[X86][InlineAsm][Bugfix] Use mem size information (*word ptr) for "global variable + registers" memory expression in inline asm.

[xiangzhangllvm]

Summary

Currently we miss the mem size info (e.g. *word ptr) for parsing MS InlineAsm
which use a global variable and one/two registers in a memory expression.

There was error of "ambiguous operand size for some instructions. (e.g. 'fmul')"

[pengfei]

LGTM.

clang/test/CodeGen/X86/ms_fmul.c

+// REQUIRES: x86-registered-target
+
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -fasm-blocks -emit-llvm %s -o - | FileCheck %s
+// RUN: %clang_cc1 -triple i386-unknown-unknown -fasm-blocks -emit-llvm %s -o - | FileCheck %s
+
+// This test is designed to check if we use the mem size info for parsing MS
+// InlineAsm which use a global variable and one/two registers in a memory
+// expression. If we not use this mem size info, there will be error of
+// ambiguous operand size for some instructions. (e.g. 'fmul')
+__attribute__((aligned (16)))
+static const unsigned int static_const_table[] = { 0x00800000, };
+
+
+void __attribute__ ((naked)) foo(void)
+{__asm{
+    fmul qword ptr [static_const_table + 0x00f0 +edx]
+    ret
+}}
+
+// CHECK-LABEL: foo
+// CHECK: call void asm sideeffect inteldialect "fmul qword ptr static_const_table[edx + $$240]\0A\09ret"

llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp

if (Info.isKind(InlineAsmIdentifierInfo::IK_Var)) {
     FrontendSize = Info.Var.Type * 8;
     Decl = Info.Var.Decl;
     IsGlobalLV = Info.Var.IsGlobalLV;
   }
   // It is widely common for MS InlineAsm to use a global variable and one/two
   // registers in a mmory expression, and though unaccessible via rip/eip.
   if (IsGlobalLV && (BaseReg || IndexReg)) {
     Operands.push_back(
-        X86Operand::CreateMem(getPointerWidth(), Disp, Start, End));
+        X86Operand::CreateMem(getPointerWidth(), Disp, Start, End, Size));
     return false;
   }
   // Otherwise, we set the base register to a non-zero value
   // if we don't know the actual value at this time.  This is necessary to
   // get the matching correct in some cases.
   BaseReg = BaseReg ? BaseReg : 1;
   Operands.push_back(X86Operand::CreateMem(
       getPointerWidth(), SegReg, Disp, BaseReg, IndexReg, Scale, Start, End,