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analyzer: fix uninit false +ves reading from DECL_HARD_REGISTER [PR108968]

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gcc/analyzer/ChangeLog:
	PR analyzer/108968
	* region-model.cc (region_model::get_rvalue_1): Handle VAR_DECLs
	with a DECL_HARD_REGISTER by returning UNKNOWN.

gcc/testsuite/ChangeLog:
	PR analyzer/108968
	* gcc.dg/analyzer/uninit-pr108968-register.c: New test.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>
This commit is contained in:
David Malcolm 2023-03-02 14:01:19 -05:00
parent 4d82022bfd
commit 20bd258d0f
2 changed files with 17 additions and 1 deletions
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9
gcc/analyzer/region-model.cc
View file

@ -2203,9 +2203,16 @@ region_model::get_rvalue_1 (path_var pv, region_model_context *ctxt) const
return get_rvalue_for_bits (TREE_TYPE (expr), reg, bits, ctxt);
}
case SSA_NAME:
case VAR_DECL:
if (DECL_HARD_REGISTER (pv.m_tree))
{
/* If it has a hard register, it doesn't have a memory region
and can't be referred to as an lvalue. */
return m_mgr->get_or_create_unknown_svalue (TREE_TYPE (pv.m_tree));
}
/* Fall through. */
case PARM_DECL:
case SSA_NAME:
case RESULT_DECL:
case ARRAY_REF:
{

9
gcc/testsuite/gcc.dg/analyzer/uninit-pr108968-register.c Normal file
View file

@ -0,0 +1,9 @@
/* { dg-do compile { target x86_64-*-* } } */
#define STACK_SIZE 4096
struct cpu_info {};
struct cpu_info *get_cpu_info(void)
{
register unsigned long sp asm("rsp");
return (struct cpu_info *)((sp | (STACK_SIZE - 1)) + 1) - 1; /* { dg-bogus "use of uninitialized value 'sp'" } */
}