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Add frontend flag for explicitly setting ccc

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Adds a new swift-frontend flag to allow users to choose which calling
convention is used to make c function calls. This hidden flag is called
`-experimental-platform-c-calling-convention`.

This behavior is needed to workaround rdar://109431863 (Swift-frontend
produces trapping llvm ir for non-trapping sil). The root cause of this
issue is that IRGen always emits c function calls with llvm's default C
calling convention. However clang may select a different (incompatible)
calling convention for the function, eventually resulting--via
InstCombine and SimplifyCFG--in a trap instead of the function call.
This failure mode is most readily seen with the triple
`armv7em-apple-none-macho` when attempting to call functions taking
struct arguments. Example unoptimized ir below:

```llvm-ir
call void @bar([4 x i32] %17, i32 2), !dbg !109
...
define internal arm_aapcs_vfpcc void @bar(
  [4 x i32] %bar.coerce, i32 noundef %x)
```

In the future it would be better to use the clang importer or some other
tool to determine the calling convention for each function instead of
setting the calling convention frontend invocation wide.

Note: I don't know for sure whether or not clang should be explicitly
annotating these functions with a calling convention instead of
aliasing C to mean ARM_AAPCS_VFP for this particular combination of
`-target`, `-mfloat-abi`, and `-mcpu`.
This commit is contained in:
Rauhul Varma
2023-05-22 23:52:46 -07:00
parent de31b13e88
commit 19f74e22e6
4 changed files with 75 additions and 2 deletions
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59
lib/Frontend/CompilerInvocation.cpp
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@@ -2807,6 +2807,65 @@ static bool ParseIRGenArgs(IRGenOptions &Opts, ArgList &Args,
return true;
}
if (const Arg *A = Args.getLastArg(options::OPT_experimental_platform_c_calling_convention)) {
Opts.ExperimentalPlatformCCallingConvention =
llvm::StringSwitch<llvm::CallingConv::ID>(A->getValue())
.Case("c", llvm::CallingConv::C)
.Case("fast", llvm::CallingConv::Fast)
.Case("cold", llvm::CallingConv::Cold)
.Case("ghc", llvm::CallingConv::GHC)
.Case("hipe", llvm::CallingConv::HiPE)
.Case("webkit_js", llvm::CallingConv::WebKit_JS)
.Case("anyreg", llvm::CallingConv::AnyReg)
.Case("preservemost", llvm::CallingConv::PreserveMost)
.Case("preserveall", llvm::CallingConv::PreserveAll)
.Case("swift", llvm::CallingConv::Swift)
.Case("cxx_fast_tls", llvm::CallingConv::CXX_FAST_TLS)
.Case("tail", llvm::CallingConv::Tail)
.Case("cfguard_check", llvm::CallingConv::CFGuard_Check)
.Case("swifttail", llvm::CallingConv::SwiftTail)
.Case("firsttargetcc", llvm::CallingConv::FirstTargetCC)
.Case("x86_stdcall", llvm::CallingConv::X86_StdCall)
.Case("x86_fastcall", llvm::CallingConv::X86_FastCall)
.Case("arm_apcs", llvm::CallingConv::ARM_APCS)
.Case("arm_aapcs", llvm::CallingConv::ARM_AAPCS)
.Case("arm_aapcs_vfp", llvm::CallingConv::ARM_AAPCS_VFP)
.Case("msp430_intr", llvm::CallingConv::MSP430_INTR)
.Case("x86_thiscall", llvm::CallingConv::X86_ThisCall)
.Case("ptx_kernel", llvm::CallingConv::PTX_Kernel)
.Case("ptx_device", llvm::CallingConv::PTX_Device)
.Case("spir_func", llvm::CallingConv::SPIR_FUNC)
.Case("spir_kernel", llvm::CallingConv::SPIR_KERNEL)
.Case("intel_ocl_bi", llvm::CallingConv::Intel_OCL_BI)
.Case("x86_64_sysv", llvm::CallingConv::X86_64_SysV)
.Case("win64", llvm::CallingConv::Win64)
.Case("x86_vectorcall", llvm::CallingConv::X86_VectorCall)
.Case("x86_intr", llvm::CallingConv::X86_INTR)
.Case("avr_intr", llvm::CallingConv::AVR_INTR)
.Case("avr_signal", llvm::CallingConv::AVR_SIGNAL)
.Case("avr_builtin", llvm::CallingConv::AVR_BUILTIN)
.Case("amdgpu_vs", llvm::CallingConv::AMDGPU_VS)
.Case("amdgpu_gs", llvm::CallingConv::AMDGPU_GS)
.Case("amdgpu_ps", llvm::CallingConv::AMDGPU_PS)
.Case("amdgpu_cs", llvm::CallingConv::AMDGPU_CS)
.Case("amdgpu_kernel", llvm::CallingConv::AMDGPU_KERNEL)
.Case("x86_regcall", llvm::CallingConv::X86_RegCall)
.Case("amdgpu_hs", llvm::CallingConv::AMDGPU_HS)
.Case("msp430_builtin", llvm::CallingConv::MSP430_BUILTIN)
.Case("amdgpu_ls", llvm::CallingConv::AMDGPU_LS)
.Case("amdgpu_es", llvm::CallingConv::AMDGPU_ES)
.Case("aarch64_vectorcall", llvm::CallingConv::AArch64_VectorCall)
.Case("aarch64_sve_vectorcall", llvm::CallingConv::AArch64_SVE_VectorCall)
.Case("wasm_emscripteninvoke", llvm::CallingConv::WASM_EmscriptenInvoke)
.Case("amdgpu_gfx", llvm::CallingConv::AMDGPU_Gfx)
.Case("m68k_intr", llvm::CallingConv::M68k_INTR)
.Case("aarch64_sme_abi_support_routines_preservemost_from_x0",
llvm::CallingConv::AArch64_SME_ABI_Support_Routines_PreserveMost_From_X0)
.Case("aarch64_sme_abi_support_routines_preservemost_from_x2",
llvm::CallingConv::AArch64_SME_ABI_Support_Routines_PreserveMost_From_X2)
.Default(llvm::CallingConv::C);
}
return false;
}