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llvm-project/clang/test/Driver/fsemantic-interposition.c

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[Driver][test] Change %itanium_abi_triple to generic ELF x86_64-windows and darwin default to PIC. They don't use PIE.
2020-02-03 13:44:01 +08:00
// RUN: %clang -target x86_64 %s -Werror -fpic -fsemantic-interposition -c -### 2>&1 | FileCheck %s
// RUN: %clang -target x86_64 %s -Werror -fPIC -fsemantic-interposition -c -### 2>&1 | FileCheck %s
[Driver] Move -fsemantic-interposition decision from cc1 to driver And add test/Driver/fsemantic-interposition.c
2020-02-03 11:30:39 +08:00
// CHECK: "-fsemantic-interposition"
Refactor how -fno-semantic-interposition sets dso_local on default visibility external linkage definitions The idea is that the CC1 default for ELF should set dso_local on default visibility external linkage definitions in the default -mrelocation-model pic mode (-fpic/-fPIC) to match COFF/Mach-O and make output IR similar. The refactoring is made available by 2820a2ca3a0e69c3f301845420e0067ffff2251b. Currently only x86 supports local aliases. We move the decision to the driver. There are three CC1 states: * -fsemantic-interposition: make some linkages interposable and make default visibility external linkage definitions dso_preemptable. * (default): selected if the target supports .Lfoo$local: make default visibility external linkage definitions dso_local * -fhalf-no-semantic-interposition: if neither option is set or the target does not support .Lfoo$local: like -fno-semantic-interposition but local aliases are not used. So references can be interposed if not optimized out. Add -fhalf-no-semantic-interposition to a few tests using the half-based semantic interposition behavior.
2021-01-01 05:59:45 +08:00
/// No-op for -fno-pic/-fpie.
// RUN: %clang -target x86_64 %s -Werror -fsemantic-interposition -c -### 2>&1 | FileCheck --check-prefix=NOOP %s
// RUN: %clang -target x86_64 %s -Werror -fPIE -fsemantic-interposition -c -### 2>&1 | FileCheck --check-prefix=NOOP %s
// NOOP-NOT: "-fsemantic-interposition"
// NOOP-NOT: "-fno-semantic-interposition"
Make explicit -fno-semantic-interposition (in -fpic mode) infer dso_local -fno-semantic-interposition is currently the CC1 default. (The opposite disables some interprocedural optimizations.) However, it does not infer dso_local: on most targets accesses to ExternalLinkage functions/variables defined in the current module still need PLT/GOT. This patch makes explicit -fno-semantic-interposition infer dso_local, so that PLT/GOT can be eliminated if targets implement local aliases for AsmPrinter::getSymbolPreferLocal (currently only x86). Currently we check whether the module flag "SemanticInterposition" is 0. If yes, infer dso_local. In the future, we can infer dso_local unless "SemanticInterposition" is 1: frontends other than clang will also benefit from the optimization if they don't bother setting the flag. (There will be risks if they do want ELF interposition: they need to set "SemanticInterposition" to 1.)
2020-05-26 06:05:35 +08:00
Refactor how -fno-semantic-interposition sets dso_local on default visibility external linkage definitions The idea is that the CC1 default for ELF should set dso_local on default visibility external linkage definitions in the default -mrelocation-model pic mode (-fpic/-fPIC) to match COFF/Mach-O and make output IR similar. The refactoring is made available by 2820a2ca3a0e69c3f301845420e0067ffff2251b. Currently only x86 supports local aliases. We move the decision to the driver. There are three CC1 states: * -fsemantic-interposition: make some linkages interposable and make default visibility external linkage definitions dso_preemptable. * (default): selected if the target supports .Lfoo$local: make default visibility external linkage definitions dso_local * -fhalf-no-semantic-interposition: if neither option is set or the target does not support .Lfoo$local: like -fno-semantic-interposition but local aliases are not used. So references can be interposed if not optimized out. Add -fhalf-no-semantic-interposition to a few tests using the half-based semantic interposition behavior.
2021-01-01 05:59:45 +08:00
/// If -fno-semantic-interposition is specified and the target supports local
/// aliases, neither CC1 option is set.
