[AVR][Clang] Implement __AVR_HAVE_*__ macros

[aykevl]

Summary

These macros are defined in avr-gcc and are useful when working with assembly.
For example, startup code needs to copy the contents of .data from flash to RAM, but should use elpm (instead of lpm) on devices with more than 64kB flash. Without __AVR_HAVE_ELPM__, there is no way to know whether the elpm instruction is supported.

Depends on D137521.

[benshi001]

clang/lib/Basic/Targets/AVR.cpp

355

ATxmega16a4 with family code 102 also supports ELPM. Could you please make a careful check on ELPM and all other features?

Generally speaking I am very glad to have this patch committed, since it fixes

https://github.com/llvm/llvm-project/issues/56157

[benshi001]

clang/lib/Basic/Targets/AVR.cpp

355

I suggest that you can make your code in accordance with https://github.com/llvm/llvm-project/blob/main/llvm/lib/Target/AVR/AVRDevices.td

[aykevl]

• Fix ArchHas3BytePC to remove arch 107 (of which no chips have more than 128kB flash)
• Fix ArchHasELPM/ArchHasELPMX to add arch 102 (it does support elpm even though avr-gcc claims it doesn't).
• Add notes where the provided macros may not be correct in all cases. It's still better than avr-gcc though.

[aykevl]

clang/lib/Basic/Targets/AVR.cpp

355

I checked all 102 family chips and indeed they all support ELPM. This looks like a bug in avr-gcc, which claims these devices don't support ELPM.

I did check AVRDevices.td but apparently I made some mistakes. I've checked again and fixed a few small issues. There are still some left but they are difficult to fix without reading AVRDevices.td directly.

[benshi001]

LGTM

clang/lib/Basic/Targets/AVR.cpp

355

That is OK enough, Thanks.

clang/lib/Basic/Targets/AVR.cpp

 //===--- AVR.cpp - Implement AVR target feature support -------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements AVR TargetInfo objects.
 //
 //===----------------------------------------------------------------------===//
 
 #include "AVR.h"
 #include "clang/Basic/MacroBuilder.h"
+#include "llvm/ADT/StringSwitch.h"
 
 using namespace clang;
 using namespace clang::targets;
 
 namespace clang {
 namespace targets {
 
 /// Information about a specific microcontroller.
static MCUInfo AVRMcus[] = {
     {"atmega3209", "__AVR_ATmega3209__", "103", 1},
     {"atmega4808", "__AVR_ATmega4808__", "103", 1},
     {"atmega4809", "__AVR_ATmega4809__", "103", 1},
 };
 
 } // namespace targets
 } // namespace clang
 
+static bool ArchHasELPM(StringRef Arch) {
+  return llvm::StringSwitch<bool>(Arch)
+    .Cases("31", "51", "6", true)
+    .Cases("102", "104", "105", "106", "107", true)
+    .Default(false);
+}
+
+static bool ArchHasELPMX(StringRef Arch) {
+  return llvm::StringSwitch<bool>(Arch)
+    .Cases("51", "6", true)
+    .Cases("102", "104", "105", "106", "107", true)
+    .Default(false);
+}
+
+static bool ArchHasMOVW(StringRef Arch) {
+  return llvm::StringSwitch<bool>(Arch)
+    .Cases("25", "35", "4", "5", "51", "6", true)
+    .Cases("102", "103", "104", "105", "106", "107", true)
+    .Default(false);
+}
+
+static bool ArchHasLPMX(StringRef Arch) {
+  return ArchHasMOVW(Arch); // same architectures
+}
+
+static bool ArchHasMUL(StringRef Arch) {
+  return llvm::StringSwitch<bool>(Arch)
+    .Cases("4", "5", "51", "6", true)
+    .Cases("102", "103", "104", "105", "106", "107", true)
+    .Default(false);
+}
+
+static bool ArchHasJMPCALL(StringRef Arch) {
+  return llvm::StringSwitch<bool>(Arch)
+    .Cases("3", "31", "35", "5", "51", "6", true)
+    .Cases("102", "103", "104", "105", "106", "107", true)
+    .Default(false);
+}
+
+static bool ArchHas3BytePC(StringRef Arch) {
+  // These devices have more than 128kB of program memory.
+  // Note:
+  //   - Not fully correct for arch 106: only about half the chips have more
+  //     than 128kB program memory and therefore a 3 byte PC.
+  //   - Doesn't match GCC entirely: avr-gcc thinks arch 107 goes beyond 128kB
+  //     but in fact it doesn't.
+  return llvm::StringSwitch<bool>(Arch)
+    .Case("6", true)
+    .Case("106", true)
+    .Default(false);
+}
+
 bool AVRTargetInfo::isValidCPUName(StringRef Name) const {
   return llvm::any_of(
       AVRMcus, [&](const MCUInfo &Info) { return Info.Name == Name; });
 }
 
