middle-end/105376 - invalid REAL_CST for DFP constant
Commit Message
We are eventually ICEing in decimal_to_decnumber on non-decimal
REAL_VALUE_TYPE that creep in from uses of build_real (..., dconst*)
for DFP types. The following extends the decimal_to_decnumber
special-casing of dconst* to build_real, avoiding the bogus REAL_CSTs
from creeping into the IL and modified to ones not handled by
the decimal_to_decnumber special casing. It also makes sure to
ICE for not handled dconst* values at the point we build the REAL_CST.
Bootstrapped and tested on x86_64-unknown-linux-gnu, OK for stage1
and eventual backporting (I'm considering making the gcc_unreachable
conditional on flag_checking on release branches).
Thanks,
Richard.
2022-04-27 Richard Biener <rguenther@suse.de>
PR middle-end/105376
* tree.cc (build_real): Special case dconst* arguments
for decimal floating point types.
* gcc.dg/pr105376.c: New testcase.
---
gcc/testsuite/gcc.dg/pr105376.c | 9 +++++++++
gcc/tree.cc | 21 +++++++++++++++++++++
2 files changed, 30 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/pr105376.c
Comments
On Thu, 28 Apr 2022, Richard Biener via Gcc-patches wrote:
> We are eventually ICEing in decimal_to_decnumber on non-decimal
> REAL_VALUE_TYPE that creep in from uses of build_real (..., dconst*)
> for DFP types. The following extends the decimal_to_decnumber
> special-casing of dconst* to build_real, avoiding the bogus REAL_CSTs
> from creeping into the IL and modified to ones not handled by
> the decimal_to_decnumber special casing. It also makes sure to
> ICE for not handled dconst* values at the point we build the REAL_CST.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu, OK for stage1
> and eventual backporting (I'm considering making the gcc_unreachable
> conditional on flag_checking on release branches).
OK.
new file mode 100644
@@ -0,0 +1,9 @@
+/* { dg-do compile { target dfp } } */
+/* { dg-options "-O -g" } */
+
+void
+foo (_Decimal64 d, _Decimal64 e)
+{
+ d -= -d;
+ d *= -e;
+}
@@ -70,6 +70,7 @@ along with GCC; see the file COPYING3. If not see
#include "escaped_string.h"
#include "gimple-range.h"
#include "gomp-constants.h"
+#include "dfp.h"
/* Tree code classes. */
@@ -2383,6 +2384,26 @@ build_real (tree type, REAL_VALUE_TYPE d)
REAL_VALUE_TYPE *dp;
int overflow = 0;
+ /* dconst{1,2,m1,half} are used in various places in
+ the middle-end and optimizers, allow them here
+ even for decimal floating point types as an exception
+ by converting them to decimal. */
+ if (DECIMAL_FLOAT_MODE_P (TYPE_MODE (type))
+ && d.cl == rvc_normal
+ && !d.decimal)
+ {
+ if (memcmp (&d, &dconst1, sizeof (d)) == 0)
+ decimal_real_from_string (&d, "1");
+ else if (memcmp (&d, &dconst2, sizeof (d)) == 0)
+ decimal_real_from_string (&d, "2");
+ else if (memcmp (&d, &dconstm1, sizeof (d)) == 0)
+ decimal_real_from_string (&d, "-1");
+ else if (memcmp (&d, &dconsthalf, sizeof (d)) == 0)
+ decimal_real_from_string (&d, "0.5");
+ else
+ gcc_unreachable ();
+ }
+
/* ??? Used to check for overflow here via CHECK_FLOAT_TYPE.
Consider doing it via real_convert now. */