[CodeGen] It's not rational to promote the local variable to unnamed global variable in CodeGen.

[hstk30-hw]

https://godbolt.org/z/vj687zjTM

For code

typedef struct {
    const char *strType;
    int dataType;
} DataTypePairT;

void init(const DataTypePairT * am);

void test() {
    DataTypePairT bitDataType[] = {
        {"uint16", 1},
        {"uint32", 2},
        {"uint64", 3},
        {"uint8", 4}
    };

    init(bitDataType);
}

LLVM will promote the local varibal bitDataType to an unnamed global variable. It's counterintuitive.

llvm-project/clang/lib/CodeGen/CGDecl.cpp

Lines 1130 to 1132 in 1329af9

	Address CodeGenModule::createUnnamedGlobalFrom(const VarDecl &D,
	llvm::Constant *Constant,
	CharUnits Align) {

It will put the data to '.data.rel.ro' section.

Maybe we can do this as an optimization, and default on it. Now we implement it in CodeGen seems not rational.

[llvmbot]

@llvm/issue-subscribers-clang-codegen

Author: None (hstk30-hw)

https://godbolt.org/z/vj687zjTM

For code

typedef struct {
    const char *strType;
    int dataType;
} DataTypePairT;

void init(const DataTypePairT * am);

void test() {
    DataTypePairT bitDataType[] = {
        {"uint16", 1},
        {"uint32", 2},
        {"uint64", 3},
        {"uint8", 4}
    };

    init(bitDataType);
}

LLVM will promote the local varibal bitDataType to an unnamed global variable. It's counterintuitive.

llvm-project/clang/lib/CodeGen/CGDecl.cpp

Lines 1130 to 1132 in 1329af9

	Address CodeGenModule::createUnnamedGlobalFrom(const VarDecl &D,
	llvm::Constant *Constant,
	CharUnits Align) {

It will put the data to '.data.rel.ro' section.

Maybe we can do this as an optimization, and default on it. Now we implement it in CodeGen seems not rational.