From 36124bbfe721aedf17089b82fcc433592366ae4e Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sun, 21 Jan 2024 19:10:39 +0000
Subject: Implement Patio byte-offset-of instruction

---
 .../backends/llvm/codegen/PatioToLlvm.java         | 41 +++++++++++++++++-----
 .../compiler/backends/wasm/PatioToWasm.java        | 19 ++++++++--
 .../shedlang/compiler/patio/PatioExampleTests.java | 36 +++++++++++++++++++
 3 files changed, 85 insertions(+), 11 deletions(-)

(limited to 'src')

diff --git a/src/main/java/org/shedlang/compiler/backends/llvm/codegen/PatioToLlvm.java b/src/main/java/org/shedlang/compiler/backends/llvm/codegen/PatioToLlvm.java
index fbeaa039..9ce9ad36 100644
--- a/src/main/java/org/shedlang/compiler/backends/llvm/codegen/PatioToLlvm.java
+++ b/src/main/java/org/shedlang/compiler/backends/llvm/codegen/PatioToLlvm.java
@@ -370,8 +370,18 @@ public class PatioToLlvm {
                 ));
             }
 
-            case PatioByteOffsetOf patioByteOffsetOf ->
-                throw new UnsupportedOperationException("TODO");
+            case PatioByteOffsetOf patioByteOffsetOf -> {
+                var destinationResult = context.addPatioLocalToLlvmLocal(patioByteOffsetOf.destination());
+                var destination = destinationResult.value();
+                context = destinationResult.context();
+
+                yield offsetOf(
+                    destination,
+                    patioByteOffsetOf.layout(),
+                    patioByteOffsetOf.offset(),
+                    context
+                );
+            }
 
             case PatioByteSizeOf patioByteSizeOf ->
                 throw new UnsupportedOperationException("TODO");
@@ -1381,14 +1391,28 @@ public class PatioToLlvm {
         List<Integer> patioOffset,
         PatioToLlvmFunctionContext context
     ) {
-        var offsetPtrResult = context.allocateLocalName(LlvmCodeGenLocalVariableSpace.OFFSET_PTR);
-        var offsetPtr = offsetPtrResult.value();
-        context = offsetPtrResult.context();
-
         var offsetResult = context.allocateLocalName(LlvmCodeGenLocalVariableSpace.OFFSET);
         var offset = offsetResult.value();
         context = offsetResult.context();
 
+        return offsetOf(
+            offset,
+            patioDataLayout,
+            patioOffset,
+            context
+        ).toResult(offset);
+    }
+
+    private static PatioToLlvmFunctionContext offsetOf(
+        LlvmVariable destination,
+        PatioDataLayout patioDataLayout,
+        List<Integer> patioOffset,
+        PatioToLlvmFunctionContext context
+    ) {
+        var offsetPtrResult = context.allocateLocalName(LlvmCodeGenLocalVariableSpace.OFFSET_PTR);
+        var offsetPtr = offsetPtrResult.value();
+        context = offsetPtrResult.context();
+
         return context
             .addInstruction(
                 new LlvmGetElementPtr(
@@ -1403,11 +1427,10 @@ public class PatioToLlvm {
             )
             .addInstruction(
                 new LlvmPtrToInt(
-                    offset,
+                    destination,
                     offsetPtr,
                     context.target().patioIntType()
                 )
-            )
-            .toResult(offset);
+            );
     }
 }
diff --git a/src/main/java/org/shedlang/compiler/backends/wasm/PatioToWasm.java b/src/main/java/org/shedlang/compiler/backends/wasm/PatioToWasm.java
index c140bf92..3bbbd41c 100644
--- a/src/main/java/org/shedlang/compiler/backends/wasm/PatioToWasm.java
+++ b/src/main/java/org/shedlang/compiler/backends/wasm/PatioToWasm.java
@@ -214,8 +214,23 @@ public class PatioToWasm {
                 yield context;
             }
 
-            case PatioByteOffsetOf patioByteOffsetOf ->
-                throw new UnsupportedOperationException("TODO");
+            case PatioByteOffsetOf patioByteOffsetOf -> {
+                context = context.addInstruction(wasmIntConst(
+                    target.patioIntType(),
+                    offsetOf(
+                        patioByteOffsetOf.layout(),
+                        patioByteOffsetOf.offset(),
+                        target
+                    )
+                ));
+
+                var destinationIndex = context.wasmLocalIndex(patioByteOffsetOf.destination());
+                context = context.addInstruction(new WasmLocalSet(destinationIndex));
+
+                yield context;
+            }
+
+
 
             case PatioByteSizeOf patioByteSizeOf ->
                 throw new UnsupportedOperationException("TODO");
diff --git a/src/test/java/org/shedlang/compiler/patio/PatioExampleTests.java b/src/test/java/org/shedlang/compiler/patio/PatioExampleTests.java
index d485e9e5..8582cfd0 100644
--- a/src/test/java/org/shedlang/compiler/patio/PatioExampleTests.java
+++ b/src/test/java/org/shedlang/compiler/patio/PatioExampleTests.java
@@ -818,6 +818,42 @@ public abstract class PatioExampleTests {
         assertThat(result, isSilentExit(47));
     }
 
+    @Test
+    public void canGetByteOffset() throws IOException, InterruptedException {
+        var patioFunction = PatioFunctionDefinition.builder()
+            .withName(FUNCTION_NAME)
+            .withReturnType(PatioTypes.INT)
+            .addLocal(Patio.val("x", PatioTypes.INT))
+            .addBodyInstruction(Patio.byteOffsetOf(
+                Patio.localRef("x"),
+                PatioDataLayouts.struct(List.of(
+                    PatioDataLayouts.struct(List.of(
+                        PatioDataLayouts.BYTE,
+                        PatioDataLayouts.BYTE
+                    )),
+                    PatioDataLayouts.struct(List.of(
+                        PatioDataLayouts.BYTE,
+                        PatioDataLayouts.BYTE,
+                        PatioDataLayouts.BYTE,
+                        PatioDataLayouts.BYTE
+                    )),
+                    PatioDataLayouts.BYTE
+                )),
+                List.of(1, 2)
+            ))
+            .addBodyInstruction(Patio.return_(
+                Patio.localRef("x")
+            ))
+            .build();
+        var patio = Patio.compilationUnit(List.of(
+            patioFunction
+        ));
+
+        var result = run(patio);
+
+        assertThat(result, isSilentExit(4));
+    }
+
     private Matcher<ExecutionResult> isSilentExit(int exitCode) {
         return allOf(
             has("stderr", x -> x.stderr(), equalTo("")),
-- 
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