http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53942
Bug #: 53942 Summary: unable to find a register to spill in class 'CREG' Classification: Unclassified Product: gcc Version: 4.7.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: rtl-optimization AssignedTo: unassig...@gcc.gnu.org ReportedBy: ncahill_...@yahoo.com This command: gcc -O2 -mtune=pentium2 -fno-inline -x c++ -std=gnu++98 -c a.c -o a.o gives this output: ### output ### a.c: In function 'unsigned char _ZL1fP2S_h.isra.0(UINT16, UINT16, UINT16, unsigned char)': a.c:25:1: error: unable to find a register to spill in class 'CREG' a.c:25:1: error: this is the insn: (insn 11 7 12 2 (parallel [ (set (reg:SI 1 dx [85]) (ashiftrt:SI (reg:SI 1 dx [85]) (reg/v:QI 81 [ i ]))) (clobber (reg:CC 17 flags)) ]) a.c:20 409 {*ashrsi3_1} (expr_list:REG_UNUSED (reg:CC 17 flags) (nil))) a.c:25: confused by earlier errors, bailing out ### end output ### when compiling this testcase: ### a.c ### typedef unsigned short UINT16; typedef unsigned int UINT32; typedef struct S_ S; struct S_ { UINT16 data[3]; UINT32 x; UINT32 y; }; static inline S *get_S() {} static unsigned char f(S *s, unsigned char i) { unsigned char c=0; unsigned char v; v = s->data[0]; c|=v; v=((s->data[1])&(1<<i))?1:0; c|=v<<1; v=((s->data[2])&0xff)&(1<<i); c|=v<<2; return c; } void g() { S *s = get_S(); s->x=f(s,6); s->y=f(s,7); } ### end a.c ### Using -mtune=i686 works. I'm using gcc 4.7.1, i686-pc-linux-gnu, 32-bit. Thank you. Neil.