Subzero: Fix x86 floating-point constant emission

src/IceTargetLoweringX8632.cpp

 //===- subzero/src/IceTargetLoweringX8632.cpp - x86-32 lowering -----------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the TargetLoweringX8632 class, which
@@ skipping 544 matching lines @@
   for (SizeT i = 0; i < CalleeSaves.size(); ++i) {
     SizeT j = CalleeSaves.size() - i - 1;
     if (j == Reg_ebp && IsEbpBasedFrame)
       continue;
     if (CalleeSaves[j] && RegsUsed[j]) {
       _pop(getPhysicalRegister(j));
     }
   }
 }
 
+template <typename T> struct PoolTypeConverter {};
+
+template <> struct PoolTypeConverter<float> {
+  typedef float PrimitiveFpType;
+  typedef uint32_t PrimitiveIntType;
+  typedef ConstantFloat IceType;
+  static const Type Ty = IceType_f32;
+  static const char *TypeName;
+  static const char *AsmTag;
+  static const char *PrintfString;
+};
+const char *PoolTypeConverter<float>::TypeName = "float";
+const char *PoolTypeConverter<float>::AsmTag = ".long";
+const char *PoolTypeConverter<float>::PrintfString = "0x%x";
+
+template <> struct PoolTypeConverter<double> {
+  typedef double PrimitiveFpType;
+  typedef uint64_t PrimitiveIntType;
+  typedef ConstantDouble IceType;
+  static const Type Ty = IceType_f64;
+  static const char *TypeName;
+  static const char *AsmTag;
+  static const char *PrintfString;
+};
+const char *PoolTypeConverter<double>::TypeName = "double";
+const char *PoolTypeConverter<double>::AsmTag = ".quad";
+const char *PoolTypeConverter<double>::PrintfString = "0x%llx";
+
+template <typename T> void TargetX8632::emitConstantPool() const {
+  Ostream &Str = Ctx->getStrEmit();
+  SizeT Align;
+  Type Ty;
+  ConstantList Pool;
+
+  Ty = T::Ty;
+  Pool = Ctx->getConstantPool(Ty);
+  Align = typeAlignInBytes(Ty);

[JF, 2014/05/23 16:35:03]

Do these in the initialization above.

[Jim Stichnoth, 2014/05/23 20:37:35]

Done.

+  Str << "\t.section\t.rodata.cst" << Align << ",\"aM\",@progbits," << Align
+      << "\n";
+  Str << "\t.align\t" << Align << "\n";
+  for (ConstantList::const_iterator I = Pool.begin(), E = Pool.end(); I != E;
+       ++I) {
+    typename T::IceType *Const = llvm::cast<typename T::IceType>(*I);
+    typename T::PrimitiveFpType Value = Const->getValue();
+    // Use memcpy() to copy bits from Value into RawValue in a way
+    // that avoids breaking strict-aliasing rules.
+    typename T::PrimitiveIntType RawValue;
+    memcpy(&RawValue, &Value, sizeof(Value));
+    char buf[30];
+    snprintf(buf, llvm::array_lengthof(buf), T::PrintfString, RawValue);

[JF, 2014/05/23 16:35:03]

Check that the return is in [0, size-1].

[Jim Stichnoth, 2014/05/23 20:37:35]

Done.

+    Str << "L$" << Ty << "$" << Const->getPoolEntryID() << ":\n";
+    Str << "\t" << T::AsmTag << "\t" << buf << "\t# " << T::TypeName << " "
+        << Value << "\n";
+  }
+}
+
+void TargetX8632::emitConstants() const {
+  emitConstantPool<PoolTypeConverter<float> >();
+  emitConstantPool<PoolTypeConverter<double> >();
+
+  // No need to emit constants from the int pool since (for x86) they
+  // are embedded as immediates in the instructions.
+}
+
 void TargetX8632::split64(Variable *Var) {
   switch (Var->getType()) {
   default:
     return;
   case IceType_i64:
   // TODO: Only consider F64 if we need to push each half when
   // passing as an argument to a function call.  Note that each half
   // is still typed as I32.
   case IceType_f64:
     break;
@@ skipping 1296 matching lines @@
         }
         assert(AvailableTypedRegisters.any());
         int32_t RegNum = AvailableTypedRegisters.find_first();
         Var->setRegNum(RegNum);
         AvailableRegisters[RegNum] = false;
       }
     }
   }
 }
 
+template <> void ConstantFloat::emit(const Cfg *Func) const {
+  Ostream &Str = Func->getContext()->getStrEmit();
+  // It would be better to prefix with ".L$" instead of "L$", but
+  // llvm-mc doesn't parse "dword ptr [.L$foo]".
+  Str << "dword ptr [L$" << IceType_f32 << "$" << getPoolEntryID() << "]";
+}
+
+template <> void ConstantDouble::emit(const Cfg *Func) const {
+  Ostream &Str = Func->getContext()->getStrEmit();
+  Str << "qword ptr [L$" << IceType_f64 << "$" << getPoolEntryID() << "]";
+}
+
 } // end of namespace Ice