================
@@ -564,6 +564,30 @@ def CBits : DXILOp<31, unary> {
let attributes = [Attributes<DXIL1_0, [ReadNone]>];
}
+def FBH : DXILOp<33, unary> {
+ let Doc = "Returns the location of the first set bit starting from "
+ "the highest order bit and working downward.";
+ let LLVMIntrinsic = int_dx_firstbituhigh;
+ let arguments = [OverloadTy];
+ let result = OverloadTy;
+ let overloads =
+ [Overloads<DXIL1_0, [Int16Ty, Int32Ty, Int64Ty]>];
+ let stages = [Stages<DXIL1_0, [all_stages]>];
+ let attributes = [Attributes<DXIL1_0, [ReadNone]>];
+}
+
+def FBSH : DXILOp<34, unary> {
+ let Doc = "Returns the location of the first set bit from "
+ "the highest order bit based on the sign.";
+ let LLVMIntrinsic = int_dx_firstbitshigh;
+ let arguments = [OverloadTy];
+ let result = OverloadTy;
+ let overloads =
+ [Overloads<DXIL1_0, [Int16Ty, Int32Ty, Int64Ty]>];
+ let stages = [Stages<DXIL1_0, [all_stages]>];
+ let attributes = [Attributes<DXIL1_0, [ReadNone]>];
+}
----------------
bogner wrote:
A few things here:
1. Please name these with the full names of the dxil ops, `FirstbitHi` and
`FirstbitSHi`
2. These need to use `unaryBits` for the `OpClass`, not `unary`
3. [The result type should be
i32](https://github.com/microsoft/DirectXShaderCompiler/blob/release-1.8.2407/utils/hct/hctdb.py#L1410),
not `OverloadTy`
I'll also that this overload set does match dxc, as indicated by
["wil"](https://github.com/microsoft/DirectXShaderCompiler/blob/release-1.8.2407/utils/hct/hctdb.py#L1407)
in hctdb.py, but I'm not entirely convinced that dxc does the right thing for
i16 or i64. For instance, in https://hlsl.godbolt.org/z/cE1sahjKa there's no
way that could return a meaningful result. That said, it's probably fine to
allow i16 and i64 match dxc, as least for now.
https://github.com/llvm/llvm-project/pull/111082
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