From b70e734ccb68123078058c441fdd6e6f9f7a0c7e Mon Sep 17 00:00:00 2001
From: Edd Barrett <vext01@gmail.com>
Date: Thu, 9 Jan 2025 14:58:58 +0000
Subject: [PATCH] Serialise debug anchors.

---
 llvm/lib/YkIR/YkIRWriter.cpp | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/llvm/lib/YkIR/YkIRWriter.cpp b/llvm/lib/YkIR/YkIRWriter.cpp
index e257b2c907e8e20..1c30e69de4d9813 100644
--- a/llvm/lib/YkIR/YkIRWriter.cpp
+++ b/llvm/lib/YkIR/YkIRWriter.cpp
@@ -48,6 +48,7 @@ class SerialiseInstructionException {
 
 #define YK_OUTLINE_FNATTR "yk_outline"
 #define YK_PROMOTE_PREFIX "__yk_promote"
+#define YK_DEBUG_ANCHOR "yk_debug_anchor"
 const char *SectionName = ".yk_ir";
 const uint32_t Magic = 0xedd5f00d;
 const uint32_t Version = 0;
@@ -74,6 +75,7 @@ enum OpCode {
   OpCodeFCmp,
   OpCodePromote,
   OpCodeFNeg,
+  OpCodeDebugAnchor,
   OpCodeUnimplemented = 255, // YKFIXME: Will eventually be deleted.
 };
 
@@ -641,6 +643,21 @@ class YkIRWriter {
     InstIdx++;
   }
 
+  void serialiseDebugAnchor(CallInst *I, FuncLowerCtxt &FLCtxt,
+                            unsigned &InstIdx) {
+    // We expect one argument: a `char *` to a message for the anchor.
+    assert(I->arg_size() == 1);
+    assert(I->getOperand(0)->getType()->isPointerTy());
+
+    // opcode:
+    serialiseOpcode(OpCodeDebugAnchor);
+    // message:
+    serialiseOperand(I, FLCtxt, I->getOperand(0));
+
+    FLCtxt.updateVLMap(I, InstIdx);
+    InstIdx++;
+  }
+
   void serialiseIndirectCallInst(CallInst *I, FuncLowerCtxt &FLCtxt,
                                  unsigned BBIdx, unsigned &InstIdx) {
 
@@ -784,6 +801,11 @@ class YkIRWriter {
       return;
     }
 
+    if (I->getCalledFunction()->getName() == YK_DEBUG_ANCHOR) {
+      serialiseDebugAnchor(I, FLCtxt, InstIdx);
+      return;
+    }
+
     // FIXME: Note that this assertion can fail if you do a direct call without
     // the correct type annotation at the call site.
     //