %bb4
bb: ; preds = %entry
br i1 undef, label %return, label %bb3
bb3: ; preds = %bb
unreachable
bb4: ; preds = %entry
br i1 undef, label %bb.nph, label %return
bb.nph: ; preds = %bb4
br label %bb5
bb5: ; preds = %bb9, %bb.nph
%indvar = phi i64 [ 0, %bb.nph ], [ %tmp12, %bb9 ] ; <i64> [#uses=1]
%tmp12 = add i64 %indvar, 1 ; <i64> [#uses=2]
%tmp13 = trunc i64 %tmp12 to i32 ; <i32> [#uses=0]
br i1 undef, label %bb9, label %bb6
bb6: ; preds = %bb5
br i1 undef, label %bb9, label %bb7
bb7: ; preds = %bb6
br i1 undef, label %bb9, label %bb8
bb8: ; preds = %bb7
unreachable
bb9: ; preds = %bb7, %bb6, %bb5
br i1 undef, label %bb5, label %return
return: ; preds = %bb9, %bb4, %bb
ret void
}