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SPV 1.4: Use OpSelect for trivial typed non-scalar/vector expressions.

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This commit is contained in:
John Kessenich
2019-01-10 18:23:06 +07:00
parent cfea59d357
commit 0c1e71a123
4 changed files with 209 additions and 5 deletions
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23
SPIRV/GlslangToSpv.cpp
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@@ -2615,6 +2615,19 @@ bool TGlslangToSpvTraverser::visitAggregate(glslang::TVisit visit, glslang::TInt
// next layer copies r-values into memory to use the access-chain mechanism
bool TGlslangToSpvTraverser::visitSelection(glslang::TVisit /* visit */, glslang::TIntermSelection* node)
{
// see if OpSelect can handle it
const auto isOpSelectable = [&]() {
if (node->getBasicType() == glslang::EbtVoid)
return false;
// OpSelect can do all other types starting with SPV 1.4
if (glslangIntermediate->getSpv().spv < glslang::EShTargetSpv_1_4) {
// pre-1.4, only scalars and vectors can be handled
if ((!node->getType().isScalar() && !node->getType().isVector()))
return false;
}
return true;
};
// See if it simple and safe, or required, to execute both sides.
// Crucially, side effects must be either semantically required or avoided,
// and there are performance trade-offs.
@@ -2633,9 +2646,7 @@ bool TGlslangToSpvTraverser::visitSelection(glslang::TVisit /* visit */, glslang
// if not required to execute both, decide based on performance/practicality...
// see if OpSelect can handle it
if ((!node->getType().isScalar() && !node->getType().isVector()) ||
node->getBasicType() == glslang::EbtVoid)
if (!isOpSelectable())
return false;
assert(node->getType() == node->getTrueBlock() ->getAsTyped()->getType() &&
@@ -2672,14 +2683,16 @@ bool TGlslangToSpvTraverser::visitSelection(glslang::TVisit /* visit */, glslang
// emit code to select between trueValue and falseValue
// see if OpSelect can handle it
if (node->getType().isScalar() || node->getType().isVector()) {
if (isOpSelectable()) {
// Emit OpSelect for this selection.
// smear condition to vector, if necessary (AST is always scalar)
if (builder.isVector(trueValue))
// Before 1.4, smear like for mix(), starting with 1.4, keep it scalar
if (glslangIntermediate->getSpv().spv < glslang::EShTargetSpv_1_4 && builder.isVector(trueValue)) {
condition = builder.smearScalar(spv::NoPrecision, condition,
builder.makeVectorType(builder.makeBoolType(),
builder.getNumComponents(trueValue)));
}
// OpSelect
result = builder.createTriOp(spv::OpSelect,