https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69399
--- Comment #9 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to H.J. Lu from comment #5)
> wide-int.h has
> if (STATIC_CONSTANT_P (xi.precision > HOST_BITS_PER_WIDE_INT)
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> This is miscompiled due to PR 65656.
>
We hit this via:
Breakpoint 1, wi::lrshift<generic_wide_int<fixed_wide_int_storage<192> >,
generic_wide_int<fixed_wide_int_storage<192> > > (x=..., y=...)
at /export/gnu/import/git/sources/gcc-release/gcc/wide-int.h:2898
2898 val[0] = xi.to_uhwi () >> shift;
(gdb) bt
#0 wi::lrshift<generic_wide_int<fixed_wide_int_storage<192> >,
generic_wide_int<fixed_wide_int_storage<192> > > (x=..., y=...)
at /export/gnu/import/git/sources/gcc-release/gcc/wide-int.h:2898
#1 0x00000000009e7bbe in
wi::rshift<generic_wide_int<fixed_wide_int_storage<192> >,
generic_wide_int<fixed_wide_int_storage<192> > > (sgn=<optimized out>,
y=..., x=...)
at /export/gnu/import/git/sources/gcc-release/gcc/wide-int.h:2947
#2 bit_value_binop_1 (code=code@entry=RSHIFT_EXPR,
type=type@entry=0x7fffefe82dc8, val=val@entry=0x7fffffffd7c0,
mask=mask@entry=0x7fffffffd790, r1type=0x7fffefe82dc8, r1val=...,
r1mask=..., r2type=0x7fffefd6b690, r2val=..., r2mask=...)
at /export/gnu/import/git/sources/gcc-release/gcc/tree-ssa-ccp.c:1348
#3 0x00000000009e9e7b in bit_value_binop (code=code@entry=RSHIFT_EXPR,
type=0x7fffefe82dc8, rhs1=rhs1@entry=0x7fffefd71708, rhs2=<optimized out>)
at /export/gnu/import/git/sources/gcc-release/gcc/tree-ssa-ccp.c:1549
#4 0x00000000009eb520 in evaluate_stmt (stmt=stmt@entry=0x7fffefe9a160)
at /export/gnu/import/git/sources/gcc-release/gcc/tree-ssa-ccp.c:1785
#5 0x00000000009ec8d2 in visit_assignment (stmt=stmt@entry=0x7fffefe9a160,
output_p=output_p@entry=0x7fffffffdba0)
at /export/gnu/import/git/sources/gcc-release/gcc/tree-ssa-ccp.c:2258
#6 0x00000000009ec9c2 in ccp_visit_stmt (stmt=0x7fffefe9a160,
taken_edge_p=0x7fffffffdba8, output_p=0x7fffffffdba0)
at /export/gnu/import/git/sources/gcc-release/gcc/tree-ssa-ccp.c:2336
---Type <return> to continue, or q <return> to quit---
#7 0x0000000000a4efcf in simulate_stmt (stmt=stmt@entry=0x7fffefe9a160)
at /export/gnu/import/git/sources/gcc-release/gcc/tree-ssa-propagate.c:348
#8 0x0000000000a50f79 in simulate_block (block=<optimized out>)
at /export/gnu/import/git/sources/gcc-release/gcc/tree-ssa-propagate.c:471
#9 ssa_propagate (
visit_stmt=visit_stmt@entry=0x9ec937 <ccp_visit_stmt(gimple, edge*,
tree*)>, visit_phi=visit_phi@entry=0x9e6aa5 <ccp_visit_phi_node(gphi*)>)
at /export/gnu/import/git/sources/gcc-release/gcc/tree-ssa-propagate.c:888
#10 0x00000000009e6295 in do_ssa_ccp ()
at /export/gnu/import/git/sources/gcc-release/gcc/tree-ssa-ccp.c:2382
#11 (anonymous namespace)::pass_ccp::execute (this=<optimized out>)
at /export/gnu/import/git/sources/gcc-release/gcc/tree-ssa-ccp.c:2415
#12 0x000000000089ca0c in execute_one_pass (pass=pass@entry=0x19b4bf0)
