[AArch64] Fix inline assembly parsing crash

[david-arm]

Summary

This patch fixes a crash encountered when compiling this code:

...
float16_t a;
__asm__("fminv %h[a], %[b], %[c].h"
        : [a] "=r" (a)
        : [b] "Upl" (b), [c] "w" (c))

The issue here is when using the 'h' modifier for a register
constraint 'r'.

[c-rhodes]

llvm/test/CodeGen/AArch64/inline-asm-constraints-bad-sve.ll

36

nit: the #1 attribute can be dropped

llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp

 // printing.
 bool AArch64AsmPrinter::printAsmRegInClass(const MachineOperand &MO,
                                            const TargetRegisterClass *RC,
                                            unsigned AltName, raw_ostream &O) {
   assert(MO.isReg() && "Should only get here with a register!");
   const TargetRegisterInfo *RI = STI->getRegisterInfo();
   Register Reg = MO.getReg();
   unsigned RegToPrint = RC->getRegister(RI->getEncodingValue(Reg));
-  assert(RI->regsOverlap(RegToPrint, Reg));
+  if (!RI->regsOverlap(RegToPrint, Reg))
+    return true;
   O << AArch64InstPrinter::getRegisterName(RegToPrint, AltName);
   return false;
 }
 
 bool AArch64AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
                                         const char *ExtraCode, raw_ostream &O) {
   const MachineOperand &MO = MI->getOperand(OpNum);
 

llvm/test/CodeGen/AArch64/inline-asm-constraints-bad-sve.ll

 ; RUN: not llc -mtriple=aarch64-none-linux-gnu -mattr=+sve -o - %s 2>&1 | FileCheck %s
 
 target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
 target triple = "aarch64-unknown-linux-gnu"
 
 ; CHECK: error: couldn't allocate input reg for constraint 'Upa'
 ; CHECK: error: couldn't allocate input reg for constraint 'r'
 ; CHECK: error: couldn't allocate output register for constraint 'w'
+; CHECK: error: unknown token in expression
 
 define <vscale x 16 x i1> @foo1(i32 *%in) {
 entry:
   %0 = load i32, i32* %in, align 4
   %1 = call <vscale x 16 x i1> asm sideeffect "mov $0.b, $1.b \0A", "=@3Upa,@3Upa"(i32 %0)
   ret <vscale x 16 x i1> %1
 }
 
 define <vscale x 4 x float> @foo2(<vscale x 4 x i32> *%in) {
 entry:
   %0 = load <vscale x 4 x i32>, <vscale x 4 x i32>* %in, align 16
   %1 = call <vscale x 4 x float> asm sideeffect "ptrue p0.s, #1 \0Afabs $0.s, p0/m, $1.s \0A", "=w,r"(<vscale x 4 x i32> %0)
   ret <vscale x 4 x float> %1
 }
 
 define <vscale x 16 x i1> @foo3(<vscale x 16 x i1> *%in) {
 entry:
   %0 = load <vscale x 16 x i1>, <vscale x 16 x i1>* %in, align 2
   %1 = call <vscale x 16 x i1> asm sideeffect "mov $0.b, $1.b \0A", "=&w,w"(<vscale x 16 x i1> %0)
   ret <vscale x 16 x i1> %1
 }
+
+define half @foo4(<vscale x 16 x i1> *%inp, <vscale x 8 x half> *%inv) {
+entry:
+  %0 = load <vscale x 16 x i1>, <vscale x 16 x i1>* %inp, align 2
+  %1 = load <vscale x 8 x half>, <vscale x 8 x half>* %inv, align 16
+  %2 = call half asm "fminv ${0:h}, $1, $2.h", "=r,@3Upl,w"(<vscale x 16 x i1> %0, <vscale x 8 x half> %1)
+  ret half %2
+}