Fix imul alias for intel syntax

[myatsina]

Summary

The "imul reg, imm" alias is not defined for intel syntax.
In intel syntax there is no w/l/q suffix for the imul instruction.

[craig.topper]

LGTM

lib/Target/X86/X86InstrInfo.td

 def : InstAlias<"jmp {*}$dst",      (JMP64m  i64mem:$dst), 0>, Requires<[In64BitMode]>;
 def : InstAlias<"call {*}$dst",     (CALL32m i32mem:$dst), 0>, Requires<[In32BitMode]>;
 def : InstAlias<"jmp {*}$dst",      (JMP32m  i32mem:$dst), 0>, Requires<[In32BitMode]>;
 def : InstAlias<"call {*}$dst",     (CALL16m i16mem:$dst), 0>, Requires<[In16BitMode]>;
 def : InstAlias<"jmp {*}$dst",      (JMP16m  i16mem:$dst), 0>, Requires<[In16BitMode]>;
 
 
 // "imul <imm>, B" is an alias for "imul <imm>, B, B".
-def : InstAlias<"imulw {$imm, $r|$r, $imm}", (IMUL16rri  GR16:$r, GR16:$r, i16imm:$imm), 0>;
-def : InstAlias<"imulw {$imm, $r|$r, $imm}", (IMUL16rri8 GR16:$r, GR16:$r, i16i8imm:$imm), 0>;
-def : InstAlias<"imull {$imm, $r|$r, $imm}", (IMUL32rri  GR32:$r, GR32:$r, i32imm:$imm), 0>;
-def : InstAlias<"imull {$imm, $r|$r, $imm}", (IMUL32rri8 GR32:$r, GR32:$r, i32i8imm:$imm), 0>;
-def : InstAlias<"imulq {$imm, $r|$r, $imm}", (IMUL64rri32 GR64:$r, GR64:$r, i64i32imm:$imm), 0>;
-def : InstAlias<"imulq {$imm, $r|$r, $imm}", (IMUL64rri8 GR64:$r, GR64:$r, i64i8imm:$imm), 0>;
+def : InstAlias<"imul{w} {$imm, $r|$r, $imm}", (IMUL16rri  GR16:$r, GR16:$r, i16imm:$imm), 0>;
+def : InstAlias<"imul{w} {$imm, $r|$r, $imm}", (IMUL16rri8 GR16:$r, GR16:$r, i16i8imm:$imm), 0>;
+def : InstAlias<"imul{l} {$imm, $r|$r, $imm}", (IMUL32rri  GR32:$r, GR32:$r, i32imm:$imm), 0>;
+def : InstAlias<"imul{l} {$imm, $r|$r, $imm}", (IMUL32rri8 GR32:$r, GR32:$r, i32i8imm:$imm), 0>;
+def : InstAlias<"imul{q} {$imm, $r|$r, $imm}", (IMUL64rri32 GR64:$r, GR64:$r, i64i32imm:$imm), 0>;
+def : InstAlias<"imul{q} {$imm, $r|$r, $imm}", (IMUL64rri8 GR64:$r, GR64:$r, i64i8imm:$imm), 0>;
 
 // inb %dx -> inb %al, %dx
 def : InstAlias<"inb\t{%dx|dx}", (IN8rr), 0>;
 def : InstAlias<"inw\t{%dx|dx}", (IN16rr), 0>;
 def : InstAlias<"inl\t{%dx|dx}", (IN32rr), 0>;
 def : InstAlias<"inb\t$port", (IN8ri i8imm:$port), 0>;
 def : InstAlias<"inw\t$port", (IN16ri i8imm:$port), 0>;
 def : InstAlias<"inl\t$port", (IN32ri i8imm:$port), 0>;

test/MC/X86/intel-syntax.s

 // CHECK: insl %dx, %es:(%rdi)
 
 outsb
 outsw
 outsd
 // CHECK: outsb (%rsi), %dx
 // CHECK: outsw (%rsi), %dx
 // CHECK: outsl (%rsi), %dx
+
+imul bx, 123
+imul ebx, 123
+imul rbx, 123
+// CHECK: imulw $123, %bx
+// CHECK: imull $123, %ebx
+// CHECK: imulq $123, %rbx