From 90c56aca2fcdd1ca0568d78aa4bde7ef5e4b3a4e Mon Sep 17 00:00:00 2001
From: Timo de Kort <dekort.timo@gmail.com>
Date: Sat, 3 Oct 2020 00:47:39 +0200
Subject: [PATCH] [spv-out] Add scalar conversion support

---
 src/back/spv/instructions.rs | 42 +++++++++++++++++++++
 src/back/spv/writer.rs       | 73 ++++++++++++++++++++++++++++++++++++
 2 files changed, 115 insertions(+)

diff --git a/src/back/spv/instructions.rs b/src/back/spv/instructions.rs
index bc5cc752d8..39a9c4e732 100644
--- a/src/back/spv/instructions.rs
+++ b/src/back/spv/instructions.rs
@@ -453,7 +453,49 @@ pub(super) fn instruction_function_call(
 //
 // Conversion Instructions
 //
+fn instruction_unary(op: Op, result_type_id: Word, id: Word, value: Word) -> Instruction {
+    let mut instruction = Instruction::new(op);
+    instruction.set_type(result_type_id);
+    instruction.set_result(id);
+    instruction.add_operand(value);
+    instruction
+}
 
+pub(super) fn instruction_convert_f_to_u(
+    result_type_id: Word,
+    id: Word,
+    float_value: Word,
+) -> Instruction {
+    instruction_unary(Op::ConvertFToU, result_type_id, id, float_value)
+}
+
+pub(super) fn instruction_convert_f_to_s(
+    result_type_id: Word,
+    id: Word,
+    float_value: Word,
+) -> Instruction {
+    instruction_unary(Op::ConvertFToS, result_type_id, id, float_value)
+}
+
+pub(super) fn instruction_convert_s_to_f(
+    result_type_id: Word,
+    id: Word,
+    signed_value: Word,
+) -> Instruction {
+    instruction_unary(Op::ConvertSToF, result_type_id, id, signed_value)
+}
+
+pub(super) fn instruction_convert_u_to_f(
+    result_type_id: Word,
+    id: Word,
+    unsigned_value: Word,
+) -> Instruction {
+    instruction_unary(Op::ConvertUToF, result_type_id, id, unsigned_value)
+}
+
+pub(super) fn instruction_bit_cast(result_type_id: Word, id: Word, operand: Word) -> Instruction {
+    instruction_unary(Op::Bitcast, result_type_id, id, operand)
+}
 //
 // Composite Instructions
 //
diff --git a/src/back/spv/writer.rs b/src/back/spv/writer.rs
index 7821d2b4e1..92b600b68e 100644
--- a/src/back/spv/writer.rs
+++ b/src/back/spv/writer.rs
@@ -1033,6 +1033,79 @@ impl Writer {
                 }
                 _ => unimplemented!("{:?}", origin),
             },
+            crate::Expression::As {
+                expr,
+                kind,
+                convert,
+            } => {
+                if !convert {
+                    return None;
+                }
+
+                let (expr_id, expr_type) = self
+                    .write_expression(
+                        ir_module,
+                        ir_function,
+                        &ir_function.expressions[*expr],
+                        block,
+                        function,
+                    )
+                    .unwrap();
+
+                let id = self.generate_id();
+                let instruction = match ir_module.types[expr_type.unwrap()].inner {
+                    crate::TypeInner::Scalar {
+                        kind: expr_kind,
+                        width,
+                    } => {
+                        let kind_type_id = self.get_type_id(
+                            &ir_module.types,
+                            LookupType::Local(LocalType::Scalar { kind: *kind, width }),
+                        );
+
+                        if *convert {
+                            super::instructions::instruction_bit_cast(kind_type_id, id, expr_id)
+                        } else {
+                            match (expr_kind, kind) {
+                                (crate::ScalarKind::Float, crate::ScalarKind::Uint) => {
+                                    super::instructions::instruction_convert_f_to_u(
+                                        kind_type_id,
+                                        id,
+                                        expr_id,
+                                    )
+                                }
+                                (crate::ScalarKind::Float, crate::ScalarKind::Sint) => {
+                                    super::instructions::instruction_convert_f_to_s(
+                                        kind_type_id,
+                                        id,
+                                        expr_id,
+                                    )
+                                }
+                                (crate::ScalarKind::Sint, crate::ScalarKind::Float) => {
+                                    super::instructions::instruction_convert_s_to_f(
+                                        kind_type_id,
+                                        id,
+                                        expr_id,
+                                    )
+                                }
+                                (crate::ScalarKind::Uint, crate::ScalarKind::Float) => {
+                                    super::instructions::instruction_convert_u_to_f(
+                                        kind_type_id,
+                                        id,
+                                        expr_id,
+                                    )
+                                }
+                                _ => unreachable!(),
+                            }
+                        }
+                    }
+                    _ => unreachable!(),
+                };
+
+                block.body.push(instruction);
+
+                Some((id, None))
+            }
             _ => unimplemented!("{:?}", expression),
         }
     }