feat: add Z{f,d,h}inx{min} extensions, modify check_f_ok for them

* Adds missing *inx* extension skeletons.
* Updates the check_f_ok IDL function to look at mstateen0.FCSR instead of
  mstatus.FS when an *inx* extension is implemented

Author: dhower-qc

arch/ext/Zdinx.yaml

@@ -0,0 +1,65 @@
+# yaml-language-server: $schema=../../schemas/ext_schema.json
+
+$schema: "ext_schema.json#"
+kind: extension
+name: Zdinx
+long_name: Double-precision floating-point instructions using integer registers
+description:
+  - id: ext-zdinx-instructions
+    normative: true
+    text: |
+      The Zdinx extension adds all of the instructions that the D extension adds, except for the
+      transfer instructions FLD, FSD, FMV.D.X, FMV.X.D, C.FLD[SP], and C.FSD[SP].
+
+  - id: ext-zdinx-semantics
+    normative: true
+    text: |
+      The Zdinx variants of these D-extension instructions have the same semantics, except that whenever
+      such an instruction would have accessed an f register, it instead accesses the x register with the
+      same number.
+
+  - id: ext-zdinx-rv32regpair
+    normative: true
+    text: |
+      Double-precision operands in RV32Zdinx are held in aligned x-register pairs, i.e., register
+      numbers must be even. Use of misaligned (odd-numbered) registers for double-width
+      floating-point operands is reserved.
+    when(): return MXLEN == 32;
+
+  - id: ext-zdinx-rv32endianness
+    normative: true
+    text: |
+      Regardless of endianness, the lower-numbered register holds the low-order bits, and the
+      higher-numbered register holds the high-order bits: e.g., bits 31:0 of a double-precision
+      operand in RV32Zdinx might be held in register x14, with bits 63:32 of that operand held
+      in x15.
+    when(): return MXLEN == 32;
+
+  - id: ext-zdinx-rv32x0
+    normative: true
+    text: |
+      When a double-width floating-point result is written to x0, the entire write takes no effect:
+      e.g., for RV32Zdinx, writing a double-precision result to x0 does not cause x1 to be written.
+    when(): return MXLEN == 32;
+
+  - id: ext-zdinx-rv32x1
+    normative: true
+    text: |
+      When x0 is used as a double-width floating-point operand, the entire operand is zero—i.e.,
+      x1 is not accessed.
+    when(): return MXLEN == 32;
+
+  - id: ext-zdinx-rv32mempair
+    normative: false
+    text: |
+      Load-pair and store-pair instructions are not provided, so transferring double-precision
+      operands in RV32Zdinx from or to memory requires two loads or stores.
+      Register moves need only a single FSGNJ.D instruction, however.
+    when(): return MXLEN == 32;
+
+type: unprivileged
+versions:
+  - version: "1.0.0"
+    state: ratified
+    ratification_date: 2021-11
+    requires: Zfinx

arch/ext/Zfh.yaml

@@ -16,3 +16,4 @@ versions:
   - version: "1.0.0"
     state: ratified
     ratification_date: null
+    requires: F

arch/ext/Zfinx.yaml

@@ -0,0 +1,27 @@
+# yaml-language-server: $schema=../../schemas/ext_schema.json
+
+$schema: "ext_schema.json#"
+kind: extension
+name: Zfinx
+long_name: Single-precision floating-point instructions using integer registers
+description:
+  - id: ext-zfinx-instructions
+    normative: true
+    text: |
+      The Zfinx extension adds all of the instructions that the F extension adds, except for the
+      transfer instructions FLW, FSW, FMV.W.X, FMV.X.W, C.FLW[SP], and C.FSW[SP].
+
+  - id: ext-zfinx-semantics
+    normative: true
+    text: |
+      The Zfinx variants of these F-extension instructions have the same semantics, except that
+      whenever such an instruction would have accessed an f register, it instead accesses the
+      x register with the same number.
+
+type: unprivileged
+versions:
+  - version: "1.0.0"
+    state: ratified
+    ratification_date: 2021-11
+    requires: Zicsr
+conflicts: F