[clang] Support -fpic -fno-semantic-interposition for AArch64 -fno-semantic-interposition (only effective with -fpic) can optimize default visibility external linkage (non-ifunc-non-COMDAT) variable access and function calls to avoid GOT/PLT, by using local aliases, e.g. ``` int var; __attribute__((optnone)) int fun(int x) { return x * x; } int test() { return fun(var); } ``` -fpic (var and fun are dso_preemptable) ``` test: // @test adrp x8, :got:var ldr x8, [x8, :got_lo12:var] ldr w0, [x8] // fun is preemptible by default in ld -shared mode. ld will create a PLT. b fun ``` vs -fpic -fno-semantic-interposition (var and fun are dso_local) ``` test: // @test .Ltest$local: adrp x8, .Lvar$local ldr w0, [x8, :lo12:.Lvar$local] // The assembler either resolves .Lfun$local at assembly time, or produces a // relocation referencing a non-preemptible section symbol (which can avoid PLT). b .Lfun$local ``` Note: Clang's default -fpic is more aggressive than GCC -fpic: interprocedural optimizations (including inlining) are available but local aliases are not used. -fpic -fsemantic-interposition can disable interprocedural optimizations. Depends on D101872 Reviewed By: peter.smith Differential Revision: https://reviews.llvm.org/D101873
2021-05-11 00:43:33 +08:00
// RUN: %clang -target aarch64 %s -Werror -fPIC -fno-semantic-interposition -c -### 2>&1 | FileCheck --check-prefix=NO %s
[clang] Support -fpic -fno-semantic-interposition for RISCV -fno-semantic-interposition (only effective with -fpic) can optimize default visibility external linkage (non-ifunc-non-COMDAT) variable access and function calls to avoid GOT/PLT, by using local aliases, e.g. ``` int var; __attribute__((optnone)) int fun(int x) { return x * x; } int test() { return fun(var); } ``` -fpic (var and fun are dso_preemptable) ``` test: .LBB1_1: auipc a0, %got_pcrel_hi(var) ld a0, %pcrel_lo(.LBB1_1)(a0) lw a0, 0(a0) // fun is preemptible by default in ld -shared mode. ld will create a PLT. tail fun@plt ``` vs -fpic -fno-semantic-interposition (var and fun are dso_local) ``` test: .Ltest$local: .LBB1_1: auipc a0, %pcrel_hi(.Lvar$local) addi a0, a0, %pcrel_lo(.LBB1_1) lw a0, 0(a0) // The assembler either resolves .Lfun$local at assembly time (-mno-relax // -fno-function-sections), or produces a relocation referencing a non-preemptible // local symbol (which can avoid PLT). tail .Lfun$local ``` Note: Clang's default -fpic is more aggressive than GCC -fpic: interprocedural optimizations (including inlining) are available but local aliases are not used. -fpic -fsemantic-interposition can disable interprocedural optimizations. Depends on D101875 Reviewed By: luismarques Differential Revision: https://reviews.llvm.org/D101876
2021-05-12 02:38:32 +08:00
// RUN: %clang -target riscv32 %s -Werror -fPIC -fno-semantic-interposition -c -### 2>&1 | FileCheck --check-prefix=NO %s
// RUN: %clang -target riscv64 %s -Werror -fPIC -fno-semantic-interposition -c -### 2>&1 | FileCheck --check-prefix=NO %s
Refactor how -fno-semantic-interposition sets dso_local on default visibility external linkage definitions The idea is that the CC1 default for ELF should set dso_local on default visibility external linkage definitions in the default -mrelocation-model pic mode (-fpic/-fPIC) to match COFF/Mach-O and make output IR similar. The refactoring is made available by 2820a2ca3a0e69c3f301845420e0067ffff2251b. Currently only x86 supports local aliases. We move the decision to the driver. There are three CC1 states: * -fsemantic-interposition: make some linkages interposable and make default visibility external linkage definitions dso_preemptable. * (default): selected if the target supports .Lfoo$local: make default visibility external linkage definitions dso_local * -fhalf-no-semantic-interposition: if neither option is set or the target does not support .Lfoo$local: like -fno-semantic-interposition but local aliases are not used. So references can be interposed if not optimized out. Add -fhalf-no-semantic-interposition to a few tests using the half-based semantic interposition behavior.
2021-01-01 05:59:45 +08:00
// RUN: %clang -target i386 %s -Werror -fPIC -fno-semantic-interposition -c -### 2>&1 | FileCheck --check-prefix=NO %s
// RUN: %clang -target x86_64 %s -Werror -fPIC -fno-semantic-interposition -c -### 2>&1 | FileCheck --check-prefix=NO %s
[Driver] Move -fsemantic-interposition decision from cc1 to driver And add test/Driver/fsemantic-interposition.c
2020-02-03 11:30:39 +08:00
// NO-NOT: "-fsemantic-interposition"
Refactor how -fno-semantic-interposition sets dso_local on default visibility external linkage definitions The idea is that the CC1 default for ELF should set dso_local on default visibility external linkage definitions in the default -mrelocation-model pic mode (-fpic/-fPIC) to match COFF/Mach-O and make output IR similar. The refactoring is made available by 2820a2ca3a0e69c3f301845420e0067ffff2251b. Currently only x86 supports local aliases. We move the decision to the driver. There are three CC1 states: * -fsemantic-interposition: make some linkages interposable and make default visibility external linkage definitions dso_preemptable. * (default): selected if the target supports .Lfoo$local: make default visibility external linkage definitions dso_local * -fhalf-no-semantic-interposition: if neither option is set or the target does not support .Lfoo$local: like -fno-semantic-interposition but local aliases are not used. So references can be interposed if not optimized out. Add -fhalf-no-semantic-interposition to a few tests using the half-based semantic interposition behavior.
2021-01-01 05:59:45 +08:00
// NO-NOT: "-fhalf-no-semantic-interposition"
/// If neither -fsemantic-interposition or -fno-semantic-interposition is specified,
/// or -fno-semantic-interposition is specified but the target does not support
/// local aliases, use the traditional half-baked behavor: interprocedural
/// optimizations are allowed but local aliases are not used. If references are
/// not optimized out, semantic interposition at runtime is possible.
// RUN: %clang -target ppc64le %s -Werror -fPIC -fno-semantic-interposition -c -### 2>&1 | FileCheck --check-prefix=HALF %s
// RUN: %clang -target x86_64 %s -Werror -fPIC -c -### 2>&1 | FileCheck --check-prefix=HALF %s
//
// HALF: "-fhalf-no-semantic-interposition"