[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, 2 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp b/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
index 901c5fc0..97cf583 100644
--- a/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
+++ b/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
@@ -1593,8 +1593,8 @@ static void insertTrivialPHIs(CHRScope *Scope,
         // Insert a trivial phi for I (phi [&I, P0], [&I, P1], ...) at
         // ExitBlock. Replace I with the new phi in UI unless UI is another
         // phi at ExitBlock.
-        PHINode *PN = PHINode::Create(I.getType(), pred_size(ExitBlock), "",
-                                      &ExitBlock->front());
+        PHINode *PN = PHINode::Create(I.getType(), pred_size(ExitBlock), "");
+        PN->insertBefore(ExitBlock->begin());
         for (BasicBlock *Pred : predecessors(ExitBlock)) {
           PN->addIncoming(&I, Pred);
         }