[llvm] 301a1d5 - RuntimeLibcalls: Invert handling of 64-bit only libcalls (#148571)

[via llvm-commits]

Author: Matt Arsenault
Date: 2025-07-15T00:59:54+09:00
New Revision: 301a1d565fccaf517d1c587d1599d595407c178b

URL: https://github.com/llvm/llvm-project/commit/301a1d565fccaf517d1c587d1599d595407c178b
DIFF: https://github.com/llvm/llvm-project/commit/301a1d565fccaf517d1c587d1599d595407c178b.diff

LOG: RuntimeLibcalls: Invert handling of 64-bit only libcalls (#148571)

Switch the default set to exclude these conditionally available
calls, so they are opt-in instead of opt-out.

Added: 
    

Modified: 
    llvm/include/llvm/IR/RuntimeLibcalls.td
    llvm/lib/IR/RuntimeLibcalls.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/IR/RuntimeLibcalls.td b/llvm/include/llvm/IR/RuntimeLibcalls.td
index 39cff4d32346f..ff343f30f0325 100644
--- a/llvm/include/llvm/IR/RuntimeLibcalls.td
+++ b/llvm/include/llvm/IR/RuntimeLibcalls.td
@@ -439,26 +439,21 @@ let IsDefault = true in {
 def __ashlhi3 : RuntimeLibcallImpl<SHL_I16>;
 def __ashlsi3 : RuntimeLibcallImpl<SHL_I32>;
 def __ashldi3 : RuntimeLibcallImpl<SHL_I64>;
-def __ashlti3 : RuntimeLibcallImpl<SHL_I128>;
 
 def __lshrhi3 : RuntimeLibcallImpl<SRL_I16>;
 def __lshrsi3 : RuntimeLibcallImpl<SRL_I32>;
 def __lshrdi3 : RuntimeLibcallImpl<SRL_I64>;
-def __lshrti3 : RuntimeLibcallImpl<SRL_I128>;
 
 def __ashrhi3 : RuntimeLibcallImpl<SRA_I16>;
 def __ashrsi3 : RuntimeLibcallImpl<SRA_I32>;
 def __ashrdi3 : RuntimeLibcallImpl<SRA_I64>;
-def __ashrti3 : RuntimeLibcallImpl<SRA_I128>;
 
 def __mulqi3 : RuntimeLibcallImpl<MUL_I8>;
 def __mulhi3 : RuntimeLibcallImpl<MUL_I16>;
 def __mulsi3 : RuntimeLibcallImpl<MUL_I32>;
 def __muldi3 : RuntimeLibcallImpl<MUL_I64>;
-def __multi3 : RuntimeLibcallImpl<MUL_I128>;
 
 def __mulosi4 : RuntimeLibcallImpl<MULO_I32>;
-def __mulodi4 : RuntimeLibcallImpl<MULO_I64>;
 
 def __divqi3 : RuntimeLibcallImpl<SDIV_I8>;
 def __divhi3 : RuntimeLibcallImpl<SDIV_I16>;
@@ -935,10 +930,29 @@ def calloc : RuntimeLibcallImpl<CALLOC>;
 } // End let IsDefault = true
 
 //--------------------------------------------------------------------
-// compiler-rt, not available for most architectures
+// compiler-rt/libgcc but 64-bit only, not available by default
 //--------------------------------------------------------------------
 
-def __muloti4 : RuntimeLibcallImpl<MULO_I128>;
+// Exist in libgcc and compiler-rt for 64-bit targets, or if
+// COMPILER_RT_ENABLE_SOFTWARE_INT128.
+defset list<RuntimeLibcallImpl> Int128RTLibcalls = {
+  def __ashlti3 : RuntimeLibcallImpl<SHL_I128>;
+  def __lshrti3 : RuntimeLibcallImpl<SRL_I128>;
+  def __ashrti3 : RuntimeLibcallImpl<SRA_I128>;
+  def __multi3 : RuntimeLibcallImpl<MUL_I128>;
+}
+
+//--------------------------------------------------------------------
+// compiler-rt only, not available by default
+//--------------------------------------------------------------------
+
+defset list<RuntimeLibcallImpl> CompilerRTOnlyInt64Libcalls = {
+  def __mulodi4 : RuntimeLibcallImpl<MULO_I64>;
+}
+
+defset list<RuntimeLibcallImpl> CompilerRTOnlyInt128Libcalls = {
+  def __muloti4 : RuntimeLibcallImpl<MULO_I128>;
+}
 
