[PATCH] D28126: [MemDep] Handle gep with zeros for invariant.group

[Piotr Padlewski via Phabricator via llvm-commits]

Prazek created this revision.
Prazek added reviewers: dberlin, nlewycky, chandlerc.
Prazek added a subscriber: llvm-commits.

gep 0, 0 is equivalent to bitcast. LLVM canonicalizes it
to getelementptr because it make SROA can then handle it.

Simple case like

void g(A &a) {

  z(a);
  if (glob)
      a.foo();

}
void testG() {

  A a;
  g(a);

}

was not devirtualized with -fstrict-vtable-pointers because luck of
handling for gep 0 in Memory Dependence Analysis


https://reviews.llvm.org/D28126

Files:
  lib/Analysis/MemoryDependenceAnalysis.cpp
  test/Transforms/GVN/invariant.group.ll
  test/Transforms/NewGVN/invariant.group.ll

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