[clang] 4ca2cad - [PowerPC] Add clang -msvr4-struct-return for 32-bit ELF
Justin Hibbits via cfe-commits
cfe-commits at lists.llvm.org
Tue Apr 21 18:19:48 PDT 2020
Author: Justin Hibbits
Date: 2020-04-21T20:17:25-05:00
New Revision: 4ca2cad947d09ba0402f5b85d165aa7fcfbd9e3e
URL: https://github.com/llvm/llvm-project/commit/4ca2cad947d09ba0402f5b85d165aa7fcfbd9e3e
DIFF: https://github.com/llvm/llvm-project/commit/4ca2cad947d09ba0402f5b85d165aa7fcfbd9e3e.diff
LOG: [PowerPC] Add clang -msvr4-struct-return for 32-bit ELF
Summary:
Change the default ABI to be compatible with GCC. For 32-bit ELF
targets other than Linux, Clang now returns small structs in registers
r3/r4. This affects FreeBSD, NetBSD, OpenBSD. There is no change for
32-bit Linux, where Clang continues to return all structs in memory.
Add clang options -maix-struct-return (to return structs in memory) and
-msvr4-struct-return (to return structs in registers) to be compatible
with gcc. These options are only for PPC32; reject them on PPC64 and
other targets. The options are like -fpcc-struct-return and
-freg-struct-return for X86_32, and use similar code.
To actually return a struct in registers, coerce it to an integer of the
same size. LLVM may optimize the code to remove unnecessary accesses to
memory, and will return i32 in r3 or i64 in r3:r4.
Fixes PR#40736
Patch by George Koehler!
Reviewed By: jhibbits, nemanjai
Differential Revision: https://reviews.llvm.org/D73290
Added:
clang/test/CodeGen/ppc32-struct-return.c
clang/test/Driver/ppc-unsupported.c
Modified:
clang/docs/ClangCommandLineReference.rst
clang/include/clang/Driver/Options.td
clang/lib/CodeGen/TargetInfo.cpp
clang/lib/Driver/ToolChains/Clang.cpp
clang/lib/Frontend/CompilerInvocation.cpp
Removed:
################################################################################
diff --git a/clang/docs/ClangCommandLineReference.rst b/clang/docs/ClangCommandLineReference.rst
index e5a649702037..c7afcf7cf605 100644
--- a/clang/docs/ClangCommandLineReference.rst
+++ b/clang/docs/ClangCommandLineReference.rst
@@ -2973,6 +2973,11 @@ Enable MT ASE (MIPS only)
PowerPC
-------
+.. option:: -maix-struct-return
+
+Override the default ABI for 32-bit targets to return all structs in memory,
+as in the Power 32-bit ABI for Linux (2011), and on AIX and Darwin.
+
.. option:: -maltivec, -mno-altivec
.. option:: -mcmpb, -mno-cmpb
@@ -3009,6 +3014,11 @@ PowerPC
.. option:: -mspe, -mno-spe
+.. option:: -msvr4-struct-return
+
+Override the default ABI for 32-bit targets to return small structs in
+registers, as in the System V ABI (1995).
+
.. option:: -mvsx, -mno-vsx
WebAssembly
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index fcfc3a387de8..889880cc86d6 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -2510,6 +2510,12 @@ def mlongcall: Flag<["-"], "mlongcall">,
Group<m_ppc_Features_Group>;
def mno_longcall : Flag<["-"], "mno-longcall">,
Group<m_ppc_Features_Group>;
+def maix_struct_return : Flag<["-"], "maix-struct-return">,
+ Group<m_Group>, Flags<[CC1Option]>,
+ HelpText<"Return all structs in memory (PPC32 only)">;
+def msvr4_struct_return : Flag<["-"], "msvr4-struct-return">,
+ Group<m_Group>, Flags<[CC1Option]>,
+ HelpText<"Return small structs in registers (PPC32 only)">;
def mvx : Flag<["-"], "mvx">, Group<m_Group>;
def mno_vx : Flag<["-"], "mno-vx">, Group<m_Group>;
diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 22128534beda..0a5fb27ba015 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -4177,12 +4177,24 @@ namespace {
/// PPC32_SVR4_ABIInfo - The 32-bit PowerPC ELF (SVR4) ABI information.
