[RemoveDIs] Reapply 3fda50d3915, insert instructions using iterators

I'd reverted this in 6c7805d5d1 after a bad stage. Original commit
messsage follows:

[NFC][RemoveDIs] Bulk update utilities to insert with iterators

As part of the RemoveDIs project we need LLVM to insert instructions using
iterators wherever possible, so that the iterators can carry a bit of
debug-info. This commit implements some of that by updating the contents of
llvm/lib/Transforms/Utils to always use iterator-versions of instruction
constructors.

There are two general flavours of update:
 * Almost all call-sites just call getIterator on an instruction
 * Several make use of an existing iterator (scenarios where the code is
   actually significant for debug-info)
The underlying logic is that any call to getFirstInsertionPt or similar
APIs that identify the start of a block need to have that iterator passed
directly to the insertion function, without being converted to a bare
Instruction pointer along the way.

I've also switched DemotePHIToStack to take an optional iterator: it needs
to take an iterator, and having a no-insert-location behaviour appears to
be important. The constructors for ICmpInst and FCmpInst have been updated
too. They're the only instructions that take block _references_ rather than
pointers for certain calls, and a future patch is going to make use of
default-null block insertion locations.

All of this should be NFC.

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/LoopRotationUtils.cpp b/llvm/lib/Transforms/Utils/LoopRotationUtils.cpp
index adae796..cec4781 100644
--- a/llvm/lib/Transforms/Utils/LoopRotationUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopRotationUtils.cpp
@@ -874,7 +874,7 @@ bool LoopRotate::rotateLoop(Loop *L, bool SimplifiedLatch) {
       // We can fold the conditional branch in the preheader, this makes things
       // simpler. The first step is to remove the extra edge to the Exit block.
       Exit->removePredecessor(OrigPreheader, true /*preserve LCSSA*/);
-      BranchInst *NewBI = BranchInst::Create(NewHeader, PHBI);
+      BranchInst *NewBI = BranchInst::Create(NewHeader, PHBI->getIterator());
       NewBI->setDebugLoc(PHBI->getDebugLoc());
       PHBI->eraseFromParent();