[NFC][RemoveDIs] Prefer iterator-insertion over instructions

Continuing the patch series to get rid of debug intrinsics [0], instruction
insertion needs to be done with iterators rather than instruction pointers,
so that we can communicate information in the iterator class. This patch
adds an iterator-taking insertBefore method and converts various call sites
to take iterators. These are all sites where such debug-info needs to be
preserved so that a stage2 clang can be built identically; it's likely that
many more will need to be changed in the future.

At this stage, this is just changing the spelling of a few operations,
which will eventually become signifiant once the debug-info bearing
iterator is used.

[0] https://discourse.llvm.org/t/rfc-instruction-api-changes-needed-to-eliminate-debug-intrinsics-from-ir/68939

Differential Revision: https://reviews.llvm.org/D152537

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/IR/BasicBlock.cpp b/llvm/lib/IR/BasicBlock.cpp
index 1081e03..d6677aa 100644
--- a/llvm/lib/IR/BasicBlock.cpp
+++ b/llvm/lib/IR/BasicBlock.cpp
@@ -220,6 +220,10 @@ const Instruction* BasicBlock::getFirstNonPHI() const {
   return nullptr;
 }
 
+BasicBlock::const_iterator BasicBlock::getFirstNonPHIIt() const {
+  return getFirstNonPHI()->getIterator();
+}
+
 const Instruction *BasicBlock::getFirstNonPHIOrDbg(bool SkipPseudoOp) const {
   for (const Instruction &I : *this) {
     if (isa<PHINode>(I) || isa<DbgInfoIntrinsic>(I))