[MLIR][SPIRVToLLVM] Conversion for inverse sqrt and tanh

[georgemitenkov]

Summary

This is a second patch on conversion of GLSL ops to LLVM dialect.
It introduces patterns to convert spv.InverseSqrt and spv.Tanh.

[bondhugula]

mlir/test/Conversion/SPIRVToLLVM/glsl-ops-to-llvm.mlir

103

CHECK-LABEL please.

110

Can drop %{{.*}}.

119

Likewise.

122

Nit: You don't need to match %{{.*}} =.

[georgemitenkov]

Addressed comments on style in tests.

[antiagainst]

mlir/lib/Conversion/SPIRVToLLVM/ConvertSPIRVToLLVM.cpp

96

a floating point scalar or vector value

mlir/lib/Conversion/SPIRVToLLVM/ConvertSPIRVToLLVM.cpp

return rewriter.create<LLVM::ConstantOp>(
         loc, dstType,
         SplatElementsAttr::get(srcType.cast<ShapedType>(),
                                minusOneIntegerAttribute(srcType, rewriter)));
   }
   return rewriter.create<LLVM::ConstantOp>(
       loc, dstType, minusOneIntegerAttribute(srcType, rewriter));
 }
 
+/// Creates `llvm.mlir.constant` with a floating-point value.
+static Value createFPConstant(Location loc, Type srcType, Type dstType,
+                              PatternRewriter &rewriter, double value) {
+  if (auto vecType = srcType.dyn_cast<VectorType>()) {
+    auto floatType = vecType.getElementType().cast<FloatType>();
+    return rewriter.create<LLVM::ConstantOp>(
+        loc, dstType,
+        SplatElementsAttr::get(vecType,
+                               rewriter.getFloatAttr(floatType, value)));
+  }
+  auto floatType = srcType.cast<FloatType>();
+  return rewriter.create<LLVM::ConstantOp>(
+      loc, dstType, rewriter.getFloatAttr(floatType, value));
+}
+
 /// Utility function for bitfiled ops:
 ///   - `BitFieldInsert`
 ///   - `BitFieldSExtract`
 ///   - `BitFieldUExtract`
 /// Truncates or extends the value. If the bitwidth of the value is the same as
 /// `dstType` bitwidth, the value remains unchanged.
 static Value optionallyTruncateOrExtend(Location loc, Value value, Type dstType,
                                         PatternRewriter &rewriter) {
matchAndRewrite(SPIRVOp operation, ArrayRef<Value> operands,
     rewriter.template replaceOpWithNewOp<LLVM::ICmpOp>(
         operation, dstType,
         rewriter.getI64IntegerAttr(static_cast<int64_t>(predicate)),
         operation.operand1(), operation.operand2());
     return success();
   }
 };
 
+class InverseSqrtPattern
+    : public SPIRVToLLVMConversion<spirv::GLSLInverseSqrtOp> {
+public:
+  using SPIRVToLLVMConversion<spirv::GLSLInverseSqrtOp>::SPIRVToLLVMConversion;
+
+  LogicalResult
+  matchAndRewrite(spirv::GLSLInverseSqrtOp op, ArrayRef<Value> operands,
+                  ConversionPatternRewriter &rewriter) const override {
+    auto srcType = op.getType();
+    auto dstType = typeConverter.convertType(srcType);
+    if (!dstType)
+      return failure();
+
+    Location loc = op.getLoc();
+    Value one = createFPConstant(loc, srcType, dstType, rewriter, 1.0);
+    Value sqrt = rewriter.create<LLVM::SqrtOp>(loc, dstType, op.operand());
+    rewriter.replaceOpWithNewOp<LLVM::FDivOp>(op, dstType, one, sqrt);
+    return success();
+  }
+};
+
 /// Converts `spv.Load` and `spv.Store` to LLVM dialect.
 template <typename SPIRVop>
 class LoadStorePattern : public SPIRVToLLVMConversion<SPIRVop> {
 public:
   using SPIRVToLLVMConversion<SPIRVop>::SPIRVToLLVMConversion;
 
   LogicalResult
   matchAndRewrite(SPIRVop op, ArrayRef<Value> operands,
matchAndRewrite(spirv::GLSLTanOp tanOp, ArrayRef<Value> operands,
     Location loc = tanOp.getLoc();
     Value sin = rewriter.create<LLVM::SinOp>(loc, dstType, tanOp.operand());
     Value cos = rewriter.create<LLVM::CosOp>(loc, dstType, tanOp.operand());
     rewriter.replaceOpWithNewOp<LLVM::FDivOp>(tanOp, dstType, sin, cos);
     return success();
   }
 };
 
