[llvm] ARM: Stop setting sincos_stret calling convention (PR #147457)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm created https://github.com/llvm/llvm-project/pull/147457

This was going out of its way to explicitly mark these as
ARM_AAPCS_VFP. This has been explicitly set since 8b40366b54bd4,
where the commit message states that "sincos" (not sincos_stret)
has a special calling convention. However, that commit also sets
the calling convention for all libcalls to ARM_AAPCS_VFP, and
getEffectiveCallingConv returns the same for CCC anyway in tests
using isWatchABI triples.

The net result of this appears to be a change in behavior when
using -float-abi=soft with isWatchABI, which have no tests so
I assume this is a theoretical combination.

If I assert
  if (getTargetMachine().getTargetTriple().isWatchABI()) {
    assert(!useSoftFloat());
    assert(getEffectiveCallingConv(CallingConv::C, false) == CallingConv::ARM_AAPCS_VFP);
  }

Only 2 tests fail the second condition, which look like copy paste accidents
using v7k triples with linux and only needed a filler triple. This is a consequence
of strangely using the target architecture in place of the OS ABI check,
as was done in 042a6c1fe19caf48af7e287dc8f6fd5fec158093

>From d84dcbfea49fe2c94a8fcc35e4c27de549ff11ca Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Tue, 8 Jul 2025 12:29:34 +0900
Subject: [PATCH] ARM: Stop setting sincos_stret calling convention

This was going out of its way to explicitly mark these as
ARM_AAPCS_VFP. This has been explicitly set since 8b40366b54bd4,
where the commit message states that "sincos" (not sincos_stret)
has a special calling convention. However, that commit also sets
the calling convention for all libcalls to ARM_AAPCS_VFP, and
getEffectiveCallingConv returns the same for CCC anyway in tests
using isWatchABI triples.

The net result of this appears to be a change in behavior when
using -float-abi=soft with isWatchABI, which have no tests so
I assume this is a theoretical combination.

If I assert
  if (getTargetMachine().getTargetTriple().isWatchABI()) {
    assert(!useSoftFloat());
    assert(getEffectiveCallingConv(CallingConv::C, false) == CallingConv::ARM_AAPCS_VFP);
  }

Only 2 tests fail the second condition, which look like copy paste accidents
using v7k triples with linux and only needed a filler triple. This is a consequence
of strangely using the target architecture in place of the OS ABI check,
as was done in 042a6c1fe19caf48af7e287dc8f6fd5fec158093
---
 llvm/lib/IR/RuntimeLibcalls.cpp | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/llvm/lib/IR/RuntimeLibcalls.cpp b/llvm/lib/IR/RuntimeLibcalls.cpp
index 2cbc2cdb79685..45b778d61d8e0 100644
--- a/llvm/lib/IR/RuntimeLibcalls.cpp
+++ b/llvm/lib/IR/RuntimeLibcalls.cpp
@@ -365,12 +365,6 @@ void RuntimeLibcallsInfo::initLibcalls(const Triple &TT,
     if (darwinHasSinCosStret(TT)) {
       setLibcallImpl(RTLIB::SINCOS_STRET_F32, RTLIB::__sincosf_stret);
       setLibcallImpl(RTLIB::SINCOS_STRET_F64, RTLIB::__sincos_stret);
-      if (TT.isWatchABI()) {
-        setLibcallImplCallingConv(RTLIB::__sincosf_stret,
-                                  CallingConv::ARM_AAPCS_VFP);
-        setLibcallImplCallingConv(RTLIB::__sincos_stret,
-                                  CallingConv::ARM_AAPCS_VFP);
-      }
     }
 
     if (darwinHasExp10(TT)) {