From 6ef69d97f54cbeb7c1d6764feb125191ad03c413 Mon Sep 17 00:00:00 2001
From: Sanjoy Das <sanjoy@playingwithpointers.com>
Date: Sun, 2 Oct 2016 00:09:49 +0000
Subject: [ConstantRange] Make getEquivalentICmp smarter

This change teaches getEquivalentICmp to be smarter about generating
ICMP_NE and ICMP_EQ predicates.

llvm-svn: 283057
---
 llvm/lib/IR/ConstantRange.cpp | 8 ++++++++
 1 file changed, 8 insertions(+)

(limited to 'llvm/lib/IR/ConstantRange.cpp')

diff --git a/llvm/lib/IR/ConstantRange.cpp b/llvm/lib/IR/ConstantRange.cpp
index 0f5c7128f3d..0dbefc7b0c2 100644
--- a/llvm/lib/IR/ConstantRange.cpp
+++ b/llvm/lib/IR/ConstantRange.cpp
@@ -147,6 +147,14 @@ bool ConstantRange::getEquivalentICmp(CmpInst::Predicate &Pred,
     Pred = isEmptySet() ? CmpInst::ICMP_ULT : CmpInst::ICMP_UGE;
     RHS = APInt(getBitWidth(), 0);
     Success = true;
+  } else if (auto *OnlyElt = getSingleElement()) {
+    Pred = CmpInst::ICMP_EQ;
+    RHS = *OnlyElt;
+    Success = true;
+  } else if (auto *OnlyMissingElt = inverse().getSingleElement()) {
+    Pred = CmpInst::ICMP_NE;
+    RHS = *OnlyMissingElt;
+    Success = true;
   } else if (getLower().isMinSignedValue() || getLower().isMinValue()) {
     Pred =
         getLower().isMinSignedValue() ? CmpInst::ICMP_SLT : CmpInst::ICMP_ULT;
-- 
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