[IR][NFC] Update IRBuilder to use InsertPosition (#96497)

Uses the new InsertPosition class (added in #94226) to simplify some of
the IRBuilder interface, and removes the need to pass a BasicBlock
alongside a BasicBlock::iterator, using the fact that we can now get the
parent basic block from the iterator even if it points to the sentinel.
This patch removes the BasicBlock argument from each constructor or call
to setInsertPoint.

This has no functional effect, but later on as we look to remove the
`Instruction *InsertBefore` argument from instruction-creation
(discussed
[here](https://discourse.llvm.org/t/psa-instruction-constructors-changing-to-iterator-only-insertion/77845)),
this will simplify the process by allowing us to deprecate the
InsertPosition constructor directly and catch all the cases where we use
instructions rather than iterators.

1 files changed, 4 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
index c7d758a..be5ff67 100644
--- a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
@@ -1069,7 +1069,7 @@ SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
 
   // Create the PHI.
   BasicBlock *Header = L->getHeader();
-  Builder.SetInsertPoint(Header, Header->begin());
+  Builder.SetInsertPoint(Header->begin());
   PHINode *PN =
       Builder.CreatePHI(ExpandTy, pred_size(Header), Twine(IVName) + ".iv");
 
@@ -1521,7 +1521,7 @@ Value *SCEVExpander::expand(const SCEV *S) {
     return I->second;
 
   SCEVInsertPointGuard Guard(Builder, this);
-  Builder.SetInsertPoint(InsertPt->getParent(), InsertPt);
+  Builder.SetInsertPoint(InsertPt);
 
   // Expand the expression into instructions.
   SmallVector<Instruction *> DropPoisonGeneratingInsts;
@@ -1656,7 +1656,7 @@ void SCEVExpander::replaceCongruentIVInc(
     else
       IP = OrigInc->getNextNonDebugInstruction()->getIterator();
 
-    IRBuilder<> Builder(IP->getParent(), IP);
+    IRBuilder<> Builder(IP);
     Builder.SetCurrentDebugLocation(IsomorphicInc->getDebugLoc());
     NewInc =
         Builder.CreateTruncOrBitCast(OrigInc, IsomorphicInc->getType(), IVName);
@@ -1759,8 +1759,7 @@ SCEVExpander::replaceCongruentIVs(Loop *L, const DominatorTree *DT,
     ++NumElim;
     Value *NewIV = OrigPhiRef;
     if (OrigPhiRef->getType() != Phi->getType()) {
-      IRBuilder<> Builder(L->getHeader(),
-                          L->getHeader()->getFirstInsertionPt());
+      IRBuilder<> Builder(L->getHeader()->getFirstInsertionPt());
       Builder.SetCurrentDebugLocation(Phi->getDebugLoc());
       NewIV = Builder.CreateTruncOrBitCast(OrigPhiRef, Phi->getType(), IVName);
     }