 void AVRTargetInfo::fillValidCPUList(SmallVectorImpl<StringRef> &Values) const {
   for (const MCUInfo &Info : AVRMcus)
     Values.push_back(Info.Name);
void AVRTargetInfo::getTargetDefines(const LangOptions &Opts,
   if (ABI == "avrtiny")
     Builder.defineMacro("__AVR_TINY__", "1");
 
   if (DefineName.size() != 0)
       Builder.defineMacro(DefineName);
 
   Builder.defineMacro("__AVR_ARCH__", Arch);
 
+  // TODO: perhaps we should use the information from AVRDevices.td instead?
+  if (ArchHasELPM(Arch))
+    Builder.defineMacro("__AVR_HAVE_ELPM__");
+  if (ArchHasELPMX(Arch))
+    Builder.defineMacro("__AVR_HAVE_ELPMX__");
+  if (ArchHasMOVW(Arch))
+    Builder.defineMacro("__AVR_HAVE_MOVW__");
+  if (ArchHasLPMX(Arch))
+    Builder.defineMacro("__AVR_HAVE_LPMX__");
+  if (ArchHasMUL(Arch))
+    Builder.defineMacro("__AVR_HAVE_MUL__");
+  if (ArchHasJMPCALL(Arch))
+    Builder.defineMacro("__AVR_HAVE_JMP_CALL__");
+  if (ArchHas3BytePC(Arch)) {
+    // Note: some devices do support eijmp/eicall even though this macro isn't
+    // set. This is the case if they have less than 128kB flash and so
+    // eijmp/eicall isn't very useful anyway. (This matches gcc, although it's
+    // debatable whether we should be bug-compatible in this case).
+    Builder.defineMacro("__AVR_HAVE_EIJMP_EICALL__");
+    Builder.defineMacro("__AVR_3_BYTE_PC__");
+  } else {
+    Builder.defineMacro("__AVR_2_BYTE_PC__");
+  }
+
   if (NumFlashBanks >= 1)
     Builder.defineMacro("__flash", "__attribute__((address_space(1)))");
   if (NumFlashBanks >= 2)
     Builder.defineMacro("__flash1", "__attribute__((address_space(2)))");
   if (NumFlashBanks >= 3)
     Builder.defineMacro("__flash2", "__attribute__((address_space(3)))");
   if (NumFlashBanks >= 4)
     Builder.defineMacro("__flash3", "__attribute__((address_space(4)))");
   if (NumFlashBanks >= 5)
     Builder.defineMacro("__flash4", "__attribute__((address_space(5)))");
   if (NumFlashBanks >= 6)
     Builder.defineMacro("__flash5", "__attribute__((address_space(6)))");
 }

clang/test/Preprocessor/avr-atmega328p.c

 // RUN: %clang_cc1 -E -dM -triple avr-unknown-unknown -target-cpu atmega328p /dev/null | FileCheck -match-full-lines %s
 
 // CHECK: #define AVR 1
 // CHECK: #define __AVR 1
 // CHECK: #define __AVR_ARCH__ 5
 // CHECK: #define __AVR_ATmega328P__ 1
+// CHECK-NOT: #define __AVR_HAVE_EIJMP_EICALL__
+// CHECK: #define __AVR_HAVE_LPMX__ 1
+// CHECK: #define __AVR_HAVE_MOVW__ 1
+// CHECK: #define __AVR_HAVE_MUL__ 1
 // CHECK: #define __AVR__ 1
 // CHECK: #define __ELF__ 1

clang/test/Preprocessor/avr-attiny104.c

 // RUN: %clang_cc1 -E -dM -triple avr-unknown-unknown -target-cpu attiny104 /dev/null | FileCheck -match-full-lines %s
 
 // CHECK: #define AVR 1
 // CHECK: #define __AVR 1
 // CHECK: #define __AVR_ARCH__ 100
 // CHECK: #define __AVR_ATtiny104__ 1
+// CHECK-NOT: #define __AVR_HAVE_MUL__ 1
 // CHECK: #define __AVR__ 1
 // CHECK: #define __ELF__ 1