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Use asm("name") consistently for IMPORT_FSTR
All platforms support this approach. Using `extern "C"` within anonymous namespace is officially undefined behaviour, so may break in future updates. Underscores removed from assembler symbol names - this was only required on some platforms to accommodate `extern "C"`.
1 parent d5ab318 commit 9e1db1a

3 files changed

Lines changed: 35 additions & 36 deletions

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‎src/include/FlashString/Object.hpp‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -78,15 +78,15 @@
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*/
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#define IMPORT_FSTR_OBJECT(name, ObjectType, file) \
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IMPORT_FSTR_DATA(FSTR_DATA_NAME(name), file) \
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extern "C" __attribute__((visibility("hidden"))) const ObjectType ASM_LABEL(FSTR_DATA_NAME(name)); \
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extern __attribute__((visibility("hidden"))) const ObjectType ASM_LABEL(FSTR_DATA_NAME(name)); \
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DEFINE_FSTR_OBJREF(name, FSTR_DATA_NAME(name))
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/**
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* @brief Like IMPORT_FSTR_OBJECT except reference is declared static constexpr
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*/
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#define IMPORT_FSTR_OBJECT_LOCAL(name, ObjectType, file) \
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IMPORT_FSTR_DATA(FSTR_DATA_NAME(name), file) \
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extern "C" __attribute__((visibility("hidden"))) const ObjectType ASM_LABEL(FSTR_DATA_NAME(name)); \
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extern __attribute__((visibility("hidden"))) const ObjectType ASM_LABEL(FSTR_DATA_NAME(name)); \
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static constexpr DEFINE_FSTR_OBJREF(name, FSTR_DATA_NAME(name))
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namespace FSTR

‎src/include/FlashString/Utility.hpp‎

Lines changed: 29 additions & 29 deletions
Original file line numberDiff line numberDiff line change
@@ -87,38 +87,38 @@ template <typename T, typename U> struct argument_type<T(U)> {
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#define STR(x) XSTR(x)
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#define XSTR(x) #x
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#ifdef __WIN32
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#define IMPORT_FSTR_DATA(name, file) \
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__asm__(".section .rodata\n" \
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".def _" STR(name) "; .scl 2; .type 32; .endef\n" \
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".align 4\n" \
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"_" STR(name) ":\n" \
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".long _" STR(name) "_end - _" STR(name) " - 4\n" \
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".incbin \"" file "\"\n" \
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"_" STR(name) "_end:\n");
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#define IMPORT_FSTR_DATA(name, file) \
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__asm__(".section .rodata\n" \
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".def " STR(name) "; .scl 2; .type 32; .endef\n" \
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".align 4\n" \
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STR(name) ":\n" \
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".long " STR(name) "_end - " STR(name) " - 4\n" \
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".incbin \"" file "\"\n" \
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STR(name) "_end:\n");
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#elif defined(__APPLE__)
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#define IMPORT_FSTR_DATA(name, file) \
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__asm__(".const_data\n" \
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".globl _" STR(name) "\n" \
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".align 4\n" "_" STR(name) ":\n" \
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".long _" STR(name) "_end - _" STR(name) " - 4\n" \
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".incbin \"" file "\"\n" \
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"_" STR(name) "_end:\n");
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#define IMPORT_FSTR_DATA(name, file) \
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__asm__(".const_data\n" \
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".globl " STR(name) "\n" \
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".align 4\n" STR(name) ":\n" \
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".long " STR(name) "_end - " STR(name) " - 4\n" \
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".incbin \"" file "\"\n" \
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STR(name) "_end:\n");
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#elif defined(__arm__)
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#define IMPORT_FSTR_DATA(name, file) \
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__asm__(".section " ICACHE_RODATA_SECTION "." STR(name) "\n" \
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".type " STR(name) ", %object\n" \
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".align 4\n" STR(name) ":\n" \
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".long _" STR(name) "_end - " STR(name) " - 4\n" \
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".incbin \"" file "\"\n" \
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"_" STR(name) "_end:\n");
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#define IMPORT_FSTR_DATA(name, file) \
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__asm__(".section " ICACHE_RODATA_SECTION "." STR(name) "\n" \
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".type " STR(name) ", %object\n" \
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".align 4\n" STR(name) ":\n" \
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".long " STR(name) "_end - " STR(name) " - 4\n" \
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".incbin \"" file "\"\n" \
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STR(name) "_end:\n");
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#else
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#define IMPORT_FSTR_DATA(name, file) \
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__asm__(".section " ICACHE_RODATA_SECTION "." STR(name) "\n" \
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".type " STR(name) ", @object\n" \
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".align 4\n" STR(name) ":\n" \
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".long _" STR(name) "_end - " STR(name) " - 4\n" \
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".incbin \"" file "\"\n" \
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"_" STR(name) "_end:\n");
115+
#define IMPORT_FSTR_DATA(name, file) \
116+
__asm__(".section " ICACHE_RODATA_SECTION "." STR(name) "\n" \
117+
".type " STR(name) ", @object\n" \
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".align 4\n" STR(name) ":\n" \
119+
".long " STR(name) "_end - " STR(name) " - 4\n" \
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".incbin \"" file "\"\n" \
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STR(name) "_end:\n");
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#endif
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// clang-format on
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‎src/include/FlashString/config.hpp‎

Lines changed: 4 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -49,10 +49,9 @@
4949

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/*
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When referencing inline assembler labels using `extern "C"` tells the compiler not to
52-
mangle the name. GCC 15 ignores this so requires an additional `asm(label)` directive.
52+
mangle the name. However, doing that inside an anonymous namespace leads to undefined
53+
behaviour and breaks with GCC 15.
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Using an explicit `asm(label)` directive makes this unambiguous.
55+
See https://gcc.gnu.org/onlinedocs/gcc/Asm-Labels.html
5356
*/
54-
#if defined(__clang__) || defined(__WIN32)
55-
#define ASM_LABEL(name) name
56-
#else
5757
#define ASM_LABEL(name) name asm(STR(name))
58-
#endif

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