[llvm-bugs] [Bug 37788] New: `llvm.experimental.stackmap` is erroneously marked `Throws`?
llvm-bugs at lists.llvm.org
Wed Jun 13 06:32:41 PDT 2018
Bug ID: 37788
Summary: `llvm.experimental.stackmap` is erroneously marked
Component: new bugs
Assignee: unassignedbugs at nondot.org
Reporter: vext01 at gmail.com
CC: llvm-bugs at lists.llvm.org
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
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
@@ -720,8 +720,7 @@ def int_invariant_group_barrier :
//===------------------------ Stackmap Intrinsics
def int_experimental_stackmap : Intrinsic<,
- [llvm_i64_ty, llvm_i32_ty, llvm_vararg_ty],
+ [llvm_i64_ty, llvm_i32_ty, llvm_vararg_ty],
def int_experimental_patchpoint_void : Intrinsic<,
In other words, remove `Throws` from the signature of
With this patch applied, I managed to run a stage 2 rustc build without the
verifier getting upset.
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