[turbofan] Various fixes to allow unboxed doubles as arguments in registers and on the stack.

src/compiler/ia32/code-generator-ia32.cc

Index: src/compiler/ia32/code-generator-ia32.cc
diff --git a/src/compiler/ia32/code-generator-ia32.cc b/src/compiler/ia32/code-generator-ia32.cc
index 298627b55bd35dfb1ba40d35da6b49fa16eca1f6..22a7ea99a66f6b44924ca81061b535ebd3170f8f 100644
--- a/src/compiler/ia32/code-generator-ia32.cc
+++ b/src/compiler/ia32/code-generator-ia32.cc
@@ -1325,31 +1325,26 @@ void CodeGenerator::AssembleReturn() {
         }
       }
       __ pop(ebp);  // Pop caller's frame pointer.
-      __ ret(0);
     } else {
       // No saved registers.
       __ mov(esp, ebp);  // Move stack pointer back to frame pointer.
       __ pop(ebp);       // Pop caller's frame pointer.
-      __ ret(0);
     }
   } else if (descriptor->IsJSFunctionCall() || needs_frame_) {
     // Canonicalize JSFunction return sites for now.
     if (return_label_.is_bound()) {
       __ jmp(&return_label_);
+      return;
     } else {
       __ bind(&return_label_);
       __ mov(esp, ebp);  // Move stack pointer back to frame pointer.
       __ pop(ebp);       // Pop caller's frame pointer.
-      int pop_count = static_cast<int>(descriptor->StackParameterCount());
-      if (pop_count == 0) {
-        __ ret(0);
-      } else {
-        __ Ret(pop_count * kPointerSize, ebx);
-      }
     }
-  } else {
-    __ ret(0);
   }
+  size_t pop_size = descriptor->StackParameterCount() * kPointerSize;
+  // Might need ecx for scratch if pop_size is too big.
+  DCHECK_EQ(0, descriptor->CalleeSavedRegisters() & ecx.bit());
+  __ Ret(static_cast<int>(pop_size), ecx);
 }