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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - `llvm.experimental.stackmap` is erroneously marked `Throws`?"
href="https://bugs.llvm.org/show_bug.cgi?id=37788">37788</a>
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<th>Summary</th>
<td>`llvm.experimental.stackmap` is erroneously marked `Throws`?
</td>
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<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>All
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>new bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>vext01@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Over the last few days I have been experimenting with inserting stackmaps from
the Rust compiler.
After inserting some `call`s (not `invoke`s) to llvm.experimental.stackmap into
rustc's llvm
codegen, and then allowing the compiler to build itself using this change, I
was surprised to see:
```
Cannot invoke an intrinsic other than donothing, patchpoint, statepoint,
coro_resume or coro_destroy
invoke void (i64, i32, ...%) @llvm.experimental.stackmap(i64 1, i32 0)
to label 13
```
As I understand, this is LLVM's way of saying, you can't `invoke` (expecting a
possible exception) an intrinsic which cannot raise an exception.
Having spoke to one of the Rust developers about this, and after trying
a few things, it seems that LLVM's inlining pass is itself allowing `call`s to
the stackmap intrinsic to be translated to `invoke`s. Then the verifier rejects
the resulting code.
We suspect that the fix is as follows:
```
diff --git a/include/llvm/IR/Intrinsics.td b/include/llvm/IR/Intrinsics.td
index a2a1f26292c..9bbe22645ac 100644
--- a/include/llvm/IR/Intrinsics.td
+++ b/include/llvm/IR/Intrinsics.td
@@ -720,8 +720,7 @@ def int_invariant_group_barrier :
Intrinsic<[llvm_anyptr_ty],
//===------------------------ Stackmap Intrinsics
-------------------------===//
//
def int_experimental_stackmap : Intrinsic<[],
- [llvm_i64_ty, llvm_i32_ty, llvm_vararg_ty],
- [Throws]>;
+ [llvm_i64_ty, llvm_i32_ty, llvm_vararg_ty],
[]>;
def int_experimental_patchpoint_void : Intrinsic<[],
[llvm_i64_ty, llvm_i32_ty,
llvm_ptr_ty, llvm_i32_ty,
```
In other words, remove `Throws` from the signature of
`int_experimental_stackmap`.
With this patch applied, I managed to run a stage 2 rustc build without the
verifier getting upset.</pre>
</div>
</p>
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