Support 'raw mangles' via leading "\1" in pragma(mangle) strings #3854
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This is a prerequisite for #3850 and enables getting hold of section start/end addresses on Mac (at least with their pragma(mangle, "\1section$start$__DATA$.minfo")
immutable ModuleInfo* __start___minfo;
pragma(mangle, "\1section$end$__DATA$.minfo")
immutable ModuleInfo* __stop___minfo; |
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What prevents this from being upstream ? |
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A DMD backend/glue layer implementation and an agreed prefix/notion, as the "\1" is AFAIK just an LLVM convention. |
gen/mangling.cpp
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| @@ -125,11 +125,15 @@ std::string getIRMangledName(VarDeclaration *vd) { | |||
| } | |||
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| std::string getIRMangledFuncName(std::string baseMangle, LINK link) { | |||
| return gABI->mangleFunctionForLLVM(std::move(baseMangle), link); | |||
| return baseMangle[0] == '\1' | |||
| ? baseMangle | |||
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Should that be a std::move? I only use C++ for LDC development at the moment, some rust creeping in… ;)
Such mangled names aren't affected by a target-specific default (C) prefix, such as `_` on Mac.
| @@ -125,11 +125,15 @@ std::string getIRMangledName(VarDeclaration *vd) { | |||
| } | |||
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| std::string getIRMangledFuncName(std::string baseMangle, LINK link) { | |||
| return gABI->mangleFunctionForLLVM(std::move(baseMangle), link); | |||
| return baseMangle[0] == '\1' | |||
| ? std::move(baseMangle) | |||
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std::move is not needed here (you are returning a func param), but (I think) are needed when passing to mangleFunctionForLLVM. Yes the c++ rules are tough and I had to look it up.
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I was worried about the ternary expression. Seems like std::move is indeed needed to avoid a full copy: https://cpp.godbolt.org/z/1e6cPzqzW
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ah interesting, good thinking.
tests/codegen/mangling_raw.d
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| // RUN: %ldc -output-ll -of=%t.ll %s && FileCheck %s < %t.ll | ||
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| // CHECK: @"\01myGlobal" = global i32 | ||
| pragma(mangle, "\1myGlobal") |
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nit: make the variable name different from the mangle (less chance for it to be accidentally correct)
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Right, good point, haven't thought about that possibility.
Such mangled names aren't affected by a target-specific default (C) prefix, such as
_on Mac.