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SPV return from main: Simplify a legacy design such returns are not jumps to exit block.

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Structured control-flow rules allow leaving the middle of a construct through
a return, but not through a jump to a block that does a return.

Addresses issue #58.
This commit is contained in:
John Kessenich
2015-09-14 20:58:02 -06:00
parent 5f5b205ce9
commit e770b3e6cf
74 changed files with 9648 additions and 9816 deletions
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32
SPIRV/SpvBuilder.cpp
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@@ -65,8 +65,7 @@ Builder::Builder(unsigned int userNumber) :
builderNumber(userNumber << 16 | SpvBuilderMagic),
buildPoint(0),
uniqueId(0),
mainFunction(0),
stageExit(0)
mainFunction(0)
{
clearAccessChain();
}
@@ -723,19 +722,10 @@ Function* Builder::makeMain()
std::vector<Id> params;
mainFunction = makeFunctionEntry(makeVoidType(), "main", params, &entry);
stageExit = new Block(getUniqueId(), *mainFunction);
return mainFunction;
}
// Comments in header
void Builder::closeMain()
{
setBuildPoint(stageExit);
stageExit->addInstruction(new Instruction(NoResult, NoType, OpReturn));
mainFunction->addBlock(stageExit);
}
// Comments in header
Function* Builder::makeFunctionEntry(Id returnType, const char* name, std::vector<Id>& paramTypes, Block **entry)
{
@@ -756,14 +746,9 @@ Function* Builder::makeFunctionEntry(Id returnType, const char* name, std::vecto
}
// Comments in header
void Builder::makeReturn(bool implicit, Id retVal, bool isMain)
void Builder::makeReturn(bool implicit, Id retVal)
{
if (isMain && retVal)
MissingFunctionality("return value from main()");
if (isMain)
createBranch(stageExit);
else if (retVal) {
if (retVal) {
Instruction* inst = new Instruction(NoResult, NoType, OpReturnValue);
inst->addIdOperand(retVal);
buildPoint->addInstruction(inst);
@@ -775,7 +760,7 @@ void Builder::makeReturn(bool implicit, Id retVal, bool isMain)
}
// Comments in header
void Builder::leaveFunction(bool main)
void Builder::leaveFunction()
{
Block* block = buildPoint;
Function& function = buildPoint->getParent();
@@ -791,10 +776,8 @@ void Builder::leaveFunction(bool main)
// Given that this block is at the end of a function, it must be right after an
// explicit return, just remove it.
function.popBlock(block);
} else if (main)
makeMainReturn(true);
else {
// We're get a return instruction at the end of the current block,
} else {
// We'll add a return instruction at the end of the current block,
// which for a non-void function is really error recovery (?), as the source
// being translated should have had an explicit return, which would have been
// followed by an unreachable block, which was handled above.
@@ -805,9 +788,6 @@ void Builder::leaveFunction(bool main)
}
}
}
if (main)
closeMain();
}
// Comments in header