riscv64: Support non 128bit vector sizes (bytecodealliance#6266)

* riscv64: Add `Zvl` extensions

* riscv64: Allow lowering SIMD operations that fit in a vector register

* riscv64: Support non 128bit vector sizes

* riscv64: Add Zvl Presets

* riscv64: Precompute `min_vec_reg_size`

cranelift/codegen/meta/src/cdsl/mod.rs

@@ -28,7 +28,7 @@ macro_rules! preset {
     () => {
         vec![]
     };
-    ($($x:ident)&&*) => {
+    ($($x:tt)&&*) => {
         {
             let mut v = Vec::new();
             $(

cranelift/codegen/meta/src/gen_types.rs

@@ -60,7 +60,7 @@ fn emit_types(fmt: &mut srcgen::Formatter) {
 
     // Emit vector definitions for common SIMD sizes.
     // Emit dynamic vector definitions.
-    for vec_size in &[64_u64, 128, 256, 512] {
+    for vec_size in &[16_u64, 32, 64, 128, 256, 512] {
         emit_vectors(*vec_size, fmt);
         emit_dynamic_vectors(*vec_size, fmt);
     }

cranelift/codegen/meta/src/isa/riscv64.rs

@@ -3,6 +3,30 @@ use crate::cdsl::settings::{SettingGroup, SettingGroupBuilder};
 
 use crate::shared::Definitions as SharedDefinitions;
 
+macro_rules! define_zvl_ext {
+    (DEF: $settings:expr, $size:expr) => {{
+        let name = concat!("has_zvl", $size, "b");
+        let desc = concat!("has extension Zvl", $size, "b?");
+        let comment = concat!(
+            "Zvl",
+            $size,
+            "b: Vector register has a minimum of ",
+            $size,
+            " bits"
+        );
+        $settings.add_bool(&name, &desc, &comment, false)
+    }};
+    ($settings:expr, $size:expr $(, $implies:expr)*) => {{
+        let has_feature = define_zvl_ext!(DEF: $settings, $size);
+
+        let name = concat!("zvl", $size, "b");
+        let desc = concat!("Has a vector register size of at least ", $size, " bits");
+
+        let preset = $settings.add_preset(&name, &desc, preset!(has_feature $( && $implies )*));
+        (has_feature, preset)
+    }};
+}
+
 fn define_settings(_shared: &SettingGroup) -> SettingGroup {
     let mut setting = SettingGroupBuilder::new("riscv64");
 
@@ -56,6 +80,25 @@ fn define_settings(_shared: &SettingGroup) -> SettingGroup {
         false,
     );
 
+    // Zvl*: Minimum Vector Length Standard Extensions
+    // These extension specifiy the minimum number of bits in a vector register.
+    // Since it is a minimum, Zvl64b implies Zvl32b, Zvl128b implies Zvl64b, etc.
+    // The V extension supports a maximum of 64K bits in a single register.
+    //
+    // See: https://github.com/riscv/riscv-v-spec/blob/master/v-spec.adoc#181-zvl-minimum-vector-length-standard-extensions
+    let (_, zvl32b) = define_zvl_ext!(setting, 32);
+    let (_, zvl64b) = define_zvl_ext!(setting, 64, zvl32b);
+    let (_, zvl128b) = define_zvl_ext!(setting, 128, zvl64b);
+    let (_, zvl256b) = define_zvl_ext!(setting, 256, zvl128b);
+    let (_, zvl512b) = define_zvl_ext!(setting, 512, zvl256b);
+    let (_, zvl1024b) = define_zvl_ext!(setting, 1024, zvl512b);
+    let (_, zvl2048b) = define_zvl_ext!(setting, 2048, zvl1024b);
+    let (_, zvl4096b) = define_zvl_ext!(setting, 4096, zvl2048b);
+    let (_, zvl8192b) = define_zvl_ext!(setting, 8192, zvl4096b);
+    let (_, zvl16384b) = define_zvl_ext!(setting, 16384, zvl8192b);
+    let (_, zvl32768b) = define_zvl_ext!(setting, 32768, zvl16384b);
+    let (_, _zvl65536b) = define_zvl_ext!(setting, 65536, zvl32768b);
+
     setting.build()
 }
 

