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Remove more dead functions.
llvm-svn: 149318
This commit is contained in:
Bill Wendling
parent
1be31fd0b1
commit
1b3c45b027
@ -10,13 +10,6 @@
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// This file implements inlining of a function into a call site, resolving
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// parameters and the return value as appropriate.
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//
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// The code in this file for handling inlines through invoke
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// instructions preserves semantics only under some assumptions about
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// the behavior of unwinders which correspond to gcc-style libUnwind
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// exception personality functions. Eventually the IR will be
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// improved to make this unnecessary, but until then, this code is
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// marked [LIBUNWIND].
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Utils/Cloning.h"
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@ -45,204 +38,6 @@ bool llvm::InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI) {
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return InlineFunction(CallSite(II), IFI);
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}
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// FIXME: New EH - Remove the functions marked [LIBUNWIND] when new EH is
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// turned on.
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/// [LIBUNWIND] Look for an llvm.eh.exception call in the given block.
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static EHExceptionInst *findExceptionInBlock(BasicBlock *bb) {
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for (BasicBlock::iterator i = bb->begin(), e = bb->end(); i != e; i++) {
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EHExceptionInst *exn = dyn_cast<EHExceptionInst>(i);
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if (exn) return exn;
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}
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return 0;
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}
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/// [LIBUNWIND] Look for the 'best' llvm.eh.selector instruction for
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/// the given llvm.eh.exception call.
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static EHSelectorInst *findSelectorForException(EHExceptionInst *exn) {
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BasicBlock *exnBlock = exn->getParent();
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EHSelectorInst *outOfBlockSelector = 0;
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for (Instruction::use_iterator
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ui = exn->use_begin(), ue = exn->use_end(); ui != ue; ++ui) {
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EHSelectorInst *sel = dyn_cast<EHSelectorInst>(*ui);
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if (!sel) continue;
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// Immediately accept an eh.selector in the same block as the
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// excepton call.
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if (sel->getParent() == exnBlock) return sel;
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// Otherwise, use the first selector we see.
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if (!outOfBlockSelector) outOfBlockSelector = sel;
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}
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return outOfBlockSelector;
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}
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/// [LIBUNWIND] Find the (possibly absent) call to @llvm.eh.selector
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/// in the given landing pad. In principle, llvm.eh.exception is
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/// required to be in the landing pad; in practice, SplitCriticalEdge
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/// can break that invariant, and then inlining can break it further.
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/// There's a real need for a reliable solution here, but until that
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/// happens, we have some fragile workarounds here.
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static EHSelectorInst *findSelectorForLandingPad(BasicBlock *lpad) {
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// Look for an exception call in the actual landing pad.
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EHExceptionInst *exn = findExceptionInBlock(lpad);
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if (exn) return findSelectorForException(exn);
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// Okay, if that failed, look for one in an obvious successor. If
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// we find one, we'll fix the IR by moving things back to the
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// landing pad.
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bool dominates = true; // does the lpad dominate the exn call
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BasicBlock *nonDominated = 0; // if not, the first non-dominated block
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BasicBlock *lastDominated = 0; // and the block which branched to it
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BasicBlock *exnBlock = lpad;
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// We need to protect against lpads that lead into infinite loops.
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SmallPtrSet<BasicBlock*,4> visited;
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visited.insert(exnBlock);
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do {
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// We're not going to apply this hack to anything more complicated
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// than a series of unconditional branches, so if the block
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// doesn't terminate in an unconditional branch, just fail. More
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// complicated cases can arise when, say, sinking a call into a
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// split unwind edge and then inlining it; but that can do almost
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// *anything* to the CFG, including leaving the selector
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// completely unreachable. The only way to fix that properly is
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// to (1) prohibit transforms which move the exception or selector
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// values away from the landing pad, e.g. by producing them with
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// instructions that are pinned to an edge like a phi, or
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// producing them with not-really-instructions, and (2) making
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// transforms which split edges deal with that.
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BranchInst *branch = dyn_cast<BranchInst>(&exnBlock->back());
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if (!branch || branch->isConditional()) return 0;
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BasicBlock *successor = branch->getSuccessor(0);
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// Fail if we found an infinite loop.
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if (!visited.insert(successor)) return 0;
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// If the successor isn't dominated by exnBlock:
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if (!successor->getSinglePredecessor()) {
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// We don't want to have to deal with threading the exception
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// through multiple levels of phi, so give up if we've already
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// followed a non-dominating edge.
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if (!dominates) return 0;
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// Otherwise, remember this as a non-dominating edge.
