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[ARMv8] Prevent generation of deprecated IT blocks on ARMv8 in Thumb mode.

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IT blocks can only be one instruction lonf, and can only contain a subset of
the 16 instructions.

Patch by Artyom Skrobov!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190309 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Joey Gouly
2013-09-09 14:21:49 +00:00
parent 7b80d9233a
commit b57d99694b
15 changed files with 427 additions and 58 deletions
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39
lib/CodeGen/IfConversion.cpp
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@ -666,32 +666,29 @@ void IfConverter::ScanInstructions(BBInfo &BBI) {
bool isPredicated = TII->isPredicated(I);
bool isCondBr = BBI.IsBrAnalyzable && I->isConditionalBranch();
if (!isCondBr) {
if (!isPredicated) {
BBI.NonPredSize++;
unsigned ExtraPredCost = 0;
unsigned NumCycles = TII->getInstrLatency(InstrItins, &*I,
&ExtraPredCost);
if (NumCycles > 1)
BBI.ExtraCost += NumCycles-1;
BBI.ExtraCost2 += ExtraPredCost;
} else if (!AlreadyPredicated) {
// FIXME: This instruction is already predicated before the
// if-conversion pass. It's probably something like a conditional move.
// Mark this block unpredicable for now.
BBI.IsUnpredicable = true;
return;
}
// A conditional branch is not predicable, but it may be eliminated.
if (isCondBr)
continue;
if (!isPredicated) {
BBI.NonPredSize++;
unsigned ExtraPredCost = 0;
unsigned NumCycles = TII->getInstrLatency(InstrItins, &*I,
&ExtraPredCost);
if (NumCycles > 1)
BBI.ExtraCost += NumCycles-1;
BBI.ExtraCost2 += ExtraPredCost;
} else if (!AlreadyPredicated) {
// FIXME: This instruction is already predicated before the
// if-conversion pass. It's probably something like a conditional move.
// Mark this block unpredicable for now.
BBI.IsUnpredicable = true;
return;
}
if (BBI.ClobbersPred && !isPredicated) {
// Predicate modification instruction should end the block (except for
// already predicated instructions and end of block branches).
if (isCondBr) {
// A conditional branch is not predicable, but it may be eliminated.
continue;
}
// Predicate may have been modified, the subsequent (currently)
// unpredicated instructions cannot be correctly predicated.
BBI.IsUnpredicable = true;