[Bug analyzer/96616] Many new analyzer failures

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96616

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by David Malcolm <dmalcolm@gcc.gnu.org>:

https://gcc.gnu.org/g:2867118ddda9b56d991c16022f7d3d634ed08313

commit r11-2708-g2867118ddda9b56d991c16022f7d3d634ed08313
Author: David Malcolm <dmalcolm@redhat.com>
Date:   Fri Aug 14 15:49:52 2020 -0400

    analyzer: fix initialization from constant pool [PR96609,PR96616]

    PR testsuite/96609 and PR analyzer/96616 report various testsuite
    failures seen on powerpc64, aarch64, and arm in new tests added by
    r11-2694-g808f4dfeb3a95f50f15e71148e5c1067f90a126d.

    Some of these failures (in gcc.dg/analyzer/init.c, and on arm
    in gcc.dg/analyzer/casts-1.c) relate to initializations from var_decls
    in the constant pool.  I wrote the tests assuming that the gimplified
    stmts would initialize the locals via a gassign of code CONSTRUCTOR,
    whereas on these targets some of the initializations are gassign from
    a VAR_DECL e.g.:
      c = *.LC0;
    where "*.LC0" is a var_decl with DECL_IN_CONSTANT_POOL set.

    For example, in test_7:
       struct coord c[2] = {{3, 4}, {5, 6}};
       __analyzer_eval (c[0].x == 3); /* { dg-warning "TRUE" } */
    after the initialization, the store was simply recording:
       cluster for: c: INIT_VAL(*.LC0)
    when I was expecting the cluster for c to have:
      cluster for: c
        key:   {kind: direct, start: 0, size: 32, next: 32}
        value: 'int' {(int)3}
        key:   {kind: direct, start: 32, size: 32, next: 64}
        value: 'int' {(int)4}
        key:   {kind: direct, start: 64, size: 32, next: 96}
        value: 'int' {(int)5}
        key:   {kind: direct, start: 96, size: 32, next: 128}
        value: 'int' {(int)6}
    The test for c[0].x == 3 would then generate:
      cluster for: _2: (SUB(SUB(INIT_VAL(*.LC0), c[(int)0]),
c[(int)0].x)==(int)3)
    which is UNKNOWN, leading to the test failing.

    This patch fixes the init.c and casts-1.c failures by special-casing
    reads from a var_decl with DECL_IN_CONSTANT_POOL set, so that they build
    a compound_svalue containing the bindings implied by the CONSTRUCTOR
    node for DECL_INITIAL.

    gcc/analyzer/ChangeLog:
            PR testsuite/96609
            PR analyzer/96616
            * region-model.cc (region_model::get_store_value): Call
            maybe_get_constant_value on decl_regions first.
            * region-model.h (decl_region::maybe_get_constant_value): New decl.
            * region.cc (decl_region::get_stack_depth): Likewise.
            (decl_region::maybe_get_constant_value): New.
            * store.cc (get_subregion_within_ctor): New.
            (binding_map::apply_ctor_to_region): New.
            * store.h (binding_map::apply_ctor_to_region): New decl.