[SYCL] Fix backwards compatibility for libraries in archive format (#4685)

With `-sycldevice` triple environment removal (as performed in
#3929), backwards compatibility has been enforced for SYCL
objects/object-format libraries only. To ensure that `.a` libraries
(archives) built by older compiler versions are usable with newer
compiler version, adjust `clang-offload-deps` to consider
`-sycldevice`-marked symbols when encountering a SYCL target.

Signed-off-by: Artem Gindinson <artem.gindinson@intel.com>

Author: Artem Gindinson

clang/test/Driver/clang-offload-deps.c

@@ -23,15 +23,28 @@
 // Generate dependencies for targets and check contents of the output bitcode files.
 //
 // RUN: clang-offload-deps -targets=openmp-x86_64-pc-linux-gnu,sycl-spir64 -outputs=%t.deps.x86_64,%t.deps.spir64 %t.fat
+// RUN: clang-offload-deps -targets=openmp-x86_64-pc-linux-gnu,sycl-spir64 -outputs=%t.deps.x86_64,%t.deps.spir64 %t.fat
 // RUN: llvm-dis -o - %t.deps.x86_64 | FileCheck %s --check-prefixes=CHECK-DEPS-X86_64
-// RUN: llvm-dis -o - %t.deps.spir64 | FileCheck %s --check-prefixes=CHECK-DEPS-SPIR64
+// RUN: llvm-dis -o - %t.deps.spir64 | FileCheck %s --check-prefixes=CHECK-DEPS-SPIR64 -DSPIRTriple=spir64
+//
+// Check that the legacy 'sycldevice' symbols are still identified correctly
+// when 'unknown' environment has been specified/implied for SYCL via
+// clang-offload-bundler's -targets
+//
+// RUN: clang-offload-bundler -type=o -targets=host-%itanium_abi_triple,openmp-x86_64-pc-linux-gnu,sycl-spir64-unknown-unknown-sycldevice -inputs=%t.host,%t.x86_64,%t.spir64 -outputs=%t.legacy-sycldevice.fat
+// Check correct behavior for multiple targets
+// RUN: clang-offload-deps -targets=openmp-x86_64-pc-linux-gnu,sycl-spir64-unknown-unknown -outputs=%t.deps.legacy.x86_64,%t.deps.legacy.spir64 %t.legacy-sycldevice.fat
+// RUN: llvm-dis -o - %t.deps.legacy.spir64 | FileCheck %s --check-prefixes=CHECK-DEPS-SPIR64 -DSPIRTriple=spir64-unknown-unknown
+// Check correct behavior for shortened triple
+// RUN: clang-offload-deps -targets=sycl-spir64 -outputs=%t.deps.legacy.spir64-short %t.legacy-sycldevice.fat
+// RUN: llvm-dis -o - %t.deps.legacy.spir64-short | FileCheck %s --check-prefixes=CHECK-DEPS-SPIR64 -DSPIRTriple=spir64
 
 // CHECK-DEPS-X86_64: target triple = "x86_64-pc-linux-gnu"
 // CHECK-DEPS-X86_64: @bar = external global i8*
 // CHECK-DEPS-X86_64: @foo = external global i8*
 // CHECK-DEPS-X86_64: @offload.symbols = hidden local_unnamed_addr global [2 x i8*] [i8* bitcast (i8** @bar to i8*), i8* bitcast (i8** @foo to i8*)]
 
-// CHECK-DEPS-SPIR64: target triple = "spir64"
+// CHECK-DEPS-SPIR64: target triple = "[[SPIRTriple]]"
 // CHECK-DEPS-SPIR64: @bar = external global i8*
 // CHECK-DEPS-SPIR64: @foo = external global i8*
 // CHECK-DEPS-SPIR64: @llvm.used = appending global [2 x i8*] [i8* bitcast (i8** @bar to i8*), i8* bitcast (i8** @foo to i8*)], section "llvm.metadata"

clang/tools/clang-offload-deps/ClangOffloadDeps.cpp

@@ -167,11 +167,33 @@ int main(int argc, const char **argv) {
     for (StringRef Symbol = DataOrErr.get(); !Symbol.empty();) {
       unsigned Len = strlen(Symbol.data());
 
+      // TODO: Consider storing Targets and Kinds in a single map-like struct,
+      // possibly reusing ClangOffloadBundler's 'OffloadTargetInfo'.
+      auto KindsIter = Kinds.begin();
       for (const std::string &Target : Targets) {
         std::string Prefix = Target + ".";
         if (Symbol.startswith(Prefix))
           Target2Symbols[Target].insert(
               Symbol.substr(Prefix.size(), Len - Prefix.size()));
+        else if (KindsIter->equals("sycl")) {
+          // FIXME: Temporary solution for supporting libraries produced by old
+          // versions of SYCL toolchain. Old versions used triples with
+          // 'sycldevice' environment component of the triple, whereas new
+          // toolchain use 'unknown' value for that triple component.
+          // We check for the legacy 'sycldevice' variant upon the negative
+          // check for a SYCL triple with 'unknown' environment.
+          std::string LegacyPrefix(Target);
+          // In case vendor and OS are not set for this target, fill these with
+          // 'unknown' so that our target has the "canonical" form of:
+          // <kind>-<arch>-<vendor>-<os>-<sycldevice>
+          while (StringRef(LegacyPrefix).count("-") < 3)
+            LegacyPrefix += "-unknown";
+          LegacyPrefix += "-sycldevice.";
+          if (Symbol.startswith(LegacyPrefix))
+            Target2Symbols[Target].insert(
+                Symbol.substr(LegacyPrefix.size(), Len - LegacyPrefix.size()));
+        }
+        ++KindsIter;
       }
 
       Symbol = Symbol.drop_front(Len + 1u);