From: Sanjoy Das <sanjoy@playingwithpointers.com>
Date: Wed, 15 Oct 2014 23:46:04 +0000 (+0000)
Subject: Revert "r219834 - Teach ScalarEvolution to sharpen range information"
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=a0b0184b334b4614ec37043a00a5b36698e1f4f4

Revert "r219834 - Teach ScalarEvolution to sharpen range information"

This change breaks the asan buildbots:
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux/builds/13468



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219878 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 8d1c632008a..b015481b76c 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -6782,44 +6782,6 @@ bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred,
                                    RHS, LHS, FoundLHS, FoundRHS);
   }
 
-  if (FoundPred == ICmpInst::ICMP_NE) {
-    // If we are predicated on something with range [a, b) known not
-    // equal to a, the range can be sharpened to [a + 1, b).  Use this
-    // fact.
-    auto CheckRange = [this, Pred, LHS, RHS](const SCEV *C, const SCEV *V) {
-      if (!isa<SCEVConstant>(C)) return false;
-
-      ConstantInt *CI = cast<SCEVConstant>(C)->getValue();
-      APInt Min = ICmpInst::isSigned(Pred) ?
-        getSignedRange(V).getSignedMin() : getUnsignedRange(V).getUnsignedMin();
-
-      if (Min!= CI->getValue()) return false; // nothing to sharpen
-      Min++;
-
-      // We know V >= Min, in the same signedness as in Pred.  We can
-      // use this to simplify slt and ult.  If the range had a single
-      // value, Min, we now know that FoundValue can never be true;
-      // and any answer is a correct answer.
-
-      switch (Pred) {
-        case ICmpInst::ICMP_SGT:
-        case ICmpInst::ICMP_UGT:
-          return isImpliedCondOperands(Pred, LHS, RHS, V, getConstant(Min));
-
-        default:
-          llvm_unreachable("don't call with predicates other than ICMP_SGT "
-                           "and ICMP_UGT");
-      }
-    };
-
-    if ((Pred == ICmpInst::ICMP_SGT) || (Pred == ICmpInst::ICMP_UGT)) {
-      // Inequality is reflexive -- check both the combinations.
-      if (CheckRange(FoundLHS, FoundRHS) || CheckRange(FoundRHS, FoundLHS)) {
-        return true;
-      }
-    }
-  }
-
   // Check whether the actual condition is beyond sufficient.
   if (FoundPred == ICmpInst::ICMP_EQ)
     if (ICmpInst::isTrueWhenEqual(Pred))
diff --git a/test/Transforms/IndVarSimplify/sharpen-range-metadata.ll b/test/Transforms/IndVarSimplify/sharpen-range-metadata.ll
deleted file mode 100644
index 5faafe6c47a..00000000000
--- a/test/Transforms/IndVarSimplify/sharpen-range-metadata.ll
+++ /dev/null
@@ -1,39 +0,0 @@
-;; RUN: opt -S < %s -indvars | FileCheck %s
-
-;; Check if llvm can narrow !range metadata based on loop entry
-;; predicates.
-
-declare void @abort()
-
-define i1 @bounded_below(i32* nocapture readonly %buffer) {
-entry:
-  %length = load i32* %buffer, !range !0
-  %entry.pred = icmp eq i32 %length, 0
-  br i1 %entry.pred, label %abort, label %loop.preheader
-
-loop.preheader:
-  br label %loop
-
-loop:
-  %idx = phi i32 [ %idx.inc, %loop.next ], [ 0, %loop.preheader ]
-  %oob.pred = icmp slt i32 %idx, %length
-  br i1 %oob.pred, label %loop.next, label %oob
-; CHECK: br i1 true, label %loop.next, label %oob
-
-loop.next:
-  %idx.inc = add i32 %idx, 1
-  %exit.pred = icmp slt i32 %idx.inc, %length
-  br i1 %exit.pred, label %loop, label %abort.loopexit
-
-abort.loopexit:
-  br label %abort
-
-abort:
-  ret i1 false
-
-oob:
-  tail call void @abort()
-  ret i1 false
-}
-
-!0 = metadata !{i32 0, i32 100}
diff --git a/test/Transforms/IndVarSimplify/widen-loop-comp.ll b/test/Transforms/IndVarSimplify/widen-loop-comp.ll
index 0930a0c4139..bfe74afe894 100644
--- a/test/Transforms/IndVarSimplify/widen-loop-comp.ll
+++ b/test/Transforms/IndVarSimplify/widen-loop-comp.ll
@@ -67,7 +67,8 @@ for.end:
 define void @test2([8 x i8]* %a, i8* %b, i8 %limit) {
 entry:
   %conv = zext i8 %limit to i32
-  br i1 undef, label %for.cond1.preheader, label %for.cond1.preheader.us
+  %cmp23 = icmp eq i8 %limit, 0
+  br i1 %cmp23, label %for.cond1.preheader, label %for.cond1.preheader.us
 
 for.cond1.preheader.us:
   %storemerge5.us = phi i32 [ 0, %entry ], [ %inc14.us, %for.inc13.us ]