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Teach if-conversion about instructions that were already predicated, e.g. conditional move. 

llvm-svn: 37964
This commit is contained in:
Evan Cheng 2007-07-06 23:24:39 +00:00
parent 9835db562f
commit 96c1457bff
1 changed files with 14 additions and 3 deletions
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17
llvm/lib/CodeGen/IfConversion.cpp
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@ -529,6 +529,7 @@ void IfConverter::ScanInstructions(BBInfo &BBI) {
if (BBI.IsDone) if (BBI.IsDone)
return; return;
bool AlreadyPredicated = BBI.Predicate.size() > 0;
// First analyze the end of BB branches. // First analyze the end of BB branches.
BBI.TrueBB = BBI.FalseBB = NULL; BBI.TrueBB = BBI.FalseBB = NULL;
BBI.BrCond.clear(); BBI.BrCond.clear();
@ -558,8 +559,18 @@ void IfConverter::ScanInstructions(BBInfo &BBI) {
bool isCondBr = BBI.IsBrAnalyzable && bool isCondBr = BBI.IsBrAnalyzable &&
(TID->Flags & M_BRANCH_FLAG) != 0 && (TID->Flags & M_BARRIER_FLAG) == 0; (TID->Flags & M_BRANCH_FLAG) != 0 && (TID->Flags & M_BARRIER_FLAG) == 0;
if (!isPredicated && !isCondBr) if (!isCondBr) {
BBI.NonPredSize++; if (!isPredicated)
BBI.NonPredSize++;
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) { if (BBI.ClobbersPred && !isPredicated) {
// Predicate modification instruction should end the block (except for // Predicate modification instruction should end the block (except for
@ -572,7 +583,7 @@ void IfConverter::ScanInstructions(BBInfo &BBI) {
} }
// Predicate may have been modified, the subsequent (currently) // Predicate may have been modified, the subsequent (currently)
// unpredocated instructions cannot be correctly predicated. // unpredicated instructions cannot be correctly predicated.
BBI.IsUnpredicable = true; BBI.IsUnpredicable = true;
return; return;
} }