[Clang][CodeGen][RISCV] Fix hard float ABI for struct with empty struct and complex

[luismarques]

Summary

Fixes bug 44904.

[luismarques]

Fix bad test.

[lenary]

LGTM - the big hint is that the new test is handled the same as f_empty_double2 as required by the ABI.

clang/test/CodeGen/riscv32-ilp32d-abi.cpp

36

Please can you add a test of { struct {}; float _Complex fc;} too, just for regression purposes?

[luismarques]

Add float Complex case, for regression test completeness.

[lenary]

LGTM

clang/lib/CodeGen/TargetInfo.cpp

bool RISCVABIInfo::detectFPCCEligibleStructHelper(QualType Ty, CharUnits CurOff,
   if (auto CTy = Ty->getAs<ComplexType>()) {
     if (Field1Ty)
       return false;
     QualType EltTy = CTy->getElementType();
     if (getContext().getTypeSize(EltTy) > FLen)
       return false;
     Field1Ty = CGT.ConvertType(EltTy);
     Field1Off = CurOff;
-    assert(CurOff.isZero() && "Unexpected offset for first field");
     Field2Ty = Field1Ty;
     Field2Off = Field1Off + getContext().getTypeSizeInChars(EltTy);
     return true;
   }
 
   if (const ConstantArrayType *ATy = getContext().getAsConstantArrayType(Ty)) {
     uint64_t ArraySize = ATy->getSize().getZExtValue();
     QualType EltTy = ATy->getElementType();

clang/test/CodeGen/riscv32-ilp32d-abi.cpp

 
 struct empty_double_float { struct {}; double f; float g; };
 
 // CHECK: define double @_Z20f_empty_double_float18empty_double_float(double %0, float %1)
 // CHECK: { [8 x i8], double, float }
 double f_empty_double_float(empty_double_float a) {
     return a.g;
 }
+
+struct empty_complex { struct {}; double _Complex fc; };
+
+// CHECK: define double @_Z15f_empty_complex13empty_complex(double %0, double %1)
+// CHECK: { [8 x i8], double, double }
+double f_empty_complex(empty_complex a) {
+    return __imag__ a.fc;
+}