class PPC32_SVR4_ABIInfo : public DefaultABIInfo {
bool IsSoftFloatABI;
+ bool IsRetSmallStructInRegABI;
CharUnits getParamTypeAlignment(QualType Ty) const;
public:
- PPC32_SVR4_ABIInfo(CodeGen::CodeGenTypes &CGT, bool SoftFloatABI)
- : DefaultABIInfo(CGT), IsSoftFloatABI(SoftFloatABI) {}
+ PPC32_SVR4_ABIInfo(CodeGen::CodeGenTypes &CGT, bool SoftFloatABI,
+ bool RetSmallStructInRegABI)
+ : DefaultABIInfo(CGT), IsSoftFloatABI(SoftFloatABI),
+ IsRetSmallStructInRegABI(RetSmallStructInRegABI) {}
+
+ ABIArgInfo classifyReturnType(QualType RetTy) const;
+
+ void computeInfo(CGFunctionInfo &FI) const override {
+ if (!getCXXABI().classifyReturnType(FI))
+ FI.getReturnInfo() = classifyReturnType(FI.getReturnType());
+ for (auto &I : FI.arguments())
+ I.info = classifyArgumentType(I.type);
+ }
Address EmitVAArg(CodeGenFunction &CGF, Address VAListAddr,
QualType Ty) const override;
@@ -4190,8 +4202,13 @@ class PPC32_SVR4_ABIInfo : public DefaultABIInfo {
class PPC32TargetCodeGenInfo : public TargetCodeGenInfo {
public:
- PPC32TargetCodeGenInfo(CodeGenTypes &CGT, bool SoftFloatABI)
- : TargetCodeGenInfo(new PPC32_SVR4_ABIInfo(CGT, SoftFloatABI)) {}
+ PPC32TargetCodeGenInfo(CodeGenTypes &CGT, bool SoftFloatABI,
+ bool RetSmallStructInRegABI)
+ : TargetCodeGenInfo(new PPC32_SVR4_ABIInfo(CGT, SoftFloatABI,
+ RetSmallStructInRegABI)) {}
+
+ static bool isStructReturnInRegABI(const llvm::Triple &Triple,
+ const CodeGenOptions &Opts);
int getDwarfEHStackPointer(CodeGen::CodeGenModule &M) const override {
// This is recovered from gcc output.
@@ -4227,6 +4244,34 @@ CharUnits PPC32_SVR4_ABIInfo::getParamTypeAlignment(QualType Ty) const {
return CharUnits::fromQuantity(4);
}
+ABIArgInfo PPC32_SVR4_ABIInfo::classifyReturnType(QualType RetTy) const {
+ uint64_t Size;
+
+ // -msvr4-struct-return puts small aggregates in GPR3 and GPR4.
+ if (isAggregateTypeForABI(RetTy) && IsRetSmallStructInRegABI &&
+ (Size = getContext().getTypeSize(RetTy)) <= 64) {
+ // System V ABI (1995), page 3-22, specified:
+ // > A structure or union whose size is less than or equal to 8 bytes
+ // > shall be returned in r3 and r4, as if it were first stored in the
+ // > 8-byte aligned memory area and then the low addressed word were
+ // > loaded into r3 and the high-addressed word into r4. Bits beyond
+ // > the last member of the structure or union are not defined.
+ //
+ // GCC for big-endian PPC32 inserts the pad before the first member,
+ // not "beyond the last member" of the struct. To stay compatible
+ // with GCC, we coerce the struct to an integer of the same size.
+ // LLVM will extend it and return i32 in r3, or i64 in r3:r4.
+ if (Size == 0)
+ return ABIArgInfo::getIgnore();
+ else {
+ llvm::Type *CoerceTy = llvm::Type::getIntNTy(getVMContext(), Size);
+ return ABIArgInfo::getDirect(CoerceTy);
+ }
+ }
+
+ return DefaultABIInfo::classifyReturnType(RetTy);
+}
+
// TODO: this implementation is now likely redundant with
// DefaultABIInfo::EmitVAArg.
