[clang] [llvm] [SPIRV] GPU intrinsics (PR #131190)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,501 @@
+//===- LowerGPUIntrinsic.cpp ----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Lower the llvm.gpu intrinsics to target specific code sequences.
+// Can be called from clang if building for a specific GPU or from the backend
+// as part of a SPIRV lowering pipeline. Initial pass can lower to amdgcn or
+// nvptx, adding further architectures means adding a column to the lookup table
+// and further intrinsics adding a row.
+//
+// The idea is for the intrinsics to represent a thin abstraction over the
+// different GPU architectures. In particular, code compiled to spirv-- without
+// specifying a specific target can be specialised at JIT time, at which point
+// this pass will rewrite those intrinsics to ones that the current backend
+// knows.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar/LowerGPUIntrinsic.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/IR/ConstantRange.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/InlineAsm.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/IntrinsicsAMDGPU.h"
+#include "llvm/IR/IntrinsicsNVPTX.h"
+#include "llvm/IR/MDBuilder.h"
+#include "llvm/IR/Module.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Pass.h"
+#include "llvm/Target/TargetOptions.h"
+#include "llvm/TargetParser/Triple.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+
+#define DEBUG_TYPE "lower-gpu-intrinsic"
+
+using namespace llvm;
+
+namespace {
+
+// For each intrinsic, specify what function to call to lower it
+typedef bool (*lowerFunction)(Module &M, IRBuilder<> &, Intrinsic::ID from,
+                              CallBase *CI);
+
+// Simple lowering, directly replace the intrinsic with a different one
+// with the same type, and optionally refine range metadata on the return value
+template <Intrinsic::ID To>
+bool S(Module &M, IRBuilder<> &, Intrinsic::ID from, CallBase *CI) {
+
+  static_assert(To != Intrinsic::not_intrinsic);
+  Intrinsic::ID GenericID = from;
+  Intrinsic::ID SpecificID = To;
+
+  bool Changed = false;
+  Function *Generic = Intrinsic::getDeclarationIfExists(&M, GenericID);
+  auto *Specific = Intrinsic::getOrInsertDeclaration(&M, SpecificID);
+
+  if ((Generic->getType() != Specific->getType()) ||
+      (Generic->getReturnType() != Specific->getReturnType()))
+    report_fatal_error("LowerGPUIntrinsic: Inconsistent types between "
+                       "intrinsics in lookup table");
+
+  CI->setCalledFunction(Specific);
+  Changed = true;
+
+  return Changed;
+}
+
+// Replace intrinsic call with a linear sequence of instructions
+typedef Value *(*builder)(Module &M, IRBuilder<> &Builder, Intrinsic::ID from,
+                          CallBase *CI);
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arsenm wrote:

using function_ref 

https://github.com/llvm/llvm-project/pull/131190