d041d5d4e0
This provides a C language `modular_format` attribute. This combines with information from the existing `format` to set the new IR `modular-format` attribute. The purpose of these attributes is to enable "modular printf". A statically linked libc can provide a modular variant of printf that only weakly references implementation routines. The link-time symbol `printf` would strongly reference aspect symbols (e.g. for float, fixed point, etc.) that are provided by those routines, restoring the status quo. However, the compiler could transform calls with constant format strings to calls to the modular printf instead, and at the same time, it would emit strong references to the aspect symbols that are needed to implement the format string. Then, the printf implementation would contain only the union of the aspects requested. See issue #146159 for context.
50 lines
2.4 KiB
C
50 lines
2.4 KiB
C
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm %s -o - | FileCheck %s
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int printf(const char *fmt, ...) __attribute__((modular_format(__modular_printf, "__printf", "float")));
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int myprintf(const char *fmt, ...) __attribute__((modular_format(__modular_printf, "__printf", "float"), format(printf, 1, 2)));
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// CHECK-LABEL: define dso_local void @test_inferred_format(
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// CHECK: {{.*}} = call i32 (ptr, ...) @printf(ptr noundef @.str) #[[ATTR:[0-9]+]]
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void test_inferred_format(void) {
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printf("hello");
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}
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// CHECK-LABEL: define dso_local void @test_explicit_format(
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// CHECK: {{.*}} = call i32 (ptr, ...) @myprintf(ptr noundef @.str) #[[ATTR:[0-9]+]]
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void test_explicit_format(void) {
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myprintf("hello");
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}
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int redecl(const char *fmt, ...) __attribute__((format(printf, 1, 2)));
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int redecl(const char *fmt, ...) __attribute__((modular_format(__dupe_impl, "__dupe", "1")));
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int redecl(const char *fmt, ...) __attribute__((modular_format(__dupe_impl, "__dupe", "1")));
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// CHECK-LABEL: define dso_local void @test_redecl(
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// CHECK: {{.*}} = call i32 (ptr, ...) @redecl(ptr noundef @.str) #[[ATTR_DUPE_IDENTICAL:[0-9]+]]
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void test_redecl(void) {
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redecl("hello");
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}
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int order1(const char *fmt, ...) __attribute__((modular_format(__modular_printf, "__printf", "a", "b"), format(printf, 1, 2)));
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int order2(const char *fmt, ...) __attribute__((modular_format(__modular_printf, "__printf", "b", "a"), format(printf, 1, 2)));
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// CHECK-LABEL: define dso_local void @test_order(
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// CHECK: {{.*}} = call i32 (ptr, ...) @order1(ptr noundef @.str) #[[ATTR_ORDER:[0-9]+]]
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// CHECK: {{.*}} = call i32 (ptr, ...) @order2(ptr noundef @.str) #[[ATTR_ORDER]]
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void test_order(void) {
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order1("hello");
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order2("hello");
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}
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int duplicate_identical(const char *fmt, ...) __attribute__((modular_format(__dupe_impl, "__dupe", "1"), modular_format(__dupe_impl, "__dupe", "1"), format(printf, 1, 2)));
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// CHECK-LABEL: define dso_local void @test_duplicate_identical(
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// CHECK: {{.*}} = call i32 (ptr, ...) @duplicate_identical(ptr noundef @.str) #[[ATTR_DUPE_IDENTICAL]]
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void test_duplicate_identical(void) {
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duplicate_identical("hello");
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}
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// CHECK: attributes #[[ATTR]] = { "modular-format"="printf,1,2,__modular_printf,__printf,float" }
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// CHECK: attributes #[[ATTR_DUPE_IDENTICAL]] = { "modular-format"="printf,1,2,__dupe_impl,__dupe,1" }
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// CHECK: attributes #[[ATTR_ORDER]] = { "modular-format"="printf,1,2,__modular_printf,__printf,a,b" }
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