+/// Convert `spv.Tanh` to
+///
+///   exp(2x) - 1
+///   -----------
+///   exp(2x) + 1
+///
+class TanhPattern : public SPIRVToLLVMConversion<spirv::GLSLTanhOp> {
+public:
+  using SPIRVToLLVMConversion<spirv::GLSLTanhOp>::SPIRVToLLVMConversion;
+
+  LogicalResult
+  matchAndRewrite(spirv::GLSLTanhOp tanhOp, ArrayRef<Value> operands,
+                  ConversionPatternRewriter &rewriter) const override {
+    auto srcType = tanhOp.getType();
+    auto dstType = typeConverter.convertType(srcType);
+    if (!dstType)
+      return failure();
+
+    Location loc = tanhOp.getLoc();
+    Value two = createFPConstant(loc, srcType, dstType, rewriter, 2.0);
+    Value multiplied =
+        rewriter.create<LLVM::FMulOp>(loc, dstType, two, tanhOp.operand());
+    Value exponential = rewriter.create<LLVM::ExpOp>(loc, dstType, multiplied);
+    Value one = createFPConstant(loc, srcType, dstType, rewriter, 1.0);
+    Value numerator =
+        rewriter.create<LLVM::FSubOp>(loc, dstType, exponential, one);
+    Value denominator =
+        rewriter.create<LLVM::FAddOp>(loc, dstType, exponential, one);
+    rewriter.replaceOpWithNewOp<LLVM::FDivOp>(tanhOp, dstType, numerator,
+                                              denominator);
+    return success();
+  }
+};
+
 class VariablePattern : public SPIRVToLLVMConversion<spirv::VariableOp> {
 public:
   using SPIRVToLLVMConversion<spirv::VariableOp>::SPIRVToLLVMConversion;
 
   LogicalResult
   matchAndRewrite(spirv::VariableOp varOp, ArrayRef<Value> operands,
                   ConversionPatternRewriter &rewriter) const override {
     auto srcType = varOp.getType();
patterns.insert<
 
       // GLSL extended instruction set ops
       DirectConversionPattern<spirv::GLSLCeilOp, LLVM::FCeilOp>,
       DirectConversionPattern<spirv::GLSLCosOp, LLVM::CosOp>,
       DirectConversionPattern<spirv::GLSLExpOp, LLVM::ExpOp>,
       DirectConversionPattern<spirv::GLSLFAbsOp, LLVM::FAbsOp>,
       DirectConversionPattern<spirv::GLSLLogOp, LLVM::LogOp>,
       DirectConversionPattern<spirv::GLSLSinOp, LLVM::SinOp>,
-      DirectConversionPattern<spirv::GLSLSqrtOp, LLVM::SqrtOp>, TanPattern,
+      DirectConversionPattern<spirv::GLSLSqrtOp, LLVM::SqrtOp>,
+      InverseSqrtPattern, TanPattern, TanhPattern,
 
       // Logical ops
       DirectConversionPattern<spirv::LogicalAndOp, LLVM::AndOp>,
       DirectConversionPattern<spirv::LogicalOrOp, LLVM::OrOp>,
       IComparePattern<spirv::LogicalEqualOp, LLVM::ICmpPredicate::eq>,
       IComparePattern<spirv::LogicalNotEqualOp, LLVM::ICmpPredicate::ne>,
       NotPattern<spirv::LogicalNotOp>,
 

mlir/test/Conversion/SPIRVToLLVM/glsl-ops-to-llvm.mlir

 
 func @tan(%arg0: f32) {
   // CHECK: %[[SIN:.*]] = "llvm.intr.sin"(%{{.*}}) : (!llvm.float) -> !llvm.float
   // CHECK: %[[COS:.*]] = "llvm.intr.cos"(%{{.*}}) : (!llvm.float) -> !llvm.float
   // CHECK: %{{.*}} = llvm.fdiv %[[SIN]], %[[COS]] : !llvm.float
   %0 = spv.GLSL.Tan %arg0 : f32
   return
 }
+
+//===----------------------------------------------------------------------===//
+// spv.GLSL.Tanh
+//===----------------------------------------------------------------------===//
+
+// CHECK-LABEL: @tanh
+func @tanh(%arg0: f32) {
+  // CHECK: %[[TWO:.*]] = llvm.mlir.constant(2.000000e+00 : f32) : !llvm.float
+  // CHECK: %[[X2:.*]] = llvm.fmul %[[TWO]], %{{.*}} : !llvm.float
+  // CHECK: %[[EXP:.*]] = "llvm.intr.exp"(%[[X2]]) : (!llvm.float) -> !llvm.float
+  // CHECK: %[[ONE:.*]] = llvm.mlir.constant(1.000000e+00 : f32) : !llvm.float
+  // CHECK: %[[T0:.*]] = llvm.fsub %[[EXP]], %[[ONE]] : !llvm.float
+  // CHECK: %[[T1:.*]] = llvm.fadd %[[EXP]], %[[ONE]] : !llvm.float
+  // CHECK: llvm.fdiv %[[T0]], %[[T1]] : !llvm.float
+  %0 = spv.GLSL.Tanh %arg0 : f32
+  return
+}
+
+//===----------------------------------------------------------------------===//
+// spv.GLSL.InverseSqrt
+//===----------------------------------------------------------------------===//
+
+// CHECK-LABEL: @inverse_sqrt
+func @inverse_sqrt(%arg0: f32) {
+  // CHECK: %[[ONE:.*]] = llvm.mlir.constant(1.000000e+00 : f32) : !llvm.float
+  // CHECK: %[[SQRT:.*]] = "llvm.intr.sqrt"(%{{.*}}) : (!llvm.float) -> !llvm.float
+  // CHECK: llvm.fdiv %[[ONE]], %[[SQRT]] : !llvm.float
+  %0 = spv.GLSL.InverseSqrt %arg0 : f32
+  return
+}