Hood ChathamandPaulo Matos
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>
19 lines
601 B
LLVM
19 lines
601 B
LLVM
; RUN: llc < %s --mtriple=wasm32-unknown-unknown -asm-verbose=false -mattr=+reference-types | FileCheck %s
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%funcref = type target("wasm.funcref")
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@funcref_global = local_unnamed_addr addrspace(1) global %funcref undef
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define %funcref @return_funcref_global() {
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;; this generates a global.get of @funcref_global
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%ref = load %funcref, ptr addrspace(1) @funcref_global
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ret %funcref %ref
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}
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; CHECK-LABEL: return_funcref_global:
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; CHECK-NEXT: .functype return_funcref_global () -> (funcref)
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; CHECK-NEXT: global.get funcref_global
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; CHECK-NEXT: end_function
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; CHECK: .globl funcref_global
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