| Message ID | 02cd01d7e1ef$b8b17570$2a146050$@nextmovesoftware.com |
|---|---|
| State | New |
| Headers | show |
| Series | PR middle-end/103406: Check for Inf before simplifying x-x. | expand |
On Thu, Nov 25, 2021 at 12:30 PM Roger Sayle <roger@nextmovesoftware.com> wrote: > > > This is a simple one line fix to the regression PR middle-end/103406, > where x - x is being folded to 0.0 even when x is +Inf or -Inf. > In GCC 11 and previously, we'd check whether the type honored NaNs > (which implicitly covered the case where the type honors infinities), > but my patch to test whether the operand could potentially be NaN > failed to also check whether the operand could potentially be Inf. > > This patch doesn't address the issue of NaN signedness from binary > arithmetic operations, just the regression. > > This patch has been tested on x86_64-pc-linux-gnu with make bootstrap > and make -k check with no new failures. Ok for mainline? OK. Thanks, Richard. > > 2021-11-25 Roger Sayle <roger@nextmovesoftware.com> > > gcc/ChangeLog > PR middle-end/103406 > * match.pd (minus @0 @0): Check tree_expr_maybe_infinite_p. > > gcc/testsuite/ChangeLog > PR middle-end/103406 > * gcc.dg/pr103406.c: New test case. > > Thanks in advance (and sorry for the inconvenience), > Roger > -- >
diff --git a/gcc/match.pd b/gcc/match.pd index f059b47..d28dfe2 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -232,7 +232,9 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) is volatile. */ (simplify (minus @0 @0) - (if (!FLOAT_TYPE_P (type) || !tree_expr_maybe_nan_p (@0)) + (if (!FLOAT_TYPE_P (type) + || (!tree_expr_maybe_nan_p (@0) + && !tree_expr_maybe_infinite_p (@0))) { build_zero_cst (type); })) (simplify (pointer_diff @@0 @0) diff --git a/gcc/testsuite/gcc.dg/pr103406.c b/gcc/testsuite/gcc.dg/pr103406.c new file mode 100644 index 0000000..9c7b83b --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr103406.c @@ -0,0 +1,14 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-optimized" } */ + +#define HUGE __DBL_MAX__ +#define INF (HUGE + HUGE) +#define NAN (INF - INF) + +double foo() { + double x = -NAN; + double y = NAN; + return x + y; +} + +/* { dg-final { scan-tree-dump-not "return 0\.0" "optimized" } } */