[AVR] Fix Avr indvar detection and strength reduction (missed optimization)

clang/lib/Basic/Targets/AVR.h

@@ -57,7 +57,8 @@ class LLVM_LIBRARY_VISIBILITY AVRTargetInfo : public TargetInfo {
     Int16Type = SignedInt;
     Char32Type = UnsignedLong;
     SigAtomicType = SignedChar;
-    resetDataLayout("e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8");
+    resetDataLayout(
+        "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-n16:8-a:8");
   }
 
   void getTargetDefines(const LangOptions &Opts,

llvm/lib/Target/AVR/AVRTargetMachine.cpp

@@ -20,6 +20,7 @@
 #include "AVR.h"
 #include "AVRMachineFunctionInfo.h"
 #include "AVRTargetObjectFile.h"
+#include "AVRTargetTransformInfo.h"
 #include "MCTargetDesc/AVRMCTargetDesc.h"
 #include "TargetInfo/AVRTargetInfo.h"
 
@@ -28,7 +29,7 @@
 namespace llvm {
 
 static const char *AVRDataLayout =
-    "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8";
+    "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-n16:8-a:8";
 
 /// Processes a CPU name.
 static StringRef getCPU(StringRef CPU) {
@@ -62,7 +63,9 @@ namespace {
 class AVRPassConfig : public TargetPassConfig {
 public:
   AVRPassConfig(AVRTargetMachine &TM, PassManagerBase &PM)
-      : TargetPassConfig(TM, PM) {}
+      : TargetPassConfig(TM, PM) {
+    EnableLoopTermFold = true;
+  }
 
   AVRTargetMachine &getAVRTargetMachine() const {
     return getTM<AVRTargetMachine>();
@@ -107,6 +110,11 @@ const AVRSubtarget *AVRTargetMachine::getSubtargetImpl(const Function &) const {
   return &SubTarget;
 }
 
+TargetTransformInfo
+AVRTargetMachine::getTargetTransformInfo(const Function &F) const {
+  return TargetTransformInfo(std::make_unique<AVRTTIImpl>(this, F));
+}
+
 MachineFunctionInfo *AVRTargetMachine::createMachineFunctionInfo(
     BumpPtrAllocator &Allocator, const Function &F,
     const TargetSubtargetInfo *STI) const {

llvm/lib/Target/AVR/AVRTargetMachine.h

@@ -48,6 +48,8 @@ class AVRTargetMachine : public CodeGenTargetMachineImpl {
   createMachineFunctionInfo(BumpPtrAllocator &Allocator, const Function &F,
                             const TargetSubtargetInfo *STI) const override;
 
+  TargetTransformInfo getTargetTransformInfo(const Function &F) const override;
+
   bool isNoopAddrSpaceCast(unsigned SrcAs, unsigned DestAs) const override {
     // While AVR has different address spaces, they are all represented by
     // 16-bit pointers that can be freely casted between (of course, a pointer

llvm/lib/Target/AVR/AVRTargetTransformInfo.h

@@ -0,0 +1,56 @@
+//===- AVRTargetTransformInfo.h - AVR 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 defines a TargetTransformInfoImplBase conforming object specific
+/// to the AVR 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_AVR_AVRTARGETTRANSFORMINFO_H
+#define LLVM_LIB_TARGET_AVR_AVRTARGETTRANSFORMINFO_H
+
+#include "AVRSubtarget.h"
+#include "AVRTargetMachine.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/CodeGen/BasicTTIImpl.h"
+#include "llvm/IR/Function.h"
+#include <optional>
+
+namespace llvm {
+
+class AVRTTIImpl final : public BasicTTIImplBase<AVRTTIImpl> {
+  using BaseT = BasicTTIImplBase<AVRTTIImpl>;
+  using TTI = TargetTransformInfo;
+
+  friend BaseT;
+
+  const AVRSubtarget *ST;
+  const AVRTargetLowering *TLI;
+
+  const AVRSubtarget *getST() const { return ST; }
+  const AVRTargetLowering *getTLI() const { return TLI; }
+
+public:
+  explicit AVRTTIImpl(const AVRTargetMachine *TM, const Function &F)
+      : BaseT(TM, F.getDataLayout()), ST(TM->getSubtargetImpl(F)),
+        TLI(ST->getTargetLowering()) {}
+
+  bool isLSRCostLess(const TargetTransformInfo::LSRCost &C1,
+                     const TargetTransformInfo::LSRCost &C2) const override {
+    if (C2.Insns == ~0u)
+      return true;
+    return 2 * C1.Insns + C1.AddRecCost + C1.SetupCost + C1.NumRegs <
+           2 * C2.Insns + C2.AddRecCost + C2.SetupCost + C2.NumRegs;
+  }
+};
+
+} // end namespace llvm
+
+#endif // LLVM_LIB_TARGET_AVR_AVRTARGETTRANSFORMINFO_H

