[Bug target/90000] Compile-time hog w/ impossible asm constraints on powerpc

["willschm at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90000

--- Comment #4 from Will Schmidt <willschm at gcc dot gnu.org> ---

I'll be attaching a proposed(/rfc) patch momentarily.

I'm able to add logic in cfgexpand.c expand_asm_stmt() to catch the use of a FP
register when our target is SOFT_FLOAT ; but the result is an ICE while trying
to process a subsequent instruction.



FAIL: gcc.target/powerpc/pr90000.c (test for excess errors)
Excess errors:
/home/willschm/gcc/gcc-patches/gcc/testsuite/gcc.target/powerpc/pr90000.c:14:3:
error: invalid fp register usage with a soft_float target


^ desired error.


during RTL pass: expand
/home/willschm/gcc/gcc-patches/gcc/testsuite/gcc.target/powerpc/pr90000.c:16:3:
internal compiler error: in operator[], at vec.h:867
0x1018dc3f vec<edge_def*, va_gc, vl_embed>::operator[](unsigned int)
        /home/willschm/gcc/gcc-patches/gcc/vec.h:867
0x103f0a0f vec<tree_node*, va_heap, vl_embed>::operator[](unsigned int)
        /home/willschm/gcc/gcc-patches/gcc/tree.h:3417
0x103f0a0f vec<tree_node*, va_heap, vl_ptr>::operator[](unsigned int)
        /home/willschm/gcc/gcc-patches/gcc/vec.h:1433
0x103f0a0f expand_asm_stmt
        /home/willschm/gcc/gcc-patches/gcc/cfgexpand.c:2959
0x103f829f expand_gimple_stmt_1
        /home/willschm/gcc/gcc-patches/gcc/cfgexpand.c:3694
0x103f829f expand_gimple_stmt
        /home/willschm/gcc/gcc-patches/gcc/cfgexpand.c:3862
0x103ffde3 expand_gimple_basic_block
        /home/willschm/gcc/gcc-patches/gcc/cfgexpand.c:5902
0x10402907 execute
        /home/willschm/gcc/gcc-patches/gcc/cfgexpand.c:6557

^ subsequent undesired.  


Per debug, the subsequent error is occurring when trying to process a
subsequent instruction.

Breakpoint 7, expand_asm_stmt (stmt=stmt@entry=0x200000c10000) at
cfgexpand.c:2920
2920      location_t locus = gimple_location (stmt);
# .MEM_3 = VDEF <.MEM_2(D)>
__asm__("#" : "=d" fr1);

(gdb) c
Continuing./tmp/pr90000.c: In function 'foo':
/tmp/pr90000.c:14:3: error: invalid fp register usage with a soft-float target
   14 |   __asm__ ("#" : "=d" (fr1)); /* { dg-error "invalid fp register usage
with a soft-float target" } */
      |   ^~~~~~~



#0  expand_asm_stmt (stmt=stmt@entry=0x200000c10058) at
cfgexpand.c:2920Breakpoint 7, expand_asm_stmt (stmt=stmt@entry=0x200000c10058)
at cfgexpand.c:2920
2920      location_t locus = gimple_location (stmt);
# VUSE <.MEM_4>
__asm__ __volatile__("#" :  : "r" r31);


(gdb) c
Continuing.
#0  fancy_abort (file=0x11912d80 "/home/willschm/gcc/gcc-patches/gcc/vec.h",
line=0x363, 
    function=0x11919948 "operator[]") at diagnostic.c:1778