ac: add reusable helpers for direct LLVM compilation

This is basically LLVMTargetMachineEmitToMemoryBuffer inlined and reworked.

struct ac_compiler_passes (opaque type) contains the main pass manager.

ac_create_llvm_passes -- the result can go to thread local storage
ac_destroy_llvm_passes -- can be called by a destructor in TLS
ac_compile_module_to_binary -- from LLVMModuleRef to ac_shader_binary

The motivation is to do the expensive call addPassesToEmitFile once
per context or thread.

Reviewed-by: Dave Airlie <airlied@redhat.com>

src/amd/common/ac_llvm_helper.cpp

@@ -29,15 +29,19 @@
 #pragma push_macro("DEBUG")
 #undef DEBUG
 
+#include "ac_binary.h"
 #include "ac_llvm_util.h"
+
 #include <llvm-c/Core.h>
-#include <llvm/Target/TargetOptions.h>
-#include <llvm/ExecutionEngine/ExecutionEngine.h>
-#include <llvm/IR/Attributes.h>
-#include <llvm/IR/CallSite.h>
+#include <llvm/Target/TargetMachine.h>
 #include <llvm/IR/IRBuilder.h>
 #include <llvm/Analysis/TargetLibraryInfo.h>
 
+#include <llvm/IR/LegacyPassManager.h>
+#if HAVE_LLVM < 0x0700
+#include "llvm/Support/raw_ostream.h"
+#endif
+
 void ac_add_attr_dereferenceable(LLVMValueRef val, uint64_t bytes)
 {
    llvm::Argument *A = llvm::unwrap<llvm::Argument>(val);
@@ -110,3 +114,54 @@ ac_dispose_target_library_info(LLVMTargetLibraryInfoRef library_info)
 {
 	delete reinterpret_cast<llvm::TargetLibraryInfoImpl *>(library_info);
 }
+
+/* The LLVM compiler is represented as a pass manager containing passes for
+ * optimizations, instruction selection, and code generation.
+ */
+struct ac_compiler_passes {
+	ac_compiler_passes(): ostream(code_string) {}
+
+	llvm::SmallString<0> code_string;  /* ELF shader binary */
+	llvm::raw_svector_ostream ostream; /* stream for appending data to the binary */
+	llvm::legacy::PassManager passmgr; /* list of passes */
+};
+
+struct ac_compiler_passes *ac_create_llvm_passes(LLVMTargetMachineRef tm)
+{
+	struct ac_compiler_passes *p = new ac_compiler_passes();
+	if (!p)
+		return NULL;
+
+	llvm::TargetMachine *TM = reinterpret_cast<llvm::TargetMachine*>(tm);
+
+	if (TM->addPassesToEmitFile(p->passmgr, p->ostream,
+#if HAVE_LLVM >= 0x0700
+				    nullptr,
+#endif
+				    llvm::TargetMachine::CGFT_ObjectFile)) {
+		fprintf(stderr, "amd: TargetMachine can't emit a file of this type!\n");
+		delete p;
+		return NULL;
+	}
+	return p;
+}
+
+void ac_destroy_llvm_passes(struct ac_compiler_passes *p)
+{
+	delete p;
+}
+
+/* This returns false on failure. */
+bool ac_compile_module_to_binary(struct ac_compiler_passes *p, LLVMModuleRef module,
+				 struct ac_shader_binary *binary)
+{
+	p->passmgr.run(*llvm::unwrap(module));
+
+	llvm::StringRef data = p->ostream.str();
+	bool success = ac_elf_read(data.data(), data.size(), binary);
+	p->code_string = ""; /* release the ELF shader binary */
+
+	if (!success)
+		fprintf(stderr, "amd: cannot read an ELF shader binary\n");
+	return success;
+}