amd/llvm: fix LLVM 15 & 16 crashes in SelectionDAG.cpp

Cc: stable

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21041>

src/amd/llvm/ac_llvm_helper.cpp

@@ -33,6 +33,10 @@
 #include <llvm/Transforms/IPO.h>
 #include <llvm/Transforms/Scalar.h>
 
+#if LLVM_VERSION_MAJOR >= 15
+#include "llvm/CodeGen/SelectionDAGNodes.h"
+#endif
+
 #include <cstring>
 
 /* DO NOT REORDER THE HEADERS
@@ -48,6 +52,37 @@
 
 using namespace llvm;
 
+#if LLVM_VERSION_MAJOR >= 15
+class RunAtExitForStaticDestructors : public SDNode
+{
+public:
+   /* getSDVTList (protected) calls getValueTypeList (private), which contains static variables. */
+   RunAtExitForStaticDestructors(): SDNode(0, 0, DebugLoc(), getSDVTList(MVT::Other))
+   {
+   }
+};
+#endif
+
+void ac_llvm_run_atexit_for_destructors(void)
+{
+#if LLVM_VERSION_MAJOR >= 15
+   /* LLVM >= 16 registers static variable destructors on the first compile, which gcc
+    * implements by calling atexit there. Before that, u_queue registers its atexit
+    * handler to kill all threads. Since exit() runs atexit handlers in the reverse order,
+    * the LLVM destructors are called first while shader compiler threads may still be
+    * running, which crashes in LLVM in SelectionDAG.cpp.
+    *
+    * The solution is to run the code that declares the LLVM static variables first,
+    * so that atexit for LLVM is registered first and u_queue is registered after that,
+    * which ensures that all u_queue threads are terminated before LLVM destructors are
+    * called.
+    *
+    * This just executes the code that declares static variables.
+    */
+   RunAtExitForStaticDestructors();
+#endif
+}
+
 bool ac_is_llvm_processor_supported(LLVMTargetMachineRef tm, const char *processor)
 {
    TargetMachine *TM = reinterpret_cast<TargetMachine *>(tm);

src/amd/llvm/ac_llvm_util.c

@@ -64,6 +64,8 @@ static void ac_init_llvm_target(void)
 
    ac_reset_llvm_all_options_occurences();
    LLVMParseCommandLineOptions(ARRAY_SIZE(argv), argv, NULL);
+
+   ac_llvm_run_atexit_for_destructors();
 }
 
 PUBLIC void ac_init_shared_llvm_once(void)

src/amd/llvm/ac_llvm_util.h

@@ -78,6 +78,7 @@ struct ac_llvm_compiler {
 
 LLVMTargetRef ac_get_llvm_target(const char *triple);
 const char *ac_get_llvm_processor_name(enum radeon_family family);
+void ac_llvm_run_atexit_for_destructors(void);
 bool ac_is_llvm_processor_supported(LLVMTargetMachineRef tm, const char *processor);
 void ac_reset_llvm_all_options_occurences();
 void ac_add_attr_dereferenceable(LLVMValueRef val, uint64_t bytes);