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, brson#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

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)>;

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;

test/MC/ARM/fconst.s

@@ -0,0 +1,22 @@
+@ RUN: llvm-mc -mcpu=cortex-a8 -triple armv7-apple-darwin -show-encoding < %s | FileCheck %s
+
+@ fconstd/fconsts aliases
+        fconsts s4, #0x0
+        fconsts s4, #0x70
+        fconstd d3, #0x0
+        fconstd d3, #0x70
+
+        fconstsne s5, #0x1
+        fconstsgt s5, #0x20
+        fconstdlt d2, #0x3
+        fconstdge d2, #0x40
+
+@ CHECK: vmov.f32        s4, #2.000000e+00 @ encoding: [0x00,0x2a,0xb0,0xee]
+@ CHECK: vmov.f32        s4, #1.000000e+00 @ encoding: [0x00,0x2a,0xb7,0xee]
+@ CHECK: vmov.f64        d3, #2.000000e+00 @ encoding: [0x00,0x3b,0xb0,0xee]
+@ CHECK: vmov.f64        d3, #1.000000e+00 @ encoding: [0x00,0x3b,0xb7,0xee]
+
+@ CHECK: vmovne.f32      s5, #2.125000e+00 @ encoding: [0x01,0x2a,0xf0,0x1e]
+@ CHECK: vmovgt.f32      s5, #8.000000e+00 @ encoding: [0x00,0x2a,0xf2,0xce]
+@ CHECK: vmovlt.f64      d2, #2.375000e+00 @ encoding: [0x03,0x2b,0xb0,0xbe]
+@ CHECK: vmovge.f64      d2, #1.250000e-01 @ encoding: [0x00,0x2b,0xb4,0xae]

test/MC/ARM/fp-const-errors.s

@@ -0,0 +1,22 @@
+@ RUN: not llvm-mc -mcpu=cortex-a8 -triple armv7-none-linux-gnueabi < %s 2>&1 | FileCheck %s
+
+@ Test for floating point constants that are out of the 8-bit encoded value range
+vmov.f32 s2, #32.0
+@ CHECK: error: invalid operand for instruction
+
+vmov.f64 d2, #32.0
+@ CHECK: error: invalid operand for instruction
+
+@ Test that vmov.f instructions do not accept an 8-bit encoded float as an operand
+vmov.f32 s1, #0x70
+@ CHECK: error: invalid floating point immediate
+
+vmov.f64 d2, #0x70
+@ CHECK: error: invalid floating point immediate
+
+@ Test that fconst instructions do not accept a float constant as an operand
+fconsts s1, #1.0
+@ CHECK: error: invalid floating point immediate
+
+fconstd d2, #1.0
+@ CHECK: error: invalid floating point immediate

test/MC/ARM/simple-fp-encoding.s

@@ -395,3 +395,46 @@
 
 @ CHECK: vmov.i32	d4, #0x0        @ encoding: [0x10,0x40,0x80,0xf2]
 @ CHECK: vmov.i32	d4, #0x42000000 @ encoding: [0x12,0x46,0x84,0xf2]
+
+@ Test encoding of floating point constants for vmov functions
+@ vfp3
+         vmov.f32 s5, #1.0
+         vmov.f32 s5, #0.125
+         vmov.f32 s5, #-1.875
+         vmov.f32 s5, #-0.59375
+
+         vmov.f64 d6, #1.0
+         vmov.f64 d6, #0.125
+         vmov.f64 d6, #-1.875
+         vmov.f64 d6, #-0.59375
+
+@ neon
+         vmov.f32 d7, #1.0
+         vmov.f32 d7, #0.125
+         vmov.f32 d7, #-1.875
+         vmov.f32 d7, #-0.59375
+
+         vmov.f32 q8, #1.0
+         vmov.f32 q8, #0.125
+         vmov.f32 q8, #-1.875
+         vmov.f32 q8, #-0.59375
+
+@ CHECK: vmov.f32        s5, #1.000000e+00 @ encoding: [0x00,0x2a,0xf7,0xee]
+@ CHECK: vmov.f32        s5, #1.250000e-01 @ encoding: [0x00,0x2a,0xf4,0xee]
+@ CHECK: vmov.f32        s5, #-1.875000e+00 @ encoding: [0x0e,0x2a,0xff,0xee]
+@ CHECK: vmov.f32        s5, #-5.937500e-01 @ encoding: [0x03,0x2a,0xfe,0xee]
+
+@ CHECK: vmov.f64        d6, #1.000000e+00 @ encoding: [0x00,0x6b,0xb7,0xee]
+@ CHECK: vmov.f64        d6, #1.250000e-01 @ encoding: [0x00,0x6b,0xb4,0xee]
+@ CHECK: vmov.f64        d6, #-1.875000e+00 @ encoding: [0x0e,0x6b,0xbf,0xee]
+@ CHECK: vmov.f64        d6, #-5.937500e-01 @ encoding: [0x03,0x6b,0xbe,0xee]
+
+@ CHECK: vmov.f32        d7, #1.000000e+00 @ encoding: [0x10,0x7f,0x87,0xf2]
+@ CHECK: vmov.f32        d7, #1.250000e-01 @ encoding: [0x10,0x7f,0x84,0xf2]
+@ CHECK: vmov.f32        d7, #-1.875000e+00 @ encoding: [0x1e,0x7f,0x87,0xf3]
+@ CHECK: vmov.f32        d7, #-5.937500e-01 @ encoding: [0x13,0x7f,0x86,0xf3]
+
+@ CHECK: vmov.f32        q8, #1.000000e+00 @ encoding: [0x50,0x0f,0xc7,0xf2]
+@ CHECK: vmov.f32        q8, #1.250000e-01 @ encoding: [0x50,0x0f,0xc4,0xf2]
+@ CHECK: vmov.f32        q8, #-1.875000e+00 @ encoding: [0x5e,0x0f,0xc7,0xf3]
+@ CHECK: vmov.f32        q8, #-5.937500e-01 @ encoding: [0x53,0x0f,0xc6,0xf3]