atrosinenko created this revision.
atrosinenko added reviewers: asl, krisb, arsenm, rjmccall, jdoerfert.
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Pass structures, classes and unions by reference on MSP430, according to
Section 3.5 of MSP430 EABI <https://www.ti.com/lit/an/slaa534a/slaa534a.pdf>.
The callee is responsible for leaving the underlying data intact.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D85917
Files:
clang/lib/CodeGen/CGCall.cpp
clang/lib/CodeGen/TargetInfo.cpp
clang/test/CodeGen/msp430-struct-or-union-args.c
Index: clang/test/CodeGen/msp430-struct-or-union-args.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/msp430-struct-or-union-args.c
@@ -0,0 +1,91 @@
+// REQUIRES: msp430-registered-target
+// RUN: %clang -target msp430 -fno-inline-functions -S -o- %s | FileCheck --check-prefixes=ASM %s
+// RUN: %clang -target msp430 -fno-inline-functions -S -emit-llvm -o- %s | FileCheck --check-prefixes=IR %s
+
+#include <limits.h>
+#include <stdint.h>
+
+// According to Section 3.5 of MSP430 EABI, structures and unions are passed
+// by reference, even if an equally-sized integer argument could be passed
+// in registers.
+
+struct S {
+ uint16_t a;
+};
+union U {
+ uint16_t a;
+};
+
+// IR: %struct.S = type { i16 }
+// IR: %union.U = type { i16 }
+
+_Static_assert(sizeof(struct S) * CHAR_BIT == 16, "Unexpected size");
+_Static_assert(sizeof(union U) * CHAR_BIT == 16, "Unexpected size");
+
+extern struct S s;
+extern union U u;
+
+// Cannot know for sure whether they change the argument
+extern void leaf_s(struct S *x);
+extern void leaf_u(union U *);
+
+// Callee is responsible for leaving the byref argument intact
+void middle_s(struct S x) {
+ // IR: define {{(dso_local )?}}void @middle_s(%struct.S* byref(%struct.S) align 2 [[S_ARG:%.+]])
+ // IR: [[S_COPY:%.+]] = alloca %struct.S, align 2
+ // IR: [[S_CASTED_COPY:%.+]] = bitcast %struct.S* [[S_COPY]] to i8*
+ // IR: [[S_CASTED_ARG:%.+]] = bitcast %struct.S* [[S_ARG]] to i8*
+ // IR: call void @llvm.memcpy.p0i8.p0i8.i16(i8* align 2 [[S_CASTED_COPY]], i8* align 2 [[S_CASTED_ARG]], i16 2, i1 false)
+ // IR: call void @leaf_s(%struct.S* [[S_COPY]])
+ // IR: ret void
+
+ // ASM: middle_s:
+ // ASM: sub #2, r1
+ // ... here memcpy() occurs ...
+ // ASM: mov r1, r12
+ // ASM-NEXT: call #leaf_s
+ // ASM-NEXT: add #2, r1
+ // ASM-NEXT: ret
+ leaf_s(&x);
+}
+void middle_u(union U x) {
+ // IR: define {{(dso_local )?}}void @middle_u(%union.U* byref(%union.U) align 2 [[U_ARG:%.+]])
+ // IR: [[U_COPY:%.+]] = alloca %union.U, align 2
+ // IR: [[U_CASTED_COPY:%.+]] = bitcast %union.U* [[U_COPY]] to i8*
+ // IR: [[U_CASTED_ARG:%.+]] = bitcast %union.U* [[U_ARG]] to i8*
+ // IR: call void @llvm.memcpy.p0i8.p0i8.i16(i8* align 2 [[U_CASTED_COPY]], i8* align 2 [[U_CASTED_ARG]], i16 2, i1 false)
+ // IR: call void @leaf_u(%union.U* [[U_COPY]])
+ // IR: ret void
+
+ // ASM: middle_u:
+ // ASM: sub #2, r1
+ // ... here memcpy() occurs ...
+ // ASM: mov r1, r12
+ // ASM-NEXT: call #leaf_u
+ // ASM-NEXT: add #2, r1
+ // ASM-NEXT: ret
+ leaf_u(&x);
+}
+
+void caller_s(void) {
+ // IR: define {{(dso_local )?}}void @caller_s()
+ // IR: call void @middle_s(%struct.S* byref(%struct.S) align 2 @s)
+ // IR: ret void
+
+ // ASM: caller_s:
+ // ASM: mov #s, r12
+ // ASM-NEXT: call #middle_s
+ // ASM-NEXT: ret
+ middle_s(s);
+}
+void caller_u(void) {
+ // IR: define dso_local void @caller_u()
+ // IR: call void @middle_u(%union.U* byref(%union.U) align 2 @u)
+ // IR: ret void
+
+ // ASM: caller_u:
+ // ASM: mov #u, r12
+ // ASM-NEXT: call #middle_u
+ // ASM-NEXT: ret
+ middle_u(u);
+}
Index: clang/lib/CodeGen/TargetInfo.cpp
===================================================================
--- clang/lib/CodeGen/TargetInfo.cpp
+++ clang/lib/CodeGen/TargetInfo.cpp
@@ -7511,11 +7511,18 @@
return DefaultABIInfo::classifyReturnType(RetTy);
}
- ABIArgInfo classifyArgumentType(QualType RetTy) const {
- if (RetTy->isAnyComplexType())
+ ABIArgInfo classifyArgumentType(QualType Ty) const {
+ if (Ty->isAnyComplexType())
return complexArgInfo();
- return DefaultABIInfo::classifyArgumentType(RetTy);
+ // According to Section 3.5 of MSP430 EABI, structs, classes and unions
+ // are passed by reference. The callee is responsible for leaving them
+ // intact.
+ if (Ty->isStructureOrClassType() || Ty->isUnionType())
+ return ABIArgInfo::getIndirectAliased(
+ getContext().getTypeAlignInChars(Ty), /*AddrSpace=*/0);
+
+ return DefaultABIInfo::classifyArgumentType(Ty);
}
// Just copy the original implementations because
Index: clang/lib/CodeGen/CGCall.cpp
===================================================================
--- clang/lib/CodeGen/CGCall.cpp
+++ clang/lib/CodeGen/CGCall.cpp
@@ -4474,23 +4474,24 @@
} else if (I->hasLValue()) {
auto LV = I->getKnownLValue();
auto AS = LV.getAddressSpace();
+ bool isByValOrRef =
+ ArgInfo.isIndirectAliased() || ArgInfo.getIndirectByVal();
- if (!ArgInfo.getIndirectByVal() ||
+ if (!isByValOrRef ||
(LV.getAlignment() < getContext().getTypeAlignInChars(I->Ty))) {
NeedCopy = true;
}
if (!getLangOpts().OpenCL) {
- if ((ArgInfo.getIndirectByVal() &&
- (AS != LangAS::Default &&
- AS != CGM.getASTAllocaAddressSpace()))) {
+ if ((isByValOrRef && (AS != LangAS::Default &&
+ AS != CGM.getASTAllocaAddressSpace()))) {
NeedCopy = true;
}
}
// For OpenCL even if RV is located in default or alloca address space
// we don't want to perform address space cast for it.
- else if ((ArgInfo.getIndirectByVal() &&
- Addr.getType()->getAddressSpace() != IRFuncTy->
- getParamType(FirstIRArg)->getPointerAddressSpace())) {
+ else if ((isByValOrRef && Addr.getType()->getAddressSpace() !=
+ IRFuncTy->getParamType(FirstIRArg)
+ ->getPointerAddressSpace())) {
NeedCopy = true;
}
}
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