From a0fdc0e6dd56616bb7519969e47518321b7a2685 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Wed, 20 Dec 2023 16:28:36 +0000
Subject: Read jmp_buf size instead of hard-coding

---
 .../backends/llvm/codegen/LlvmPatioCodeGen.java    | 25 +++++++++++++++++----
 .../llvm/codegen/errors/SizeofJmpBufError.java     | 10 +++++++++
 src/main/java/org/shedlang/compiler/util/Lazy.java | 26 ++++++++++++++++++++++
 3 files changed, 57 insertions(+), 4 deletions(-)
 create mode 100644 src/main/java/org/shedlang/compiler/backends/llvm/codegen/errors/SizeofJmpBufError.java
 create mode 100644 src/main/java/org/shedlang/compiler/util/Lazy.java

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/backends/llvm/codegen/LlvmPatioCodeGen.java b/src/main/java/org/shedlang/compiler/backends/llvm/codegen/LlvmPatioCodeGen.java
index c82f0a05..a680f3b7 100644
--- a/src/main/java/org/shedlang/compiler/backends/llvm/codegen/LlvmPatioCodeGen.java
+++ b/src/main/java/org/shedlang/compiler/backends/llvm/codegen/LlvmPatioCodeGen.java
@@ -3,18 +3,23 @@ package org.shedlang.compiler.backends.llvm.codegen;
 import org.pcollections.PVector;
 import org.pcollections.TreePVector;
 import org.shedlang.compiler.backends.llvm.LlvmCodeGenLocalVariableSpace;
+import org.shedlang.compiler.backends.llvm.codegen.errors.SizeofJmpBufError;
 import org.shedlang.compiler.backends.llvm.ir.ast.*;
 import org.shedlang.compiler.backends.llvm.ir.ast.instructions.*;
 import org.shedlang.compiler.backends.llvm.ir.ast.operands.*;
 import org.shedlang.compiler.backends.llvm.ir.ast.types.LlvmType;
 import org.shedlang.compiler.backends.llvm.ir.ast.types.LlvmTypes;
+import org.shedlang.compiler.filesystem.ShedCompilerFiles;
 import org.shedlang.compiler.patio.ast.*;
 import org.shedlang.compiler.patio.ast.instructions.*;
 import org.shedlang.compiler.patio.ast.operands.*;
 import org.shedlang.compiler.patio.ast.types.*;
+import org.shedlang.compiler.util.Lazy;
 import org.shedlang.compiler.util.Lists;
 import org.shedlang.compiler.util.P;
 
+import java.io.IOException;
+import java.nio.file.Files;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
@@ -34,9 +39,21 @@ public class LlvmPatioCodeGen {
     private static final LlvmType EXCEPTION_TAG_TYPE = LlvmTypes.INT_32;
     private static final LlvmType EXCEPTION_VALUE_TYPE = LlvmTypes.INT_64;
 
-    private static LlvmType jmpBufData() {
-        // TODO: find size of jmp_buf properly
-        return LlvmTypes.array(200, LlvmTypes.INT_8);
+    private static final Lazy<Integer> JMP_BUF_SIZE = Lazy.of(() -> readJmpBufSize());
+
+    private static int readJmpBufSize() {
+        try {
+            var sizeofJmpBufString = Files.readString(
+                ShedCompilerFiles.getRoot().resolve("runtime/target/amd64/sizeof_jmp_buf.txt")
+            );
+            return Integer.parseInt(sizeofJmpBufString.strip());
+        } catch (IOException e) {
+            throw new SizeofJmpBufError();
+        }
+    }
+
+    private static LlvmType jmpBufType() {
+        return LlvmTypes.array(JMP_BUF_SIZE.get(), LlvmTypes.INT_8);
     }
 
     private static final LlvmFunctionDeclaration SETJMP_DECLARATION = new LlvmFunctionDeclaration(
@@ -671,7 +688,7 @@ public class LlvmPatioCodeGen {
 
                 context = context.addInstruction(new LlvmAlloca(
                     jmpBuf,
-                    jmpBufData()
+                    jmpBufType()
                 ));
 
                 var previousExceptionHandlerResult = context.allocateLocalName(LlvmCodeGenLocalVariableSpace.TRY_PREVIOUS_EXCEPTION_HANDLER);
diff --git a/src/main/java/org/shedlang/compiler/backends/llvm/codegen/errors/SizeofJmpBufError.java b/src/main/java/org/shedlang/compiler/backends/llvm/codegen/errors/SizeofJmpBufError.java
new file mode 100644
index 00000000..5594bc71
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/backends/llvm/codegen/errors/SizeofJmpBufError.java
@@ -0,0 +1,10 @@
+package org.shedlang.compiler.backends.llvm.codegen.errors;
+
+import org.shedlang.compiler.errors.InternalCompilerError;
+import org.shedlang.compiler.sources.Sources;
+
+public class SizeofJmpBufError extends InternalCompilerError {
+    public SizeofJmpBufError() {
+        super("Could not find size of jmp_buf", Sources.NULL);
+    }
+}
diff --git a/src/main/java/org/shedlang/compiler/util/Lazy.java b/src/main/java/org/shedlang/compiler/util/Lazy.java
new file mode 100644
index 00000000..951f56bd
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/util/Lazy.java
@@ -0,0 +1,26 @@
+package org.shedlang.compiler.util;
+
+import java.util.Optional;
+import java.util.function.Supplier;
+
+public class Lazy<T> {
+    public static <T> Lazy<T> of(Supplier<T> supplier) {
+        return new Lazy<>(supplier);
+    }
+
+    private final Supplier<T> supplier;
+    private Optional<T> value;
+
+    private Lazy(Supplier<T> supplier) {
+        this.supplier = supplier;
+        this.value = Optional.empty();
+    }
+
+    public T get() {
+        if (this.value.isEmpty()) {
+            this.value = Optional.of(this.supplier.get());
+        }
+
+        return this.value.get();
+    }
+}
-- 
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