cranelift/codegen/src/isa/riscv64/inst/mod.rs

@@ -761,7 +761,25 @@ impl MachInst for Inst {
             F32 => Ok((&[RegClass::Float], &[F32])),
             F64 => Ok((&[RegClass::Float], &[F64])),
             I128 => Ok((&[RegClass::Int, RegClass::Int], &[I64, I64])),
-            _ if ty.is_vector() && ty.bits() == 128 => Ok((&[RegClass::Float], &[types::I8X16])),
+            _ if ty.is_vector() => {
+                debug_assert!(ty.bits() <= 512);
+
+                // Here we only need to return a SIMD type with the same size as `ty`.
+                // We use these types for spills and reloads, so prefer types with lanes <= 31
+                // since that fits in the immediate field of `vsetivli`.
+                const SIMD_TYPES: [[Type; 1]; 6] = [
+                    [types::I8X2],
+                    [types::I8X4],
+                    [types::I8X8],
+                    [types::I8X16],
+                    [types::I16X16],
+                    [types::I32X16],
+                ];
+                let idx = (ty.bytes().ilog2() - 1) as usize;
+                let ty = &SIMD_TYPES[idx][..];
+
+                Ok((&[RegClass::Float], ty))
+            }
             _ => Err(CodegenError::Unsupported(format!(
                 "Unexpected SSA-value type: {}",
                 ty

cranelift/codegen/src/isa/riscv64/inst_vector.isle

@@ -99,6 +99,14 @@
   (if-let $I64 (lane_type ty))
   (VecElementWidth.E64))
 
+(decl pure min_vec_reg_size () u64)
+(extern constructor min_vec_reg_size min_vec_reg_size)
+
+;; An extractor that matches any type that is known to fit in a single vector
+;; register.
+(decl ty_vec_fits_in_register (Type) Type)
+(extern extractor ty_vec_fits_in_register ty_vec_fits_in_register)
+
 ;;;; Instruction Helpers ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 ;; As noted in the RISC-V Vector Extension Specification, rs2 is the first

cranelift/codegen/src/isa/riscv64/lower.isle

@@ -28,14 +28,14 @@
 ;;;; Rules for `iadd` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 ;; Base case, simply adding things in registers.
-(rule 0 (lower (has_type (fits_in_64 ty) (iadd x y)))
+(rule 0 (lower (has_type (ty_int_ref_scalar_64 ty) (iadd x y)))
   (rv_add x y))
 
 ;; Special cases for when one operand is an immediate that fits in 12 bits.
-(rule 1 (lower (has_type (fits_in_64 ty) (iadd x (imm12_from_value y))))
+(rule 1 (lower (has_type (ty_int_ref_scalar_64 ty) (iadd x (imm12_from_value y))))
   (alu_rr_imm12 (select_addi ty) x y))
 
-(rule 2 (lower (has_type (fits_in_64 ty) (iadd (imm12_from_value x) y)))
+(rule 2 (lower (has_type (ty_int_ref_scalar_64 ty) (iadd (imm12_from_value x) y)))
   (alu_rr_imm12 (select_addi ty) y x))
 
 ;; Special case when one of the operands is uextended
@@ -98,8 +98,7 @@
     (value_regs low high)))
 
 ;; SIMD Vectors
-(rule 8 (lower (has_type (ty_vec128_int ty) (iadd x y)))
-  (if-let $true (has_v))
+(rule 8 (lower (has_type (ty_vec_fits_in_register ty) (iadd x y)))
   (rv_vadd_vv x y ty))
 
 ;;; Rules for `uadd_overflow_trap` ;;;;;;;;;;;;;
@@ -815,8 +814,7 @@
   (gen_load_128 p offset flags))
 
 (rule 2
-  (lower (has_type (ty_vec128_int ty) (load flags p @ (value_type (ty_addr64 _)) offset)))
-  (if-let $true (has_v))
+  (lower (has_type (ty_vec_fits_in_register ty) (load flags p @ (value_type (ty_addr64 _)) offset)))
   (let ((eew VecElementWidth (element_width_from_type ty)))
     (vec_load eew (VecAMode.UnitStride (gen_amode p offset $I64)) flags ty)))
 
@@ -845,8 +843,7 @@
   (gen_store_128 p offset flags x))
 
