Add ARM fconsts/fconstd aliases for vmov.f32/vmov.f64

This commit adds the pre-UAL aliases of fconsts and fconstd for
vmov.f32 and vmov.f64. They use an InstAlias rather than a
MnemonicAlias to properly support the predicate operand.

We need to support encoded 8-bit constants in order to implement the
pre-UAL fconsts/fconstd aliases for vmov.f32/vmov.f64, so this
commit also fixes parsing of encoded floating point constants used
in vmov.f32/vmov.f64 instructions. Now we can support assembly code
like this:

  fconsts s0, #0x70

which is equivalent to vmov.f32 s0, #1.0.

Most of the code was already in place to support this feature.
Previously the code was trying to accept encoded 8-bit float
constants for the vmov.f32/vmov.f64 instructions.  It looks like the
support for parsing encoded floats was lost in a refactoring in
commit r148556 and we did not have any tests in place to catch it.

The change in this commit is to keep the parsed value as a 32-bit
float instead of a 64-bit double because that is what the isFPImm()
function expects to find. There is no loss of precision by using a
32-bit float here because we are still limited to an 8-bit encoded
value in the end.

Additionally, we explicitly reject encoded 8-bit floats for
vmovf.32/64. This is the same as the current behavior, but we now do
it explicitly rather than accidently.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198697 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 23 insertions, 7 deletions

diff --git a/lib/Target/ARM/ARMInstrVFP.td b/lib/Target/ARM/ARMInstrVFP.td
index a5494819d1..1d7802a2c7 100644
--- a/lib/Target/ARM/ARMInstrVFP.td
+++ b/lib/Target/ARM/ARMInstrVFP.td
@@ -1762,3 +1762,14 @@ def : VFP2InstAlias<"vmov${p}.f64 $Dn, $Rt, $Rt2",
 // VMOVD does.
 def : VFP2InstAlias<"vmov${p} $Sd, $Sm",
                     (VMOVS SPR:$Sd, SPR:$Sm, pred:$p)>;
+
+// FCONSTD/FCONSTS alias for vmov.f64/vmov.f32
+// These aliases provide added functionality over vmov.f instructions by
+// allowing users to write assembly containing encoded floating point constants
+// (e.g. #0x70 vs #1.0).  Without these alises there is no way for the
+// assembler to accept encoded fp constants (but the equivalent fp-literal is
+// accepted directly by vmovf).
+def : VFP3InstAlias<"fconstd${p} $Dd, $val",
+                    (FCONSTD DPR:$Dd, vfp_f64imm:$val, pred:$p)>;
+def : VFP3InstAlias<"fconsts${p} $Sd, $val",
+                    (FCONSTS SPR:$Sd, vfp_f32imm:$val, pred:$p)>;
diff --git a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index 1145fe7040..47f7eca09a 100644
--- a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -4620,8 +4620,12 @@ parseFPImm(SmallVectorImpl<MCParsedAsmOperand*> &Operands) {
   // for these:
   // vmov.i{8|16|32|64} <dreg|qreg>, #imm
   ARMOperand *TyOp = static_cast<ARMOperand*>(Operands[2]);
-  if (!TyOp->isToken() || (TyOp->getToken() != ".f32" &&
-                           TyOp->getToken() != ".f64"))
+  bool isVmovf = TyOp->isToken() && (TyOp->getToken() == ".f32" ||
+                                     TyOp->getToken() == ".f64");
+  ARMOperand *Mnemonic = static_cast<ARMOperand*>(Operands[0]);
+  bool isFconst = Mnemonic->isToken() && (Mnemonic->getToken() == "fconstd" ||
+                                          Mnemonic->getToken() == "fconsts");
+  if (!(isVmovf || isFconst))
     return MatchOperand_NoMatch;
 
   Parser.Lex(); // Eat '#' or '$'.
@@ -4634,7 +4638,7 @@ parseFPImm(SmallVectorImpl<MCParsedAsmOperand*> &Operands) {
   }
   const AsmToken &Tok = Parser.getTok();
   SMLoc Loc = Tok.getLoc();
-  if (Tok.is(AsmToken::Real)) {
+  if (Tok.is(AsmToken::Real) && isVmovf) {
     APFloat RealVal(APFloat::IEEEsingle, Tok.getString());
     uint64_t IntVal = RealVal.bitcastToAPInt().getZExtValue();
     // If we had a '-' in front, toggle the sign bit.
@@ -4647,15 +4651,16 @@ parseFPImm(SmallVectorImpl<MCParsedAsmOperand*> &Operands) {
   }
   // Also handle plain integers. Instructions which allow floating point
   // immediates also allow a raw encoded 8-bit value.
-  if (Tok.is(AsmToken::Integer)) {
+  if (Tok.is(AsmToken::Integer) && isFconst) {
     int64_t Val = Tok.getIntVal();
     Parser.Lex(); // Eat the token.
     if (Val > 255 || Val < 0) {
       Error(Loc, "encoded floating point value out of range");
       return MatchOperand_ParseFail;
     }
-    double RealVal = ARM_AM::getFPImmFloat(Val);
-    Val = APFloat(APFloat::IEEEdouble, RealVal).bitcastToAPInt().getZExtValue();
+    float RealVal = ARM_AM::getFPImmFloat(Val);
+    Val = APFloat(RealVal).bitcastToAPInt().getZExtValue();
+
     Operands.push_back(ARMOperand::CreateImm(
         MCConstantExpr::Create(Val, getContext()), S,
         Parser.getTok().getLoc()));
@@ -4910,7 +4915,7 @@ StringRef ARMAsmParser::splitMnemonic(StringRef Mnemonic,
         Mnemonic == "fmrs" || Mnemonic == "fsqrts" || Mnemonic == "fsubs" ||
         Mnemonic == "fsts" || Mnemonic == "fcpys" || Mnemonic == "fdivs" ||
         Mnemonic == "fmuls" || Mnemonic == "fcmps" || Mnemonic == "fcmpzs" ||
-        Mnemonic == "vfms" || Mnemonic == "vfnms" ||
+        Mnemonic == "vfms" || Mnemonic == "vfnms" || Mnemonic == "fconsts" ||
         (Mnemonic == "movs" && isThumb()))) {
     Mnemonic = Mnemonic.slice(0, Mnemonic.size() - 1);
     CarrySetting = true;