[lld] Allow input files from compatible architectures on EC targets.

[jacek]

Summary

Rebased, extended ARM64X tests.

[mstorsjo]

I think this looks reasonable

lld/COFF/SymbolTable.cpp

42

Just to check that I've understood correctly here... We don't really expect the input of an individual object file to ever be ARM64X, but only ARM64, AMD64 or ARM64EC, while ARM64X is an image level flag to indicate that it contains both ARM64 and (ARM64EC or AMD64), more or less?

(I don't mind keeping the case here just for completeness anyway though.)

[jacek]

lld/COFF/SymbolTable.cpp

42

We do expect ARM64X on input as well. Individual input object file with its machine value of ARM64X are rare and weird, but they do exist and llvm-cvtres can produce them with https://reviews.llvm.org/D148517 I will update patches with tests for them. According to my testing, ARM64X objects are accepted by link.exe for all targets: ARM64, ARM64EC and ARM64X.

In case of linked images, ARM64X is not used as machine type in PE COFF header. ARM64 is used instead and CHPE metadata referenced by load config distinguishes such files from pure ARM64. From linker point of view, CHPE metadata and load config are provided by CRT libraries, but there is a number of synthetic symbols that linker will have to provide that CRT uses to fill it. (I have enough of those symbols prototyped in my tree to get basic ARM64EC working, not yet ARM64X).

[mstorsjo]

Overall still looking good, thanks!

lld/COFF/SymbolTable.cpp

42

Oh, right, thanks for clarifying!

lld/test/COFF/arm64ec.test

36

Would it be worthwhile to have a few negative tests too? E.g. to test that arm64ec output refuses to include a regular arm64 input object file, or that arm64 output refuses to include arm64ec and x86_64?

[jacek]

I added negative tests and pushed, thanks.

lld/COFF/SymbolTable.cpp

 namespace lld::coff {
 
 StringRef ltrim1(StringRef s, const char *chars) {
   if (!s.empty() && strchr(chars, s[0]))
     return s.substr(1);
   return s;
 }
 
+static bool compatibleMachineType(COFFLinkerContext &ctx, MachineTypes mt) {
+  if (mt == IMAGE_FILE_MACHINE_UNKNOWN)
+    return true;
+  switch (ctx.config.machine) {
+  case ARM64:
+    return mt == ARM64 || mt == ARM64X;
+  case ARM64EC:
+    return COFF::isArm64EC(mt) || mt == AMD64;
+  case ARM64X:
+    return COFF::isAnyArm64(mt) || mt == AMD64;
+  default:
+    return ctx.config.machine == mt;
+  }
+}
+
 void SymbolTable::addFile(InputFile *file) {
   log("Reading " + toString(file));
   if (file->lazy) {
     if (auto *f = dyn_cast<BitcodeFile>(file))
       f->parseLazy();
     else
       cast<ObjFile>(file)->parseLazy();
   } else {
     file->parse();
     if (auto *f = dyn_cast<ObjFile>(file)) {
       ctx.objFileInstances.push_back(f);
     } else if (auto *f = dyn_cast<BitcodeFile>(file)) {
       ctx.bitcodeFileInstances.push_back(f);
     } else if (auto *f = dyn_cast<ImportFile>(file)) {
       ctx.importFileInstances.push_back(f);
     }
   }
 
   MachineTypes mt = file->getMachineType();
   if (ctx.config.machine == IMAGE_FILE_MACHINE_UNKNOWN) {
     ctx.config.machine = mt;
     ctx.driver.addWinSysRootLibSearchPaths();
-  } else if (mt != IMAGE_FILE_MACHINE_UNKNOWN && ctx.config.machine != mt) {
+  } else if (!compatibleMachineType(ctx, mt)) {
     error(toString(file) + ": machine type " + machineToStr(mt) +
           " conflicts with " + machineToStr(ctx.config.machine));
     return;
   }
 
   ctx.driver.parseDirectives(file);
 }
 

lld/test/COFF/arm64ec.test

-REQUIRES: aarch64
+REQUIRES: aarch64, x86
 RUN: split-file %s %t.dir && cd %t.dir
 
