wangleiat created this revision.
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Prior to this patch, paramter or return value whose type was a
structure containing empty structure members and fewer than three
floating-point members did not meet the calling convention.
With this patch, an empty struct will always be passed.
An empty struct type that is not non-trivial for the purposes of calls
will be treated as though it were the following C type:
struct {
char c;
};
Change-Id: If5c7f499d38d1853261dc1dae6620b8fc9db7fd3
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D151298
Files:
clang/docs/ReleaseNotes.rst
clang/lib/CodeGen/TargetInfo.cpp
clang/test/CodeGenCXX/LoongArch/abi-lp64d-empty-struct.cpp
Index: clang/test/CodeGenCXX/LoongArch/abi-lp64d-empty-struct.cpp
===================================================================
--- clang/test/CodeGenCXX/LoongArch/abi-lp64d-empty-struct.cpp
+++ clang/test/CodeGenCXX/LoongArch/abi-lp64d-empty-struct.cpp
@@ -6,14 +6,13 @@
/// If the empty struct is a struct's member, will be treated as
/// fixed-point member.
/// WOA: Bit width of the argument.
-/// FIXME: Empty struct is always passed or returned in C++ mode.
/// 1. 0 < WOA <= GRLEN
/// 1.a. Only fixed-point members.
struct empty_s {};
-// CHECK-LABEL: define dso_local void @_Z12empty_struct7empty_s
-// CHECK-SAME: () #[[ATTR0:[0-9]+]] {
+// CHECK-LABEL: define dso_local i64 @_Z12empty_struct7empty_s
+// CHECK-SAME: (i64 [[E_COERCE:%.*]]) #[[ATTR0:[0-9]+]] {
struct empty_s empty_struct(struct empty_s e) {
return e;
}
@@ -39,8 +38,8 @@
char c;
float f32;
};
-// CHECK-LABEL: define dso_local { i8, float } @_Z23empty_char_float_struct18empty_char_float_s
-// CHECK-SAME: (i8 [[TMP0:%.*]], float [[TMP1:%.*]]) #[[ATTR0:[0-9]+]] {
+// CHECK-LABEL: define dso_local i64 @_Z23empty_char_float_struct18empty_char_float_s
+// CHECK-SAME: (i64 [[S_COERCE:%.*]]) #[[ATTR0:[0-9]+]] {
struct empty_char_float_s empty_char_float_struct(struct empty_char_float_s s) {
return s;
}
@@ -51,8 +50,8 @@
struct empty_s e;
float f32;
};
-// CHECK-LABEL: define dso_local float @_Z18empty_float_struct13empty_float_s
-// CHECK-SAME: (float [[TMP0:%.*]]) #[[ATTR0:[0-9]+]] {
+// CHECK-LABEL: define dso_local { i8, float } @_Z18empty_float_struct13empty_float_s
+// CHECK-SAME: (i8 [[TMP0:%.*]], float [[TMP1:%.*]]) #[[ATTR0:[0-9]+]] {
struct empty_float_s empty_float_struct(struct empty_float_s s) {
return s;
}
@@ -62,8 +61,8 @@
struct empty_s e;
};
-// CHECK-LABEL: define dso_local float @_Z18float_empty_struct13float_empty_s
-// CHECK-SAME: (float [[TMP0:%.*]]) #[[ATTR0:[0-9]+]] {
+// CHECK-LABEL: define dso_local { float, i8 } @_Z18float_empty_struct13float_empty_s
+// CHECK-SAME: (float [[TMP0:%.*]], i8 [[TMP1:%.*]]) #[[ATTR0:[0-9]+]] {
struct float_empty_s float_empty_struct(struct float_empty_s s) {
return s;
}
@@ -92,8 +91,8 @@
struct empty_s e;
double f64;
};
-// CHECK-LABEL: define dso_local double @_Z19empty_double_struct14empty_double_s
-// CHECK-SAME: (double [[TMP0:%.*]]) #[[ATTR0:[0-9]+]] {
+// CHECK-LABEL: define dso_local { i8, double } @_Z19empty_double_struct14empty_double_s
+// CHECK-SAME: (i8 [[TMP0:%.*]], double [[TMP1:%.*]]) #[[ATTR0:[0-9]+]] {
struct empty_double_s empty_double_struct(struct empty_double_s s) {
return s;
}
@@ -102,8 +101,8 @@
double f64;
struct empty_s e;
};
-// CHECK-LABEL: define dso_local double @_Z19double_empty_struct14double_empty_s
-// CHECK-SAME: (double [[TMP0:%.*]]) #[[ATTR0:[0-9]+]] {
+// CHECK-LABEL: define dso_local { double, i8 } @_Z19double_empty_struct14double_empty_s
+// CHECK-SAME: (double [[TMP0:%.*]], i8 [[TMP1:%.*]]) #[[ATTR0:[0-9]+]] {
struct double_empty_s double_empty_struct(struct double_empty_s s) {
return s;
}
@@ -115,8 +114,8 @@
float f32;
char c;
