[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, 1 deletions

diff --git a/llvm/lib/CodeGen/SelectOptimize.cpp b/llvm/lib/CodeGen/SelectOptimize.cpp
index e7f31d4..65801aa 100644
--- a/llvm/lib/CodeGen/SelectOptimize.cpp
+++ b/llvm/lib/CodeGen/SelectOptimize.cpp
@@ -505,7 +505,8 @@ void SelectOptimize::convertProfitableSIGroups(SelectGroups &ProfSIGroups) {
     for (auto It = ASI.rbegin(); It != ASI.rend(); ++It) {
       SelectInst *SI = *It;
       // The select itself is replaced with a PHI Node.
-      PHINode *PN = PHINode::Create(SI->getType(), 2, "", &EndBlock->front());
+      PHINode *PN = PHINode::Create(SI->getType(), 2, "");
+      PN->insertBefore(EndBlock->begin());
       PN->takeName(SI);
       PN->addIncoming(getTrueOrFalseValue(SI, true, INS), TrueBlock);
       PN->addIncoming(getTrueOrFalseValue(SI, false, INS), FalseBlock);