Add support for ISubBorrow SPIRV instruction (KhronosGroup#2168)

This commit implements bidirectional translation of the llvm.usub.with.overflow and the ISubBorrow intrinsic.
Intrinsic llvm.usub.with.overflow returns struct which second element have a type of i1.
The llvm type i1 is, in llvm-spirv, directly translated to BoolType.
SPIRV specification requires that the composite which returns from ISubBorrow needs to have both elements of the same type.
In result, current implementation is not compliant and should be considered temporary.

Author: bwlodarcz

lib/SPIRV/SPIRVReader.cpp

@@ -2471,13 +2471,21 @@ Value *SPIRVToLLVM::transValueWithoutDecoration(SPIRVValue *BV, Function *F,
     return mapValue(BV,
                     transRelational(static_cast<SPIRVInstruction *>(BV), BB));
   case OpIAddCarry: {
-    IRBuilder Builder(BB);
+    IRBuilder<> Builder(BB);
     auto *BC = static_cast<SPIRVBinary *>(BV);
     return mapValue(BV, Builder.CreateBinaryIntrinsic(
                             Intrinsic::uadd_with_overflow,
                             transValue(BC->getOperand(0), F, BB),
                             transValue(BC->getOperand(1), F, BB)));
   }
+  case OpISubBorrow: {
+    IRBuilder<> Builder(BB);
+    auto *BC = static_cast<SPIRVBinary *>(BV);
+    return mapValue(BV, Builder.CreateBinaryIntrinsic(
+                            Intrinsic::usub_with_overflow,
+                            transValue(BC->getOperand(0), F, BB),
+                            transValue(BC->getOperand(1), F, BB)));
+  }
   case OpGetKernelWorkGroupSize:
   case OpGetKernelPreferredWorkGroupSizeMultiple:
     return mapValue(

lib/SPIRV/SPIRVWriter.cpp

@@ -3364,6 +3364,7 @@ bool LLVMToSPIRVBase::isKnownIntrinsic(Intrinsic::ID Id) {
   case Intrinsic::trap:
   case Intrinsic::arithmetic_fence:
   case Intrinsic::uadd_with_overflow:
+  case Intrinsic::usub_with_overflow:
     return true;
   default:
     // Unknown intrinsics' declarations should always be translated
@@ -3782,6 +3783,11 @@ SPIRVValue *LLVMToSPIRVBase::transIntrinsicInst(IntrinsicInst *II,
                              transValue(II->getArgOperand(0), BB),
                              transValue(II->getArgOperand(1), BB), BB);
   }
+  case Intrinsic::usub_with_overflow: {
+    return BM->addBinaryInst(OpISubBorrow, transType(II->getType()),
+                             transValue(II->getArgOperand(0), BB),
+                             transValue(II->getArgOperand(1), BB), BB);
+  }
   case Intrinsic::memset: {
     // Generally there is no direct mapping of memset to SPIR-V.  But it turns
     // out that memset is emitted by Clang for initialization in default

lib/SPIRV/libSPIRV/SPIRVEntry.h

@@ -1006,7 +1006,6 @@ _SPIRV_OP(ImageDrefGather)
 _SPIRV_OP(QuantizeToF16)
 _SPIRV_OP(ArrayLength)
 _SPIRV_OP(OuterProduct)
-_SPIRV_OP(ISubBorrow)
 _SPIRV_OP(SMulExtended)
 _SPIRV_OP(UMulExtended)
 _SPIRV_OP(DPdx)

lib/SPIRV/libSPIRV/SPIRVInstruction.h

@@ -664,6 +664,7 @@ _SPIRV_OP(IAdd)
 _SPIRV_OP(IAddCarry)
 _SPIRV_OP(FAdd)
 _SPIRV_OP(ISub)
+_SPIRV_OP(ISubBorrow)
 _SPIRV_OP(FSub)
 _SPIRV_OP(IMul)
 _SPIRV_OP(FMul)

lib/SPIRV/libSPIRV/SPIRVOpCode.h

@@ -71,7 +71,7 @@ inline bool isAtomicOpCode(Op OpCode) {
 }
 inline bool isBinaryOpCode(Op OpCode) {
   return ((unsigned)OpCode >= OpIAdd && (unsigned)OpCode <= OpFMod) ||
-         OpCode == OpDot || OpCode == OpIAddCarry;
+         OpCode == OpDot || OpCode == OpIAddCarry || OpCode == OpISubBorrow;
 }
 
