From e0b8a6d542817ca464c46033e0c6323c23d2aeac Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sat, 17 Jun 2023 00:31:56 +0100
Subject: Add code for calculating size of an LLVM type in LLVM IR

---
 .../llvm/LlvmCompilerLocalVariableSpace.java       |  2 +
 .../compiler/backends/llvm/LlvmSizeOf.java         | 45 ++++++++++++++++++++++
 2 files changed, 47 insertions(+)
 create mode 100644 src/main/java/org/shedlang/compiler/backends/llvm/LlvmSizeOf.java

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/backends/llvm/LlvmCompilerLocalVariableSpace.java b/src/main/java/org/shedlang/compiler/backends/llvm/LlvmCompilerLocalVariableSpace.java
index 457fa7c5..27d7a4d0 100644
--- a/src/main/java/org/shedlang/compiler/backends/llvm/LlvmCompilerLocalVariableSpace.java
+++ b/src/main/java/org/shedlang/compiler/backends/llvm/LlvmCompilerLocalVariableSpace.java
@@ -6,6 +6,8 @@ public enum LlvmCompilerLocalVariableSpace {
     CLOSURE_FUNCTION_POINTER_POINTER("closureFunctionPointerPointer"),
     CLOSURE_ENVIRONMENT_POINTER("closureEnvironmentPointer"),
     FIELD_POINTER("fieldPointer"),
+    SIZE_PTR("size_ptr"),
+    SIZE("size"),
     TEMPORARY("tmp");
 
     private final String name;
diff --git a/src/main/java/org/shedlang/compiler/backends/llvm/LlvmSizeOf.java b/src/main/java/org/shedlang/compiler/backends/llvm/LlvmSizeOf.java
new file mode 100644
index 00000000..d26e8635
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/backends/llvm/LlvmSizeOf.java
@@ -0,0 +1,45 @@
+package org.shedlang.compiler.backends.llvm;
+
+import org.shedlang.compiler.backends.llvm.ir.ast.instructions.LlvmGetElementPtr;
+import org.shedlang.compiler.backends.llvm.ir.ast.instructions.LlvmPtrToInt;
+import org.shedlang.compiler.backends.llvm.ir.ast.operands.LlvmOperand;
+import org.shedlang.compiler.backends.llvm.ir.ast.operands.LlvmOperandNull;
+import org.shedlang.compiler.backends.llvm.ir.ast.operands.LlvmTypedOperand;
+import org.shedlang.compiler.backends.llvm.ir.ast.types.LlvmType;
+import org.shedlang.compiler.backends.llvm.ir.ast.types.LlvmTypes;
+
+import java.util.List;
+
+public class LlvmSizeOf {
+    private LlvmSizeOf() {
+    }
+
+    public static LlvmCompilerResult<LlvmOperand> sizeOf(LlvmType type, LlvmCompilerContext context) {
+        var sizePtrResult = context.generateVariableLocal(LlvmCompilerLocalVariableSpace.SIZE_PTR);
+        var sizePtr = sizePtrResult.value();
+        context = sizePtrResult.context();
+
+        var sizeResult = context.generateVariableLocal(LlvmCompilerLocalVariableSpace.SIZE);
+        var size = sizeResult.value();
+        context = sizeResult.context();
+
+        return context
+            .addInstruction(
+                new LlvmGetElementPtr(
+                    sizePtr,
+                    LlvmTypes.pointer(type),
+                    new LlvmOperandNull(),
+                    List.of(LlvmTypedOperand.arrayIndex(0))
+                )
+            )
+            .addInstruction(
+                new LlvmPtrToInt(
+                    size,
+                    LlvmTypes.pointer(type),
+                    sizePtr,
+                    LlvmTypes.INT_64
+                )
+            )
+            .toResult(size);
+    }
+}
-- 
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