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dominates = false;
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nonDominated = successor;
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lastDominated = exnBlock;
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}
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exnBlock = successor;
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// Can we stop here?
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exn = findExceptionInBlock(exnBlock);
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} while (!exn);
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// Look for a selector call for the exception we found.
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EHSelectorInst *selector = findSelectorForException(exn);
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if (!selector) return 0;
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// The easy case is when the landing pad still dominates the
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// exception call, in which case we can just move both calls back to
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// the landing pad.
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if (dominates) {
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selector->moveBefore(lpad->getFirstNonPHI());
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exn->moveBefore(selector);
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return selector;
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}
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// Otherwise, we have to split at the first non-dominating block.
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// The CFG looks basically like this:
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// lpad:
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// phis_0
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// insnsAndBranches_1
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// br label %nonDominated
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// nonDominated:
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// phis_2
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// insns_3
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// %exn = call i8* @llvm.eh.exception()
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// insnsAndBranches_4
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// %selector = call @llvm.eh.selector(i8* %exn, ...
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// We need to turn this into:
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// lpad:
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// phis_0
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// %exn0 = call i8* @llvm.eh.exception()
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// %selector0 = call @llvm.eh.selector(i8* %exn0, ...
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// insnsAndBranches_1
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// br label %split // from lastDominated
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// nonDominated:
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// phis_2 (without edge from lastDominated)
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// %exn1 = call i8* @llvm.eh.exception()
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// %selector1 = call i8* @llvm.eh.selector(i8* %exn1, ...
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// br label %split
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// split:
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// phis_2 (edge from lastDominated, edge from split)
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// %exn = phi ...
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// %selector = phi ...
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// insns_3
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// insnsAndBranches_4
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assert(nonDominated);
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assert(lastDominated);
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// First, make clones of the intrinsics to go in lpad.
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EHExceptionInst *lpadExn = cast<EHExceptionInst>(exn->clone());
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EHSelectorInst *lpadSelector = cast<EHSelectorInst>(selector->clone());
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lpadSelector->setArgOperand(0, lpadExn);
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lpadSelector->insertBefore(lpad->getFirstNonPHI());
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lpadExn->insertBefore(lpadSelector);
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// Split the non-dominated block.
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BasicBlock *split =
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nonDominated->splitBasicBlock(nonDominated->getFirstNonPHI(),
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nonDominated->getName() + ".lpad-fix");
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// Redirect the last dominated branch there.
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cast<BranchInst>(lastDominated->back()).setSuccessor(0, split);
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// Move the existing intrinsics to the end of the old block.
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selector->moveBefore(&nonDominated->back());
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exn->moveBefore(selector);
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Instruction *splitIP = &split->front();
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// For all the phis in nonDominated, make a new phi in split to join
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// that phi with the edge from lastDominated.
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for (BasicBlock::iterator
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i = nonDominated->begin(), e = nonDominated->end(); i != e; ++i) {
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PHINode *phi = dyn_cast<PHINode>(i);
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if (!phi) break;
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PHINode *splitPhi = PHINode::Create(phi->getType(), 2, phi->getName(),
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splitIP);
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phi->replaceAllUsesWith(splitPhi);
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splitPhi->addIncoming(phi, nonDominated);
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splitPhi->addIncoming(phi->removeIncomingValue(lastDominated),
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lastDominated);
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}
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// Make new phis for the exception and selector.
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PHINode *exnPhi = PHINode::Create(exn->getType(), 2, "", splitIP);
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exn->replaceAllUsesWith(exnPhi);
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selector->setArgOperand(0, exn); // except for this use
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exnPhi->addIncoming(exn, nonDominated);
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exnPhi->addIncoming(lpadExn, lastDominated);
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PHINode *selectorPhi = PHINode::Create(selector->getType(), 2, "", splitIP);
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selector->replaceAllUsesWith(selectorPhi);
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selectorPhi->addIncoming(selector, nonDominated);
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selectorPhi->addIncoming(lpadSelector, lastDominated);
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return lpadSelector;
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}
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namespace {
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/// A class for recording information about inlining through an invoke.
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class InvokeInliningInfo {
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@ -285,12 +80,6 @@ namespace {
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return OuterUnwindDest;
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}
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EHSelectorInst *getOuterSelector() {
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if (!OuterSelector)
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OuterSelector = findSelectorForLandingPad(OuterUnwindDest);
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return OuterSelector;
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}
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BasicBlock *getInnerUnwindDest();
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LandingPadInst *getLandingPadInst() const { return CallerLPad; }
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