};
-// CHECK-LABEL: define dso_local { float, i8 } @_Z23empty_float_char_struct18empty_float_char_s
-// CHECK-SAME: (float [[TMP0:%.*]], i8 [[TMP1:%.*]]) #[[ATTR0:[0-9]+]] {
+// CHECK-LABEL: define dso_local [2 x i64] @_Z23empty_float_char_struct18empty_float_char_s
+// CHECK-SAME: ([2 x i64] [[S_COERCE:%.*]]) #[[ATTR0:[0-9]+]] {
struct empty_float_char_s empty_float_char_struct(struct empty_float_char_s s) {
return s;
}
@@ -126,8 +125,8 @@
float f32;
double f64;
};
-// CHECK-LABEL: define dso_local { float, double } @_Z25empty_float_double_struct20empty_float_double_s
-// CHECK-SAME: (float [[TMP0:%.*]], double [[TMP1:%.*]]) #[[ATTR0:[0-9]+]] {
+// CHECK-LABEL: define dso_local [2 x i64] @_Z25empty_float_double_struct20empty_float_double_s
+// CHECK-SAME: ([2 x i64] [[S_COERCE:%.*]]) #[[ATTR0:[0-9]+]] {
struct empty_float_double_s empty_float_double_struct(struct empty_float_double_s s) {
return s;
}
@@ -150,8 +149,8 @@
double f64;
struct empty_s e2;
};
-// CHECK-LABEL: define dso_local double @_Z25empty_double_empty_struct20empty_double_empty_s
-// CHECK-SAME: (double [[TMP0:%.*]]) #[[ATTR0:[0-9]+]] {
+// CHECK-LABEL: define dso_local void @_Z25empty_double_empty_struct20empty_double_empty_s
+// CHECK-SAME: (ptr noalias sret([[STRUCT_EMPTY_DOUBLE_EMPTY_S:%.*]]) align 8 [[AGG_RESULT:%.*]], ptr noundef [[S:%.*]]) #[[ATTR0:[0-9]+]] {
struct empty_double_empty_s empty_double_empty_struct(struct empty_double_empty_s s) {
return s;
}
Index: clang/lib/CodeGen/TargetInfo.cpp
===================================================================
--- clang/lib/CodeGen/TargetInfo.cpp
+++ clang/lib/CodeGen/TargetInfo.cpp
@@ -11927,9 +11927,9 @@
llvm::Type *&Field2Ty, CharUnits &Field2Off) const {
bool IsInt = Ty->isIntegralOrEnumerationType();
bool IsFloat = Ty->isRealFloatingType();
+ uint64_t Size = getContext().getTypeSize(Ty);
if (IsInt || IsFloat) {
- uint64_t Size = getContext().getTypeSize(Ty);
if (IsInt && Size > GRLen)
return false;
// Can't be eligible if larger than the FP registers. Half precision isn't
@@ -11954,6 +11954,24 @@
return false;
}
+ if (isEmptyRecord(getContext(), Ty, true)) {
+ // Ignore the empty record in C mode.
+ if (Size == 0)
+ return true;
+ // Treat the empty record as char in C++ mode.
+ if (!Field1Ty) {
+ Field1Ty = llvm::Type::getInt8Ty(getVMContext());
+ Field1Off = CurOff;
+ return true;
+ }
+ if (!Field2Ty) {
+ Field2Ty = llvm::Type::getInt8Ty(getVMContext());
+ Field2Off = CurOff;
+ return true;
+ }
+ return false;
+ }
+
if (auto CTy = Ty->getAs<ComplexType>()) {
if (Field1Ty)
return false;
@@ -11985,8 +12003,6 @@
// copy constructor are not eligible for the FP calling convention.
if (getRecordArgABI(Ty, CGT.getCXXABI()))
return false;
- if (isEmptyRecord(getContext(), Ty, true))
- return true;
const RecordDecl *RD = RTy->getDecl();
// Unions aren't eligible unless they're empty (which is caught above).
if (RD->isUnion())
@@ -12121,12 +12137,12 @@
CGCXXABI::RAA_DirectInMemory);
}
- // Ignore empty structs/unions.
- if (isEmptyRecord(getContext(), Ty, true))
- return ABIArgInfo::getIgnore();
-
uint64_t Size = getContext().getTypeSize(Ty);
+ // Empty records of size 0 are always ignored.
+ if (isEmptyRecord(getContext(), Ty, true) && Size == 0)
+ return ABIArgInfo::getIgnore();
+
// Pass floating point values via FARs if possible.
if (IsFixed && Ty->isFloatingType() && !Ty->isComplexType() &&
FRLen >= Size && FARsLeft) {
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -554,6 +554,8 @@
- Patchable function entry (``-fpatchable-function-entry``) is now supported
on LoongArch.
+- Fixed incorrect ABI lowering related to the handling of empty structs in C++
+ parameter passing.
RISC-V Support
^^^^^^^^^^^^^^
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