llvm/test/CodeGen/AVR/bug-143247.ll

@@ -8,18 +8,18 @@ define void @complex_sbi() {
 ; CHECK:       ; %bb.0: ; %entry
 ; CHECK-NEXT:    push r16
 ; CHECK-NEXT:    push r17
-; CHECK-NEXT:    ldi r24, 0
+; CHECK-NEXT:    ldi r24, 1
 ; CHECK-NEXT:    ldi r25, 0
 ; CHECK-NEXT:  .LBB0_1: ; %while.cond
 ; CHECK-NEXT:    ; =>This Inner Loop Header: Depth=1
 ; CHECK-NEXT:    sbi 1, 7
-; CHECK-NEXT:    adiw r24, 1
 ; CHECK-NEXT:    movw r16, r24
 ; CHECK-NEXT:    andi r24, 15
 ; CHECK-NEXT:    andi r25, 0
 ; CHECK-NEXT:    adiw r24, 1
 ; CHECK-NEXT:    call nil
 ; CHECK-NEXT:    movw r24, r16
+; CHECK-NEXT:    adiw r24, 1
 ; CHECK-NEXT:    rjmp .LBB0_1
 entry:
   br label %while.cond

llvm/test/CodeGen/AVR/load.ll

@@ -1,4 +1,4 @@
-; RUN: llc -mattr=avr6,sram < %s -mtriple=avr -verify-machineinstrs | FileCheck %s
+; RUN: llc -mattr=avr6,sram < %s -mtriple=avr-none -verify-machineinstrs | FileCheck %s
 
 define i8 @load8(ptr %x) {
 ; CHECK-LABEL: load8:
@@ -98,9 +98,31 @@ while.end:                                        ; preds = %while.body, %entry
   ret i16 %r.0.lcssa
 }
 
+define i16 @load16postincloopreduce(ptr %p, i16 %cnt) {
+; CHECK-LABEL: load16postincloopreduce:
+; CHECK: ld {{.*}}, {{[XYZ]}}+
+; CHECK: ld {{.*}}, {{[XYZ]}}+
+entry:
+  %cmp3 = icmp sgt i16 %cnt, 0
+  br i1 %cmp3, label %for.body, label %for.cond.cleanup
+for.cond.cleanup:                                 ; preds = %for.body, %entry
+  %sum.0.lcssa = phi i16 [ 0, %entry ], [ %add, %for.body ]
+  ret i16 %sum.0.lcssa
+for.body:                                         ; preds = %entry, %for.body
+  %i.06 = phi i16 [ %inc, %for.body ], [ 0, %entry ]
+  %sum.05 = phi i16 [ %add, %for.body ], [ 0, %entry ]
+  %p.addr.04 = phi ptr [ %incdec.ptr, %for.body ], [ %p, %entry ]
+  %incdec.ptr = getelementptr inbounds nuw i8, ptr %p.addr.04, i16 2
+  %0 = load i16, ptr %p.addr.04, align 1
+  %add = add nsw i16 %0, %sum.05
+  %inc = add nuw nsw i16 %i.06, 1
+  %exitcond.not = icmp eq i16 %inc, %cnt
+  br i1 %exitcond.not, label %for.cond.cleanup, label %for.body
+}
+
 define i8 @load8predec(ptr %x, i8 %y) {
 ; CHECK-LABEL: load8predec:
-; CHECK: ld {{.*}}, -{{[XYZ]}}
+; TODO: ld {{.*}}, -{{[XYZ]}}
 entry:
   %tobool6 = icmp eq i8 %y, 0
   br i1 %tobool6, label %while.end, label %while.body
@@ -121,8 +143,8 @@ while.end:                                        ; preds = %while.body, %entry
 
 define i16 @load16predec(ptr %x, i16 %y) {
 ; CHECK-LABEL: load16predec:
-; CHECK: ld {{.*}}, -{{[XYZ]}}
-; CHECK: ld {{.*}}, -{{[XYZ]}}
+; TODO: ld {{.*}}, -{{[XYZ]}}
+; TODO: ld {{.*}}, -{{[XYZ]}}
 entry:
   %tobool2 = icmp eq i16 %y, 0
   br i1 %tobool2, label %while.end, label %while.body

llvm/test/CodeGen/AVR/shift.ll

@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc < %s -mtriple=avr -mtriple=avr -verify-machineinstrs | FileCheck %s
+; RUN: llc < %s -mtriple=avr-none -verify-machineinstrs | FileCheck %s
 
 ; Optimize for speed.
 define i8 @shift_i8_i8_speed(i8 %a, i8 %b) {

llvm/test/CodeGen/AVR/store.ll

@@ -94,7 +94,7 @@ while.end:                                        ; preds = %while.body, %entry
 
 define void @store8predec(ptr %x, i8 %y) {
 ; CHECK-LABEL: store8predec:
-; CHECK: st -{{[XYZ]}}, {{.*}}
+; TODO: st -{{[XYZ]}}, {{.*}}
 entry:
   %tobool3 = icmp eq i8 %y, 0
   br i1 %tobool3, label %while.end, label %while.body
@@ -112,8 +112,8 @@ while.end:                                        ; preds = %while.body, %entry
 
 define void @store16predec(ptr %x, i16 %y) {
 ; CHECK-LABEL: store16predec:
-; CHECK: st -{{[XYZ]}}, {{.*}}
-; CHECK: st -{{[XYZ]}}, {{.*}}
+; TODO: st -{{[XYZ]}}, {{.*}}
+; TODO: st -{{[XYZ]}}, {{.*}}
 entry:
   %tobool3 = icmp eq i16 %y, 0
   br i1 %tobool3, label %while.end, label %while.body