[llvm] [Mips] Remove unused function templates (NFC) (PR #202971)

[Aditya Medhane via llvm-commits]

https://github.com/flash1729 updated https://github.com/llvm/llvm-project/pull/202971

>From 8f6132ded4824c8acf1017ee9b13f8bbd47ee01c Mon Sep 17 00:00:00 2001
From: flash1729 <sherlockedaditya at gmail.com>
Date: Wed, 10 Jun 2026 19:12:40 +0530
Subject: [PATCH 1/2] [Mips] Remove unused function templates (NFC)

A few function templates in the Mips MC layer have no callers anywhere, so they
never get instantiated and trip `-Wunused-template`. They all live in `.cpp`
files, so this is plain dead-code removal.

`MipsELFObjectWriter.cpp`: `copy_if_else` and `find_best` lost their only user
when `sortRelocs` was rewritten in #104723. The `FindBestPredicateResult` enum
existed only for `find_best`, so it goes too.

`MipsDisassembler.cpp`: `DecodeDAHIDATIMMR6` isn't referenced by any
`DecoderMethod`. The r6 DAHI/DATI instructions decode through its sibling
`DecodeDAHIDATI`, which is what the generated tables actually call.

NFC: removes uninstantiated templates only.

Part of #202945.
---
 .../Mips/Disassembler/MipsDisassembler.cpp    | 15 -----
 .../Mips/MCTargetDesc/MipsELFObjectWriter.cpp | 55 -------------------
 2 files changed, 70 deletions(-)

diff --git a/llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp b/llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp
index 808ff67428c12..bbd614fc64423 100644
--- a/llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp
+++ b/llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp
@@ -338,21 +338,6 @@ static DecodeStatus DecodeINSVE_DF(MCInst &MI, InsnType insn, uint64_t Address,
   return MCDisassembler::Success;
 }
 
-template <typename InsnType>
-static DecodeStatus DecodeDAHIDATIMMR6(MCInst &MI, InsnType insn,
-                                       uint64_t Address,
-                                       const MCDisassembler *Decoder) {
-  InsnType Rs = fieldFromInstruction(insn, 16, 5);
-  InsnType Imm = fieldFromInstruction(insn, 0, 16);
-  MI.addOperand(MCOperand::createReg(getReg(Decoder, Mips::GPR64RegClassID,
-                                       Rs)));
-  MI.addOperand(MCOperand::createReg(getReg(Decoder, Mips::GPR64RegClassID,
-                                       Rs)));
-  MI.addOperand(MCOperand::createImm(Imm));
-
-  return MCDisassembler::Success;
-}
-
 template <typename InsnType>
 static DecodeStatus DecodeDAHIDATI(MCInst &MI, InsnType insn, uint64_t Address,
                                    const MCDisassembler *Decoder) {
diff --git a/llvm/lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp b/llvm/lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp
index 680d27927ba36..4defb4f12db69 100644
--- a/llvm/lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp
+++ b/llvm/lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp
@@ -54,63 +54,8 @@ class MipsELFObjectWriter : public MCELFObjectTargetWriter {
   void sortRelocs(std::vector<ELFRelocationEntry> &Relocs) override;
 };
 
-/// The possible results of the Predicate function used by find_best.
-enum FindBestPredicateResult {
-  FindBest_NoMatch = 0,  ///< The current element is not a match.
-  FindBest_Match,        ///< The current element is a match but better ones are
-                         ///  possible.
-  FindBest_PerfectMatch, ///< The current element is an unbeatable match.
-};
-
 } // end anonymous namespace
 
-/// Copy elements in the range [First, Last) to d1 when the predicate is true or
-/// d2 when the predicate is false. This is essentially both std::copy_if and
-/// std::remove_copy_if combined into a single pass.
-template <class InputIt, class OutputIt1, class OutputIt2, class UnaryPredicate>
-static std::pair<OutputIt1, OutputIt2> copy_if_else(InputIt First, InputIt Last,
-                                                    OutputIt1 d1, OutputIt2 d2,
-                                                    UnaryPredicate Predicate) {
-  for (InputIt I = First; I != Last; ++I) {
-    if (Predicate(*I)) {
-      *d1 = *I;
-      d1++;
-    } else {
-      *d2 = *I;
-      d2++;
-    }
-  }
-
-  return std::make_pair(d1, d2);
-}
-
-/// Find the best match in the range [First, Last).
-///
-/// An element matches when Predicate(X) returns FindBest_Match or
-/// FindBest_PerfectMatch. A value of FindBest_PerfectMatch also terminates
-/// the search. BetterThan(A, B) is a comparator that returns true when A is a
-/// better match than B. The return value is the position of the best match.
-///
-/// This is similar to std::find_if but finds the best of multiple possible
-/// matches.
-template <class InputIt, class UnaryPredicate, class Comparator>
-static InputIt find_best(InputIt First, InputIt Last, UnaryPredicate Predicate,
-                         Comparator BetterThan) {
-  InputIt Best = Last;
-
-  for (InputIt I = First; I != Last; ++I) {
-    unsigned Matched = Predicate(*I);
-    if (Matched != FindBest_NoMatch) {
-      if (Best == Last || BetterThan(*I, *Best))
-        Best = I;
-    }
-    if (Matched == FindBest_PerfectMatch)
-      break;
-  }
-
-  return Best;
-}
-
 /// Determine the low relocation that matches the given relocation.
 /// If the relocation does not need a low relocation then the return value
 /// is ELF::R_MIPS_NONE.

>From 201e27b9b3a450cec70ad1f37f0f6dcdf37cbec7 Mon Sep 17 00:00:00 2001
From: flash1729 <sherlockedaditya at gmail.com>
Date: Wed, 10 Jun 2026 20:36:51 +0530
Subject: [PATCH 2/2] Re-trigger CI build