https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99828
Bug ID: 99828 Summary: inlining failed in call to ‘always_inline’ ‘memcpy’: --param max-inline-insns-auto limit reached Product: gcc Version: 11.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: lto Assignee: unassigned at gcc dot gnu.org Reporter: marxin at gcc dot gnu.org CC: hubicka at gcc dot gnu.org, marxin at gcc dot gnu.org Target Milestone: --- Noticed by Andi Kleen in kernel, reduced to: $ cat 1.i __attribute__((__always_inline__)) void *memcpy(); void *foo = memcpy; $ touch 2.s $ cat 3.i int kasan_check_range(); int __memcpy(); enum { false, true } memcpy(void *dest, void *src, long len) { if (kasan_check_range(len, false, 0) || kasan_check_range(len, true, 0)) return __memcpy(dest, src, len); } int *LZ4_decompress_generic_outputSize_op; int mlen; LZ4_decompress_generic_outputSize_match() { { __builtin_memcpy(LZ4_decompress_generic_outputSize_op, LZ4_decompress_generic_outputSize_match, mlen); } } $ gcc 1.i 2.s 3.i -c -flto -Os -shared && gcc [123].o -shared 1.i:1:42: warning: ‘always_inline’ function might not be inlinable [-Wattributes] 1 | __attribute__((__always_inline__)) void *memcpy(); | ^~~~~~ 3.i:5:1: warning: conflicting types for built-in function ‘memcpy’; expected ‘void *(void *, const void *, long unsigned int)’ [-Wbuiltin-declaration-mismatch] 5 | memcpy(void *dest, void *src, long len) { | ^~~~~~ 3.i:1:1: note: ‘memcpy’ is declared in header ‘<string.h>’ +++ |+#include <string.h> 1 | int kasan_check_range(); 3.i:13:1: warning: return type defaults to ‘int’ [-Wimplicit-int] 13 | LZ4_decompress_generic_outputSize_match() { | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1.i:1:42: warning: type of ‘memcpy’ does not match original declaration [-Wlto-type-mismatch] 1 | __attribute__((__always_inline__)) void *memcpy(); | ^ 3.i:5:1: note: return value type mismatch 5 | memcpy(void *dest, void *src, long len) { | ^ <built-in>: warning: type of ‘__builtin_memcpy’ does not match original declaration [-Wlto-type-mismatch] 3.i:5:1: note: return value type mismatch 3.i:5:1: note: ‘memcpy’ was previously declared here 3.i:5:1: note: code may be misoptimized unless ‘-fno-strict-aliasing’ is used 3.i: In function ‘LZ4_decompress_generic_outputSize_match’: 1.i:1:42: error: inlining failed in call to ‘always_inline’ ‘memcpy’: --param max-inline-insns-auto limit reached 1 | __attribute__((__always_inline__)) void *memcpy(); | ^ 3.i:15:5: note: called from here 15 | __builtin_memcpy(LZ4_decompress_generic_outputSize_op, | ^ lto-wrapper: fatal error: gcc returned 1 exit status compilation terminated. /usr/bin/ld: error: lto-wrapper failed collect2: error: ld returned 1 exit status