[all-commits] [llvm/llvm-project] db03c2: [AMDGPU] Re-apply: Implement vop3p complex pattern...

[Shoreshen via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: db03c27763656948323a50b9706da912c581e6f2
      https://github.com/llvm/llvm-project/commit/db03c27763656948323a50b9706da912c581e6f2
  Author: Shoreshen <372660931 at qq.com>
  Date:   2025-07-04 (Fri, 04 Jul 2025)

  Changed paths:
    M llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
    M llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.h
    M llvm/test/CodeGen/AMDGPU/GlobalISel/fmul.v2f16.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/llvm.amdgcn.sdot2.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/llvm.amdgcn.udot2.ll
    M llvm/test/CodeGen/AMDGPU/packed-fp32.ll
    M llvm/test/CodeGen/AMDGPU/strict_fsub.f16.ll

  Log Message:
  -----------
  [AMDGPU] Re-apply: Implement vop3p complex pattern optmization for gisel (#136262)

This is a fix up for patch
https://github.com/llvm/llvm-project/pull/130234, which is reverted in
https://github.com/llvm/llvm-project/pull/136249

The main reason of building failure are:

1. 
   ```

/home/botworker/bbot/amdgpu-offload-rhel-9-cmake-build-only/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp:
In function ‘llvm::SmallVector<std::pair<const llvm::MachineOperand*,
SrcStatus> > getSrcStats(const llvm::MachineOperand*, const
llvm::MachineRegisterInfo&, searchOptions, int)’:

/home/botworker/bbot/amdgpu-offload-rhel-9-cmake-build-only/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp:4669:
error: could not convert ‘Statlist’ from ‘SmallVector<[...],4>’ to
‘SmallVector<[...],3>’
    4669 |   return Statlist;
   ```
2. 
   ```

/home/b/sanitizer-aarch64-linux/build/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp:4554:1:
error: non-void function does not return a value in all control paths
[-Werror,-Wreturn-type]
    4554 | }
        | ^

/home/b/sanitizer-aarch64-linux/build/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp:4644:39:
error: overlapping comparisons always evaluate to true
[-Werror,-Wtautological-overlap-compare]
4644 | (Stat >= SrcStatus::NEG_START || Stat <= SrcStatus::NEG_END)) {
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

/home/b/sanitizer-aarch64-linux/build/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp:4893:66:
error: captured structured bindings are a C++20 extension
[-Werror,-Wc++20-extensions]
4893 | [=](MachineInstrBuilder &MIB) { MIB.addImm(getAllKindImm(Op)); },
| ^

/home/b/sanitizer-aarch64-linux/build/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp:4890:9:
note: 'Op' declared here
    4890 |   auto [Op, Mods] = selectVOP3PModsImpl(&Root, MRI, IsDOT);
        |         ^

/home/b/sanitizer-aarch64-linux/build/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp:4894:52:
error: captured structured bindings are a C++20 extension
[-Werror,-Wc++20-extensions]
4894 | [=](MachineInstrBuilder &MIB) { MIB.addImm(Mods); } // src_mods
        |                                                    ^

/home/b/sanitizer-aarch64-linux/build/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp:4890:13:
note: 'Mods' declared here
    4890 |   auto [Op, Mods] = selectVOP3PModsImpl(&Root, MRI, IsDOT);
        |             ^

/home/b/sanitizer-aarch64-linux/build/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp:4899:50:
error: captured structured bindings are a C++20 extension
[-Werror,-Wc++20-extensions]
4899 | [=](MachineInstrBuilder &MIB) { MIB.addReg(Op->getReg()); },
        |                                                  ^

/home/b/sanitizer-aarch64-linux/build/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp:4890:9:
note: 'Op' declared here
    4890 |   auto [Op, Mods] = selectVOP3PModsImpl(&Root, MRI, IsDOT);
        |         ^

/home/b/sanitizer-aarch64-linux/build/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp:4900:50:
error: captured structured bindings are a C++20 extension
[-Werror,-Wc++20-extensions]
4900 | [=](MachineInstrBuilder &MIB) { MIB.addImm(Mods); } // src_mods
        |                                                  ^

/home/b/sanitizer-aarch64-linux/build/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp:4890:13:
note: 'Mods' declared here
    4890 |   auto [Op, Mods] = selectVOP3PModsImpl(&Root, MRI, IsDOT);
        |             ^
   6 errors generated.
   ```

Both error cannot be reproduced at my local machine, the fix applied
are:
1. In `llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp` function
`getSrcStats` replace
   ```
SmallVector<std::pair<const MachineOperand *, SrcStatus>, 4> Statlist;
   ```
   with
   ```
   SmallVector<std::pair<const MachineOperand *, SrcStatus>> Statlist;
   ```
2. In `llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp` function
`AMDGPUInstructionSelector::selectVOP3PRetHelper` replace
   ```
   auto [Op, Mods] = selectVOP3PModsImpl(&Root, MRI, IsDOT);
   ```
   with
   ```
   auto Results = selectVOP3PModsImpl(&Root, MRI, IsDOT);
   const MachineOperand *Op = Results.first;
   unsigned Mods = Results.second;
   ```

These change hasn't be testified since both errors cannot be reproduced
in local



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