Reserve space for scalar FP returns in the stack frame

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.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 479 matching lines @@
   uint32_t SpillAreaPaddingBytes = 0;
   uint32_t LocalsSlotsPaddingBytes = 0;
   alignStackSpillAreas(Traits::X86_RET_IP_SIZE_BYTES + PreservedRegsSizeBytes,
                        SpillAreaAlignmentBytes, GlobalsSize,
                        LocalsSlotsAlignmentBytes, &SpillAreaPaddingBytes,
                        &LocalsSlotsPaddingBytes);
   SpillAreaSizeBytes += SpillAreaPaddingBytes + LocalsSlotsPaddingBytes;
   uint32_t GlobalsAndSubsequentPaddingSize =
       GlobalsSize + LocalsSlotsPaddingBytes;
 
+  // Functions returning scalar floating point types may need to convert values
+  // from an in-register xmm value to the top of the x87 floating point stack.
+  // This is done by a movp[sd] and an fld[sd].  Ensure there is enough scratch
+  // space on the stack for this.
+  const Type ReturnType = Func->getReturnType();
+  if (isScalarFloatingType(ReturnType)) {
+    // Avoid misaligned double-precicion load/store.
+    NeedsStackAlignment = true;
+    SpillAreaSizeBytes =
+        std::max(typeWidthInBytesOnStack(ReturnType), SpillAreaSizeBytes);
+  }
+
   // Align esp if necessary.
   if (NeedsStackAlignment) {
     uint32_t StackOffset =
         Traits::X86_RET_IP_SIZE_BYTES + PreservedRegsSizeBytes;
     uint32_t StackSize =
         Traits::applyStackAlignment(StackOffset + SpillAreaSizeBytes);
     SpillAreaSizeBytes = StackSize - StackOffset;
   }
 
   // Combine fixed allocations into SpillAreaSizeBytes if we are emitting the
@@ skipping 484 matching lines @@
 // case the high-level table has extra entries.
 #define X(tag, sizeLog2, align, elts, elty, str)                               \
   static_assert(_table1_##tag == _table2_##tag,                                \
                 "Inconsistency between ICETYPEX8632_TABLE and ICETYPE_TABLE");
 ICETYPE_TABLE
 #undef X
 } // end of namespace dummy3
 } // end of anonymous namespace
 
 } // end of namespace Ice