 inline bool isShiftOpCode(Op OpCode) {

test/llvm-intrinsics/usub.with.overflow.ll

@@ -0,0 +1,58 @@
+; RUN: llvm-as %s -o %t.bc
+; RUN: llvm-spirv %t.bc -spirv-text -o - | FileCheck --check-prefix CHECK-SPIRV %s
+; RUN: llvm-spirv %t.bc -o %t.spv
+; Current implementation doesn't comply with specification and should be fixed in future.
+; TODO: spirv-val %t.spv
+; RUN: llvm-spirv -r %t.spv -o %t.rev.bc
+; RUN: llvm-dis %t.rev.bc -o - | FileCheck --check-prefix CHECK-LLVM %s
+
+target triple = "spir64-unknown-unknown"
+
+
+; CHECK-SPIRV: TypeInt [[#I16TYPE:]] 16
+; CHECK-SPIRV: TypeInt [[#I32TYPE:]] 32
+; CHECK-SPIRV: TypeInt [[#I64TYPE:]] 64
+; CHECK-SPIRV: TypeBool [[#BTYPE:]]
+; CHECK-SPIRV: TypeStruct [[#S0TYPE:]] [[#I16TYPE]] [[#BTYPE]]
+; CHECK-SPIRV: TypeStruct [[#S1TYPE:]] [[#I32TYPE]] [[#BTYPE]]
+; CHECK-SPIRV: TypeStruct [[#S2TYPE:]] [[#I64TYPE]] [[#BTYPE]]
+; CHECK-SPIRV: TypeVector [[#V4XI32TYPE:]] [[#I32TYPE]] 4
+; CHECK-SPIRV: TypeVector [[#V4XBTYPE:]] [[#BTYPE]] 4
+; CHECK-SPIRV: TypeStruct [[#S3TYPE:]] [[#V4XI32TYPE]] [[#V4XBTYPE]]
+; CHECK-SPIRV: ISubBorrow [[#S0TYPE]]
+; CHECK-SPIRV: ISubBorrow [[#S1TYPE]]
+; CHECK-SPIRV: ISubBorrow [[#S2TYPE]]
+; CHECK-SPIRV: ISubBorrow [[#S3TYPE]]
+; CHECK-LLVM: call { i16, i1 } @llvm.usub.with.overflow.i16(i16 %a, i16 %b)
+; CHECK-LLVM: call { i32, i1 } @llvm.usub.with.overflow.i32(i32 %a, i32 %b)
+; CHECK-LLVM: call { i64, i1 } @llvm.usub.with.overflow.i64(i64 %a, i64 %b)
+; CHECK-LLVM: call { <4 x i32>, <4 x i1> } @llvm.usub.with.overflow.v4i32(<4 x i32> %a, <4 x i32> %b)
+
+define spir_func void @test_usub_with_overflow_i16(i16 %a, i16 %b) {
+entry:
+  %res = call {i16, i1} @llvm.usub.with.overflow.i16(i16 %a, i16 %b)
+  ret void
+}
+
+define spir_func void @test_usub_with_overflow_i32(i32 %a, i32 %b) {
+entry:
+  %res = call {i32, i1} @llvm.usub.with.overflow.i32(i32 %a, i32 %b)
+  ret void
+}
+
+define spir_func void @test_usub_with_overflow_i64(i64 %a, i64 %b) {
+entry:
+  %res = call {i64, i1} @llvm.usub.with.overflow.i64(i64 %a, i64 %b)
+  ret void
+}
+
+define spir_func void @test_usub_with_overflow_v4i32(<4 x i32> %a, <4 x i32> %b) {
+entry:
+ %res = call {<4 x i32>, <4 x i1>} @llvm.usub.with.overflow.v4i32(<4 x i32> %a, <4 x i32> %b)
+ ret void
+}
+
+declare {i16, i1} @llvm.usub.with.overflow.i16(i16 %a, i16 %b)
+declare {i32, i1} @llvm.usub.with.overflow.i32(i32 %a, i32 %b)
+declare {i64, i1} @llvm.usub.with.overflow.i64(i64 %a, i64 %b)
+declare {<4 x i32>, <4 x i1>} @llvm.usub.with.overflow.v4i32(<4 x i32> %a, <4 x i32> %b)