[SPIR-V] Introduce a command line option to support compatibility with Khronos SPIRV Translator (#86101)

SPIRV-LLVM-Translator project
(https://github.com/KhronosGroup/SPIRV-LLVM-Translator) from Khronos
Group is a tool and a library for bi-directional translation between
SPIR-V and LLVM IR. In its backward translation from SPIR-V to LLVM IR
SPIRV-LLVM-Translator isn't necessarily able to cover the same SPIR-V
patterns/instructions set that SPIRV Backend produces, even if we target
the same SPIR-V version in both SPIRV-LLVM-Translator and SPIRV Backend
projects.

To improve interoperability and ability to apply SPIRV Backend output in
different products this PR introduces a notion of a mode of SPIR-V
output that is compatible with a subset of SPIR-V supported by
SPIRV-LLVM-Translator. This includes a new command line option that
doesn't influence default behavior of SPIRV Backend and one test case
that demonstrates how this command line option may be used to get a
practical benefit of producing that one of two possible and similar
output options that can be understood by SPIRV-LLVM-Translator.

Author: VyacheslavLevytskyy

llvm/lib/Target/SPIRV/SPIRVSubtarget.cpp

@@ -27,6 +27,11 @@ using namespace llvm;
 #define GET_SUBTARGETINFO_CTOR
 #include "SPIRVGenSubtargetInfo.inc"
 
+static cl::opt<bool>
+    SPVTranslatorCompat("translator-compatibility-mode",
+                        cl::desc("SPIR-V Translator compatibility mode"),
+                        cl::Optional, cl::init(false));
+
 cl::list<SPIRV::Extension::Extension> Extensions(
     "spirv-extensions", cl::desc("SPIR-V extensions"), cl::ZeroOrMore,
     cl::Hidden,
@@ -157,8 +162,9 @@ bool SPIRVSubtarget::isAtLeastOpenCLVer(uint32_t VerToCompareTo) const {
 }
 
 // If the SPIR-V version is >= 1.4 we can call OpPtrEqual and OpPtrNotEqual.
+// In SPIR-V Translator compatibility mode this feature is not available.
 bool SPIRVSubtarget::canDirectlyComparePointers() const {
-  return isAtLeastVer(SPIRVVersion, 14);
+  return !SPVTranslatorCompat && isAtLeastVer(SPIRVVersion, 14);
 }
 
 void SPIRVSubtarget::initAvailableExtensions() {

llvm/test/CodeGen/SPIRV/instructions/ptrcmp.ll

@@ -1,7 +1,13 @@
 ; RUN: llc -O0 -mtriple=spirv32-unknown-unknown %s -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -O0 -mtriple=spirv32-unknown-unknown %s -o - -filetype=obj | spirv-val %}
+
+; RUN: llc -O0 -mtriple=spirv32-unknown-unknown %s --translator-compatibility-mode -o - | FileCheck %s --check-prefix=CHECK-COMPAT
+; RUN: %if spirv-tools %{ llc -O0 -mtriple=spirv32-unknown-unknown %s --translator-compatibility-mode -o - -filetype=obj | spirv-val %}
 
 ; CHECK-DAG: OpName [[EQ:%.*]] "test_eq"
 ; CHECK-DAG: OpName [[NE:%.*]] "test_ne"
+; CHECK-COMPAT-DAG: OpName [[EQ:%.*]] "test_eq"
+; CHECK-COMPAT-DAG: OpName [[NE:%.*]] "test_ne"
 ; CHECK-DAG: OpName [[ULT:%.*]] "test_ult"
 ; CHECK-DAG: OpName [[SLT:%.*]] "test_slt"
 ; CHECK-DAG: OpName [[ULE:%.*]] "test_ule"
@@ -19,6 +25,9 @@
 ; CHECK-NEXT: [[R:%.*]] = OpPtrEqual {{%.+}} [[A]] [[B]]
 ; CHECK-NEXT: OpReturnValue [[R]]
 ; CHECK-NEXT: OpFunctionEnd
+; CHECK-COMPAT: [[EQ]] = OpFunction
+; CHECK-COMPAT-NOT: OpPtrEqual
+; CHECK-COMPAT: OpFunctionEnd
 define i1 @test_eq(i16* %a, i16* %b) {
   %r = icmp eq i16* %a, %b
   ret i1 %r
@@ -31,6 +40,9 @@ define i1 @test_eq(i16* %a, i16* %b) {
 ; CHECK-NEXT: [[R:%.*]] = OpPtrNotEqual {{%.+}} [[A]] [[B]]
 ; CHECK-NEXT: OpReturnValue [[R]]
 ; CHECK-NEXT: OpFunctionEnd
+; CHECK-COMPAT: [[NE]] = OpFunction
+; CHECK-COMPAT-NOT: OpPtrNotEqual
+; CHECK-COMPAT: OpFunctionEnd
 define i1 @test_ne(i16* %a, i16* %b) {
   %r = icmp ne i16* %a, %b
   ret i1 %r