[PATCH] D60377: [ConstantRange] Add PreferredResultType support for unionWith()

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


================
Comment at: llvm/lib/IR/ConstantRange.cpp:470
 
+static ConstantRange getPreferredRange(
+    const ConstantRange &CR1, const ConstantRange &CR2,
----------------
Please do this as preparatory NFC commit.


================
Comment at: llvm/lib/IR/ConstantRange.cpp:609
   if (!isUpperWrapped() && !CR.isUpperWrapped()) {
-    if (CR.Upper.ult(Lower) || Upper.ult(CR.Lower)) {
-      // If the two ranges are disjoint, find the smaller gap and bridge it.
-      APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Upper;
-      if (d1.ult(d2))
-        return ConstantRange(Lower, CR.Upper);
-      return ConstantRange(CR.Lower, Upper);
-    }
+    if (CR.Upper.ult(Lower) || Upper.ult(CR.Lower))
+      return getPreferredRange(
----------------
And here we have
```
    //  L---U            : this
    //        L---U      : CR
or
    //        L---U      : this
    //  L---U            : CR

=>

    //  L---------U      : this
or
    //        L--------- : this
    // -----U            : CR
```
?


================
Comment at: llvm/lib/IR/ConstantRange.cpp:635
     //       L---U       : CR
-    //    <d1>  <d2>
-    if (Upper.ule(CR.Lower) && CR.Upper.ule(Lower)) {
-      APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Upper;
-      if (d1.ult(d2))
-        return ConstantRange(Lower, CR.Upper);
-      return ConstantRange(CR.Lower, Upper);
-    }
+    if (Upper.ult(CR.Lower) && CR.Upper.ult(Lower))
+      return getPreferredRange(
----------------
So we will produce 
```
    // ----U       L---- : this
    //       L---U       : CR
=>
    // ----------U L----
or
    // ----U L----------
```
and in either case we bridge either of the gaps?


================
Comment at: llvm/unittests/IR/ConstantRangeTest.cpp:367
+template<typename Fn1, typename Fn2>
+void testBinarySetOperationExhaustive(Fn1 OpFn, Fn2 InResultFn) {
   unsigned Bits = 4;
----------------
Also, could you please do this as NFC commit


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D60377/new/

https://reviews.llvm.org/D60377