765f0d14fe
Originally #71540 by Paolo Matos, I picked it up and finished it. Resolves https://github.com/llvm/llvm-project/issues/69894. Model WebAssembly externref and funcref as target("wasm.externref") / target("wasm.funcref") TargetExtTypes instead of pointers in non-integral address spaces 10 and 20. The entire WebAssemblyLowerRefTypesIntPtrConv can be removed. This breaks the GlobalISel handling for reference types, I just disabled GlobalISel handling for functions that use them. I added intrinsics for `wasm.ptr.to_funcref` and `wasm.funcref.to_ptr`. ptr.to_funcref does a table.get from the indirect function pointer table. As a special case, 0 is converted to the null funcref rather than doing table.get on 0. `wasm.funcref.to_ptr` is only handled when we call it immediately, otherwise it will fail to lower. We could dynamically put the funcref into the table to make it work but that would require a stack of spilled funcrefs and isn't worth the effort. In the process of looking into this, I noticed that clang used to allow casting from funcref to function pointer but if the cast result escaped it would hit `Cannot select: FUNCREF_TO_PTR` in the backend. I added a diagnostic that says "a funcref can only be converted to a pointer to be directly called" to make this a little cleaner. cc @QuantumSegfault --------- Co-authored-by: Paulo Matos <pmatos@igalia.com>
30 lines
1.3 KiB
LLVM
30 lines
1.3 KiB
LLVM
; RUN: not llc < %s --mtriple=wasm32-unknown-unknown -mattr=+reference-types 2>&1 | FileCheck %s
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; We have only implemented a lowering for llvm.wasm.funcref.to_ptr its result
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; feeds directly into an indirect call. Check that we diagnose the case where we
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; spill the result rather than crashing in the backend.
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%funcref = type target("wasm.funcref")
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declare ptr @llvm.wasm.funcref.to_ptr(%funcref)
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declare void @sink(ptr)
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; CHECK: error: {{.*}}in function escape_via_store {{.*}}: a funcref can only be converted to a pointer to be directly called; the resulting pointer cannot otherwise be used
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define void @escape_via_store(%funcref %ref, ptr %dst) {
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%p = call ptr @llvm.wasm.funcref.to_ptr(%funcref %ref)
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store ptr %p, ptr %dst
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ret void
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}
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; CHECK: error: {{.*}}in function escape_via_return {{.*}}: a funcref can only be converted to a pointer to be directly called; the resulting pointer cannot otherwise be used
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define ptr @escape_via_return(%funcref %ref) {
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%p = call ptr @llvm.wasm.funcref.to_ptr(%funcref %ref)
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ret ptr %p
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}
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; CHECK: error: {{.*}}in function escape_via_arg {{.*}}: a funcref can only be converted to a pointer to be directly called; the resulting pointer cannot otherwise be used
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define void @escape_via_arg(%funcref %ref) {
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%p = call ptr @llvm.wasm.funcref.to_ptr(%funcref %ref)
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call void @sink(ptr %p)
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ret void
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}
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