add (and document) the ability for alias results to have

fixed physical registers.  Start moving fp comparison
aliases to the .td file (which default to using %st1 if
nothing is specified).

llvm-svn: 118352

2 files changed, 16 insertions, 13 deletions

diff --git a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
index 9ab6b56c8f0..eaa69f1708d 100644
--- a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -821,7 +821,7 @@ ParseInstruction(StringRef Name, SMLoc NameLoc,
 
   // The assembler accepts these instructions with no operand as a synonym for
   // an instruction acting on st(1).  e.g. "fxch" -> "fxch %st(1)".
-  if ((Name == "fxch" || Name == "fucom" || Name == "fucomp" ||
+  if ((Name == "fxch" ||
        Name == "faddp" || Name == "fsubp" || Name == "fsubrp" ||
        Name == "fmulp" || Name == "fdivp" || Name == "fdivrp") &&
       Operands.size() == 1) {
@@ -829,18 +829,6 @@ ParseInstruction(StringRef Name, SMLoc NameLoc,
                                              NameLoc, NameLoc));
   }
 
-  // The assembler accepts these instructions with two few operands as a synonym
-  // for taking %st(1),%st(0) or X, %st(0).
-  if ((Name == "fcomi" || Name == "fucomi" || Name == "fucompi" ||
-       Name == "fcompi" ) &&
-      Operands.size() < 3) {
-    if (Operands.size() == 1)
-      Operands.push_back(X86Operand::CreateReg(MatchRegisterName("st(1)"),
-                                               NameLoc, NameLoc));
-    Operands.push_back(X86Operand::CreateReg(MatchRegisterName("st(0)"),
-                                             NameLoc, NameLoc));
-  }
-
   return false;
 }
 
@@ -854,6 +842,8 @@ MatchAndEmitInstruction(SMLoc IDLoc,
 
   // First, handle aliases that expand to multiple instructions.
   // FIXME: This should be replaced with a real .td file alias mechanism.
+  // Also, MatchInstructionImpl should do actually *do* the EmitInstruction
+  // call.
   if (Op->getToken() == "fstsw" || Op->getToken() == "fstcw" ||
       Op->getToken() == "fstsww" || Op->getToken() == "fstcww" ||
       Op->getToken() == "finit" || Op->getToken() == "fsave" ||
diff --git a/llvm/lib/Target/X86/X86InstrInfo.td b/llvm/lib/Target/X86/X86InstrInfo.td
index 7fec0141ce4..fdb29837fd7 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.td
+++ b/llvm/lib/Target/X86/X86InstrInfo.td
@@ -1377,6 +1377,19 @@ def : InstAlias<"clrw $reg", (XOR16rr GR16:$reg, GR16:$reg)>;
 def : InstAlias<"clrl $reg", (XOR32rr GR32:$reg, GR32:$reg)>;
 def : InstAlias<"clrq $reg", (XOR64rr GR64:$reg, GR64:$reg)>;
 
+// Default arguments for various fp stack instructions.
+def : InstAlias<"fucom",        (UCOM_Fr   ST1)>;
+def : InstAlias<"fucomp",       (UCOM_FPr  ST1)>;
+def : InstAlias<"fcomi",        (COM_FIr   ST1)>;
+def : InstAlias<"fcomi   $reg", (COM_FIr   RST:$reg)>;
+def : InstAlias<"fcomip",       (COM_FIPr  ST1)>;
+def : InstAlias<"fcomip  $reg", (COM_FIPr  RST:$reg)>;
+def : InstAlias<"fucomi",       (UCOM_FIr  ST1)>;
+def : InstAlias<"fucomi  $reg", (UCOM_FIr  RST:$reg)>;
+def : InstAlias<"fucomip",      (UCOM_FIPr ST1)>;
+def : InstAlias<"fucomip $reg", (UCOM_FIPr RST:$reg)>;
+
+
 // We accepts "fnstsw %eax" even though it only writes %ax.
 def : InstAlias<"fnstsw %eax", (FNSTSW8r)>;
 def : InstAlias<"fnstsw %al" , (FNSTSW8r)>;