From b8a6bbc6c521341daef7a839975a9d79e4ad329f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Ol=C5=A1=C3=A1k?= <marek.olsak@amd.com>
Date: Fri, 22 Apr 2022 14:05:18 -0400
Subject: [PATCH] ac/llvm: don't create the target machine if the LLVM
 processor is unsupported

If a processor is unsupported, LLVM chooses "tahiti", which hangs
everything except gfx6. Check for support manually.

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16112>
---
 src/amd/llvm/ac_llvm_helper.cpp | 7 +++++++
 src/amd/llvm/ac_llvm_util.c     | 9 ++++++++-
 src/amd/llvm/ac_llvm_util.h     | 1 +
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/amd/llvm/ac_llvm_helper.cpp b/src/amd/llvm/ac_llvm_helper.cpp
index 0e2e207c3a4..1fee75f30c5 100644
--- a/src/amd/llvm/ac_llvm_helper.cpp
+++ b/src/amd/llvm/ac_llvm_helper.cpp
@@ -28,6 +28,7 @@
 #include <llvm/IR/IRBuilder.h>
 #include <llvm/IR/LegacyPassManager.h>
 #include <llvm/Target/TargetMachine.h>
+#include <llvm/MC/MCSubtargetInfo.h>
 #include <llvm/Transforms/IPO.h>
 
 #include <cstring>
@@ -43,6 +44,12 @@
 #include "ac_llvm_build.h"
 #include "util/macros.h"
 
+bool ac_is_llvm_processor_supported(LLVMTargetMachineRef tm, const char *processor)
+{
+   llvm::TargetMachine *TM = reinterpret_cast<llvm::TargetMachine *>(tm);
+   return TM->getMCSubtargetInfo()->isCPUStringValid(processor);
+}
+
 void ac_add_attr_dereferenceable(LLVMValueRef val, uint64_t bytes)
 {
    llvm::Argument *A = llvm::unwrap<llvm::Argument>(val);
diff --git a/src/amd/llvm/ac_llvm_util.c b/src/amd/llvm/ac_llvm_util.c
index 9f215d8e0aa..d22ed0667b9 100644
--- a/src/amd/llvm/ac_llvm_util.c
+++ b/src/amd/llvm/ac_llvm_util.c
@@ -189,11 +189,18 @@ static LLVMTargetMachineRef ac_create_target_machine(enum radeon_family family,
    assert(family >= CHIP_TAHITI);
    const char *triple = (tm_options & AC_TM_SUPPORTS_SPILL) ? "amdgcn-mesa-mesa3d" : "amdgcn--";
    LLVMTargetRef target = ac_get_llvm_target(triple);
+   const char *name = ac_get_llvm_processor_name(family);
 
    LLVMTargetMachineRef tm =
-      LLVMCreateTargetMachine(target, triple, ac_get_llvm_processor_name(family), "", level,
+      LLVMCreateTargetMachine(target, triple, name, "", level,
                               LLVMRelocDefault, LLVMCodeModelDefault);
 
+   if (!ac_is_llvm_processor_supported(tm, name)) {
+      LLVMDisposeTargetMachine(tm);
+      fprintf(stderr, "amd: LLVM doesn't support %s, bailing out...\n", name);
+      return NULL;
+   }
+
    if (out_triple)
       *out_triple = triple;
 
diff --git a/src/amd/llvm/ac_llvm_util.h b/src/amd/llvm/ac_llvm_util.h
index a568c1fc70b..3c76c716a15 100644
--- a/src/amd/llvm/ac_llvm_util.h
+++ b/src/amd/llvm/ac_llvm_util.h
@@ -90,6 +90,7 @@ struct ac_llvm_compiler {
 };
 
 const char *ac_get_llvm_processor_name(enum radeon_family family);
+bool ac_is_llvm_processor_supported(LLVMTargetMachineRef tm, const char *processor);
 void ac_add_attr_dereferenceable(LLVMValueRef val, uint64_t bytes);
 void ac_add_attr_alignment(LLVMValueRef val, uint64_t bytes);
 bool ac_is_sgpr_param(LLVMValueRef param);