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nv50/ir/opt: Fix tryPropagateBranch for BBs with several exit branches. 

Comments and "if (bf->cfg.incidentCount() == 1)" condition added
by Christoph Bumiller.
This commit is contained in:
Francisco Jerez 2013-02-06 14:12:44 +01:00 committed by Christoph Bumiller
parent 572bf83ec0
commit 5959d4247a
1 changed files with 33 additions and 29 deletions
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62
src/gallium/drivers/nv50/codegen/nv50_ir_peephole.cpp
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@ -1885,42 +1885,46 @@ FlatteningPass::mayPredicate(const Instruction *insn, const Value *pred) const
return true;
}
// If we conditionally skip over or to a branch instruction, replace it.
// If we jump to BRA/RET/EXIT, replace the jump with it.
// NOTE: We do not update the CFG anymore here !
//
// TODO: Handle cases where we skip over a branch (maybe do that elsewhere ?):
// BB:0
// @p0 bra BB:2 -> @!p0 bra BB:3 iff (!) BB:2 immediately adjoins BB:1
// BB1:
// bra BB:3
// BB2:
// ...
// BB3:
// ...
void
FlatteningPass::tryPropagateBranch(BasicBlock *bb)
{
BasicBlock *bf = NULL;
unsigned int i;
for (Instruction *i = bb->getExit(); i && i->op == OP_BRA; i = i->prev) {
BasicBlock *bf = i->asFlow()->target.bb;
if (bb->cfg.outgoingCount() != 2)
return;
if (!bb->getExit() || bb->getExit()->op != OP_BRA)
return;
Graph::EdgeIterator ei = bb->cfg.outgoing();
if (bf->getInsnCount() != 1)
continue;
for (i = 0; !ei.end(); ++i, ei.next()) {
bf = BasicBlock::get(ei.getNode());
if (bf->getInsnCount() == 1)
break;
FlowInstruction *bra = i->asFlow();
FlowInstruction *rep = bf->getExit()->asFlow();
if (!rep || rep->getPredicate())
continue;
if (rep->op != OP_BRA &&
rep->op != OP_JOIN &&
rep->op != OP_EXIT)
continue;
// TODO: If there are multiple branches to @rep, only the first would
// be replaced, so only remove them after this pass is done ?
// Also, need to check all incident blocks for fall-through exits and
// add the branch there.
bra->op = rep->op;
bra->target.bb = rep->target.bb;
if (bf->cfg.incidentCount() == 1)
bf->remove(rep);
}
if (ei.end() || !bf->getExit())
return;
FlowInstruction *bra = bb->getExit()->asFlow();
FlowInstruction *rep = bf->getExit()->asFlow();
if (rep->getPredicate())
return;
if (rep->op != OP_BRA &&
rep->op != OP_JOIN &&
rep->op != OP_EXIT)
return;
bra->op = rep->op;
bra->target.bb = rep->target.bb;
if (i) // 2nd out block means branch not taken
bra->cc = inverseCondCode(bra->cc);
bf->remove(rep);
}
bool