[llvm-branch-commits] [llvm] ARM: Mark more generic libgcc functions as available (PR #210961)

[Matt Arsenault via llvm-branch-commits]

https://github.com/arsenm updated https://github.com/llvm/llvm-project/pull/210961

>From 95bf2431a38f571d15303b85c9d6e867371f337f Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Tue, 21 Jul 2026 13:20:25 +0200
Subject: [PATCH] ARM: Mark more generic libgcc functions as available

Generic libgcc/compiler-rt functions coexist with aeabi variants
(e.g., __divsi3  and __aeabi_idiv) according to my reading of the
build. At least in compiler-rt, they are aliases (such that I'm not sure
what the point of ever emitting the __aeabi name is).

They were previously removed from the available set on AEABI+AAPCS targets
to force selection of the preferred __aeabi_* variants, back when
only one implementation per libcall could be recorded.

Now that multiple implementations can be available per libcall, stop hiding
the generics and select the __aeabi_* variant explicitly as the preferred
implemntation. This reduces the number of special cases to consider for
future libcalls info improvements.

Co-authored-by: Claude (Claude-Opus-4.8) <noreply at anthropic.com>
---
 llvm/include/llvm/IR/RuntimeLibcalls.td |  7 +--
 llvm/lib/Target/ARM/ARMSubtarget.cpp    | 62 +++++++++++++++++++++++++
 2 files changed, 63 insertions(+), 6 deletions(-)

