From e1a73f6ca3facaae75b365fc4b8978ab0717cb2f Mon Sep 17 00:00:00 2001
From: Hans Wennborg <hans@hanshq.net>
Date: Wed, 26 Sep 2012 14:01:53 +0000
Subject: [PATCH] Address Duncan's comments on r164684:

- Put statistics in alphabetical order
- Don't use getZextValue when building TableInt, just use APInts
- Introduce Create{Z,S}ExtOrTrunc in IRBuilder.

llvm-svn: 164696
---
 include/llvm/IRBuilder.h                      | 24 +++++++++++++++++++
 lib/Transforms/Utils/SimplifyCFG.cpp          | 14 ++++-------
 .../SimplifyCFG/switch_to_lookup_table.ll     |  4 ++--
 3 files changed, 31 insertions(+), 11 deletions(-)

diff --git a/include/llvm/IRBuilder.h b/include/llvm/IRBuilder.h
index ff64660a429..f9d219f3a05 100644
--- a/include/llvm/IRBuilder.h
+++ b/include/llvm/IRBuilder.h
@@ -995,6 +995,30 @@ public:
   Value *CreateSExt(Value *V, Type *DestTy, const Twine &Name = "") {
     return CreateCast(Instruction::SExt, V, DestTy, Name);
   }
+  /// CreateZExtOrTrunc - Create a ZExt or Trunc from the integer value V to
+  /// DestTy. Return the value untouched if the type of V is already DestTy.
+  Value *CreateZExtOrTrunc(Value *V, IntegerType *DestTy,
+                           const Twine &Name = "") {
+    assert(isa<IntegerType>(V->getType()) && "Can only zero extend integers!");
+    IntegerType *IntTy = cast<IntegerType>(V->getType());
+    if (IntTy->getBitWidth() < DestTy->getBitWidth())
+      return CreateZExt(V, DestTy, Name);
+    if (IntTy->getBitWidth() > DestTy->getBitWidth())
+      return CreateTrunc(V, DestTy, Name);
+    return V;
+  }
+  /// CreateSExtOrTrunc - Create a SExt or Trunc from the integer value V to
+  /// DestTy. Return the value untouched if the type of V is already DestTy.
+  Value *CreateSExtOrTrunc(Value *V, IntegerType *DestTy,
+                           const Twine &Name = "") {
+    assert(isa<IntegerType>(V->getType()) && "Can only sign extend integers!");
+    IntegerType *IntTy = cast<IntegerType>(V->getType());
+    if (IntTy->getBitWidth() < DestTy->getBitWidth())
+      return CreateSExt(V, DestTy, Name);
+    if (IntTy->getBitWidth() > DestTy->getBitWidth())
+      return CreateTrunc(V, DestTy, Name);
+    return V;
+  }
   Value *CreateFPToUI(Value *V, Type *DestTy, const Twine &Name = ""){
     return CreateCast(Instruction::FPToUI, V, DestTy, Name);
   }
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index d7468a18908..299c0596da3 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -58,10 +58,10 @@ static cl::opt<bool>
 SinkCommon("simplifycfg-sink-common", cl::Hidden, cl::init(true),
        cl::desc("Sink common instructions down to the end block"));
 
-STATISTIC(NumSpeculations, "Number of speculative executed instructions");
-STATISTIC(NumLookupTables, "Number of switch instructions turned into lookup tables");
 STATISTIC(NumBitMaps, "Number of switch instructions turned into bitmaps");
+STATISTIC(NumLookupTables, "Number of switch instructions turned into lookup tables");
 STATISTIC(NumSinkCommons, "Number of common instructions sunk down to the end block");
+STATISTIC(NumSpeculations, "Number of speculative executed instructions");
 
 namespace {
   /// ValueEqualityComparisonCase - Represents a case of a switch.
@@ -3347,7 +3347,8 @@ SwitchLookupTable::SwitchLookupTable(Module &M,
     APInt TableInt(TableSize * IT->getBitWidth(), 0);
     for (uint64_t I = TableSize; I > 0; --I) {
       TableInt <<= IT->getBitWidth();
-      TableInt |= cast<ConstantInt>(TableContents[I - 1])->getZExtValue();
+      ConstantInt *Val = cast<ConstantInt>(TableContents[I - 1]);
+      TableInt |= Val->getValue().zext(TableInt.getBitWidth());
     }
     BitMap = ConstantInt::get(M.getContext(), TableInt);
     BitMapElementTy = IT;
@@ -3379,12 +3380,7 @@ Value *SwitchLookupTable::BuildLookup(Value *Index, IRBuilder<> &Builder) {
       // Cast Index to the same type as the bitmap.
       // Note: The Index is <= the number of elements in the table, so
       // truncating it to the width of the bitmask is safe.
-      Value *ShiftAmt = Index;
-      IntegerType *IndexTy = cast<IntegerType>(Index->getType());
-      if (IndexTy->getBitWidth() < MapTy->getBitWidth())
-        ShiftAmt = Builder.CreateZExt(ShiftAmt, MapTy, "switch.zext");
-      else if (IndexTy->getBitWidth() > MapTy->getBitWidth())
-        ShiftAmt = Builder.CreateTrunc(ShiftAmt, MapTy, "switch.trunc");
+      Value *ShiftAmt = Builder.CreateZExtOrTrunc(Index, MapTy, "switch.cast");
 
       // Multiply the shift amount by the element width.
       ShiftAmt = Builder.CreateMul(ShiftAmt,
diff --git a/test/Transforms/SimplifyCFG/switch_to_lookup_table.ll b/test/Transforms/SimplifyCFG/switch_to_lookup_table.ll
index 97c80b9d48a..ef9d51669d3 100644
--- a/test/Transforms/SimplifyCFG/switch_to_lookup_table.ll
+++ b/test/Transforms/SimplifyCFG/switch_to_lookup_table.ll
@@ -221,8 +221,8 @@ lor.end:
 ; CHECK-NEXT: %0 = icmp ult i8 %switch.tableidx, 59
 ; CHECK-NEXT: br i1 %0, label %switch.lookup, label %lor.end
 ; CHECK: switch.lookup:
-; CHECK-NEXT: %switch.zext = zext i8 %switch.tableidx to i59
-; CHECK-NEXT: %switch.shiftamt = mul i59 %switch.zext, 1
+; CHECK-NEXT: %switch.cast = zext i8 %switch.tableidx to i59
+; CHECK-NEXT: %switch.shiftamt = mul i59 %switch.cast, 1
 ; CHECK-NEXT: %switch.downshift = lshr i59 -288230375765830623, %switch.shiftamt
 ; CHECK-NEXT: %switch.masked = trunc i59 %switch.downshift to i1
 ; CHECK-NEXT: br label %lor.end