[SPARC] Add TTI implementation for getPopcntSupport (llvm#178843)

koachan · web-flow · commit 1bfa71743b08 · 2026-02-10T01:28:27.000+07:00
This is to inform the middle-end transform passes about the capabilities of the codegen backend. This should solve the issue where popcount loops not gets converted properly to `popc`, even if it's available (llvm#171969).
diff --git a/llvm/lib/Target/Sparc/CMakeLists.txt b/llvm/lib/Target/Sparc/CMakeLists.txt
@@ -30,8 +30,10 @@ add_llvm_target(SparcCodeGen
   SparcSubtarget.cpp
   SparcTargetMachine.cpp
   SparcTargetObjectFile.cpp
+  SparcTargetTransformInfo.cpp
 
   LINK_COMPONENTS
+  Analysis
   AsmPrinter
   CodeGen
   CodeGenTypes
@@ -43,6 +45,7 @@ add_llvm_target(SparcCodeGen
   Support
   Target
   TargetParser
+  TransformUtils
 
   ADD_TO_COMPONENT
   Sparc
diff --git a/llvm/lib/Target/Sparc/SparcTargetMachine.cpp b/llvm/lib/Target/Sparc/SparcTargetMachine.cpp
@@ -14,6 +14,7 @@
 #include "Sparc.h"
 #include "SparcMachineFunctionInfo.h"
 #include "SparcTargetObjectFile.h"
+#include "SparcTargetTransformInfo.h"
 #include "TargetInfo/SparcTargetInfo.h"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/CodeGen/TargetPassConfig.h"
@@ -149,6 +150,11 @@ TargetPassConfig *SparcTargetMachine::createPassConfig(PassManagerBase &PM) {
   return new SparcPassConfig(*this, PM);
 }
 
+TargetTransformInfo
+SparcTargetMachine::getTargetTransformInfo(const Function &F) const {
+  return TargetTransformInfo(std::make_unique<SparcTTIImpl>(this, F));
+}
+
 void SparcPassConfig::addIRPasses() {
   addPass(createAtomicExpandLegacyPass());
 
diff --git a/llvm/lib/Target/Sparc/SparcTargetMachine.h b/llvm/lib/Target/Sparc/SparcTargetMachine.h
@@ -40,6 +40,7 @@ class SparcTargetMachine : public CodeGenTargetMachineImpl {
   TargetLoweringObjectFile *getObjFileLowering() const override {
     return TLOF.get();
   }
+  TargetTransformInfo getTargetTransformInfo(const Function &F) const override;
 
   MachineFunctionInfo *
   createMachineFunctionInfo(BumpPtrAllocator &Allocator, const Function &F,
diff --git a/llvm/lib/Target/Sparc/SparcTargetTransformInfo.cpp b/llvm/lib/Target/Sparc/SparcTargetTransformInfo.cpp
@@ -0,0 +1,22 @@
+//===-- SparcTargetTransformInfo.cpp - SPARC specific TTI -----------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "SparcTargetTransformInfo.h"
+#include "llvm/Support/MathExtras.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "sparctti"
+
+TargetTransformInfo::PopcntSupportKind
+SparcTTIImpl::getPopcntSupport(unsigned TyWidth) const {
+  assert(isPowerOf2_32(TyWidth) && "Type width must be power of 2");
+  if (ST->usePopc())
+    return TTI::PSK_FastHardware;
+  return TTI::PSK_Software;
+}
diff --git a/llvm/lib/Target/Sparc/SparcTargetTransformInfo.h b/llvm/lib/Target/Sparc/SparcTargetTransformInfo.h
@@ -0,0 +1,50 @@
+//===-- SparcTargetTransformInfo.cpp - SPARC specific TTI--------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// This file a TargetTransformInfoImplBase conforming object specific to the
+/// SPARC target machine. It uses the target's detailed information to
+/// provide more precise answers to certain TTI queries, while letting the
+/// target independent and default TTI implementations handle the rest.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TARGET_SPARC_SPARCTARGETTRANSFORMINFO_H
+#define LLVM_LIB_TARGET_SPARC_SPARCTARGETTRANSFORMINFO_H
+
+#include "SparcTargetMachine.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/CodeGen/BasicTTIImpl.h"
+
+namespace llvm {
+
+class SparcTTIImpl final : public BasicTTIImplBase<SparcTTIImpl> {
+  typedef BasicTTIImplBase<SparcTTIImpl> BaseT;
+  typedef TargetTransformInfo TTI;
+  friend BaseT;
+
+  const SparcSubtarget *ST;
+  const SparcTargetLowering *TLI;
+
+  const SparcSubtarget *getST() const { return ST; }
+  const SparcTargetLowering *getTLI() const { return TLI; }
+
+public:
+  explicit SparcTTIImpl(const SparcTargetMachine *TM, const Function &F)
+      : BaseT(TM, F.getDataLayout()), ST(TM->getSubtargetImpl(F)),
+        TLI(ST->getTargetLowering()) {}
+
+  /// \name Scalar TTI Implementations
+  /// @{
+
+  TTI::PopcntSupportKind getPopcntSupport(unsigned TyWidth) const override;
+  /// @}
+};
+
+} // end namespace llvm
+
+#endif
diff --git a/llvm/test/Transforms/LoopIdiom/Sparc/lit.local.cfg b/llvm/test/Transforms/LoopIdiom/Sparc/lit.local.cfg
@@ -0,0 +1,2 @@
+if not "Sparc" in config.root.targets:
+    config.unsupported = True
diff --git a/llvm/test/Transforms/LoopIdiom/Sparc/popcnt.ll b/llvm/test/Transforms/LoopIdiom/Sparc/popcnt.ll

Original file line number	Diff line number	Diff line change
`@@ -40,6 +40,7 @@ class SparcTargetMachine : public CodeGenTargetMachineImpl {`
`40`	`40`	`TargetLoweringObjectFile *getObjFileLowering() const override {`
`41`	`41`	`return TLOF.get();`
`42`	`42`	`}`
	`43`	`+ TargetTransformInfo getTargetTransformInfo(const Function &F) const override;`
`43`	`44`
`44`	`45`	`MachineFunctionInfo *`
`45`	`46`	`createMachineFunctionInfo(BumpPtrAllocator &Allocator, const Function &F,`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+if not "Sparc" in config.root.targets:`
	`2`	`+ config.unsupported = True`