Address PPC32_SVR4_ABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAList,
@@ -4382,6 +4427,25 @@ Address PPC32_SVR4_ABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAList,
return Result;
}
+bool PPC32TargetCodeGenInfo::isStructReturnInRegABI(
+ const llvm::Triple &Triple, const CodeGenOptions &Opts) {
+ assert(Triple.getArch() == llvm::Triple::ppc);
+
+ switch (Opts.getStructReturnConvention()) {
+ case CodeGenOptions::SRCK_Default:
+ break;
+ case CodeGenOptions::SRCK_OnStack: // -maix-struct-return
+ return false;
+ case CodeGenOptions::SRCK_InRegs: // -msvr4-struct-return
+ return true;
+ }
+
+ if (Triple.isOSBinFormatELF() && !Triple.isOSLinux())
+ return true;
+
+ return false;
+}
+
bool
PPC32TargetCodeGenInfo::initDwarfEHRegSizeTable(CodeGen::CodeGenFunction &CGF,
llvm::Value *Address) const {
@@ -10264,10 +10328,14 @@ const TargetCodeGenInfo &CodeGenModule::getTargetCodeGenInfo() {
return SetCGInfo(new ARMTargetCodeGenInfo(Types, Kind));
}
- case llvm::Triple::ppc:
+ case llvm::Triple::ppc: {
+ bool IsSoftFloat =
+ CodeGenOpts.FloatABI == "soft" || getTarget().hasFeature("spe");
+ bool RetSmallStructInRegABI =
+ PPC32TargetCodeGenInfo::isStructReturnInRegABI(Triple, CodeGenOpts);
return SetCGInfo(
- new PPC32TargetCodeGenInfo(Types, CodeGenOpts.FloatABI == "soft" ||
- getTarget().hasFeature("spe")));
+ new PPC32TargetCodeGenInfo(Types, IsSoftFloat, RetSmallStructInRegABI));
+ }
case llvm::Triple::ppc64:
if (Triple.isOSBinFormatELF()) {
PPC64_SVR4_ABIInfo::ABIKind Kind = PPC64_SVR4_ABIInfo::ELFv1;
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 415ef27eee0a..2c44b2a4e9b4 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4535,6 +4535,19 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
CmdArgs.push_back(A->getValue());
}
+ if (Arg *A = Args.getLastArg(options::OPT_maix_struct_return,
+ options::OPT_msvr4_struct_return)) {
+ if (TC.getArch() != llvm::Triple::ppc) {
+ D.Diag(diag::err_drv_unsupported_opt_for_target)
+ << A->getSpelling() << RawTriple.str();
+ } else if (A->getOption().matches(options::OPT_maix_struct_return)) {
+ CmdArgs.push_back("-maix-struct-return");
+ } else {
+ assert(A->getOption().matches(options::OPT_msvr4_struct_return));
+ CmdArgs.push_back("-msvr4-struct-return");
+ }
+ }
+
if (Arg *A = Args.getLastArg(options::OPT_fpcc_struct_return,
options::OPT_freg_struct_return)) {
if (TC.getArch() != llvm::Triple::x86) {
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index fc93dfafc5fc..6a988670eb02 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1297,11 +1297,18 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args) << Val;
}
- if (Arg *A = Args.getLastArg(OPT_fpcc_struct_return, OPT_freg_struct_return)) {
- if (A->getOption().matches(OPT_fpcc_struct_return)) {
+ // X86_32 has -fppc-struct-return and -freg-struct-return.
+ // PPC32 has -maix-struct-return and -msvr4-struct-return.
+ if (Arg *A =
+ Args.getLastArg(OPT_fpcc_struct_return, OPT_freg_struct_return,
+ OPT_maix_struct_return, OPT_msvr4_struct_return)) {
+ const Option &O = A->getOption();
+ if (O.matches(OPT_fpcc_struct_return) ||
+ O.matches(OPT_maix_struct_return)) {
Opts.setStructReturnConvention(CodeGenOptions::SRCK_OnStack);
} else {
- assert(A->getOption().matches(OPT_freg_struct_return));
+ assert(O.matches(OPT_freg_struct_return) ||
+ O.matches(OPT_msvr4_struct_return));
Opts.setStructReturnConvention(CodeGenOptions::SRCK_InRegs);
}
}
diff --git a/clang/test/CodeGen/ppc32-struct-return.c b/clang/test/CodeGen/ppc32-struct-return.c
new file mode 100644
index 000000000000..30a6a26820b0
--- /dev/null
+++ b/clang/test/CodeGen/ppc32-struct-return.c
@@ -0,0 +1,88 @@
+// REQUIRES: powerpc-registered-target
+// RUN: %clang_cc1 -triple powerpc-unknown-freebsd \
+// RUN: -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-SVR4