diff --git a/llvm/include/llvm/IR/RuntimeLibcalls.td b/llvm/include/llvm/IR/RuntimeLibcalls.td
index 52a62647f50d2..c0a20650bbf8d 100644
--- a/llvm/include/llvm/IR/RuntimeLibcalls.td
+++ b/llvm/include/llvm/IR/RuntimeLibcalls.td
@@ -2516,12 +2516,7 @@ def ARMSystemLibrary
            EABIHalfConvertCalls,
            GNUEABIHalfConvertCalls,
            ARMDoubleToHalfCalls,
-
-           LibcallImpls<(add AEABIOverrides),
-             RuntimeLibcallAvailability<[{
-               (!hasAEABILibcalls(TT) || !isAAPCS_ABI(TT, ABIName)) &&
-               !TT.isOSWindows()
-            }]>>,
+           LibcallImpls<(add AEABIOverrides), isNotOSWindows>,
            // Use divmod compiler-rt calls for iOS 5.0 and later.
            LibcallImpls<(add __divmodsi4, __udivmodsi4),
                         RuntimeLibcallAvailability<[{TT.isOSBinFormatMachO() &&
diff --git a/llvm/lib/Target/ARM/ARMSubtarget.cpp b/llvm/lib/Target/ARM/ARMSubtarget.cpp
index 00ec0b749fb37..928620a5b0c1e 100644
--- a/llvm/lib/Target/ARM/ARMSubtarget.cpp
+++ b/llvm/lib/Target/ARM/ARMSubtarget.cpp
@@ -197,6 +197,68 @@ void ARMSubtarget::initLibcallLoweringInfo(LibcallLoweringInfo &Info) const {
         Info.setLibcallImpl(LC.Op, LC.Impl);
     }
   }
+
+  static const struct {
+    const RTLIB::Libcall Op;
+    const RTLIB::LibcallImpl Impl;
+  } AEABISelected[] = {
+      // Double-precision arithmetic.
+      {RTLIB::ADD_F64, RTLIB::impl___aeabi_dadd},
+      {RTLIB::DIV_F64, RTLIB::impl___aeabi_ddiv},
+      {RTLIB::MUL_F64, RTLIB::impl___aeabi_dmul},
+      {RTLIB::SUB_F64, RTLIB::impl___aeabi_dsub},
+      // Double-precision comparisons.
+      {RTLIB::OEQ_F64, RTLIB::impl___aeabi_dcmpeq},
+      {RTLIB::OLT_F64, RTLIB::impl___aeabi_dcmplt},
+      {RTLIB::OLE_F64, RTLIB::impl___aeabi_dcmple},
+      {RTLIB::OGE_F64, RTLIB::impl___aeabi_dcmpge},
+      {RTLIB::OGT_F64, RTLIB::impl___aeabi_dcmpgt},
+      {RTLIB::UO_F64, RTLIB::impl___aeabi_dcmpun},
+      // Single-precision arithmetic.
+      {RTLIB::ADD_F32, RTLIB::impl___aeabi_fadd},
+      {RTLIB::DIV_F32, RTLIB::impl___aeabi_fdiv},
+      {RTLIB::MUL_F32, RTLIB::impl___aeabi_fmul},
+      {RTLIB::SUB_F32, RTLIB::impl___aeabi_fsub},
+      // Single-precision comparisons.
+      {RTLIB::OEQ_F32, RTLIB::impl___aeabi_fcmpeq},
+      {RTLIB::OLT_F32, RTLIB::impl___aeabi_fcmplt},
+      {RTLIB::OLE_F32, RTLIB::impl___aeabi_fcmple},
+      {RTLIB::OGE_F32, RTLIB::impl___aeabi_fcmpge},
+      {RTLIB::OGT_F32, RTLIB::impl___aeabi_fcmpgt},
+      {RTLIB::UO_F32, RTLIB::impl___aeabi_fcmpun},
+      // Floating-point to integer conversions.
+      {RTLIB::FPTOSINT_F64_I32, RTLIB::impl___aeabi_d2iz},
+      {RTLIB::FPTOUINT_F64_I32, RTLIB::impl___aeabi_d2uiz},
+      {RTLIB::FPTOSINT_F64_I64, RTLIB::impl___aeabi_d2lz},
+      {RTLIB::FPTOUINT_F64_I64, RTLIB::impl___aeabi_d2ulz},
+      {RTLIB::FPTOSINT_F32_I32, RTLIB::impl___aeabi_f2iz},
+      {RTLIB::FPTOUINT_F32_I32, RTLIB::impl___aeabi_f2uiz},
+      {RTLIB::FPTOSINT_F32_I64, RTLIB::impl___aeabi_f2lz},
+      {RTLIB::FPTOUINT_F32_I64, RTLIB::impl___aeabi_f2ulz},
+      // Integer to floating-point conversions.
+      {RTLIB::SINTTOFP_I32_F64, RTLIB::impl___aeabi_i2d},
+      {RTLIB::UINTTOFP_I32_F64, RTLIB::impl___aeabi_ui2d},
+      {RTLIB::SINTTOFP_I64_F64, RTLIB::impl___aeabi_l2d},
+      {RTLIB::UINTTOFP_I64_F64, RTLIB::impl___aeabi_ul2d},
+      {RTLIB::SINTTOFP_I32_F32, RTLIB::impl___aeabi_i2f},
+      {RTLIB::UINTTOFP_I32_F32, RTLIB::impl___aeabi_ui2f},
+      {RTLIB::SINTTOFP_I64_F32, RTLIB::impl___aeabi_l2f},
+      {RTLIB::UINTTOFP_I64_F32, RTLIB::impl___aeabi_ul2f},
+      // Long long helpers.
+      {RTLIB::MUL_I64, RTLIB::impl___aeabi_lmul},
+      {RTLIB::SHL_I64, RTLIB::impl___aeabi_llsl},
+      {RTLIB::SRL_I64, RTLIB::impl___aeabi_llsr},
+      {RTLIB::SRA_I64, RTLIB::impl___aeabi_lasr},
+      // Integer division.
+      {RTLIB::SDIV_I32, RTLIB::impl___aeabi_idiv},
+      {RTLIB::UDIV_I32, RTLIB::impl___aeabi_uidiv},
+  };
+
+  const RTLIB::RuntimeLibcallsInfo &RTLCI = Info.getRuntimeLibcallsInfo();
+  for (const auto &LC : AEABISelected) {
+    if (RTLCI.isAvailable(LC.Impl))
+      Info.setLibcallImpl(LC.Op, LC.Impl);
+  }
 }
 
 bool ARMSubtarget::isXRaySupported() const {