[CVP] Process binary operations even when def is local

Summary:
This patch adds processing of binary operations when the def of operands are in
the same block (i.e. local processing).

Earlier we bailed out in such cases (the bail out was introduced in rL252032)
because LVI at that time was more precise about context at the end of basic
blocks, which implied local def and use analysis didn't benefit CVP.

Since then we've added support for LVI in presence of assumes and guards. The
test cases added show how local def processing in CVP helps adding more
information to the ashr, sdiv, srem and add operators.

Note: processCmp which suffers from the same problem will
be handled in a later patch.

Reviewers: philip, apilipenko, SjoerdMeijer, hfinkel

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D38766

llvm-svn: 315634

1 files changed, 4 insertions, 16 deletions

diff --git a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index 28157783daa..44d3e6ad8d4 100644
--- a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -335,18 +335,6 @@ static bool processCallSite(CallSite CS, LazyValueInfo *LVI) {
   return true;
 }
 
-// Helper function to rewrite srem and sdiv. As a policy choice, we choose not
-// to waste compile time on anything where the operands are local defs.  While
-// LVI can sometimes reason about such cases, it's not its primary purpose.
-static bool hasLocalDefs(BinaryOperator *SDI) {
-  for (Value *O : SDI->operands()) {
-    auto *I = dyn_cast<Instruction>(O);
-    if (I && I->getParent() == SDI->getParent())
-      return true;
-  }
-  return false;
-}
-
 static bool hasPositiveOperands(BinaryOperator *SDI, LazyValueInfo *LVI) {
   Constant *Zero = ConstantInt::get(SDI->getType(), 0);
   for (Value *O : SDI->operands()) {
@@ -358,7 +346,7 @@ static bool hasPositiveOperands(BinaryOperator *SDI, LazyValueInfo *LVI) {
 }
 
 static bool processSRem(BinaryOperator *SDI, LazyValueInfo *LVI) {
-  if (SDI->getType()->isVectorTy() || hasLocalDefs(SDI) ||
+  if (SDI->getType()->isVectorTy() ||
       !hasPositiveOperands(SDI, LVI))
     return false;
 
@@ -376,7 +364,7 @@ static bool processSRem(BinaryOperator *SDI, LazyValueInfo *LVI) {
 /// conditions, this can sometimes prove conditions instcombine can't by
 /// exploiting range information.
 static bool processSDiv(BinaryOperator *SDI, LazyValueInfo *LVI) {
-  if (SDI->getType()->isVectorTy() || hasLocalDefs(SDI) ||
+  if (SDI->getType()->isVectorTy() ||
       !hasPositiveOperands(SDI, LVI))
     return false;
 
@@ -391,7 +379,7 @@ static bool processSDiv(BinaryOperator *SDI, LazyValueInfo *LVI) {
 }
 
 static bool processAShr(BinaryOperator *SDI, LazyValueInfo *LVI) {
-  if (SDI->getType()->isVectorTy() || hasLocalDefs(SDI))
+  if (SDI->getType()->isVectorTy())
     return false;
 
   Constant *Zero = ConstantInt::get(SDI->getType(), 0);
@@ -415,7 +403,7 @@ static bool processAdd(BinaryOperator *AddOp, LazyValueInfo *LVI) {
   if (DontProcessAdds)
     return false;
 
-  if (AddOp->getType()->isVectorTy() || hasLocalDefs(AddOp))
+  if (AddOp->getType()->isVectorTy())
     return false;
 
   bool NSW = AddOp->hasNoSignedWrap();