[llvm] [InstCombine] Add support for ptrtoaddr in pointer difference folds (PR #164428)

[Nikita Popov via llvm-commits]

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@@ -2760,21 +2760,21 @@ Instruction *InstCombinerImpl::visitSub(BinaryOperator &I) {
   // Optimize pointer differences into the same array into a size.  Consider:
   //  &A[10] - &A[0]: we should compile this to "10".
   Value *LHSOp, *RHSOp;
-  if (match(Op0, m_PtrToInt(m_Value(LHSOp))) &&
-      match(Op1, m_PtrToInt(m_Value(RHSOp))))
+  if (match(Op0, m_PtrToIntOrAddr(m_Value(LHSOp))) &&
+      match(Op1, m_PtrToIntOrAddr(m_Value(RHSOp))))
     if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType(),
                                                I.hasNoUnsignedWrap()))
       return replaceInstUsesWith(I, Res);
 
   // trunc(p)-trunc(q) -> trunc(p-q)
-  if (match(Op0, m_Trunc(m_PtrToInt(m_Value(LHSOp)))) &&
-      match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp)))))
+  if (match(Op0, m_Trunc(m_PtrToIntOrAddr(m_Value(LHSOp)))) &&
+      match(Op1, m_Trunc(m_PtrToIntOrAddr(m_Value(RHSOp)))))
     if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType(),
                                                /* IsNUW */ false))
       return replaceInstUsesWith(I, Res);
 
-  if (match(Op0, m_ZExt(m_PtrToIntSameSize(DL, m_Value(LHSOp)))) &&
-      match(Op1, m_ZExtOrSelf(m_PtrToInt(m_Value(RHSOp))))) {
+  if (match(Op0, m_ZExt(m_PtrToIntOrAddr_GEAddrSize(DL, m_Value(LHSOp)))) &&
+      match(Op1, m_ZExtOrSelf(m_PtrToIntOrAddr(m_Value(RHSOp))))) {
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nikic wrote:

I've also added some tests with mixed ptrtoint/ptrtoaddr. These are okay for the non-zext folds, but not okay for the zext fold. (At least as written -- it would require ensuring that the zext is from the same size.)

https://github.com/llvm/llvm-project/pull/164428