[AArch64] Reject inline asm with FP registers when FP is disabled.

[efriedma]

Summary

Otherwise, we would crash trying to lower the asm.

[t.p.northover]

LGTM.

lib/Target/AArch64/AArch64ISelLowering.cpp

AArch64TargetLowering::getRegForInlineAsmConstraint(
     const TargetRegisterInfo *TRI, StringRef Constraint, MVT VT) const {
   if (Constraint.size() == 1) {
     switch (Constraint[0]) {
     case 'r':
       if (VT.getSizeInBits() == 64)
         return std::make_pair(0U, &AArch64::GPR64commonRegClass);
       return std::make_pair(0U, &AArch64::GPR32commonRegClass);
     case 'w':
+      if (!Subtarget->hasFPARMv8())
+        break;
       if (VT.getSizeInBits() == 16)
         return std::make_pair(0U, &AArch64::FPR16RegClass);
       if (VT.getSizeInBits() == 32)
         return std::make_pair(0U, &AArch64::FPR32RegClass);
       if (VT.getSizeInBits() == 64)
         return std::make_pair(0U, &AArch64::FPR64RegClass);
       if (VT.getSizeInBits() == 128)
         return std::make_pair(0U, &AArch64::FPR128RegClass);
       break;
     // The instructions that this constraint is designed for can
     // only take 128-bit registers so just use that regclass.
     case 'x':
+      if (!Subtarget->hasFPARMv8())
+        break;
       if (VT.getSizeInBits() == 128)
         return std::make_pair(0U, &AArch64::FPR128_loRegClass);
       break;
     }
   }
   if (StringRef("{cc}").equals_lower(Constraint))
     return std::make_pair(unsigned(AArch64::NZCV), &AArch64::CCRRegClass);
 
if ((Size == 4 || Size == 5) && Constraint[0] == '{' &&
         } else {
           Res.first = AArch64::FPR128RegClass.getRegister(RegNo);
           Res.second = &AArch64::FPR128RegClass;
         }
       }
     }
   }
 
+  if (Res.second && !Subtarget->hasFPARMv8() &&
+      !AArch64::GPR32allRegClass.hasSubClassEq(Res.second) &&
+      !AArch64::GPR64allRegClass.hasSubClassEq(Res.second))
+    return std::make_pair(0U, nullptr);
+
   return Res;
 }
 
 /// LowerAsmOperandForConstraint - Lower the specified operand into the Ops
 /// vector.  If it is invalid, don't add anything to Ops.
 void AArch64TargetLowering::LowerAsmOperandForConstraint(
     SDValue Op, std::string &Constraint, std::vector<SDValue> &Ops,
     SelectionDAG &DAG) const {

test/CodeGen/AArch64/inlineasm-illegal-type.ll

+;RUN:  not llc -mtriple=aarch64-linux-gnu -mattr=-fp-armv8 < %s 2>&1 | FileCheck %s
+
+; CHECK: error: couldn't allocate output register for constraint '{d0}'
+; CHECK: error: couldn't allocate output register for constraint 'w'
+
+define hidden double @test1(double %xx) local_unnamed_addr #0 {
+entry:
+  %0 = tail call double asm "frintp ${0:d}, ${0:d}", "={d0}"()
+  ret double %0
+}
+
+define hidden double @test2(double %xx) local_unnamed_addr #0 {
+entry:
+  %0 = tail call double asm "frintp ${0:d}, ${0:d}", "=w"()
+  ret double %0
+}
+