commit 0170bd5d111f55f45f993a749727ce2815cc0b16
author Joachim Meyer <5982050+fodinabor@users.noreply.github.com> Tue May 21 17:31:50 2024 -0700
committer GitHub <noreply@github.com> Tue May 21 17:31:50 2024 -0700
tree de467bd9d11c2ee247aa54d7d395f2139b275b4e
parent 79a32609759af317a62184c2c7b1300263a336c8

[MDBuilder] `mergeCallbackEncodings` fails due to inspecting the wrong node (#92466)

Given the following metadata as, with `!6` as `ExistingCallbacks` and
`!8` as `NewCB`:
```
!6 = !{!7}
!7 = !{i64 0, i1 false}
!8 = !{i64 2, i64 3, i1 false}
```
The merge function should add `!8` to the list of `!6`, i.e. `!6 =
!{!7,!8}`. However, at the moment the check if this is legal, tries to
interpret `!7` as integer instead of it's operand.

llvm/lib/IR/MDBuilder.cpp

diff --git a/llvm/lib/IR/MDBuilder.cpp b/llvm/lib/IR/MDBuilder.cpp
index 0bf41d7..bd68db3 100644
--- a/llvm/lib/IR/MDBuilder.cpp
+++ b/llvm/lib/IR/MDBuilder.cpp
@@ -86,9 +86,8 @@
 }
 
 MDNode *MDBuilder::createFunctionSectionPrefix(StringRef Prefix) {
-  return MDNode::get(Context,
-                     {createString("function_section_prefix"),
-                      createString(Prefix)});
+  return MDNode::get(
+      Context, {createString("function_section_prefix"), createString(Prefix)});
 }
 
 MDNode *MDBuilder::createRange(const APInt &Lo, const APInt &Hi) {
@@ -148,9 +147,10 @@
   for (unsigned u = 0; u < NumExistingOps; u++) {
     Ops[u] = ExistingCallbacks->getOperand(u);
 
-    auto *OldCBCalleeIdxAsCM = cast<ConstantAsMetadata>(Ops[u]);
+    auto *OldCBCalleeIdxAsCM =
+        cast<ConstantAsMetadata>(cast<MDNode>(Ops[u])->getOperand(0));
     uint64_t OldCBCalleeIdx =
-      cast<ConstantInt>(OldCBCalleeIdxAsCM->getValue())->getZExtValue();
+        cast<ConstantInt>(OldCBCalleeIdxAsCM->getValue())->getZExtValue();
     (void)OldCBCalleeIdx;
     assert(NewCBCalleeIdx != OldCBCalleeIdx &&
            "Cannot map a callback callee index twice!");
@@ -339,8 +339,8 @@
 
 MDNode *MDBuilder::createIrrLoopHeaderWeight(uint64_t Weight) {
   Metadata *Vals[] = {
-    createString("loop_header_weight"),
-    createConstant(ConstantInt::get(Type::getInt64Ty(Context), Weight)),
+      createString("loop_header_weight"),
+      createConstant(ConstantInt::get(Type::getInt64Ty(Context), Weight)),
   };
   return MDNode::get(Context, Vals);
 }