http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47580
Summary: Powerpc GCC fails test gcc.dg/pr41551.c if built with --with-cpu=power7 Product: gcc Version: 4.6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target AssignedTo: meiss...@gcc.gnu.org ReportedBy: meiss...@gcc.gnu.org Host: powerpc64-linux Target: powerpc64-linux Build: powerpc64-linux Test gcc.dg/pr41551.c fails for powerpc if the default target is power7. This is due to the fact that the expander for floatunsdidf (and others) uses gpc_reg_operand: (define_expand "floatunsdidf2" [(set (match_operand:DF 0 "gpc_reg_operand" "") (unsigned_float:DF (match_operand:DI 1 "gpc_reg_operand" "")))] "TARGET_HARD_FLOAT && (TARGET_FCFIDU || VECTOR_UNIT_VSX_P (DFmode))" "") However, the corresponding VSX matcher uses vsx_register_operand: (define_insn "vsx_floatuns<VSi><mode>2" [(set (match_operand:VSX_B 0 "vsx_register_operand" "=<VSr>,?wa") (unsigned_float:VSX_B (match_operand:<VSI> 1 "vsx_register_operand" "<VSr2>,<VSr3>")))] "VECTOR_UNIT_VSX_P (<MODE>mode)" "x<VSv>cvux<VSc><VSs> %x0,%x1" [(set_attr "type" "<VStype_simple>") (set_attr "fp_type" "<VSfptype_simple>")]) Gpc_reg_operand allows the virtual stack registers while vsx_register_operand does not. Since the test is: __extension__ typedef __SIZE_TYPE__ size_t; int main(void) { int var, *p = &var; return (double)(size_t)(p); } It means the expander creates: (insn 5 4 6 3 (set (reg:DF 125) (unsigned_float:DF (reg/f:DI 115 virtual-stack-vars))) pr41551.c:11 -1 (nil)) Which then doesn't match when the target is VSX. There are several different ways this can be solved: 1) Allow virtual stack registers to be used in the vsx register operands. 2) Add a new predicate that doesn't allow virtual stack registers in the expander; 3) Add code in the expander to copy the results if it is in a virtual register.