[ConstantFold] inttoptr, ptrtoaddr is valid cast pair

Author: XChy

llvm/lib/IR/Instructions.cpp

@@ -2847,6 +2847,7 @@ unsigned CastInst::isEliminableCastPair(
   // FPTRUNC       >       FloatPt      n/a        FloatPt      n/a
   // FPEXT         <       FloatPt      n/a        FloatPt      n/a
   // PTRTOINT     n/a      Pointer      n/a        Integral   Unsigned
+  // PTRTOADDR    n/a      Pointer      n/a        Integral   Unsigned
   // INTTOPTR     n/a      Integral   Unsigned     Pointer      n/a
   // BITCAST       =       FirstClass   n/a       FirstClass    n/a
   // ADDRSPCST    n/a      Pointer      n/a        Pointer      n/a
@@ -2878,7 +2879,7 @@ unsigned CastInst::isEliminableCastPair(
     { 99,99,99, 2, 2,99,99, 8, 2,99,99,99, 4, 0}, // FPExt          |
     {  1, 0, 0,99,99, 0, 0,99,99,99,99, 7, 3, 0}, // PtrToInt       |
     {  1, 0, 0,99,99, 0, 0,99,99,99,99, 0, 3, 0}, // PtrToAddr      |
-    { 99,99,99,99,99,99,99,99,99,11,99,99,15, 0}, // IntToPtr       |
+    { 99,99,99,99,99,99,99,99,99,11, 0,99,15, 0}, // IntToPtr       |
     {  5, 5, 5, 0, 0, 5, 5, 0, 0,16,16, 5, 1,14}, // BitCast        |
     {  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,13,12}, // AddrSpaceCast -+
   };

llvm/test/Transforms/InstCombine/constant-expr-datalayout.ll

@@ -32,3 +32,17 @@ define i64 @OpenFilter(i64 %x) {
   %r = zext i8 %t to i64
   ret i64 %r
 }
+
+define i64 @ptr2addr1() {
+; CHECK-LABEL: @ptr2addr1(
+; CHECK-NEXT:    ret i64 ptrtoaddr (ptr inttoptr (i64 1 to ptr) to i64)
+;
+  ret i64 ptrtoaddr (ptr getelementptr (i8, ptr null, i64 1) to i64)
+}
+
+define i64 @ptr2addr2() {
+; CHECK-LABEL: @ptr2addr2(
+; CHECK-NEXT:    ret i64 ptrtoaddr (ptr inttoptr (i64 123 to ptr) to i64)
+;
+  ret i64 ptrtoaddr (ptr inttoptr (i64 123 to ptr) to i64)
+}