[X86] Use extended vector register classes in getRegForInlineAsmConstraint to support x/y/zmm16-31 when the type is mismatched.

[craig.topper]

Summary

The FR32/FR64/VR128/VR256 register classes don't contain the upper 16 registers. For most cases we use the default implementation which will find any register class that contains the register in question if the VT is legal for the register class. But if the VT is i32 or i64, we won't find a matching register class and will instead up in the code modified in this patch.

If the requested register is x/y/zmm16-31 we weren't returning a register class that contains those registers and will hit an assertion in the caller.

To fix this, I've changed to use the extended register class instead. I don't believe we need a subtarget check to see if avx512 is enabled. The default implementation just pick whatever register class it finds first. I checked and we currently pick FR32X for XMM0 with an f32 type using the default implementation regardless of whether avx512 is enabled. So I assume its it is ok to do the same for i32.

[craig.topper]

Add the whole patch not just the test.

[rnk]

lgtm

llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

X86TargetLowering::getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI,
   } else if (isFRClass(*Class)) {
     // Handle references to XMM physical registers that got mapped into the
     // wrong class.  This can happen with constraints like {xmm0} where the
     // target independent register mapper will just pick the first match it can
     // find, ignoring the required type.
 
     // TODO: Handle f128 and i128 in FR128RegClass after it is tested well.
     if (VT == MVT::f32 || VT == MVT::i32)
-      Res.second = &X86::FR32RegClass;
+      Res.second = &X86::FR32XRegClass;
     else if (VT == MVT::f64 || VT == MVT::i64)
-      Res.second = &X86::FR64RegClass;
-    else if (TRI->isTypeLegalForClass(X86::VR128RegClass, VT))
-      Res.second = &X86::VR128RegClass;
-    else if (TRI->isTypeLegalForClass(X86::VR256RegClass, VT))
-      Res.second = &X86::VR256RegClass;
+      Res.second = &X86::FR64XRegClass;
+    else if (TRI->isTypeLegalForClass(X86::VR128XRegClass, VT))
+      Res.second = &X86::VR128XRegClass;
+    else if (TRI->isTypeLegalForClass(X86::VR256XRegClass, VT))
+      Res.second = &X86::VR256XRegClass;
     else if (TRI->isTypeLegalForClass(X86::VR512RegClass, VT))
       Res.second = &X86::VR512RegClass;
     else {
       // Type mismatch and not a clobber: Return an error;
       Res.first = 0;
       Res.second = nullptr;
     }
   } else if (isVKClass(*Class)) {