[PATCH] D65017: [InstCombine] Teach foldOrOfICmps to allow icmp eq MIN_INT/MAX to be part of a range comparision.

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp:2262
+    case ICmpInst::ICMP_SGT:
+      // We can treat equality of MIN_SINT as being ULE MIN_SINT.
+      if (LHSC->isMinValue(true))
----------------
ULE -> SLE


================
Comment at: llvm/test/Transforms/InstCombine/and-or-icmps.ll:316
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ugt i32 [[X_OFF]], 2147483645
+; CHECK-NEXT:    ret i1 [[TMP1]]
 ;
----------------
This seems like a weird choice that the range check code is making. We could also generate

```
%x.off = add i32 %x, 1
%c = icmp ult i32 %x.off, -2147483646
```

with smaller constants.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D65017/new/

https://reviews.llvm.org/D65017