 (rule 2
-  (lower (store flags x @ (value_type (ty_vec128_int ty)) p @ (value_type (ty_addr64 _)) offset))
-  (if-let $true (has_v))
+  (lower (store flags x @ (value_type (ty_vec_fits_in_register ty)) p @ (value_type (ty_addr64 _)) offset))
   (let ((eew VecElementWidth (element_width_from_type ty)))
     (vec_store eew (VecAMode.UnitStride (gen_amode p offset $I64)) x flags ty)))
 

cranelift/codegen/src/isa/riscv64/lower/isle.rs

@@ -33,23 +33,67 @@ type VecMachLabel = Vec<MachLabel>;
 type VecArgPair = Vec<ArgPair>;
 use crate::machinst::valueregs;
 
-/// The main entry point for lowering with ISLE.
-pub(crate) fn lower(
-    lower_ctx: &mut Lower<MInst>,
-    backend: &Riscv64Backend,
-    inst: Inst,
-) -> Option<InstOutput> {
-    // TODO: reuse the ISLE context across lowerings so we can reuse its
-    // internal heap allocations.
-    let mut isle_ctx = IsleContext { lower_ctx, backend };
-    generated_code::constructor_lower(&mut isle_ctx, inst)
+pub(crate) struct RV64IsleContext<'a, 'b, I, B>
+where
+    I: VCodeInst,
+    B: LowerBackend,
+{
+    pub lower_ctx: &'a mut Lower<'b, I>,
+    pub backend: &'a B,
+    /// Precalucated value for the minimum vector register size. Will be 0 if
+    /// vectors are not supported.
+    min_vec_reg_size: u64,
 }
 
-impl IsleContext<'_, '_, MInst, Riscv64Backend> {
+impl<'a, 'b> RV64IsleContext<'a, 'b, MInst, Riscv64Backend> {
     isle_prelude_method_helpers!(Riscv64ABICaller);
+
+    fn new(lower_ctx: &'a mut Lower<'b, MInst>, backend: &'a Riscv64Backend) -> Self {
+        Self {
+            lower_ctx,
+            backend,
+            min_vec_reg_size: Self::compute_min_vec_reg_size(backend),
+        }
+    }
+
+    fn compute_min_vec_reg_size(backend: &Riscv64Backend) -> u64 {
+        let flags = &backend.isa_flags;
+        let entries = [
+            (flags.has_zvl65536b(), 65536),
+            (flags.has_zvl32768b(), 32768),
+            (flags.has_zvl16384b(), 16384),
+            (flags.has_zvl8192b(), 8192),
+            (flags.has_zvl4096b(), 4096),
+            (flags.has_zvl2048b(), 2048),
+            (flags.has_zvl1024b(), 1024),
+            (flags.has_zvl512b(), 512),
+            (flags.has_zvl256b(), 256),
+            // In order to claim the Application Profile V extension, a minimum
+            // register size of 128 is required. i.e. V implies Zvl128b.
+            (flags.has_v(), 128),
+            (flags.has_zvl128b(), 128),
+            (flags.has_zvl64b(), 64),
+            (flags.has_zvl32b(), 32),
+        ];
+
+        for (has_flag, size) in entries.into_iter() {
+            if has_flag {
+                return size;
+            }
+        }
+
+        return 0;
+    }
+
+    #[inline]
+    fn emit_list(&mut self, list: &SmallInstVec<MInst>) {
+        for i in list {
+            self.lower_ctx.emit(i.clone());
+        }
+    }
 }
 
-impl generated_code::Context for IsleContext<'_, '_, MInst, Riscv64Backend> {
+impl generated_code::Context for RV64IsleContext<'_, '_, MInst, Riscv64Backend> {
     isle_lower_prelude_methods!();
     isle_prelude_caller_methods!(Riscv64MachineDeps, Riscv64ABICaller);
 
@@ -437,17 +481,33 @@ impl generated_code::Context for IsleContext<'_, '_, MInst, Riscv64Backend> {
     fn vstate_from_type(&mut self, ty: Type) -> VState {
         VState::from_type(ty)
     }
-}
 
