Subzero: Aggressive LEA

src/IceInstX86BaseImpl.h

Index: src/IceInstX86BaseImpl.h
diff --git a/src/IceInstX86BaseImpl.h b/src/IceInstX86BaseImpl.h
index cfc36d44a4fb3827d3329385015dc6de47a9631b..8e5f5a602c458114dfa4ed6bb62a736eeafe6dfc 100644
--- a/src/IceInstX86BaseImpl.h
+++ b/src/IceInstX86BaseImpl.h
@@ -2025,6 +2025,21 @@ template <typename TraitsType>
 void InstImpl<TraitsType>::InstX86Lea::emit(const Cfg *Func) const {
   if (!BuildDefs::dump())
     return;
+
+  auto *MemOp = llvm::dyn_cast<X86OperandMem>(this->getSrc(0));
+  if (MemOp != nullptr && getFlags().getAggressiveLea() &&
+      MemOp->getBase()->getRegNum() == this->getDest()->getRegNum() &&
+      MemOp->getIndex() == nullptr && MemOp->getShift() == 0) {
+    // Reverts back to Add when the Lea is a 2-address instruction
+    auto *Add = InstImpl<TraitsType>::InstX86Add::create(
+        const_cast<Cfg *>(Func), this->getDest(), MemOp->getOffset());
+    //TODO: Remove const_cast by emitting code for add directly.

[Jim Stichnoth, 2016/08/01 21:08:41]

TODO(owner)

also, odd that there's no spaced after "//"...

[manasijm, 2016/08/01 23:14:58]

Done.

+    // Using the allocator does not help because the constructor for
+    // InstX86Lea takes a non-const Cfg *
+    Add->emit(Func);
+    return;
+  }
+
   Ostream &Str = Func->getContext()->getStrEmit();
   assert(this->getSrcSize() == 1);
   assert(this->getDest()->hasReg());