[all-commits] [llvm/llvm-project] 948abf: [PowerPC] Add BCDCOPYSIGN and BCDSETSIGN Instructi...

[Aditi Medhane via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 948abf1bf5e481d05af8dee4e5a8201152394bae
      https://github.com/llvm/llvm-project/commit/948abf1bf5e481d05af8dee4e5a8201152394bae
  Author: Aditi Medhane <aditimedhane73 at gmail.com>
  Date:   2025-08-19 (Tue, 19 Aug 2025)

  Changed paths:
    M clang/include/clang/Basic/BuiltinsPPC.def
    M clang/lib/Basic/Targets/PPC.cpp
    M clang/lib/Sema/SemaPPC.cpp
    A clang/test/CodeGen/PowerPC/builtins-bcd-format-conversion.c
    M llvm/include/llvm/IR/IntrinsicsPowerPC.td
    M llvm/lib/Target/PowerPC/PPCInstrAltivec.td
    A llvm/test/CodeGen/PowerPC/builtins-bcd-format-conversion.ll

  Log Message:
  -----------
  [PowerPC] Add BCDCOPYSIGN and BCDSETSIGN Instruction Support (#144874)

Support the following BCD format conversion builtins for PowerPC.

- `__builtin_bcdcopysign` – Conversion that returns the decimal value of
the first parameter combined with the sign code of the second parameter.
`
- `__builtin_bcdsetsign` – Conversion that sets the sign code of the
input parameter in packed decimal format.

> Note: This built-in function is valid only when all following
conditions are met:
> -qarch is set to utilize POWER9 technology.
> The bcd.h file is included.

## Prototypes

```c
vector unsigned char __builtin_bcdcopysign(vector unsigned char, vector unsigned char);
vector unsigned char __builtin_bcdsetsign(vector unsigned char, unsigned char);
```

## Usage Details

`__builtin_bcdsetsign`: Returns the packed decimal value of the first
parameter combined with the sign code.
The sign code is set according to the following rules:
- If the packed decimal value of the first parameter is positive, the
following rules apply:
     - If the second parameter is 0, the sign code is set to 0xC.
     - If the second parameter is 1, the sign code is set to 0xF.
- If the packed decimal value of the first parameter is negative, the
sign code is set to 0xD.
> notes:
>     The second parameter can only be 0 or 1.
> You can determine whether a packed decimal value is positive or
negative as follows:
> - Packed decimal values with sign codes **0xA, 0xC, 0xE, or 0xF** are
interpreted as positive.
> - Packed decimal values with sign codes **0xB or 0xD** are interpreted
as negative.

---------

Co-authored-by: Aditi-Medhane <aditi.medhane at ibm.com>



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