-impl IsleContext<'_, '_, MInst, Riscv64Backend> {
+    fn min_vec_reg_size(&mut self) -> u64 {
+        self.min_vec_reg_size
+    }
+
     #[inline]
-    fn emit_list(&mut self, list: &SmallInstVec<MInst>) {
-        for i in list {
-            self.lower_ctx.emit(i.clone());
+    fn ty_vec_fits_in_register(&mut self, ty: Type) -> Option<Type> {
+        if ty.is_vector() && (ty.bits() as u64) <= self.min_vec_reg_size() {
+            Some(ty)
+        } else {
+            None
         }
     }
 }
 
+/// The main entry point for lowering with ISLE.
+pub(crate) fn lower(
+    lower_ctx: &mut Lower<MInst>,
+    backend: &Riscv64Backend,
+    inst: Inst,
+) -> Option<InstOutput> {
+    // TODO: reuse the ISLE context across lowerings so we can reuse its
+    // internal heap allocations.
+    let mut isle_ctx = RV64IsleContext::new(lower_ctx, backend);
+    generated_code::constructor_lower(&mut isle_ctx, inst)
+}
+
 /// The main entry point for branch lowering with ISLE.
 pub(crate) fn lower_branch(
     lower_ctx: &mut Lower<MInst>,
@@ -457,7 +517,7 @@ pub(crate) fn lower_branch(
 ) -> Option<()> {
     // TODO: reuse the ISLE context across lowerings so we can reuse its
     // internal heap allocations.
-    let mut isle_ctx = IsleContext { lower_ctx, backend };
+    let mut isle_ctx = RV64IsleContext::new(lower_ctx, backend);
     generated_code::constructor_lower_branch(&mut isle_ctx, branch, &targets.to_vec())
 }
 

cranelift/codegen/src/isle_prelude.rs

@@ -303,6 +303,11 @@ macro_rules! isle_common_prelude_methods {
             }
         }
 
+        #[inline]
+        fn ty_int_ref_scalar_64_extract(&mut self, ty: Type) -> Option<Type> {
+            self.ty_int_ref_scalar_64(ty)
+        }
+
         #[inline]
         fn ty_32(&mut self, ty: Type) -> Option<Type> {
             if ty.bits() == 32 {

cranelift/codegen/src/prelude.isle

@@ -340,10 +340,11 @@
 (decl ty_64 (Type) Type)
 (extern extractor ty_64 ty_64)
 
-;; A pure constructor that only matches scalar integers, and references that can
-;; fit in 64 bits.
+;; A pure constructor/extractor that only matches scalar integers, and
+;; references that can fit in 64 bits.
 (decl pure partial ty_int_ref_scalar_64 (Type) Type)
 (extern constructor ty_int_ref_scalar_64 ty_int_ref_scalar_64)
+(extern extractor ty_int_ref_scalar_64 ty_int_ref_scalar_64_extract)
 
 ;; An extractor that matches 32- and 64-bit types only.
 (decl ty_32_or_64 (Type) Type)

cranelift/filetests/filetests/isa/riscv64/simd-iadd-big.clif

@@ -0,0 +1,40 @@
+test compile precise-output
+set unwind_info=false
+target riscv64 has_v has_zvl2048b
+
+
+
+function %iadd_i64x4(i64x4, i64x4) -> i64x4 {
+block0(v0:i64x4, v1:i64x4):
+    v2 = iadd v0, v1
+    return v2
+}
+
+; VCode:
+; block0:
+;   vadd.vv v10,v11,v10 #avl=4, #vtype=(e64, m1, ta, ma)
+;   ret
+; 
+; Disassembled:
+; block0: ; offset 0x0
+;   .byte 0x57, 0x70, 0x82, 0xcd
+;   .byte 0x57, 0x05, 0xb5, 0x02
+;   ret
+
+function %iadd_i64x8(i64x8, i64x8) -> i64x8 {
+block0(v0:i64x8, v1:i64x8):
+    v2 = iadd v0, v1
+    return v2
+}
+
+; VCode:
+; block0:
+;   vadd.vv v10,v11,v10 #avl=8, #vtype=(e64, m1, ta, ma)
+;   ret
+; 
+; Disassembled:
+; block0: ; offset 0x0
+;   .byte 0x57, 0x70, 0x84, 0xcd
+;   .byte 0x57, 0x05, 0xb5, 0x02
+;   ret
+