[PR107608,range-ops] Avoid folding into INF when flag_trapping_math.
Commit Message
As discussed in the PR, for trapping math, do not fold overflowing
operations into +-INF as doing so could elide a trap.
There is a minor adjustment to known_isinf() where it was mistakenly
returning true for an [infinity U NAN], whereas it should only return
true when the range is exclusively +INF or -INF. This is benign, as
there were no users of known_isinf up to now.
I had some testsuite issues with:
> FAIL: c-c++-common/diagnostic-format-sarif-file-4.c -std=gnu++14 scan-sarif-file "text": " int \\\\u6587\\\\u5b57\\\\u5316\\\\u3051 =
> FAIL: c-c++-common/diagnostic-format-sarif-file-4.c -std=gnu++17 scan-sarif-file "text": " int \\\\u6587\\\\u5b57\\\\u5316\\\\u3051 =
> FAIL: c-c++-common/diagnostic-format-sarif-file-4.c -std=gnu++20 scan-sarif-file "text": " int \\\\u6587\\\\u5b57\\\\u5316\\\\u3051 =
> FAIL: c-c++-common/diagnostic-format-sarif-file-4.c -std=gnu++98 scan-sarif-file "text": " int \\\\u6587\\\\u5b57\\\\u5316\\\\u3051 =
> FAIL: g++.dg/pr71488.C (test for excess errors)
> FAIL: g++.dg/guality/pr55665.C -O2 -flto -fno-use-linker-plugin -flto-partition=none line 23 p == 40
> FAIL: c-c++-common/diagnostic-format-sarif-file-4.c -Wc++-compat scan-sarif-file "text": " int \\\\u6587\\\\u5b57\\\\u5316\\\\u3051 =
< FAIL: g++.dg/pr71488.C (test for excess errors)
< FAIL: g++.dg/guality/pr55665.C -O2 -flto -fno-use-linker-plugin -flto-partition=none line 23 p == 40
> FAIL: ./index0-out.go execution, -O0 -g -fno-var-tracking-assignments
> FAIL: go.test/test/fixedbugs/issue27836.dir/Äfoo.go -O -I. (test for excess errors)
> FAIL: go.test/test/fixedbugs/issue27836.dir/Ämain.go -O -I. (test for excess errors)
But they seem to be transient issues on my machine, as re-running them
manually don't cause any issues. Also, the tests themselves have
nothing to do with floats so I don't see how they could be related.
Tested on x86-64 Linux.
I also ran the glibc testsuite (git sources) on x86-64 and this patch
fixes:
-FAIL: math/test-double-lgamma
-FAIL: math/test-double-log1p
-FAIL: math/test-float-lgamma
-FAIL: math/test-float-log1p
-FAIL: math/test-float128-catan
-FAIL: math/test-float128-catanh
-FAIL: math/test-float128-lgamma
-FAIL: math/test-float128-log
-FAIL: math/test-float128-log1p
-FAIL: math/test-float128-y0
-FAIL: math/test-float128-y1
-FAIL: math/test-float32-lgamma
-FAIL: math/test-float32-log1p
-FAIL: math/test-float32x-lgamma
-FAIL: math/test-float32x-log1p
-FAIL: math/test-float64-lgamma
-FAIL: math/test-float64-log1p
-FAIL: math/test-float64x-lgamma
-FAIL: math/test-ldouble-lgamma
OK for trunk?
PR tree-optimization/107608
gcc/ChangeLog:
* range-op-float.cc (range_operator_float::fold_range): Avoid
folding into INF when flag_trapping_math.
* value-range.h (frange::known_isinf): Return false for possible NANs.
---
gcc/range-op-float.cc | 21 +++++++++++++++++++++
gcc/value-range.h | 1 +
2 files changed, 22 insertions(+)
@@ -91,6 +91,27 @@ range_operator_float::fold_range (frange &r, tree type,
else
r.clear_nan ();
+ // If the result has overflowed and flag_trapping_math, folding this
+ // operation could elide an overflow or division by zero exception.
+ // Avoid returning a singleton +-INF, to keep the propagators (DOM
+ // and substitute_and_fold_engine) from folding. See PR107608.
+ if (flag_trapping_math
+ && MODE_HAS_INFINITIES (TYPE_MODE (type))
+ && r.known_isinf () && !op1.known_isinf () && !op2.known_isinf ())
+ {
+ REAL_VALUE_TYPE inf = r.lower_bound ();
+ if (real_isneg (&inf))
+ {
+ REAL_VALUE_TYPE min = real_min_representable (type);
+ r.set (type, inf, min);
+ }
+ else
+ {
+ REAL_VALUE_TYPE max = real_max_representable (type);
+ r.set (type, max, inf);
+ }
+ }
+
return true;
}
@@ -1300,6 +1300,7 @@ inline bool
frange::known_isinf () const
{
return (m_kind == VR_RANGE
+ && !maybe_isnan ()
&& real_identical (&m_min, &m_max)
&& real_isinf (&m_min));
}