+// RUN: %clang_cc1 -triple powerpc-unknown-linux \
+// RUN: -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-AIX
+// RUN: %clang_cc1 -triple powerpc-unknown-linux -maix-struct-return \
+// RUN: -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-AIX
+// RUN: %clang_cc1 -triple powerpc-unknown-linux -msvr4-struct-return \
+// RUN: -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-SVR4
+// RUN: %clang_cc1 -triple powerpc-unknown-netbsd \
+// RUN: -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-SVR4
+// RUN: %clang_cc1 -triple powerpc-unknown-openbsd \
+// RUN: -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-SVR4
+// RUN: %clang_cc1 -triple powerpc-unknown-openbsd -maix-struct-return \
+// RUN: -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-AIX
+// RUN: %clang_cc1 -triple powerpc-unknown-openbsd -msvr4-struct-return \
+// RUN: -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-SVR4
+
+typedef struct {
+} Zero;
+typedef struct {
+ char c;
+} One;
+typedef struct {
+ short s;
+} Two;
+typedef struct {
+ char c[3];
+} Three;
+typedef struct {
+ float f;
+} Four; // svr4 to return i32, not float
+typedef struct {
+ char c[5];
+} Five;
+typedef struct {
+ short s[3];
+} Six;
+typedef struct {
+ char c[7];
+} Seven;
+typedef struct {
+ int i;
+ char c;
+} Eight; // padded for alignment
+typedef struct {
+ char c[9];
+} Nine;
+
+// CHECK-AIX-LABEL: define void @ret0(%struct.Zero* noalias sret {{[^,]*}})
+// CHECK-SVR4-LABEL: define void @ret0()
+Zero ret0(void) { return (Zero){}; }
+
+// CHECK-AIX-LABEL: define void @ret1(%struct.One* noalias sret {{[^,]*}})
+// CHECK-SVR4-LABEL: define i8 @ret1()
+One ret1(void) { return (One){'a'}; }
+
+// CHECK-AIX-LABEL: define void @ret2(%struct.Two* noalias sret {{[^,]*}})
+// CHECK-SVR4-LABEL: define i16 @ret2()
+Two ret2(void) { return (Two){123}; }
+
+// CHECK-AIX-LABEL: define void @ret3(%struct.Three* noalias sret {{[^,]*}})
+// CHECK-SVR4-LABEL: define i24 @ret3()
+Three ret3(void) { return (Three){"abc"}; }
+
+// CHECK-AIX-LABEL: define void @ret4(%struct.Four* noalias sret {{[^,]*}})
+// CHECK-SVR4-LABEL: define i32 @ret4()
+Four ret4(void) { return (Four){0.4}; }
+
+// CHECK-AIX-LABEL: define void @ret5(%struct.Five* noalias sret {{[^,]*}})
+// CHECK-SVR4-LABEL: define i40 @ret5()
+Five ret5(void) { return (Five){"abcde"}; }
+
+// CHECK-AIX-LABEL: define void @ret6(%struct.Six* noalias sret {{[^,]*}})
+// CHECK-SVR4-LABEL: define i48 @ret6()
+Six ret6(void) { return (Six){12, 34, 56}; }
+
+// CHECK-AIX-LABEL: define void @ret7(%struct.Seven* noalias sret {{[^,]*}})
+// CHECK-SVR4-LABEL: define i56 @ret7()
+Seven ret7(void) { return (Seven){"abcdefg"}; }
+
+// CHECK-AIX-LABEL: define void @ret8(%struct.Eight* noalias sret {{[^,]*}})
+// CHECK-SVR4-LABEL: define i64 @ret8()
+Eight ret8(void) { return (Eight){123, 'a'}; }
+
+// CHECK-AIX-LABEL: define void @ret9(%struct.Nine* noalias sret {{[^,]*}})
+// CHECK-SVR4-LABEL: define void @ret9(%struct.Nine* noalias sret {{[^,]*}})
+Nine ret9(void) { return (Nine){"abcdefghi"}; }
diff --git a/clang/test/Driver/ppc-unsupported.c b/clang/test/Driver/ppc-unsupported.c
new file mode 100644
index 000000000000..84760c8c435b
--- /dev/null
+++ b/clang/test/Driver/ppc-unsupported.c
@@ -0,0 +1,10 @@
+// REQUIRES: powerpc-registered-target
+// RUN: not %clang -target powerpc64-unknown-freebsd -maix-struct-return \
+// RUN: -c %s 2>&1 | FileCheck %s
+// RUN: not %clang -target powerpc64-unknown-freebsd -msvr4-struct-return \
+// RUN: -c %s 2>&1 | FileCheck %s
+// RUN: not %clang -target powerpc64le-unknown-linux -maix-struct-return \
+// RUN: -c %s 2>&1 | FileCheck %s
+// RUN: not %clang -target powerpc64le-unknown-linux -msvr4-struct-return \
+// RUN: -c %s 2>&1 | FileCheck %s
+// CHECK: unsupported option
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