[PATCH] [SLSR] handle candidate form &B[i * S]

[hfinkel at anl.gov]

================
Comment at: lib/Transforms/Scalar/StraightLineStrengthReduce.cpp:214
@@ +213,3 @@
+
+  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getPointerOperand())) {
+    BaseGV = GV;
----------------
Don't need the { } here.

================
Comment at: lib/Transforms/Scalar/StraightLineStrengthReduce.cpp:366
@@ +365,3 @@
+      ConstantInt *RHS = nullptr;
+      // TODO: handle shl. e.g., we could treat (S << 2) as (S * 4).
+      if (match(Idx, m_Mul(m_Value(LHS), m_ConstantInt(RHS)))) {
----------------
Can't you use SCEV to do that here? If you do, then you get the shift case for free. If the problem here is the loss of the information on the NSW, please comment on that.


================
Comment at: lib/Transforms/Scalar/StraightLineStrengthReduce.cpp:444
@@ +443,3 @@
+      } else {
+        // C = inttoptr(ptrtoint(Basis) + Bump)
+        Reduced = Builder.CreatePtrToInt(Basis.Ins, IntPtrTy);
----------------
No, please don't do that. Cast the pointer to an i8* (in the appropriate address space), and use a GEP.

http://reviews.llvm.org/D7459

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