+RUN: llvm-mc -filetype=obj -triple=aarch64-windows arm64-data-sym.s -o arm64-data-sym.obj
 RUN: llvm-mc -filetype=obj -triple=arm64ec-windows arm64ec-data-sym.s -o arm64ec-data-sym.obj
+RUN: llvm-mc -filetype=obj -triple=x86_64-windows x86_64-data-sym.s -o x86_64-data-sym.obj
 RUN: llvm-cvtres -machine:arm64x -out:arm64x-resource.obj %S/Inputs/resource.res
 
 RUN: lld-link -out:test.dll -machine:arm64ec arm64ec-data-sym.obj -dll -noentry
 RUN: llvm-readobj --file-headers test.dll | FileCheck -check-prefix=ARM64EC-HEADER %s
 ARM64EC-HEADER:      Format: COFF-x86-64
 ARM64EC-HEADER-NEXT: Arch: x86_64
 ARM64EC-HEADER-NEXT: AddressSize: 64bit
 ARM64EC-HEADER:      Machine: IMAGE_FILE_MACHINE_AMD64 (0x8664)
 
 RUN: lld-link -out:test.dll -machine:arm64x arm64x-resource.obj -dll -noentry
 RUN: llvm-readobj --file-headers test.dll | FileCheck -check-prefix=ARM64X-HEADER %s
 ARM64X-HEADER:      Machine: IMAGE_FILE_MACHINE_ARM64 (0xAA64)
 
+arm64x object files are allowed with -machine:arm64 as well
+RUN: lld-link -out:test.dll -machine:arm64 arm64x-resource.obj -dll -noentry
+
+RUN: lld-link -out:test.dll -machine:arm64ec arm64ec-data-sym.obj x86_64-data-sym.obj \
+RUN:          arm64x-resource.obj -dll -noentry
+RUN: llvm-readobj --file-headers test.dll | FileCheck -check-prefix=ARM64EC-HEADER %s
+
+RUN: llvm-readobj --hex-dump=.data test.dll | FileCheck -check-prefix=ARM64EC-DATA %s
+ARM64EC-DATA: 02020202 03030303
+
+RUN: lld-link -out:test.dll -machine:arm64x x86_64-data-sym.obj arm64-data-sym.obj \
+RUN:          arm64ec-data-sym.obj arm64x-resource.obj -dll -noentry
+RUN: llvm-readobj --file-headers test.dll | FileCheck -check-prefix=ARM64X-HEADER %s
+
+RUN: llvm-readobj --hex-dump=.data test.dll | FileCheck -check-prefix=ARM64X-DATA %s
+ARM64X-DATA: 03030303 01010101 02020202
+
+RUN: not lld-link -out:test.dll -machine:arm64 arm64-data-sym.obj arm64ec-data-sym.obj \
+RUN:              -dll -noentry 2>&1 | FileCheck -check-prefix=INCOMPAT1 %s
+INCOMPAT1: lld-link: error: arm64ec-data-sym.obj: machine type arm64ec conflicts with arm64
+
+RUN: not lld-link -out:test.dll -machine:arm64ec arm64ec-data-sym.obj arm64-data-sym.obj \
+RUN:              -dll -noentry 2>&1 | FileCheck -check-prefix=INCOMPAT2 %s
+INCOMPAT2: lld-link: error: arm64-data-sym.obj: machine type arm64 conflicts with arm64ec
+
+RUN: not lld-link -out:test.dll -machine:arm64 arm64-data-sym.obj x86_64-data-sym.obj \
+RUN:              -dll -noentry 2>&1 | FileCheck -check-prefix=INCOMPAT3 %s
+INCOMPAT3: lld-link: error: x86_64-data-sym.obj: machine type x64 conflicts with arm64
+
 #--- arm64ec-data-sym.s
     .data
     .globl arm64ec_data_sym
     .p2align 2, 0x0
 arm64ec_data_sym:
     .word 0x02020202
+
+#--- arm64-data-sym.s
+    .data
+    .globl arm64_data_sym
+    .p2align 2, 0x0
+arm64_data_sym:
+    .word 0x01010101
+
+#--- x86_64-data-sym.s
+    .data
+    .globl x86_64_data_sym
+    .p2align 2, 0x0
+x86_64_data_sym:
+    .long 0x03030303