Method stitchConditionalJumps

libyul/backends/evm/StackLayoutGenerator.cpp:530–574

}

void StackLayoutGenerator::stitchConditionalJumps(CFG::BasicBlock const& _block)
{
	util::BreadthFirstSearch<CFG::BasicBlock const*> breadthFirstSearch{{&_block}};
	breadthFirstSearch.run([&](CFG::BasicBlock const* _block, auto _addChild) {
		auto& info = m_layout.blockInfos.at(_block);
		std::visit(util::GenericVisitor{
			[&](CFG::BasicBlock::MainExit const&) {},
			[&](CFG::BasicBlock::Jump const& _jump)
			{
				if (!_jump.backwards)
					_addChild(_jump.target);
			},
			[&](CFG::BasicBlock::ConditionalJump const& _conditionalJump)
			{
				auto& zeroTargetInfo = m_layout.blockInfos.at(_conditionalJump.zero);
				auto& nonZeroTargetInfo = m_layout.blockInfos.at(_conditionalJump.nonZero);
				Stack exitLayout = info.exitLayout;

				// The last block must have produced the condition at the stack top.
				yulAssert(!exitLayout.empty(), "");
				yulAssert(exitLayout.back() == _conditionalJump.condition, "");
				// The condition is consumed by the jump.
				exitLayout.pop_back();

				auto fixJumpTargetEntry = [&](Stack const& _originalEntryLayout) -> Stack {
					Stack newEntryLayout = exitLayout;
					// Whatever the block being jumped to does not actually require, can be marked as junk.
					for (auto& slot: newEntryLayout)
						if (!util::contains(_originalEntryLayout, slot))
							slot = JunkSlot{};
					// Make sure everything the block being jumped to requires is actually present or can be generated.
					for (auto const& slot: _originalEntryLayout)
						yulAssert(canBeFreelyGenerated(slot) || util::contains(newEntryLayout, slot), "");
					return newEntryLayout;
				};
				zeroTargetInfo.entryLayout = fixJumpTargetEntry(zeroTargetInfo.entryLayout);
				nonZeroTargetInfo.entryLayout = fixJumpTargetEntry(nonZeroTargetInfo.entryLayout);
				_addChild(_conditionalJump.zero);
				_addChild(_conditionalJump.nonZero);
			},
			[&](CFG::BasicBlock::FunctionReturn const&) {},
			[&](CFG::BasicBlock::Terminated const&) { },
		}, _block->exit);
	});
}

Stack StackLayoutGenerator::combineStack(Stack const& _stack1, Stack const& _stack2, size_t _reachableStackDepth)
{