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analyzer: fix ICE on vector casts [PR104159] 

PR analyzer/104159 describes an ICE attempting to convert a vector_cst,
which occurs when symbolically executing within a recursive call on:

  _4 = BIT_FIELD_REF <w_3(D), 32, 0>;
  _1 = VIEW_CONVERT_EXPR<T>(_4);

where the BIT_FIELD_REF leads to a get_or_create_cast from
  VEC<long, 8> to VEC<unsigned 4>
which get_code_for_cast erroneously picks NOP_EXPR for the cast, leading
to a bogus input to the VIEW_CONVERT_EXPR.

This patch fixes the issue by giving up on attempts to cast symbolic
values of vector types, treating the result of such casts as unknowable.

gcc/analyzer/ChangeLog:
	PR analyzer/104159
	* region-model-manager.cc
	(region_model_manager::get_or_create_cast): Bail out if the types
	are the same.  Don't attempt to handle casts involving vector
	types.

gcc/testsuite/ChangeLog:
	PR analyzer/104159
	* gcc.dg/analyzer/torture/pr104159.c: New test.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>
This commit is contained in:
David Malcolm 2022-01-21 09:56:56 -05:00
parent 6c1a93102b
commit 45b999f642
2 changed files with 29 additions and 0 deletions
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11
gcc/analyzer/region-model-manager.cc
View File

@ -497,6 +497,17 @@ const svalue *
region_model_manager::get_or_create_cast (tree type, const svalue *arg)
{
gcc_assert (type);
/* No-op if the types are the same. */
if (type == arg->get_type ())
return arg;
/* Don't attempt to handle casts involving vector types for now. */
if (TREE_CODE (type) == VECTOR_TYPE
|| (arg->get_type ()
&& TREE_CODE (arg->get_type ()) == VECTOR_TYPE))
return get_or_create_unknown_svalue (type);
enum tree_code op = get_code_for_cast (type, arg->get_type ());
return get_or_create_unaryop (type, op, arg);
}

18
gcc/testsuite/gcc.dg/analyzer/torture/pr104159.c Normal file
View File

@ -0,0 +1,18 @@
/* { dg-additional-options "-Wno-analyzer-use-of-uninitialized-value" } */
typedef int __attribute__((__vector_size__(4))) T;
typedef unsigned __attribute__((__vector_size__(4))) U;
typedef unsigned __attribute__((__vector_size__(16))) V;
typedef unsigned long __attribute__((__vector_size__(16))) W;
U u;
T t;
void
foo(W w) {
U u = __builtin_shufflevector((V)w, u, 0);
t = (T){} + u + u;
foo((W){});
for (;;)
;
}