[Clang][CodeGen][RISCV] Fix hard float ABI test cases with empty struct

The code seemed not to account for the field 1 offset.

Differential Revision: https://reviews.llvm.org/D91270

(cherry picked from commit fa8f5bf)

Author: luismarques

clang/lib/CodeGen/TargetInfo.cpp

@@ -10490,7 +10490,7 @@ bool RISCVABIInfo::detectFPCCEligibleStruct(QualType Ty, llvm::Type *&Field1Ty,
     NeededArgFPRs++;
   else if (Field2Ty)
     NeededArgGPRs++;
-  return IsCandidate;
+  return true;
 }
 
 // Call getCoerceAndExpand for the two-element flattened struct described by
@@ -10516,15 +10516,15 @@ ABIArgInfo RISCVABIInfo::coerceAndExpandFPCCEligibleStruct(
 
   CharUnits Field2Align =
       CharUnits::fromQuantity(getDataLayout().getABITypeAlignment(Field2Ty));
-  CharUnits Field1Size =
+  CharUnits Field1End = Field1Off +
       CharUnits::fromQuantity(getDataLayout().getTypeStoreSize(Field1Ty));
-  CharUnits Field2OffNoPadNoPack = Field1Size.alignTo(Field2Align);
+  CharUnits Field2OffNoPadNoPack = Field1End.alignTo(Field2Align);
 
   CharUnits Padding = CharUnits::Zero();
   if (Field2Off > Field2OffNoPadNoPack)
     Padding = Field2Off - Field2OffNoPadNoPack;
-  else if (Field2Off != Field2Align && Field2Off > Field1Size)
-    Padding = Field2Off - Field1Size;
+  else if (Field2Off != Field2Align && Field2Off > Field1End)
+    Padding = Field2Off - Field1End;
 
   bool IsPacked = !Field2Off.isMultipleOf(Field2Align);
 

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

@@ -4,17 +4,15 @@
 struct empty_float2 { struct {}; float f; float g; };
 
 // CHECK: define float @_Z14f_empty_float212empty_float2(float %0, float %1)
-// FIXME: Extraneous padding before the second float
-// CHECK: { [4 x i8], float, [4 x i8], float }
+// CHECK: { [4 x i8], float, float }
 float f_empty_float2(empty_float2 a) {
     return a.g;
 }
 
 struct empty_double2 { struct {}; double f; double g; };
 
 // CHECK: define double @_Z15f_empty_double213empty_double2(double %0, double %1)
-// FIXME: Extraneous padding before the second double
-// CHECK: { [8 x i8], double, [8 x i8], double }
+// CHECK: { [8 x i8], double, double }
 double f_empty_double2(empty_double2 a) {
     return a.g;
 }
@@ -30,8 +28,7 @@ double f_empty_float_double(empty_float_double a) {
 struct empty_double_float { struct {}; double f; float g; };
 
 // CHECK: define double @_Z20f_empty_double_float18empty_double_float(double %0, float %1)
-// FIXME: Extraneous padding before the float
-// CHECK: { [8 x i8], double, [8 x i8], float }
+// CHECK: { [8 x i8], double, float }
 double f_empty_double_float(empty_double_float a) {
     return a.g;
 }