From 845435c86ac9fdc92093b7f1459589324b73d41f Mon Sep 17 00:00:00 2001
From: Philip Reames <listmail@philipreames.com>
Date: Tue, 16 Feb 2016 17:14:30 +0000
Subject: [PATCH] Revert 260705, it appears to be causing pr26628

The root issue appears to be a confusion around what makeNoWrapRegion actually does.   It seems likely we need two versions of this function with slightly different semantics.

llvm-svn: 260981
---
 llvm/lib/Analysis/LazyValueInfo.cpp                | 21 ---------
 .../Transforms/CorrelatedValuePropagation/basic.ll | 55 ----------------------
 2 files changed, 76 deletions(-)

diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index d21b1bd..8f12111 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -961,27 +961,6 @@ bool LazyValueInfoCache::solveBlockValueConstantRange(LVILatticeVal &BBLV,
   if (isa<BinaryOperator>(BBI)) {
     if (ConstantInt *RHS = dyn_cast<ConstantInt>(BBI->getOperand(1))) {
       RHSRange = ConstantRange(RHS->getValue());
-
-      // Try to use information about wrap flags to refine the range LHS can
-      // legally have.  This is a slightly weird way to implement forward
-      // propagation over overflowing instructions, but it seems to be the only
-      // clean one we have.  NOTE: Because we may have speculated the
-      // instruction, we can't constrain other uses of LHS even if they would
-      // seem to be equivelent control dependent with this op.
-      if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(BBI)) {
-        unsigned WrapKind = 0;
-        if (OBO->hasNoSignedWrap())
-          WrapKind |= OverflowingBinaryOperator::NoSignedWrap;
-        if (OBO->hasNoUnsignedWrap())
-          WrapKind |= OverflowingBinaryOperator::NoUnsignedWrap;
-
-        if (WrapKind) {
-          auto OpCode = static_cast<Instruction::BinaryOps>(BBI->getOpcode());
-          auto NoWrapCR =
-            ConstantRange::makeNoWrapRegion(OpCode, RHS->getValue(), WrapKind);
-          LHSRange = LHSRange.intersectWith(NoWrapCR);
-        }
-      }
     } else {
       BBLV.markOverdefined();
       return true;
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll b/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
index b0dacbf..9d1253a 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
@@ -199,58 +199,3 @@ out:
 next:
   ret void
 }
-
-; Can we use nsw in LVI to prove lack of overflow?
-define i1 @add_nsw(i32 %s) {
-; CHECK-LABEL: @add_nsw(
-entry:
-  %cmp = icmp sgt i32 %s, 0
-  br i1 %cmp, label %positive, label %out
-
-positive:
-  %add = add nsw i32 %s, 1
-  %res = icmp sgt i32 %add, 0
-  br label %next
-next:
-; CHECK: next:
-; CHECK: ret i1 true
-  ret i1 %res
-out:
-  ret i1 false
-}
-
-define i1 @add_nsw2(i32 %s) {
-; CHECK-LABEL: @add_nsw2(
-entry:
-  %cmp = icmp sge i32 %s, 0
-  br i1 %cmp, label %positive, label %out
-
-positive:
-  %add = add nsw i32 %s, 1
-  %res = icmp ne i32 %add, 0
-  br label %next
-next:
-; CHECK: next:
-; CHECK: ret i1 true
-  ret i1 %res
-out:
-  ret i1 false
-}
-
-define i1 @add_nuw(i32 %s) {
-; CHECK-LABEL: @add_nuw(
-entry:
-  %cmp = icmp ult i32 %s, 400
-  br i1 %cmp, label %positive, label %out
-
-positive:
-  %add = add nsw i32 %s, 1
-  %res = icmp ne i32 %add, -100
-  br label %next
-next:
-; CHECK: next:
-; CHECK: ret i1 true
-  ret i1 %res
-out:
-  ret i1 false
-}
-- 
2.7.4