[llvm-commits] [llvm] r136313 - /llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp

[John McCall]

On Jul 27, 2011, at 5:38 PM, Bill Wendling wrote:
> Author: void
> Date: Wed Jul 27 19:38:23 2011
> New Revision: 136313
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=136313&view=rev
> Log:
> Initial stab at getting inlining working with the EH rewrite.
> 
> This takes the new 'resume' instruction and turns it into a direct jump to the
> caller's landing pad code. The caller's landingpad instruction is merged with
> the landingpad instructions of the callee. This is a bit rough and makes some
> assumptions in how the code works. But it passes a simple test.

+void InvokeInliningInfo::forwardResume(ResumeInst *RI) {

I would suggest patterning this code more closely after forwardEHResume:
1. Make getInnerUnwindDest() recognize a LandingPadInst in the outer
  landing pad;  if present, set up a InnerEHValues PHI instead of the
  InnerSelectionPHI / InnerExceptionPHI.
2. Teach forwardEHResume how to forward to either an InnerEHValues PHI
  (with a pair of insertvalues) or a Selection/Exception PHI pair, or just have it
  assert that it's an S/E PHI pair.
3. Teach forwardResume how to forward to either an InnerEHValues PHI
  or a Selection/Exception PHI pair (with a pair of extractvalues), or just have
  it assert that it's an EHValues PHI.

+/// mergeLandingPadClauses - Visit all of the landing pad instructions merge the
+/// clauses from the new destination (the caller's landing pad).
+void InvokeInliningInfo::mergeLandingPadClauses(ResumeInst *RI) {
+  for (SmallVectorImpl<LandingPadInst*>::iterator
+         I = CalleeLPads.begin(), E = CalleeLPads.end(); I != E; ++I)
+    for (unsigned i = 0, e = CallerLPad->getNumClauses(); i != e; ++i)
+      (*I)->addClause(CallerLPad->getClauseType(i),
+                      CallerLPad->getClauseValue(i));
+}

I don't see the value in queuing up the landingpad instructions here;
just merge in the caller's clauses as you find them.  That would have
the added advantage of not adding the clauses twice if you find two
or more resume instructions in the callee.

Also, you're not merging the cleanup bit.

You might find it useful to assert that personalities and return types match,
just to catch mistakes in your preflight check.

It might be a good idea to have LandingPadInst provide a
reserveClauses(unsigned) method, and you might also want to
explicitly constrain addClause and getClauseValue to take and
return a Constant*.

John.