[ARM] Fix a check in vmov/vmvn immediate parsing

[miyuki]

Summary

Currently the check is incorrect and the following invalid
instruction is accepted and incorrectly assembled:

vmov.i32        d2, #0x00a500a6

This patch fixes the issue.

[miyuki]

Renato, could you please also look at this patch (it is a dependency for https://reviews.llvm.org/D44467)

[rengolin]

LGTM, thanks!

lib/Target/ARM/AsmParser/ARMAsmParser.cpp

for (unsigned i = 1; i < NumBytes; ++i) {
         return false;
     }
     return true;
   }
 
   bool isNEONi16ByteReplicate() const { return isNEONByteReplicate(2); }
   bool isNEONi32ByteReplicate() const { return isNEONByteReplicate(4); }
 
+  static bool isValidNEONi32vmovImm(int64_t Value) {
+    // i32 value with set bits only in one byte X000, 0X00, 00X0, or 000X,
+    // for VMOV/VMVN only, 00Xf or 0Xff are also accepted.
+    return ((Value & 0xffffffffffffff00) == 0) ||
+           ((Value & 0xffffffffffff00ff) == 0) ||
+           ((Value & 0xffffffffff00ffff) == 0) ||
+           ((Value & 0xffffffff00ffffff) == 0) ||
+           ((Value & 0xffffffffffff00ff) == 0xff) ||
+           ((Value & 0xffffffffff00ffff) == 0xffff);
+  }
+
   bool isNEONi32vmov() const {
     if (isNEONByteReplicate(4))
       return false; // Let it to be classified as byte-replicate case.
     if (!isImm())
       return false;
     const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
     // Must be a constant.
     if (!CE)
       return false;
-    int64_t Value = CE->getValue();
-    // i32 value with set bits only in one byte X000, 0X00, 00X0, or 000X,
-    // for VMOV/VMVN only, 00Xf or 0Xff are also accepted.
-    // FIXME: This is probably wrong and a copy and paste from previous example
-    return (Value >= 0 && Value < 256) ||
-      (Value >= 0x0100 && Value <= 0xff00) ||
-      (Value >= 0x010000 && Value <= 0xff0000) ||
-      (Value >= 0x01000000 && Value <= 0xff000000) ||
-      (Value >= 0x01ff && Value <= 0xffff && (Value & 0xff) == 0xff) ||
-      (Value >= 0x01ffff && Value <= 0xffffff && (Value & 0xffff) == 0xffff);
+    return isValidNEONi32vmovImm(CE->getValue());
   }
 
   bool isNEONi32vmovNeg() const {
     if (!isImm()) return false;
     const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
     // Must be a constant.
     if (!CE) return false;
-    int64_t Value = ~CE->getValue();
-    // i32 value with set bits only in one byte X000, 0X00, 00X0, or 000X,
-    // for VMOV/VMVN only, 00Xf or 0Xff are also accepted.
-    // FIXME: This is probably wrong and a copy and paste from previous example
-    return (Value >= 0 && Value < 256) ||
-      (Value >= 0x0100 && Value <= 0xff00) ||
-      (Value >= 0x010000 && Value <= 0xff0000) ||
-      (Value >= 0x01000000 && Value <= 0xff000000) ||
-      (Value >= 0x01ff && Value <= 0xffff && (Value & 0xff) == 0xff) ||
-      (Value >= 0x01ffff && Value <= 0xffffff && (Value & 0xffff) == 0xffff);
+    return isValidNEONi32vmovImm(~CE->getValue());
   }
 
   bool isNEONi64splat() const {
     if (!isImm()) return false;
     const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
     // Must be a constant.
     if (!CE) return false;
     uint64_t Value = CE->getValue();

test/MC/ARM/vmov-vmvn-illegal-cases.s

 @ RUN: not llvm-mc -triple=armv7-linux-gnueabi %s 2>&1 | FileCheck %s
 .text
 
 @ CHECK: error: invalid instruction, any one of the following would fix this:
 @ CHECK-NEXT: vmov.i32        d2, #0xffffffab
 @ CHECK: note: operand must be a register in range [d0, d31]
 @ CHECK: note: invalid operand for instruction
 @ CHECK: error: invalid instruction, any one of the following would fix this:
 @ CHECK-NEXT: vmov.i32        q2, #0xffffffab
 @ CHECK: note: operand must be a register in range [q0, q15]
 @ CHECK: note: invalid operand for instruction
 @ CHECK: error: invalid instruction, any one of the following would fix this:
+@ CHECK-NEXT: vmov.i32        d2, #0x00a500a6
+@ CHECK: note: operand must be a register in range [d0, d31]
+@ CHECK: note: invalid operand for instruction
+@ CHECK: error: invalid instruction, any one of the following would fix this:
 @ CHECK-NEXT: vmov.i16        q2, #0xffab
 @ CHECK: note: operand must be a register in range [q0, q15]
 @ CHECK: note: invalid operand for instruction
 @ CHECK: error: invalid instruction, any one of the following would fix this:
 @ CHECK-NEXT: vmov.i16        q2, #0xffab
 @ CHECK: note: operand must be a register in range [q0, q15]
 @ CHECK: note: invalid operand for instruction
 
 @ CHECK: error: invalid instruction, any one of the following would fix this:
 @ CHECK-NEXT: vmvn.i32        d2, #0xffffffab
 @ CHECK: note: operand must be a register in range [d0, d31]
 @ CHECK: note: invalid operand for instruction
 @ CHECK: error: invalid instruction, any one of the following would fix this:
 @ CHECK-NEXT: vmvn.i32        q2, #0xffffffab
 @ CHECK: note: operand must be a register in range [q0, q15]
 @ CHECK: note: invalid operand for instruction
 @ CHECK: error: invalid instruction, any one of the following would fix this:
+@ CHECK-NEXT: vmvn.i32        d2, #0x00a500a6
+@ CHECK: note: operand must be a register in range [d0, d31]
+@ CHECK: note: invalid operand for instruction
+@ CHECK: error: invalid instruction, any one of the following would fix this:
 @ CHECK-NEXT: vmvn.i16        q2, #0xffab
 @ CHECK: note: operand must be a register in range [q0, q15]
 @ CHECK: note: invalid operand for instruction
 @ CHECK: error: invalid instruction, any one of the following would fix this:
 @ CHECK-NEXT: vmvn.i16        q2, #0xffab
 @ CHECK: note: operand must be a register in range [q0, q15]
 @ CHECK: note: invalid operand for instruction
 
         vmov.i32        d2, #0xffffffab
         vmov.i32        q2, #0xffffffab
+        vmov.i32        d2, #0x00a500a6
         vmov.i16        q2, #0xffab
         vmov.i16        q2, #0xffab
 
         vmvn.i32        d2, #0xffffffab
         vmvn.i32        q2, #0xffffffab
+        vmvn.i32        d2, #0x00a500a6
         vmvn.i16        q2, #0xffab
         vmvn.i16        q2, #0xffab