clang miss assembler error?

It seems to me, that clang++ miss errors in assembler code that g++ pick up. Or am I missing some compiler flag for clang? I'm new to assembler code.

Using clang++ I have compiled and linked my application error and warning free, yet I have had nasty segmentation faults. Switching to g++, I on the other hand I got these errors:

GO_F_ImageColourConversion.cpp: Assembler messages:
GO_F_ImageColourConversion.cpp:4679: Error: `(%rsi,%edx,2)' is not a valid base/index expression 
GO_F_ImageColourConversion.cpp:4682: Error: `(%rcx,%edx,1)' is not a valid base/index expression

I am using these compiler flags: -DLINUX -g -Wno-deprecated -D_GNU_SOURCE -D_REENTRANT -D__STDC_CONSTANT_MACROS -fPIC -fPIE

I have the following code (omitting unrelevant parts):

Ipp8u * pSrc;
Ipp8u * pDst;
int x, y;

                asm volatile
                    (
                     "movl      (%1, %0, 2), %%eax;\n"
                     "shlw      $8, %%ax;\n"
                     "shrl      $8, %%eax;\n"
                     "movw      %%ax, (%2, %0, 1);\n"

                    : /* no output */
                    : "r" (x), "r" (pSrc), "r" (pDst)
                    : "eax", "memory");
            }

From looking at this answer on SO, I realized I had a 32/64 bit isssue (I am porting to 64-bit).The Ipp8u* is 8 bit but int only 4 bit on my machine.

Changing the int to uintptr_t x, y; seems to fix the issue. Why does clang not give error on compile?