Revert "Re-apply:" Emit DW_OP_implicit_value for Floating point constants""

This patch reverts commit `59a76d957a26` as it has caused failure on the
big endian PowerPC buildbots (as well as the SystemZ buildbots).

Author: amy-kwan

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -2488,7 +2488,6 @@ void DwarfDebug::emitDebugLocValue(const AsmPrinter &AP, const DIBasicType *BT,
       DwarfExpr.addSignedConstant(Value.getInt());
     else
       DwarfExpr.addUnsignedConstant(Value.getInt());
-    DwarfExpr.addExpression(std::move(ExprCursor));
   } else if (Value.isLocation()) {
     MachineLocation Location = Value.getLoc();
     DwarfExpr.setLocation(Location, DIExpr);
@@ -2509,24 +2508,10 @@ void DwarfDebug::emitDebugLocValue(const AsmPrinter &AP, const DIBasicType *BT,
       DwarfExpr.addExpression(std::move(ExprCursor));
       return;
   } else if (Value.isConstantFP()) {
-    if (AP.getDwarfVersion() >= 4 && AP.getDwarfDebug()->tuneForGDB()) {
-      DwarfExpr.addConstantFP(Value.getConstantFP()->getValueAPF());
-      return;
-    } else if (Value.getConstantFP()
-                   ->getValueAPF()
-                   .bitcastToAPInt()
-                   .getBitWidth() <= 64 /*bits*/) {
-      DwarfExpr.addUnsignedConstant(
-          Value.getConstantFP()->getValueAPF().bitcastToAPInt());
-      DwarfExpr.addExpression(std::move(ExprCursor));
-      return;
-    }
-    LLVM_DEBUG(
-        dbgs()
-        << "Skipped DwarfExpression creation for ConstantFP of size: "
-        << Value.getConstantFP()->getValueAPF().bitcastToAPInt().getBitWidth()
-        << " bits\n");
+    APInt RawBytes = Value.getConstantFP()->getValueAPF().bitcastToAPInt();
+    DwarfExpr.addUnsignedConstant(RawBytes);
   }
+  DwarfExpr.addExpression(std::move(ExprCursor));
 }
 
 void DebugLocEntry::finalize(const AsmPrinter &AP,

llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp

@@ -25,8 +25,6 @@
 
 using namespace llvm;
 
-#define DEBUG_TYPE "dwarfdebug"
-
 void DwarfExpression::emitConstu(uint64_t Value) {
   if (Value < 32)
     emitOp(dwarf::DW_OP_lit0 + Value);
@@ -221,36 +219,6 @@ void DwarfExpression::addUnsignedConstant(const APInt &Value) {
   }
 }
 
-void DwarfExpression::addConstantFP(const APFloat &Value) {
-  assert(isImplicitLocation() || isUnknownLocation());
-  APInt RawBytes = Value.bitcastToAPInt();
-  int NumBytes = RawBytes.getBitWidth() / 8;
-  const char *Data = (const char *)RawBytes.getRawData();
-  emitOp(dwarf::DW_OP_implicit_value);
-  if (NumBytes == 4 /*float*/ || NumBytes == 8 /*double*/) {
-    emitUnsigned(NumBytes /*Size of the block in bytes*/);
-    for (int i = 0; i < NumBytes; ++i)
-      emitData1(Data[i]);
-    return;
-  }
-  if (NumBytes == 10 /*long double*/) {
-    // long double IEEE representation uses 80 bits(10 bytes).
-    // 6 bytes are padded to make it 128 bits(16 bytes) due to
-    // addressing restrictions.
-    emitUnsigned(16 /*Size of the block in bytes*/);
-    // Emit the block of bytes.
-    for (int i = 0; i < NumBytes; ++i)
-      emitData1(Data[i]);
-    // Emit the rest as padding bytes.
-    for (int i = 0; i < 16 - NumBytes; ++i)
-      emitData1(0);
-    return;
-  }
-  LLVM_DEBUG(
-      dbgs() << "Skipped DW_OP_implicit_value creation for ConstantFP of size: "
-             << RawBytes.getBitWidth() << " bits\n");
-}
-
 bool DwarfExpression::addMachineRegExpression(const TargetRegisterInfo &TRI,
                                               DIExpressionCursor &ExprCursor,
                                               unsigned MachineReg,

llvm/lib/CodeGen/AsmPrinter/DwarfExpression.h

@@ -299,9 +299,6 @@ class DwarfExpression {
   /// Emit an unsigned constant.
   void addUnsignedConstant(const APInt &Value);
 
-  /// Emit floating point constant.
-  void addConstantFP(const APFloat &Value);
-
   /// Lock this down to become a memory location description.
   void setMemoryLocationKind() {
     assert(isUnknownLocation());

llvm/test/DebugInfo/X86/float_const_loclist.ll

@@ -20,10 +20,12 @@
 ;
 ; CHECK: .debug_info contents:
 ; CHECK: DW_TAG_variable
+; CHECK-NEXT:  DW_AT_location {{.*}} (
+; CHECK-NEXT:    [0x[[START:.*]], 0x[[END:.*]]): DW_OP_constu 0xc8f5c28f5c28f800, DW_OP_piece 0x8, DW_OP_constu 0x4000, DW_OP_bit_piece 0x10 0x40)
 ; CHECK-NEXT:  DW_AT_name {{.*}}"ld"
 ; CHECK: DW_TAG_variable
 ; CHECK-NEXT:  DW_AT_location {{.*}} (
-; CHECK-NEXT:    [0x{{.*}}, 0x{{.*}}): DW_OP_constu 0x4048f5c3)
+; CHECK-NEXT:    [0x[[START]], 0x[[END]]): DW_OP_constu 0x4048f5c3)
 ; CHECK-NEXT:  DW_AT_name {{.*}}"f"
 
 source_filename = "test.c"