Reassociate x + -0.1234 * y into x - 0.1234 * y

[oota-llvm.git] / lib / Transforms / Scalar / ConstantHoisting.cpp

diff --git a/lib/Transforms/Scalar/ConstantHoisting.cpp b/lib/Transforms/Scalar/ConstantHoisting.cpp
index 9b7ed816ad985e5e6d5b2f91ac41691fd6db4a9e..763d02b9fcd64d70b866171482facbee9497445a 100644 (file)
--- a/lib/Transforms/Scalar/ConstantHoisting.cpp
+++ b/lib/Transforms/Scalar/ConstantHoisting.cpp
@@ -43,6 +43,7 @@
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/Debug.h"
+#include <tuple>
 
 using namespace llvm;
 
@@ -118,7 +119,8 @@ class ConstantHoisting : public FunctionPass {
   SmallVector<ConstantInfo, 8> ConstantVec;
 public:
   static char ID; // Pass identification, replacement for typeid
-  ConstantHoisting() : FunctionPass(ID), TTI(0), DT(0), Entry(0) {
+  ConstantHoisting() : FunctionPass(ID), TTI(nullptr), DT(nullptr),
+                       Entry(nullptr) {
     initializeConstantHoistingPass(*PassRegistry::getPassRegistry());
   }
 
@@ -207,7 +209,16 @@ bool ConstantHoisting::runOnFunction(Function &Fn) {
 /// \brief Find the constant materialization insertion point.
 Instruction *ConstantHoisting::findMatInsertPt(Instruction *Inst,
                                                unsigned Idx) const {
-  // The simple and common case.
+  // If the operand is a cast instruction, then we have to materialize the
+  // constant before the cast instruction.
+  if (Idx != ~0U) {
+    Value *Opnd = Inst->getOperand(Idx);
+    if (auto CastInst = dyn_cast<Instruction>(Opnd))
+      if (CastInst->isCast())
+        return CastInst;
+  }
+
+  // The simple and common case. This also includes constant expressions.
   if (!isa<PHINode>(Inst) && !isa<LandingPadInst>(Inst))
     return Inst;
 
@@ -229,7 +240,7 @@ findConstantInsertionPoint(const ConstantInfo &ConstInfo) const {
   SmallPtrSet<BasicBlock *, 8> BBs;
   for (auto const &RCI : ConstInfo.RebasedConstants)
     for (auto const &U : RCI.Uses)
-      BBs.insert(U.Inst->getParent());
+      BBs.insert(findMatInsertPt(U.Inst, U.OpndIdx)->getParent());
 
   if (BBs.count(Entry))
     return &Entry->front();