at /export/gnu/import/git/sources/gcc-release/gcc/passes.c:2330
#13 0x000000000089cd62 in execute_pass_list_1 (pass=0x19b4bf0)
at /export/gnu/import/git/sources/gcc-release/gcc/passes.c:2382
#14 0x000000000089cd7f in execute_pass_list_1 (pass=0x19b4a70,
pass@entry=0x19b48f0)
at /export/gnu/import/git/sources/gcc-release/gcc/passes.c:2383
#15 0x000000000089cd9c in execute_pass_list (fn=0x7fffefe98000, pass=0x19b48f0)
at /export/gnu/import/git/sources/gcc-release/gcc/passes.c:2393
#16 0x000000000089ba57 in do_per_function_toporder (
callback=callback@entry=0x89cd83 <execute_pass_list(function*, opt_pass*)>,
---Type <return> to continue, or q <return> to quit---
data=0x19b48f0) at /export/gnu/import/git/sources/gcc-release/gcc/passes.c:1728
#17 0x000000000089d3e3 in execute_ipa_pass_list (pass=0x19b4890)
at /export/gnu/import/git/sources/gcc-release/gcc/passes.c:2736
#18 0x000000000066f3ac in ipa_passes ()
at /export/gnu/import/git/sources/gcc-release/gcc/cgraphunit.c:2172
#19 symbol_table::compile (this=this@entry=0x7fffefd6b000)
at /export/gnu/import/git/sources/gcc-release/gcc/cgraphunit.c:2313
#20 0x0000000000670be5 in symbol_table::finalize_compilation_unit (
this=0x7fffefd6b000)
at /export/gnu/import/git/sources/gcc-release/gcc/cgraphunit.c:2462
#21 0x000000000058ea41 in c_write_global_declarations ()
at /export/gnu/import/git/sources/gcc-release/gcc/c/c-decl.c:10822
#22 0x0000000000939509 in compile_file ()
at /export/gnu/import/git/sources/gcc-release/gcc/toplev.c:613
#23 0x000000000093b3c4 in do_compile ()
at /export/gnu/import/git/sources/gcc-release/gcc/toplev.c:2067
#24 toplev::main (this=this@entry=0x7fffffffdf60, argc=argc@entry=15,
argv=argv@entry=0x7fffffffe068)
at /export/gnu/import/git/sources/gcc-release/gcc/toplev.c:2165
#25 0x0000000000f50ab7 in main (argc=15, argv=0x7fffffffe068)
at /export/gnu/import/git/sources/gcc-release/gcc/main.c:39
(gdb) p x
$2 = (const generic_wide_int<fixed_wide_int_storage<192> > &) @0x7fffffffd670:
{<fixed_wide_int_storage<192>> = {val = {4294967169, 0, 140737217214936, 92},
len = 1}, static is_sign_extended = <optimized out>}
(gdb) p y
$3 = (const generic_wide_int<fixed_wide_int_storage<192> > &) @0x7fffffffd640:
{<fixed_wide_int_storage<192>> = {val = {64, 824633720833, -4294967168,
140737218308160}, len = 1}, static is_sign_extended = <optimized out>}
(gdb) p xi
$3 = {<wide_int_ref_storage<true>> = {<wi::storage_ref> = {
val = 0x7fffffffcfe0, len = 2, precision = 192}, scratch = {64,
8589921072}}, static is_sign_extended = <optimized out>}
(gdb) p yi
$4 = {<wide_int_ref_storage<true>> = {<wi::storage_ref> = {
val = 0x7fffffffcbc0, len = 1, precision = 192}, scratch = {
140737488344768, 140737488343008}},
static is_sign_extended = <optimized out>}
(gdb)
Somehow PR 65656 miscompiled:
if (STATIC_CONSTANT_P (xi.precision > HOST_BITS_PER_WIDE_INT)
? xi.len == 1 && xi.val[0] >= 0
: xi.precision <= HOST_BITS_PER_WIDE_INT)
which turned the expression into true and hit
val[0] = xi.to_uhwi () >> shift;
result.set_len (1);
