Add meta definitions for floating point operations.

Rename the Select instruction format to Ternary since it is also used by the fma
instruction.

cranelift/docs/langref.rst

@@ -771,73 +771,48 @@ Floating point operations
 These operations generally follow IEEE 754-2008 semantics.
 
 .. autoinst:: fcmp
+.. autoinst:: fadd
+.. autoinst:: fsub
+.. autoinst:: fmul
+.. autoinst:: fdiv
+.. autoinst:: sqrt
+.. autoinst:: fma
 
-.. inst:: fadd x,y
+Sign bit manipulations
+~~~~~~~~~~~~~~~~~~~~~~
 
-    Floating point addition.
+The sign manipulating instructions work as bitwise operations, so they don't
+have special behavior for signaling NaN operands. The exponent and trailing
+significand bits are always preserved.
 
-.. inst:: fsub x,y
+.. autoinst:: fneg
+.. autoinst:: fabs
+.. autoinst:: fcopysign
 
-    Floating point subtraction.
+Minimum and maximum
+~~~~~~~~~~~~~~~~~~~
 
-.. inst:: fneg x
+These instructions return the larger or smaller of their operands. They differ
+in their handling of quiet NaN inputs. Note that signaling NaN operands always
+cause a NaN result.
 
-    Floating point negation.
+When comparing zeroes, these instructions behave as if :math:`-0.0 < 0.0`.
 
-    :result: ``x`` with its sign bit inverted.
+.. autoinst:: fmin
+.. autoinst:: fminnum
+.. autoinst:: fmax
+.. autoinst:: fmaxnum
 
-    Note that this is a pure bitwise operation.
+Rounding
+~~~~~~~~
 
-.. inst:: fabs x
+These instructions round their argument to a nearby integral value, still
+represented as a floating point number.
 
-    Floating point absolute value.
-
-    :result: ``x`` with its sign bit cleared.
-
-    Note that this is a pure bitwise operation.
-
-.. inst::  a = fcopysign x, y
-
-    Floating point copy sign.
-
-    :result: ``x`` with its sign changed to that of ``y``.
-
-    Note that this is a pure bitwise operation. The sign bit from ``y`` is
-    copied to the sign bit of ``x``.
-
-.. inst:: a = fmul x, y
-.. inst:: a = fdiv x, y
-.. inst:: a = fmin x, y
-.. inst:: a = fminnum x, y
-.. inst:: a = fmax x, y
-.. inst:: a = fmaxnum x, y
-
-.. inst:: a = ceil x
-
-    Round floating point round to integral, towards positive infinity.
-
-.. inst:: floor x
-
-    Round floating point round to integral, towards negative infinity.
-
-.. inst:: trunc x
-
-    Round floating point round to integral, towards zero.
-
-.. inst:: nearest x
-
-    Round floating point round to integral, towards nearest with ties to even.
-
-.. inst:: sqrt x
-
-    Floating point square root.
-
-.. inst:: a = fma x, y, z
-
-    Floating point fused multiply-and-add.
-
-    Computes :math:`a := xy+z` wihtout any intermediate rounding of the
-    product.
+.. autoinst:: ceil
+.. autoinst:: floor
+.. autoinst:: trunc
+.. autoinst:: nearest
 
 Conversion operations
 ---------------------

cranelift/src/libcretonne/instructions.rs

@@ -159,7 +159,7 @@ pub enum InstructionData {
         second_result: Value,
         args: [Value; 2],
     },
-    Select {
+    Ternary {
         opcode: Opcode,
         ty: Type,
         args: [Value; 3],

cranelift/src/libcretonne/write.rs

@@ -194,7 +194,7 @@ pub fn write_instruction(w: &mut Write, func: &Function, inst: Inst) -> Result {
         BinaryImm { arg, imm, .. } => writeln!(w, " {}, {}", arg, imm),
         BinaryImmRev { imm, arg, .. } => writeln!(w, " {}, {}", imm, arg),
         BinaryOverflow { args, .. } => writeln!(w, " {}, {}", args[0], args[1]),
-        Select { args, .. } => writeln!(w, " {}, {}, {}", args[0], args[1], args[2]),
+        Ternary { args, .. } => writeln!(w, " {}, {}, {}", args[0], args[1], args[2]),
         InsertLane { lane, args, .. } => writeln!(w, " {}, {}, {}", args[0], lane, args[1]),
         ExtractLane { lane, arg, .. } => writeln!(w, " {}, {}", arg, lane),
         IntCompare { cond, args, .. } => writeln!(w, " {}, {}, {}", cond, args[0], args[1]),

cranelift/src/libreader/parser.rs

@@ -815,13 +815,15 @@ impl<'a> Parser<'a> {
                     args: [lhs, rhs],
                 }
             }
-            InstructionFormat::Select => {
+            InstructionFormat::Ternary => {
+                // Names here refer to the `select` instruction.
+                // This format is also use by `fma`.
                 let ctrl_arg = try!(self.match_value("expected SSA value control operand"));
                 try!(self.match_token(Token::Comma, "expected ',' between operands"));
                 let true_arg = try!(self.match_value("expected SSA value true operand"));
                 try!(self.match_token(Token::Comma, "expected ',' between operands"));
                 let false_arg = try!(self.match_value("expected SSA value false operand"));
-                InstructionData::Select {
+                InstructionData::Ternary {
                     opcode: opcode,
                     ty: VOID,
                     args: [ctrl_arg, true_arg, false_arg],