[x86] Fix printing of register operands with q modifier.

Emit 32-bit register names instead of 64-bit register names if the target does
not have 64-bit general purpose registers.

<rdar://problem/14653996>

llvm-svn: 205067

llvm/lib/Target/X86/X86AsmPrinter.cpp

@@ -363,9 +363,11 @@ static bool printAsmMRegister(X86AsmPrinter &P, const MachineOperand &MO,
   case 'k': // Print SImode register
     Reg = getX86SubSuperRegister(Reg, MVT::i32);
     break;
-  case 'q': // Print DImode register
-    // FIXME: gcc will actually print e instead of r for 32-bit.
-    Reg = getX86SubSuperRegister(Reg, MVT::i64);
+  case 'q':
+    // Print 64-bit register names if 64-bit integer registers are available.
+    // Otherwise, print 32-bit register names.
+    MVT::SimpleValueType Ty = P.getSubtarget().is64Bit() ? MVT::i64 : MVT::i32;
+    Reg = getX86SubSuperRegister(Reg, Ty);
     break;
   }
 

llvm/test/CodeGen/X86/inline-asm-modifier-q.ll

@@ -0,0 +1,12 @@
+; RUN: llc < %s -march=x86 -no-integrated-as | FileCheck %s
+
+; If the target does not have 64-bit integer registers, emit 32-bit register
+; names.
+
+; CHECK: movq (%e{{[abcd]}}x, %ebx, 4)
+
+define void @q_modifier(i32* %p) {
+entry:
+  tail call void asm sideeffect "movq (${0:q}, %ebx, 4), %mm0", "r,~{dirflag},~{fpsr},~{flags}"(i32* %p)
+  ret void
+}