commit 4cf2cf18c97d17c8e5662955c7048d072c711415
author Craig Topper <craig.topper@sifive.com> Wed Dec 04 10:42:49 2024 -0800
committer GitHub <noreply@github.com> Wed Dec 04 10:42:49 2024 -0800
tree a7932fad4c2401ec17ac3a55bde736fabe635dd8
parent 0d1e762da7ad22e31e98cf372a692027ff0bb610

[RISCV][GISel] Stop over promoting G_SITOFP/UITOFP libcalls on RV64. (#118597)

When we have legal instructions we want to promote to sXLen and let isel
pattern matching removing the and/sext_inreg.

When using a libcall we want to use a 'si' libcall for small types
instead of 'di'. To match the RV64 ABI, we need to sign extend `unsigned
int` arguments. We reuse the shouldSignExtendTypeInLibCall hook from
SelectionDAG.

llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp

diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index d4323cd..cf835ad 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -882,11 +882,20 @@
 
 static LegalizerHelper::LegalizeResult
 conversionLibcall(MachineInstr &MI, MachineIRBuilder &MIRBuilder, Type *ToType,
-                  Type *FromType, LostDebugLocObserver &LocObserver) {
+                  Type *FromType, LostDebugLocObserver &LocObserver,
+                  const TargetLowering &TLI, bool IsSigned = false) {
+  CallLowering::ArgInfo Arg = {MI.getOperand(1).getReg(), FromType, 0};
+  if (FromType->isIntegerTy()) {
+    if (TLI.shouldSignExtendTypeInLibCall(FromType, IsSigned))
+      Arg.Flags[0].setSExt();
+    else
+      Arg.Flags[0].setZExt();
+  }
+
   RTLIB::Libcall Libcall = getConvRTLibDesc(MI.getOpcode(), ToType, FromType);
-  return createLibcall(
-      MIRBuilder, Libcall, {MI.getOperand(0).getReg(), ToType, 0},
-      {{MI.getOperand(1).getReg(), FromType, 0}}, LocObserver, &MI);
+  return createLibcall(MIRBuilder, Libcall,
+                       {MI.getOperand(0).getReg(), ToType, 0}, Arg, LocObserver,
+                       &MI);
 }
 
 static RTLIB::Libcall
@@ -1308,7 +1317,7 @@
     if (!FromTy || !ToTy)
       return UnableToLegalize;
     LegalizeResult Status =
-        conversionLibcall(MI, MIRBuilder, ToTy, FromTy, LocObserver);
+        conversionLibcall(MI, MIRBuilder, ToTy, FromTy, LocObserver, TLI);
     if (Status != Legalized)
       return Status;
     break;
@@ -1329,7 +1338,7 @@
     if ((ToSize != 32 && ToSize != 64 && ToSize != 128) || !FromTy)
       return UnableToLegalize;
     LegalizeResult Status = conversionLibcall(
-        MI, MIRBuilder, Type::getIntNTy(Ctx, ToSize), FromTy, LocObserver);
+        MI, MIRBuilder, Type::getIntNTy(Ctx, ToSize), FromTy, LocObserver, TLI);
     if (Status != Legalized)
       return Status;
     break;
@@ -1341,8 +1350,10 @@
         getFloatTypeForLLT(Ctx, MRI.getType(MI.getOperand(0).getReg()));
     if ((FromSize != 32 && FromSize != 64 && FromSize != 128) || !ToTy)
       return UnableToLegalize;
-    LegalizeResult Status = conversionLibcall(
-        MI, MIRBuilder, ToTy, Type::getIntNTy(Ctx, FromSize), LocObserver);
+    bool IsSigned = MI.getOpcode() == TargetOpcode::G_SITOFP;
+    LegalizeResult Status =
+        conversionLibcall(MI, MIRBuilder, ToTy, Type::getIntNTy(Ctx, FromSize),
+                          LocObserver, TLI, IsSigned);
     if (Status != Legalized)
       return Status;
     break;