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X86 Peephole: fold loads to the source register operand if possible.

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Machine CSE and other optimizations can remove instructions so folding
is possible at peephole while not possible at ISel.

rdar://10554090 and rdar://11873276


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160919 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Manman Ren
2012-07-28 16:48:01 +00:00
parent cdfbcdeeed
commit 0eb3edea9c
10 changed files with 167 additions and 50 deletions
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22
lib/CodeGen/PeepholeOptimizer.cpp
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@@ -78,6 +78,7 @@ STATISTIC(NumReuse, "Number of extension results reused");
STATISTIC(NumBitcasts, "Number of bitcasts eliminated");
STATISTIC(NumCmps, "Number of compares eliminated");
STATISTIC(NumImmFold, "Number of move immediate folded");
STATISTIC(NumLoadFold, "Number of loads folded");
namespace {
class PeepholeOptimizer : public MachineFunctionPass {
@@ -441,6 +442,7 @@ bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
SmallPtrSet<MachineInstr*, 8> LocalMIs;
SmallSet<unsigned, 4> ImmDefRegs;
DenseMap<unsigned, MachineInstr*> ImmDefMIs;
SmallSet<unsigned, 4> FoldAsLoadDefRegs;
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
MachineBasicBlock *MBB = &*I;
@@ -448,6 +450,7 @@ bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
LocalMIs.clear();
ImmDefRegs.clear();
ImmDefMIs.clear();
FoldAsLoadDefRegs.clear();
bool First = true;
MachineBasicBlock::iterator PMII;
@@ -489,6 +492,25 @@ bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
Changed |= foldImmediate(MI, MBB, ImmDefRegs, ImmDefMIs);
}
MachineInstr *DefMI = 0;
MachineInstr *FoldMI = TII->optimizeLoadInstr(MI, MRI, FoldAsLoadDefRegs,
DefMI);
if (FoldMI) {
// Update LocalMIs since we replaced MI with FoldMI and deleted DefMI.
LocalMIs.erase(MI);
LocalMIs.erase(DefMI);
LocalMIs.insert(FoldMI);
MI->eraseFromParent();
DefMI->eraseFromParent();
++NumLoadFold;
// MI is replaced with FoldMI.
Changed = true;
PMII = FoldMI;
MII = llvm::next(PMII);
continue;
}
First = false;
PMII = MII;
++MII;