[SelectionDAG] Fix assertion failure on inline asm register type mismatch (#166615)

Resolves #166057

---------

Co-authored-by: Phoebe Wang <phoebe.wang@intel.com>

Author: ahmednoursphinx

clang/lib/CodeGen/Targets/X86.cpp

@@ -27,6 +27,14 @@ bool IsX86_MMXType(llvm::Type *IRType) {
 static llvm::Type *X86AdjustInlineAsmType(CodeGen::CodeGenFunction &CGF,
                                           StringRef Constraint,
                                           llvm::Type *Ty) {
+  bool IsMMXCons = llvm::StringSwitch<bool>(Constraint)
+                       .Cases({"y", "&y", "^Ym"}, true)
+                       .Default(false);
+  if (IsMMXCons && Ty->isVectorTy() &&
+      cast<llvm::VectorType>(Ty)->getPrimitiveSizeInBits().getFixedValue() !=
+          64)
+    return nullptr; // Invalid MMX constraint
+
   if (Constraint == "k") {
     llvm::Type *Int1Ty = llvm::Type::getInt1Ty(CGF.getLLVMContext());
     return llvm::FixedVectorType::get(Int1Ty, Ty->getScalarSizeInBits());

clang/test/CodeGen/X86/mmx-inline-asm-error.c

@@ -1,13 +1,15 @@
 // RUN: %clang_cc1 -verify -triple x86_64-unknown-unknown -emit-llvm-only %s
+// RUN: %clang_cc1 -verify=omp -triple x86_64-unknown-unknown -emit-llvm-only -fopenmp %s
 typedef int vec256 __attribute__((ext_vector_type(8)));
 
 vec256 foo(vec256 in) {
   vec256 out;
 
   asm("something %0" : : "y"(in)); // expected-error {{invalid input size for constraint 'y'}}
+  // omp-error@+1 {{invalid type 'vec256' (vector of 8 'int' values) in asm input for constraint 'y'}}
   asm("something %0" : "=y"(out)); // expected-error {{invalid output size for constraint '=y'}}
+  // omp-error@+1 {{invalid type 'vec256' (vector of 8 'int' values) in asm input for constraint 'y'}}
   asm("something %0, %0" : "+y"(out)); // expected-error {{invalid output size for constraint '+y'}}
 
   return out;
 }
-