sketch out the planned instruction alias mechanism, add some comments about
how the push/pop mnemonic aliases are wrong.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@117857 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/llvm/Target/Target.td b/include/llvm/Target/Target.td
index 87faa6b..5748560 100644
--- a/include/llvm/Target/Target.td
+++ b/include/llvm/Target/Target.td
@@ -567,6 +567,18 @@
list<Predicate> Predicates = [];
}
+/// InstAlias - This defines an alternate assembly syntax that is allowed to
+/// match an instruction that has a different (more canonical) assembly
+/// representation.
+class InstAlias<dag Outs, dag Ins, string Asm, dag Result> {
+ dag OutOperandList = Outs; // An dag containing the MI def operand list.
+ dag InOperandList = Ins; // An dag containing the MI use operand list.
+ string AsmString = Asm; // The .s format to match the instruction with.
+ dag ResultInst = Result; // The MCInst to generate.
+
+ // Predicates - Predicates that must be true for this to match.
+ list<Predicate> Predicates = [];
+}
//===----------------------------------------------------------------------===//
// AsmWriter - This class can be implemented by targets that need to customize
diff --git a/lib/Target/X86/X86InstrInfo.td b/lib/Target/X86/X86InstrInfo.td
index 3af3911..ab9869a 100644
--- a/lib/Target/X86/X86InstrInfo.td
+++ b/lib/Target/X86/X86InstrInfo.td
@@ -1258,6 +1258,17 @@
// Assembler Aliases
//===----------------------------------------------------------------------===//
+// movsx aliases
+def : InstAlias<(outs GR32:$dst), (ins GR8 :$src),
+ "movsx $src, $dst",
+ (MOVSX32rr8 GR32:$dst, GR8:$src)>;
+def : InstAlias<(outs GR32:$dst), (ins GR16:$src),
+ "movsx $src, $dst",
+ (MOVSX32rr16 GR32:$dst, GR16:$src)>;
+
+
+// TODO: lidtl/lidtq can be opcode aliases, perhaps others.
+
def : MnemonicAlias<"iret", "iretl">;
def : MnemonicAlias<"sysret", "sysretl">;
def : MnemonicAlias<"cbw", "cbtw">;
@@ -1272,6 +1283,9 @@
def : MnemonicAlias<"popf", "popfq">, Requires<[In64BitMode]>;
def : MnemonicAlias<"popfd", "popfl">;
+// FIXME: This is wrong for "push reg". "push %bx" should turn into pushw in
+// all modes. However: "push (addr)" and "push $42" should default to
+// pushl/pushq depending on the current mode. Similar for "pop %bx"
def : MnemonicAlias<"push", "pushl">, Requires<[In32BitMode]>;
def : MnemonicAlias<"push", "pushq">, Requires<[In64BitMode]>;
def : MnemonicAlias<"pushf", "pushfl">, Requires<[In32BitMode]>;