[PATCH] D113800: [amdgpu] Don't crash on empty global ctor/dtor

[Jon Chesterfield via Phabricator via llvm-commits]

JonChesterfield created this revision.
JonChesterfield added reviewers: rksharma, t-tye, b-sumner, yaxunl, arsenm.
Herald added subscribers: foad, kerbowa, hiraditya, tpr, dstuttard, nhaehnle, jvesely, kzhuravl.
JonChesterfield requested review of this revision.
Herald added subscribers: llvm-commits, wdng.
Herald added a project: LLVM.

Global ctor/dtor can be an empty array, which is a Constant not a
ConstantArray. The cast<ConstantArray> therefore asserts / crashes.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D113800

Files:
  llvm/lib/Target/AMDGPU/AMDGPUCtorDtorLowering.cpp
  llvm/test/CodeGen/AMDGPU/lower-empty-ctor-dtor.ll


Index: llvm/test/CodeGen/AMDGPU/lower-empty-ctor-dtor.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AMDGPU/lower-empty-ctor-dtor.ll
@@ -0,0 +1,9 @@
+; RUN: opt -S -mtriple=amdgcn--  -amdgpu-lower-ctor-dtor < %s | FileCheck %s
+; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx700 -filetype=obj -o - < %s | llvm-readelf -s - 2>&1 | FileCheck %s
+
+ at llvm.global_ctors = appending global [0 x { i32, void ()*, i8* }] zeroinitializer
+ at llvm.global_dtors = appending global [0 x { i32, void ()*, i8* }] zeroinitializer
+
+; No amdgpu_kernels emitted for empty global_ctors
+; CHECK-NOT: amdgcn.device.init
+; CHECK-NOT: amdgcn.device.fini
Index: llvm/lib/Target/AMDGPU/AMDGPUCtorDtorLowering.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPUCtorDtorLowering.cpp
+++ llvm/lib/Target/AMDGPU/AMDGPUCtorDtorLowering.cpp
@@ -52,8 +52,8 @@
   bool createInitOrFiniKernel(Module &M, GlobalVariable *GV, bool IsCtor) {
     if (!GV)
       return false;
-    ConstantArray *GA = cast<ConstantArray>(GV->getInitializer());
-    if (GA->getNumOperands() == 0)
+    ConstantArray *GA = dyn_cast<ConstantArray>(GV->getInitializer());
+    if (!GA || GA->getNumOperands() == 0)
       return false;
     Function *InitOrFiniKernel = createInitOrFiniKernelFunction(M, IsCtor);
     IRBuilder<> IRB(InitOrFiniKernel->getEntryBlock().getTerminator());


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