Add back r153360 with a fix for enums that cover all the 32 bit values.

Thanks to NAKAMURA Takumi for finding it!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@153383 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/CGExpr.cpp

@@ -860,6 +860,62 @@ llvm::Value *CodeGenFunction::EmitLoadOfScalar(LValue lvalue) {
                           lvalue.getType(), lvalue.getTBAAInfo());
 }
 
+static bool hasBooleanRepresentation(QualType Ty) {
+  if (Ty->isBooleanType())
+    return true;
+
+  if (const EnumType *ET = Ty->getAs<EnumType>())
+    return ET->getDecl()->getIntegerType()->isBooleanType();
+
+  return false;
+}
+
+llvm::MDNode *CodeGenFunction::getRangeForLoadFromType(QualType Ty) {
+  const EnumType *ET = Ty->getAs<EnumType>();
+  bool IsRegularCPlusPlusEnum = getLangOpts().CPlusPlus && ET &&
+    !ET->getDecl()->isFixed();
+  bool IsBool = hasBooleanRepresentation(Ty);
+  llvm::Type *LTy;
+  if (!IsBool && !IsRegularCPlusPlusEnum)
+    return NULL;
+
+  llvm::APInt Min;
+  llvm::APInt End;
+  if (IsBool) {
+    Min = llvm::APInt(8, 0);
+    End = llvm::APInt(8, 2);
+    LTy = Int8Ty;
+  } else {
+    const EnumDecl *ED = ET->getDecl();
+    LTy = ConvertTypeForMem(ED->getIntegerType());
+    unsigned Bitwidth = LTy->getScalarSizeInBits();
+    unsigned NumNegativeBits = ED->getNumNegativeBits();
+    unsigned NumPositiveBits = ED->getNumPositiveBits();
+
+    if (NumNegativeBits) {
+      unsigned NumBits = std::max(NumNegativeBits, NumPositiveBits + 1);
+      assert(NumBits <= Bitwidth);
+      End = llvm::APInt(Bitwidth, 1) << (NumBits - 1);
+      Min = -End;
+    } else {
+      assert(NumPositiveBits <= Bitwidth);
+      End = llvm::APInt(Bitwidth, 1) << NumPositiveBits;
+      Min = llvm::APInt(Bitwidth, 0);
+    }
+  }
+
+  if (End == Min)
+    return NULL;
+
+  llvm::Value *LowAndHigh[2];
+  LowAndHigh[0] = llvm::ConstantInt::get(LTy, Min);
+  LowAndHigh[1] = llvm::ConstantInt::get(LTy, End);
+
+  llvm::LLVMContext &C = getLLVMContext();
+  llvm::MDNode *Range = llvm::MDNode::get(C, LowAndHigh);
+  return Range;
+}
+
 llvm::Value *CodeGenFunction::EmitLoadOfScalar(llvm::Value *Addr, bool Volatile,
                                               unsigned Alignment, QualType Ty,
                                               llvm::MDNode *TBAAInfo) {
@@ -874,18 +930,16 @@ llvm::Value *CodeGenFunction::EmitLoadOfScalar(llvm::Value *Addr, bool Volatile,
   if (Ty->isAtomicType())
     Load->setAtomic(llvm::SequentiallyConsistent);
 
-  return EmitFromMemory(Load, Ty);
-}
+  if (CGM.getCodeGenOpts().OptimizationLevel > 0)
+    if (llvm::MDNode *RangeInfo = getRangeForLoadFromType(Ty))
+      Load->setMetadata(llvm::LLVMContext::MD_range, RangeInfo);
 
-static bool isBooleanUnderlyingType(QualType Ty) {
-  if (const EnumType *ET = dyn_cast<EnumType>(Ty))
-    return ET->getDecl()->getIntegerType()->isBooleanType();
-  return false;
+  return EmitFromMemory(Load, Ty);
 }
 
 llvm::Value *CodeGenFunction::EmitToMemory(llvm::Value *Value, QualType Ty) {
   // Bool has a different representation in memory than in registers.
-  if (Ty->isBooleanType() || isBooleanUnderlyingType(Ty)) {
+  if (hasBooleanRepresentation(Ty)) {
     // This should really always be an i1, but sometimes it's already
     // an i8, and it's awkward to track those cases down.
     if (Value->getType()->isIntegerTy(1))
@@ -898,7 +952,7 @@ llvm::Value *CodeGenFunction::EmitToMemory(llvm::Value *Value, QualType Ty) {
 
 llvm::Value *CodeGenFunction::EmitFromMemory(llvm::Value *Value, QualType Ty) {
   // Bool has a different representation in memory than in registers.
-  if (Ty->isBooleanType() || isBooleanUnderlyingType(Ty)) {
+  if (hasBooleanRepresentation(Ty)) {
     assert(Value->getType()->isIntegerTy(8) && "memory rep of bool not i8");
     return Builder.CreateTrunc(Value, Builder.getInt1Ty(), "tobool");
   }

lib/CodeGen/CodeGenFunction.h

@@ -2522,6 +2522,7 @@ public:
                      unsigned AccuracyD = 1);
 
 private:
+  llvm::MDNode *getRangeForLoadFromType(QualType Ty);
   void EmitReturnOfRValue(RValue RV, QualType Ty);
 
