[x86] Allow address-size overrides for SCAS{8,16,32,64} (PR9385)

llvm-svn: 199805

llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp

@@ -2361,6 +2361,14 @@ ParseInstruction(ParseInstructionInfo &Info, StringRef Name, SMLoc NameLoc,
        Name == "stosl" || Name == "stosd" || Name == "stosq"))
     Operands.push_back(DefaultMemDIOperand(NameLoc));
 
+  // Transform "scas[bwlq]" into "scas[bwlq] ($DIREG)" for appropriate
+  // values of $DIREG according to the mode. It would be nice if this
+  // could be achieved with InstAlias in the tables.
+  if (Name.startswith("scas") && Operands.size() == 1 &&
+      (Name == "scas" || Name == "scasb" || Name == "scasw" ||
+       Name == "scasl" || Name == "scasd" || Name == "scasq"))
+    Operands.push_back(DefaultMemDIOperand(NameLoc));
+
   // FIXME: Hack to handle recognize s{hr,ar,hl} $1, <op>.  Canonicalize to
   // "shift <op>".
   if ((Name.startswith("shr") || Name.startswith("sar") ||

llvm/lib/Target/X86/X86InstrInfo.td

@@ -1157,11 +1157,14 @@ let Defs = [RCX,RDI], Uses = [RAX,RCX,RDI,EFLAGS] in
 def STOSQ : RI<0xAB, RawFrmDst, (outs dstidx64:$dst), (ins),
                "stosq\t{%rax, $dst|$dst, rax}", [], IIC_STOS>;
 
-def SCAS8 : I<0xAE, RawFrm, (outs), (ins), "scasb", [], IIC_SCAS>;
+def SCAS8 : I<0xAE, RawFrmDst, (outs), (ins dstidx8:$dst),
-def SCAS16 : I<0xAF, RawFrm, (outs), (ins), "scasw", [], IIC_SCAS>, OpSize;
+              "scasb\t{$dst, %al|al, $dst}", [], IIC_SCAS>;
-def SCAS32 : I<0xAF, RawFrm, (outs), (ins), "scas{l|d}", [], IIC_SCAS>,
+def SCAS16 : I<0xAF, RawFrmDst, (outs), (ins dstidx16:$dst),
-               OpSize16;
+               "scasw\t{$dst, %ax|ax, $dst}", [], IIC_SCAS>, OpSize;
-def SCAS64 : RI<0xAF, RawFrm, (outs), (ins), "scasq", [], IIC_SCAS>;
+def SCAS32 : I<0xAF, RawFrmDst, (outs), (ins dstidx32:$dst),
+               "scas{l|d}\t{$dst, %eax|eax, $dst}", [], IIC_SCAS>, OpSize16;
+def SCAS64 : RI<0xAF, RawFrmDst, (outs), (ins dstidx64:$dst),
+                "scasq\t{$dst, %rax|rax, $dst}", [], IIC_SCAS>;
 
 def CMPS8 : I<0xA6, RawFrm, (outs), (ins), "cmpsb", [], IIC_CMPS>;
 def CMPS16 : I<0xA7, RawFrm, (outs), (ins), "cmpsw", [], IIC_CMPS>, OpSize;
@@ -2432,6 +2435,18 @@ def : InstAlias<"stos {%ax, $dst|$dst, ax}", (STOSW dstidx16:$dst), 0>;
 def : InstAlias<"stos {%eax, $dst|$dst, eax}", (STOSL dstidx32:$dst), 0>;
 def : InstAlias<"stos {%rax, $dst|$dst, rax}", (STOSQ dstidx64:$dst), 0>, Requires<[In64BitMode]>;
 
+// scas aliases. Accept the destination being omitted because it's implicit
+// in the mnemonic, or the mnemonic suffix being omitted because it's implicit
+// in the destination.
+def : InstAlias<"scasb $dst", (SCAS8 dstidx8:$dst),  0>;
+def : InstAlias<"scasw $dst", (SCAS16 dstidx16:$dst), 0>;
+def : InstAlias<"scas{l|d} $dst", (SCAS32 dstidx32:$dst), 0>;
+def : InstAlias<"scasq $dst", (SCAS64 dstidx64:$dst), 0>, Requires<[In64BitMode]>;
+def : InstAlias<"scas {$dst, %al|al, $dst}", (SCAS8 dstidx8:$dst),  0>;
+def : InstAlias<"scas {$dst, %ax|ax, $dst}", (SCAS16 dstidx16:$dst), 0>;
+def : InstAlias<"scas {$dst, %eax|eax, $dst}", (SCAS32 dstidx32:$dst), 0>;
+def : InstAlias<"scas {$dst, %rax|rax, $dst}", (SCAS64 dstidx64:$dst), 0>, Requires<[In64BitMode]>;
+
 // div and idiv aliases for explicit A register.
 def : InstAlias<"div{b}\t{$src, %al|al, $src}", (DIV8r  GR8 :$src)>;
 def : InstAlias<"div{w}\t{$src, %ax|ax, $src}", (DIV16r GR16:$src)>;

llvm/test/MC/X86/index-operations.s

@@ -74,3 +74,23 @@ stos %rax, (%edi)
 // 64: 	stosq %rax, %es:(%edi) # encoding: [0x48,0x67,0xab]
 // ERR32: only available in 64-bit mode
 // ERR16: only available in 64-bit mode
+
+scas %es:(%edi), %al
+// 64: scasb %es:(%edi), %al # encoding: [0x67,0xae]
+// 32: scasb %es:(%edi), %al # encoding: [0xae]
+// 16: scasb %es:(%edi), %al # encoding: [0x67,0xae]
+
+scasq %es:(%edi)
+// 64: scasq %es:(%edi), %rax # encoding: [0x48,0x67,0xaf]
+// ERR32: 64-bit
+// ERR16: 64-bit
+
+scasl %es:(%edi), %al
+// ERR64: invalid operand
+// ERR32: invalid operand
+// ERR16: invalid operand
+
+scas %es:(%di), %ax
+// ERR64: invalid 16-bit base register
+// 16: scasw %es:(%di), %ax # encoding: [0xaf]
+// 32: scasw %es:(%di), %ax # encoding: [0x66,0x67,0xaf]