From bca3cb32ef9e37c62b4e282917a0d57c4e8a5362 Mon Sep 17 00:00:00 2001
From: dheaton-arm <Damian.Heaton@arm.com>
Date: Mon, 6 Sep 2021 11:50:21 +0100
Subject: [PATCH 1/2] Implement `Shuffle` for the interpreter

Implemented `Shuffle` for the Cranelift interpreter, to shuffle two SIMD
vectors together based on an immediate mask of 16 bytes.

Copyright (c) 2021, Arm Limited
---
 .../filetests/runtests/simd-shuffle.clif      | 12 +++++++++
 cranelift/interpreter/src/step.rs             | 25 ++++++++++++++++++-
 2 files changed, 36 insertions(+), 1 deletion(-)
 create mode 100644 cranelift/filetests/filetests/runtests/simd-shuffle.clif

diff --git a/cranelift/filetests/filetests/runtests/simd-shuffle.clif b/cranelift/filetests/filetests/runtests/simd-shuffle.clif
new file mode 100644
index 0000000000..d4151953e6
--- /dev/null
+++ b/cranelift/filetests/filetests/runtests/simd-shuffle.clif
@@ -0,0 +1,12 @@
+test interpret
+test run
+target aarch64
+set enable_simd
+target x86_64
+
+function %shuffle_i8x16(i8x16, i8x16) -> i8x16 {
+block0(v0: i8x16, v1: i8x16):
+    v2 = shuffle v0, v1, [3 0 31 26 100 6 12 11 23 13 24 4 2 15 17 5]
+    return v2
+}
+; run: %shuffle_i8x16([1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16], [17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32]) == [4 1 32 27 0 7 13 12 24 14 25 5 3 16 18 6]
diff --git a/cranelift/interpreter/src/step.rs b/cranelift/interpreter/src/step.rs
index ce53528c20..638db5937c 100644
--- a/cranelift/interpreter/src/step.rs
+++ b/cranelift/interpreter/src/step.rs
@@ -776,7 +776,30 @@ where
             arg(0)?,
             ValueConversionKind::RoundNearestEven(ctrl_ty),
         )?),
-        Opcode::Shuffle => unimplemented!("Shuffle"),
+        Opcode::Shuffle => {
+            if let InstructionData::Shuffle { mask, .. } = inst {
+                let mask = state
+                    .get_current_function()
+                    .dfg
+                    .immediates
+                    .get(mask)
+                    .unwrap()
+                    .as_slice();
+                let a = Value::into_array(&arg(0)?)?;
+                let b = Value::into_array(&arg(1)?)?;
+                let mut new = [0u8; 16];
+                for i in 0..mask.len() {
+                    if (mask[i] as usize) < a.len() {
+                        new[i] = a[mask[i] as usize];
+                    } else if (mask[i] as usize - a.len()) < b.len() {
+                        new[i] = b[mask[i] as usize - a.len()];
+                    } // else leave as 0.
+                }
+                assign(Value::vector(new, ctrl_ty)?)
+            } else {
+                unreachable!();
+            }
+        }
         Opcode::Swizzle => {
             let x = Value::into_array(&arg(0)?)?;
             let s = Value::into_array(&arg(1)?)?;

From 4a4f940facf98d172243805c25ce4456fc39b8bd Mon Sep 17 00:00:00 2001
From: dheaton-arm <Damian.Heaton@arm.com>
Date: Fri, 10 Sep 2021 12:36:33 +0100
Subject: [PATCH 2/2] Move immediate value retrieval to `imm`

Copyright (c) 2021, Arm Limited
---
 cranelift/interpreter/src/step.rs | 42 +++++++++++++++----------------
 1 file changed, 21 insertions(+), 21 deletions(-)

diff --git a/cranelift/interpreter/src/step.rs b/cranelift/interpreter/src/step.rs
index 638db5937c..bfba030176 100644
--- a/cranelift/interpreter/src/step.rs
+++ b/cranelift/interpreter/src/step.rs
@@ -76,6 +76,16 @@ where
                     .as_slice();
                 DataValue::V128(buffer.try_into().expect("a 16-byte data buffer"))
             }
+            InstructionData::Shuffle { mask, .. } => {
+                let mask = state
+                    .get_current_function()
+                    .dfg
+                    .immediates
+                    .get(mask)
+                    .unwrap()
+                    .as_slice();
+                DataValue::V128(mask.try_into().expect("a 16-byte vector mask"))
+            }
             _ => inst.imm_value().unwrap(),
         })
     };
@@ -777,28 +787,18 @@ where
             ValueConversionKind::RoundNearestEven(ctrl_ty),
         )?),
         Opcode::Shuffle => {
-            if let InstructionData::Shuffle { mask, .. } = inst {
-                let mask = state
-                    .get_current_function()
-                    .dfg
-                    .immediates
-                    .get(mask)
-                    .unwrap()
-                    .as_slice();
-                let a = Value::into_array(&arg(0)?)?;
-                let b = Value::into_array(&arg(1)?)?;
-                let mut new = [0u8; 16];
-                for i in 0..mask.len() {
-                    if (mask[i] as usize) < a.len() {
-                        new[i] = a[mask[i] as usize];
-                    } else if (mask[i] as usize - a.len()) < b.len() {
-                        new[i] = b[mask[i] as usize - a.len()];
-                    } // else leave as 0.
-                }
-                assign(Value::vector(new, ctrl_ty)?)
-            } else {
-                unreachable!();
+            let mask = imm().into_array()?;
+            let a = Value::into_array(&arg(0)?)?;
+            let b = Value::into_array(&arg(1)?)?;
+            let mut new = [0u8; 16];
+            for i in 0..mask.len() {
+                if (mask[i] as usize) < a.len() {
+                    new[i] = a[mask[i] as usize];
+                } else if (mask[i] as usize - a.len()) < b.len() {
+                    new[i] = b[mask[i] as usize - a.len()];
+                } // else leave as 0.
             }
+            assign(Value::vector(new, ctrl_ty)?)
         }
         Opcode::Swizzle => {
             let x = Value::into_array(&arg(0)?)?;