   /// ExpandTypeFromArgs - Reconstruct a structure of type \arg Ty

test/CodeGen/pr12251.c

@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 %s -emit-llvm -O1 -relaxed-aliasing -o - | FileCheck %s
+
+enum e1 {e1_a = -1 };
+enum e1 g1(enum e1 *x) {
+  return *x;
+}
+
+// CHECK: define i32 @g1
+// CHECK: load i32* %x, align 4
+// CHECK-NOT: range
+// CHECK: ret

test/CodeGenCXX/pr12251.cpp

@@ -0,0 +1,139 @@
+// RUN: %clang_cc1 %s -emit-llvm -O1 -relaxed-aliasing -std=c++11 -o - | FileCheck %s
+
+bool f(bool *x) {
+  return *x;
+}
+// CHECK: define zeroext i1 @_Z1fPb
+// CHECK: load i8* %{{.*}}, align 1, !range !0
+
+enum e1 { };
+e1 g1(e1 *x) {
+  return *x;
+}
+// CHECK: define i32 @_Z2g1P2e1
+// CHECK: load i32* %x, align 4, !range !1
+
+enum e2 { e2_a = 0 };
+e2 g2(e2 *x) {
+  return *x;
+}
+// CHECK: define i32 @_Z2g2P2e2
+// CHECK: load i32* %x, align 4, !range !1
+
+enum e3 { e3_a = 16 };
+e3 g3(e3 *x) {
+  return *x;
+}
+// CHECK: define i32 @_Z2g3P2e3
+// CHECK: load i32* %x, align 4, !range !2
+
+enum e4 { e4_a = -16};
+e4 g4(e4 *x) {
+  return *x;
+}
+// CHECK: define i32 @_Z2g4P2e4
+// CHECK: load i32* %x, align 4, !range !3
+
+enum e5 { e5_a = -16, e5_b = 16};
+e5 g5(e5 *x) {
+  return *x;
+}
+// CHECK: define i32 @_Z2g5P2e5
+// CHECK: load i32* %x, align 4, !range !4
+
+enum e6 { e6_a = -1 };
+e6 g6(e6 *x) {
+  return *x;
+}
+// CHECK: define i32 @_Z2g6P2e6
+// CHECK: load i32* %x, align 4, !range !5
+
+enum e7 { e7_a = -16, e7_b = 2};
+e7 g7(e7 *x) {
+  return *x;
+}
+// CHECK: define i32 @_Z2g7P2e7
+// CHECK: load i32* %x, align 4, !range !3
+
+enum e8 { e8_a = -17};
+e8 g8(e8 *x) {
+  return *x;
+}
+// CHECK: define i32 @_Z2g8P2e8
+// CHECK: load i32* %x, align 4, !range !4
+
+enum e9 { e9_a = 17};
+e9 g9(e9 *x) {
+  return *x;
+}
+// CHECK: define i32 @_Z2g9P2e9
+// CHECK: load i32* %x, align 4, !range !2
+
+enum e10 { e10_a = -16, e10_b = 32};
+e10 g10(e10 *x) {
+  return *x;
+}
+// CHECK: define i32 @_Z3g10P3e10
+// CHECK: load i32* %x, align 4, !range !6
+
+enum e11 {e11_a = 4294967296 };
+enum e11 g11(enum e11 *x) {
+  return *x;
+}
+// CHECK: define i64 @_Z3g11P3e11
+// CHECK: load i64* %x, align {{[84]}}, !range !7
+
+enum e12 {e12_a = 9223372036854775808U };
+enum e12 g12(enum e12 *x) {
+  return *x;
+}
+// CHECK: define i64 @_Z3g12P3e12
+// CHECK: load i64* %x, align {{[84]}}
+// CHECK-NOT: range
+// CHECK: ret
+
+enum e13 : char {e13_a = -1 };
+e13 g13(e13 *x) {
+  return *x;
+}
+// CHECK: define signext i8 @_Z3g13P3e13
+// CHECK: load i8* %x, align 1
+// CHECK-NOT: range
+// CHECK: ret
+
+enum class e14 {e14_a = 1};
+e14 g14(e14 *x) {
+  return *x;
+}
+// CHECK: define i32 @_Z3g14P3e14
+// CHECK: load i32* %x, align 4
+// CHECK-NOT: range
+// CHECK: ret
+
+enum e15 { e15_a = 2147483648 };
+e15 g15(e15 *x) {
+  return *x;
+}
+// CHECK: define i32 @_Z3g15P3e15
+// CHECK: load i32* %x, align 4
+// CHECK-NOT: range
+// CHECK: ret
+
+enum e16 { e16_a = -2147483648 };
+e16 g16(e16 *x) {
+  return *x;
+}
+// CHECK: define i32 @_Z3g16P3e16q
+// CHECK: load i32* %x, align 4
+// CHECK-NOT: range
+// CHECK: ret
+
+
+// CHECK: !0 = metadata !{i8 0, i8 2}
+// CHECK: !1 = metadata !{i32 0, i32 1}
+// CHECK: !2 = metadata !{i32 0, i32 32}
+// CHECK: !3 = metadata !{i32 -16, i32 16}
+// CHECK: !4 = metadata !{i32 -32, i32 32}
+// CHECK: !5 = metadata !{i32 -1, i32 1}
+// CHECK: !6 = metadata !{i32 -64, i32 64}
+// CHECK: !7 = metadata !{i64 0, i64 8589934592}