[IR] Implement DataLayout::getPointerTypeSizeInBits using getPointerSizeInBits directly

Currently we use getTypeSizeInBits which contains a switch statement to dispatch based on what the Type is. We know we always have a pointer type here, but the compiler isn't able to figure out that out to remove the switch.

This patch changes it to just call handle the pointer type directly by calling getPointerSizeInBits without going through a switch.

getPointerTypeSizeInBits is called pretty often, particularly by getOrEnforceKnownAlignment which is used by InstCombine. This should speed that up a little bit.

Differential Revision: https://reviews.llvm.org/D31841

llvm-svn: 300475

1 files changed, 2 insertions, 5 deletions

diff --git a/llvm/lib/IR/DataLayout.cpp b/llvm/lib/IR/DataLayout.cpp
index 6f90ce59856..c72057ed146 100644
--- a/llvm/lib/IR/DataLayout.cpp
+++ b/llvm/lib/IR/DataLayout.cpp
@@ -608,11 +608,8 @@ unsigned DataLayout::getPointerSize(unsigned AS) const {
 unsigned DataLayout::getPointerTypeSizeInBits(Type *Ty) const {
   assert(Ty->isPtrOrPtrVectorTy() &&
          "This should only be called with a pointer or pointer vector type");
-
-  if (Ty->isPointerTy())
-    return getTypeSizeInBits(Ty);
-
-  return getTypeSizeInBits(Ty->getScalarType());
+  Ty = Ty->getScalarType();
+  return getPointerSizeInBits(cast<PointerType>(Ty)->getAddressSpace());
 }
 
 /*!