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| author | Jakub Jelinek <jakub@redhat.com> | 2022-04-28 12:33:59 +0200 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2022-04-28 12:33:59 +0200 |
| commit | 89dbf9a5f55e0f7565865d1b38e681ef7d76afaf (patch) | |
| tree | e54771b4494e2b4a7f0eedb788597b67b1c14be2 | |
| parent | 8094526109034c6c6af44de47612e97319b2c7c5 (diff) | |
| download | gcc-89dbf9a5f55e0f7565865d1b38e681ef7d76afaf.zip gcc-89dbf9a5f55e0f7565865d1b38e681ef7d76afaf.tar.gz gcc-89dbf9a5f55e0f7565865d1b38e681ef7d76afaf.tar.bz2 | |
i386: Fix up ix86_gimplify_va_arg [PR105331]
On the following testcase we emit a bogus
'va_arg_tmp.5' may be used uninitialized
warning. The reason is that when gimplifying the addr = &temp;
statement, the va_arg_tmp temporary var for which we emit ADDR_EXPR
is not TREE_ADDRESSABLE, prepare_gimple_addressable emits some extra
code to initialize the newly addressable var from its previous value,
but it is a new variable which hasn't been initialized yet and will
be later, so we end up initializing it with uninitialized SSA_NAME:
va_arg_tmp.6 = va_arg_tmp.5_14(D);
addr.2_16 = &va_arg_tmp.6;
_17 = MEM[(double *)sse_addr.4_13];
MEM[(double * {ref-all})addr.2_16] = _17;
and with -O1 we actually don't DSE it before the warning is emitted.
If we make the temp TREE_ADDRESSABLE before the gimplification, then
this prepare_gimple_addressable path isn't taken and we effectively
omit the first statement above and so the bogus warning is gone.
I went through other backends and didn't find another instance of this
problem.
2022-04-28 Jakub Jelinek <jakub@redhat.com>
PR target/105331
* config/i386/i386.cc (ix86_gimplify_va_arg): Mark va_arg_tmp
temporary TREE_ADDRESSABLE before trying to gimplify ADDR_EXPR
of it.
* gcc.dg/pr105331.c: New test.
| -rw-r--r-- | gcc/config/i386/i386.cc | 1 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/pr105331.c | 11 |
2 files changed, 12 insertions, 0 deletions
diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc index 52040da..b16df5b 100644 --- a/gcc/config/i386/i386.cc +++ b/gcc/config/i386/i386.cc @@ -4891,6 +4891,7 @@ ix86_gimplify_va_arg (tree valist, tree type, gimple_seq *pre_p, { int i, prev_size = 0; tree temp = create_tmp_var (type, "va_arg_tmp"); + TREE_ADDRESSABLE (temp) = 1; /* addr = &temp; */ t = build1 (ADDR_EXPR, build_pointer_type (type), temp); diff --git a/gcc/testsuite/gcc.dg/pr105331.c b/gcc/testsuite/gcc.dg/pr105331.c new file mode 100644 index 0000000..06cf6d6 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr105331.c @@ -0,0 +1,11 @@ +/* PR target/105331 */ +/* { dg-do compile } */ +/* { dg-options "-O -Wuninitialized" } */ + +#include <stdarg.h> + +int +foo (va_list *va) +{ + return va_arg (*va, double _Complex); /* { dg-bogus "may be used uninitialized" } */ +} |