a1da746157
For the GPU, we emit external kernels that call the initializers and
constructors, however if we had a persistent kernel like in the `_start`
kernel for the `libc` project, we could initialize the standard way of
calling constructors. This patch adds new global variables containing
pointers to the constructors to be called. If these are placed in the
`.init_array` and `.fini_array` sections, then the backend will handle
them specially. The linker will then provide the `__init_array_` and
`__fini_array_` sections to traverse them. An implementation would look
like this.
```
extern uintptr_t __init_array_start[];
extern uintptr_t __init_array_end[];
extern uintptr_t __fini_array_start[];
extern uintptr_t __fini_array_end[];
using InitCallback = void(int, char **, char **);
using FiniCallback = void(void);
extern "C" [[gnu::visibility("protected"), clang::amdgpu_kernel]] void
_start(int argc, char **argv, char **envp) {
uint64_t init_array_size = __init_array_end - __init_array_start;
for (uint64_t i = 0; i < init_array_size; ++i)
reinterpret_cast<InitCallback *>(__init_array_start[i])(argc, argv, env);
uint64_t fini_array_size = __fini_array_end - __fini_array_start;
for (uint64_t i = 0; i < fini_array_size; ++i)
reinterpret_cast<FiniCallback *>(__fini_array_start[i])();
}
```
Reviewed By: yaxunl
Differential Revision: https://reviews.llvm.org/D149340
41 lines
1.8 KiB
LLVM
41 lines
1.8 KiB
LLVM
; RUN: opt -S -mtriple=amdgcn-- -amdgpu-lower-ctor-dtor < %s | FileCheck %s
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; RUN: opt -S -mtriple=amdgcn-- -passes=amdgpu-lower-ctor-dtor < %s | FileCheck %s
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; Make sure we get the same result if we run multiple times
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; RUN: opt -S -mtriple=amdgcn-- -passes=amdgpu-lower-ctor-dtor,amdgpu-lower-ctor-dtor < %s | FileCheck %s
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; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx700 -filetype=obj -o - < %s | llvm-readelf -s - 2>&1 | FileCheck %s -check-prefix=VISIBILITY
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; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx700 -filetype=obj -o - < %s | llvm-readelf -S - 2>&1 | FileCheck %s -check-prefix=SECTION
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@llvm.global_ctors = appending addrspace(1) global [1 x { i32, ptr, ptr }] [{ i32, ptr, ptr } { i32 1, ptr @foo, ptr null }]
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@llvm.global_dtors = appending addrspace(1) global [1 x { i32, ptr, ptr }] [{ i32, ptr, ptr } { i32 1, ptr @bar, ptr null }]
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; CHECK: @llvm.used = appending global [2 x ptr] [ptr @amdgcn.device.init, ptr @amdgcn.device.fini]
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; CHECK-LABEL: amdgpu_kernel void @amdgcn.device.init() #0
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; CHECK-NEXT: call void @foo
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; CHECK-NEXT: ret void
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; CHECK-LABEL: amdgpu_kernel void @amdgcn.device.fini() #1
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; CHECK-NEXT: call void @bar
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; CHECK-NEXT: ret void
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; CHECK-NOT: amdgcn.device.
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; VISIBILITY: FUNC GLOBAL PROTECTED {{.*}} amdgcn.device.init
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; VISIBILITY: OBJECT GLOBAL DEFAULT {{.*}} amdgcn.device.init.kd
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; VISIBILITY: FUNC GLOBAL PROTECTED {{.*}} amdgcn.device.fini
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; VISIBILITY: OBJECT GLOBAL DEFAULT {{.*}} amdgcn.device.fini.kd
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; SECTION: .init_array.1 INIT_ARRAY {{.*}} {{.*}} 000008 00 WA 0 0 8
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; SECTION: .fini_array.1 FINI_ARRAY {{.*}} {{.*}} 000008 00 WA 0 0 8
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define internal void @foo() {
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ret void
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}
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define internal void @bar() {
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ret void
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}
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; CHECK: attributes #0 = { "device-init" }
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; CHECK: attributes #1 = { "device-fini" }
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