arch/ext/Zhinx.yaml

@@ -4,17 +4,23 @@ $schema: "ext_schema.json#"
 kind: extension
 name: Zhinx
 long_name: Half-precision floating-point instructions using integer registers
-description: |
-  The Zhinx extension provides analogous half-precision floating-point instructions. The Zhinx extension
-  depends upon the Zfinx extension.
-  The Zhinx extension adds all of the instructions that the Zfh extension adds, except for the transfer
-  instructions FLH, FSH, FMV.H.X, and FMV.X.H.
-  The Zhinx variants of these Zfh-extension instructions have the same semantics, except that whenever
-  such an instruction would have accessed an f register, it instead accesses the x register with the same
-  number.
+description:
+  - id: ext-zhinx-instructions
+    normative: true
+    text: |
+      The Zhinx extension adds all of the instructions that the Zfh extension adds, except for the
+      transfer instructions FLH, FSH, FMV.H.X, and FMV.X.H.
+
+  - id: ext-zhinx-semantics
+    normative: true
+    text: |
+      The Zhinx variants of these Zfh-extension instructions have the same semantics, except that
+      whenever such an instruction would have accessed an f register, it instead accesses the x
+      register with the same number.
 
 type: unprivileged
 versions:
   - version: "1.0.0"
     state: ratified
     ratification_date: 2021-11
+    requires: Zfinx

arch/ext/Zhinxmin.yaml

@@ -0,0 +1,27 @@
+# yaml-language-server: $schema=../../schemas/ext_schema.json
+
+$schema: "ext_schema.json#"
+kind: extension
+name: Zhinxmin
+long_name: Minimal support for half-precision floating-point instructions using integer registers
+description:
+  - id: ext-zhinxmin-instructions
+    normative: true
+    text: |
+      The Zhinxmin extension includes the following instructions from the Zhinx extension:
+      FCVT.S.H and FCVT.H.S.
+    when(): return !implemented?(Zdinx);
+
+  - id: ext-zhinxmin-instructions-with-zdinx
+    normative: true
+    text: |
+      The Zhinxmin extension includes the following instructions from the Zhinx extension:
+      FCVT.S.H, FCVT.H.S, FCVT.D.H, and FCVT.H.D.
+    when(): return implemented?(Zdinx);
+
+type: unprivileged
+versions:
+  - version: "1.0.0"
+    state: ratified
+    ratification_date: 2021-11
+    requires: Zfinx

arch/isa/fp.idl

@@ -125,16 +125,42 @@ function check_f_ok {
   arguments
     Bits<INSTR_ENC_SIZE> encoding
   description {
-    Checks if instructions from the `F` extension can be executed, and, if not,
+    Checks if instructions from a floating point extension can be executed, and, if not,
     raise an exception.
   }
   body {
-    if (MUTABLE_MISA_F && CSR[misa].F == 0) {
-      raise(ExceptionCode::IllegalInstruction, mode(), encoding);
-    }
+    # All Z*inx extensions depend on Zfinx, so we only have to check if Zfinx is implemented
+    if (implemented?(ExtensionName::Zfinx)) {
+      # mstateen0.FCSR disables all modes
+      if (implemented?(ExtensionName::Smstateen) && (CSR[mstateen0].FCSR == 0)) {
+        raise(ExceptionCode::IllegalInstruction, mode(), enoding);
+      }
 
-    if (CSR[mstatus].FS == 0) {
-      raise(ExceptionCode::IllegalInstruction, mode(), encoding);
+      # sstateen0.FCSR disables all modes except M
+      if (implemented?(ExtensionName::Sstateen) &&
+          (mode() != PrivilegeMode::M) &&
+          (CSR[sstateen0].FCSR == 0)) {
+        raise(ExceptionCode::IllegalInstruction, mode(), enoding);
+      }
+
+      # hstateen0.FCSR disables VS and VU
+      if (implemented?(ExtensionName::Sstateen) &&
+          implemented?(ExtensionName::H) &&
+          (CSR[misa].H == 1) &&
+          virtual_mode?() &&
+          (CSR[hstateen0].FCSR == 0)) {
+        raise(ExceptionCode::IllegalInstruction, mode(), enoding);
+      }
+    } else if (implemented?(ExtensionName::F)) {
+      if (MUTABLE_MISA_F && CSR[misa].F == 0) {
+        raise(ExceptionCode::IllegalInstruction, mode(), encoding);
+      }
+
+      if (CSR[mstatus].FS == 0) {
+        raise(ExceptionCode::IllegalInstruction, mode(), encoding);
+      }
+    } else {
+      assert(false, "check_f_ok called when no FP extension is implemented");
     }
   }
 }