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#include "slang-ir-propagate-func-properties.h"
#include "slang-ir.h"
#include "slang-ir-insts.h"
#include "slang-ir-util.h"
namespace Slang
{
bool propagateFuncProperties(IRModule* module)
{
bool result = false;
List<IRFunc*> workList;
HashSet<IRFunc*> workListSet;
auto addToWorkList = [&](IRFunc* f)
{
if (workListSet.Add(f))
workList.add(f);
};
auto addCallersToWorkList = [&](IRFunc* f)
{
if (auto g = findOuterGeneric(f))
{
for (auto use = g->firstUse; use; use = use->nextUse)
{
if (use->getUser()->getOp() == kIROp_Specialize)
{
auto specialize = use->getUser();
for (auto iuse = specialize->firstUse; iuse; iuse = iuse->nextUse)
{
if (auto userFunc = getParentFunc(iuse->getUser()))
addToWorkList(userFunc);
}
}
}
return;
}
for (auto use = f->firstUse; use; use = use->nextUse)
{
if (use->getUser()->getOp() == kIROp_Call)
{
if (auto userFunc = getParentFunc(use->getUser()))
addToWorkList(userFunc);
}
}
};
for (;;)
{
bool changed = false;
workList.clear();
workListSet.Clear();
// Add side effect free functions and their transitive callers to work list.
for (auto inst : module->getGlobalInsts())
{
auto genericInst = as<IRGeneric>(inst);
if (genericInst)
{
inst = findGenericReturnVal(genericInst);
}
if (auto func = as<IRFunc>(inst))
{
if (func->findDecoration<IRReadNoneDecoration>())
{
addCallersToWorkList(func);
}
}
}
// Add remaining functions to work list.
for (auto inst : module->getGlobalInsts())
{
auto genericInst = as<IRGeneric>(inst);
if (genericInst)
{
inst = findGenericReturnVal(genericInst);
}
if (auto func = as<IRFunc>(inst))
{
addToWorkList(func);
}
}
IRBuilder builder(module);
for (Index i = 0; i < workList.getCount(); i++)
{
auto f = workList[i];
bool hasSideEffectCall = false;
if (f->findDecoration<IRReadNoneDecoration>())
continue;
// Never propagate to functions without a body.
if (f->getFirstBlock() == nullptr)
continue;
if (f->findDecoration<IRTargetIntrinsicDecoration>())
continue;
for (auto block : f->getBlocks())
{
for (auto inst : block->getChildren())
{
// Is this inst known to not have global side effect/analyzable?
if (inst->mightHaveSideEffects())
{
switch (inst->getOp())
{
case kIROp_ifElse:
case kIROp_unconditionalBranch:
case kIROp_Switch:
case kIROp_Return:
case kIROp_loop:
case kIROp_Store:
case kIROp_Call:
case kIROp_Param:
case kIROp_Unreachable:
break;
default:
// We have a inst that has side effect and is not understood by this method.
// e.g. bufferStore, discard, etc.
hasSideEffectCall = true;
break;
}
}
if (auto call = as<IRCall>(inst))
{
auto callee = getResolvedInstForDecorations(call->getCallee());
switch (callee->getOp())
{
default:
// We are calling an unknown function, so we have to assume
// there are side effects in the call.
hasSideEffectCall = true;
break;
case kIROp_Func:
if (!callee->findDecoration<IRReadNoneDecoration>())
{
hasSideEffectCall = true;
break;
}
}
}
// Are any operands defined in global scope?
for (UInt o = 0; o < inst->getOperandCount(); o++)
{
auto operand = inst->getOperand(o);
if (getParentFunc(operand) == f)
continue;
if (as<IRConstant>(operand))
continue;
if (as<IRType>(operand))
continue;
switch (operand->getOp())
{
case kIROp_Specialize:
case kIROp_LookupWitness:
case kIROp_StructKey:
case kIROp_WitnessTable:
case kIROp_WitnessTableEntry:
case kIROp_undefined:
case kIROp_Func:
continue;
default:
break;
}
hasSideEffectCall = true;
break;
}
}
if (hasSideEffectCall)
break;
}
if (!hasSideEffectCall)
{
builder.addDecoration(f, kIROp_ReadNoneDecoration);
addCallersToWorkList(f);
changed = true;
}
}
result |= changed;
if (!changed)
break;
}
return result;
}
}
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