[DivRempairs] add a pass to optimize div/rem pairs (PR31028)

This is intended to be a superset of the functionality from D31037 (EarlyCSE) but implemented 
as an independent pass, so there's no stretching of scope and feature creep for an existing pass. 
I also proposed a weaker version of this for SimplifyCFG in D30910. And I initially had almost 
this same functionality as an addition to CGP in the motivating example of PR31028:
https://bugs.llvm.org/show_bug.cgi?id=31028

The advantage of positioning this ahead of SimplifyCFG in the pass pipeline is that it can allow 
more flattening. But it needs to be after passes (InstCombine) that could sink a div/rem and
undo the hoisting that is done here.

Decomposing remainder may allow removing some code from the backend (PPC and possibly others).

Differential Revision: https://reviews.llvm.org/D37121 

llvm-svn: 312862

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/TargetTransformInfo.cpp b/llvm/lib/Analysis/TargetTransformInfo.cpp
index 0884eea329a..21977ededb2 100644
--- a/llvm/lib/Analysis/TargetTransformInfo.cpp
+++ b/llvm/lib/Analysis/TargetTransformInfo.cpp
@@ -176,6 +176,10 @@ bool TargetTransformInfo::isLegalMaskedScatter(Type *DataType) const {
   return TTIImpl->isLegalMaskedScatter(DataType);
 }
 
+bool TargetTransformInfo::hasDivRemOp(Type *DataType, bool IsSigned) const {
+  return TTIImpl->hasDivRemOp(DataType, IsSigned);
+}
+
 bool TargetTransformInfo::prefersVectorizedAddressing() const {
   return TTIImpl->prefersVectorizedAddressing();
 }