From 608d59f535b9981602d4553b18f346e8aee25cc2 Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanaka@apple.com>
Date: Thu, 16 Oct 2014 01:17:02 +0000
Subject: [PATCH] Revert r219832.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219884 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../InstCombine/InstructionCombining.cpp      | 31 ----------
 test/Transforms/InstCombine/narrow-switch.ll  | 61 -------------------
 2 files changed, 92 deletions(-)
 delete mode 100644 test/Transforms/InstCombine/narrow-switch.ll

diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp
index e158c11b1fd..ac0c01e3c7b 100644
--- a/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2075,37 +2075,6 @@ Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
 
 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
   Value *Cond = SI.getCondition();
-  unsigned BitWidth = cast<IntegerType>(Cond->getType())->getBitWidth();
-  APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
-  computeKnownBits(Cond, KnownZero, KnownOne);
-  unsigned LeadingKnownZeros = KnownZero.countLeadingOnes();
-  unsigned LeadingKnownOnes = KnownOne.countLeadingOnes();
-
-  // Compute the number of leading bits we can ignore.
-  for (auto &C : SI.cases()) {
-    LeadingKnownZeros = std::min(
-        LeadingKnownZeros, C.getCaseValue()->getValue().countLeadingZeros());
-    LeadingKnownOnes = std::min(
-        LeadingKnownOnes, C.getCaseValue()->getValue().countLeadingOnes());
-  }
-
-  unsigned NewWidth = BitWidth - std::max(LeadingKnownZeros, LeadingKnownOnes);
-
-  // Truncate the condition operand if the new type is equal to or larger than
-  // the largest legal integer type. We need to be conservative here since
-  // x86 generates redundant zero-extenstion instructions if the operand is
-  // truncated to i8 or i16.
-  if (BitWidth > NewWidth && NewWidth >= DL->getLargestLegalIntTypeSize()) {
-    IntegerType *Ty = IntegerType::get(SI.getContext(), NewWidth);
-    Builder->SetInsertPoint(&SI);
-    Value *NewCond = Builder->CreateTrunc(SI.getCondition(), Ty, "trunc");
-    SI.setCondition(NewCond);
-
-    for (auto &C : SI.cases())
-      static_cast<SwitchInst::CaseIt *>(&C)->setValue(
-          ConstantInt::get(Ty, C.getCaseValue()->getValue().getZExtValue()));
-  }
-
   if (Instruction *I = dyn_cast<Instruction>(Cond)) {
     if (I->getOpcode() == Instruction::Add)
       if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
diff --git a/test/Transforms/InstCombine/narrow-switch.ll b/test/Transforms/InstCombine/narrow-switch.ll
deleted file mode 100644
index f649afcce80..00000000000
--- a/test/Transforms/InstCombine/narrow-switch.ll
+++ /dev/null
@@ -1,61 +0,0 @@
-; RUN: opt < %s -instcombine -S | FileCheck %s
-
-target datalayout = "e-m:o-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"
-
-; CHECK-LABEL: define i32 @positive1
-; CHECK: switch i32
-; CHECK: i32 10, label
-; CHECK: i32 100, label
-; CHECK: i32 1001, label
-
-define i32 @positive1(i64 %a) {
-entry:
-  %and = and i64 %a, 4294967295
-  switch i64 %and, label %sw.default [
-    i64 10, label %return
-    i64 100, label %sw.bb1
-    i64 1001, label %sw.bb2
-  ]
-
-sw.bb1:
-  br label %return
-
-sw.bb2:
-  br label %return
-
-sw.default:
-  br label %return
-
-return:
-  %retval.0 = phi i32 [ 24, %sw.default ], [ 123, %sw.bb2 ], [ 213, %sw.bb1 ], [ 231, %entry ]
-  ret i32 %retval.0
-}
-
-; CHECK-LABEL: define i32 @negative1
-; CHECK: switch i32
-; CHECK: i32 -10, label
-; CHECK: i32 -100, label
-; CHECK: i32 -1001, label
-
-define i32 @negative1(i64 %a) {
-entry:
-  %or = or i64 %a, -4294967296
-  switch i64 %or, label %sw.default [
-    i64 -10, label %return
-    i64 -100, label %sw.bb1
-    i64 -1001, label %sw.bb2
-  ]
-
-sw.bb1:
-  br label %return
-
-sw.bb2:
-  br label %return
-
-sw.default:
-  br label %return
-
-return:
-  %retval.0 = phi i32 [ 24, %sw.default ], [ 123, %sw.bb2 ], [ 213, %sw.bb1 ], [ 231, %entry ]
-  ret i32 %retval.0
-}
-- 
2.40.0