 //--------------------------------------------------------------------
 // Define implementation other libcalls
@@ -1034,21 +1048,6 @@ defset list<RuntimeLibcallImpl> LibmF128FiniteLibcalls = {
 defvar AllDefaultRuntimeLibcallImpls
   = !filter(entry, !instances<RuntimeLibcallImpl>(), entry.IsDefault);
 
-// Exist in libgcc and compiler-rt for 64-bit targets, or if
-// COMPILER_RT_ENABLE_SOFTWARE_INT128.
-defvar Int128RTLibcalls = [
-   __ashlti3, __lshrti3, __ashrti3, __multi3
-];
-
-// Only available in compiler-rt
-defvar CompilerRTOnlyInt64Libcalls = [
-  __mulodi4
-];
-
-defvar CompilerRTOnlyInt128Libcalls = [
-  __muloti4
-];
-
 defvar DefaultRuntimeLibcallImpls_f80 =
     !filter(entry, AllDefaultRuntimeLibcallImpls,
             !match(!cast<string>(entry.Provides), "F80"));
@@ -1064,12 +1063,9 @@ defvar DefaultRuntimeLibcallImpls_f128 =
 defvar DefaultRuntimeLibcallImpls =
 !listremove(
   !listremove(
-    !listremove(
-        !listremove(AllDefaultRuntimeLibcallImpls, Int128RTLibcalls),
-                    !listconcat(CompilerRTOnlyInt64Libcalls,
-                                CompilerRTOnlyInt128Libcalls)),
-                    DefaultRuntimeLibcallImpls_f80),
-                    DefaultRuntimeLibcallImpls_ppcf128);
+    !listremove(AllDefaultRuntimeLibcallImpls, Int128RTLibcalls),
+                DefaultRuntimeLibcallImpls_f80),
+                DefaultRuntimeLibcallImpls_ppcf128);
 
 /// Default set of libcall impls for 32-bit architectures.
 defvar DefaultLibcallImpls32 = DefaultRuntimeLibcallImpls;

diff  --git a/llvm/lib/IR/RuntimeLibcalls.cpp b/llvm/lib/IR/RuntimeLibcalls.cpp
index 3dd894ad6c50e..74cde5e9cee92 100644
--- a/llvm/lib/IR/RuntimeLibcalls.cpp
+++ b/llvm/lib/IR/RuntimeLibcalls.cpp
@@ -139,6 +139,10 @@ void RuntimeLibcallsInfo::initLibcalls(const Triple &TT,
                                        EABI EABIVersion, StringRef ABIName) {
   setTargetRuntimeLibcallSets(TT, FloatABI);
 
+  // Early exit for targets that have fully ported to tablegen.
+  if (TT.isAMDGPU() || TT.isNVPTX() || TT.isWasm())
+    return;
+
   // Use the f128 variants of math functions on x86
   if (TT.isX86() && TT.isGNUEnvironment())
     setLongDoubleIsF128Libm(*this, /*FiniteOnlyFuncs=*/true);
@@ -241,15 +245,13 @@ void RuntimeLibcallsInfo::initLibcalls(const Triple &TT,
   if (TT.isARM() || TT.isThumb())
     setARMLibcallNames(*this, TT, FloatABI, EABIVersion);
 
-  if (!TT.isWasm()) {
-    // These libcalls are only available in compiler-rt, not libgcc.
-    if (TT.isArch32Bit()) {
-      setLibcallImpl(RTLIB::SHL_I128, RTLIB::Unsupported);
-      setLibcallImpl(RTLIB::SRL_I128, RTLIB::Unsupported);
-      setLibcallImpl(RTLIB::SRA_I128, RTLIB::Unsupported);
-      setLibcallImpl(RTLIB::MUL_I128, RTLIB::Unsupported);
-      setLibcallImpl(RTLIB::MULO_I64, RTLIB::Unsupported);
-    }
+  // These libcalls are only available in compiler-rt, not libgcc.
+  if (TT.isArch64Bit()) {
+    setLibcallImpl(RTLIB::SHL_I128, RTLIB::__ashlti3);
+    setLibcallImpl(RTLIB::SRL_I128, RTLIB::__lshrti3);
+    setLibcallImpl(RTLIB::SRA_I128, RTLIB::__ashrti3);
+    setLibcallImpl(RTLIB::MUL_I128, RTLIB::__multi3);
+    setLibcallImpl(RTLIB::MULO_I64, RTLIB::__mulodi4);
   }
 
   if (TT.getArch() == Triple::ArchType::msp430) {