https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80492
--- Comment #1 from Georg-Johann Lay <gjl at gcc dot gnu.org> --- Created attachment 41249 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41249&action=edit loopasm.s: Generated assembly Assembler output as generated with $ avr-gcc loopasm.c -O2 -dp -S -std=gnu99 The source code issues two "syscalls" arranged in a loop: static __inline__ __attribute__((__always_inline__)) void syscall_7 (int v1, int v2) { register int r20 __asm ("20") = v1; register int r24 __asm ("24") = v2; __asm __volatile__ ("/* SYSCALL_7 %0 %1 */" :: "r" (r20), "r" (r24)); } void do_syscalls (void) { for (int s = 0; s < 2; s++) { syscall_7 (0, 8); syscall_7 (1, 9); } } The generated assembler misses some of the arguments; the asm reads: do_syscalls: ldi r20,0 ; 5 *movhi/2 [length = 2] ldi r21,0 ldi r24,lo8(8) ; 6 *movhi/5 [length = 2] ldi r25,0 /* SYSCALL_7 r20 r24 */ ldi r20,lo8(1) ; 8 *movhi/5 [length = 2] ldi r21,0 ldi r24,lo8(9) ; 9 *movhi/5 [length = 2] ldi r25,0 /* SYSCALL_7 r20 r24 */ /* SYSCALL_7 r20 r24 */ /* SYSCALL_7 r20 r24 */ ret ; 18 return [length = 1] The 1st syscall_7 is expanded correctly: insns 5/6 load 0/8 to specified regs, then follows SYSCALL_7. The 2st syscall_7 is expanded correctly: insns 8/9 load 1/9 to specified regs, then follows SYSCALL_7. The 3rd and 4th syscall_7 are expanded incorrect: Inline asm SYSCALL_7 is performed without setting the specified regs to their values. == configure == Configured with: ../../gcc.gnu.org/gcc-6-branch/configure --target=avr --prefix=/local/gnu/install/gcc-6-avr-mingw32 --host=i386-mingw32 --build=x86_64-linux-gnu --enable-languages=c,c++ --disable-nls --disable-shared --enable-lto --with-dwarf2 --with-gnu-ld --with-gnu-as Thread model: single gcc version 6.3.1 20161222 [gcc-6-branch revision 243886] (GCC)
