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| author | Roger Sayle <roger@nextmovesoftware.com> | 2022-03-12 09:20:52 +0000 |
|---|---|---|
| committer | Roger Sayle <roger@nextmovesoftware.com> | 2022-03-12 09:20:52 +0000 |
| commit | 72c243017dee611bf3c32ea7bfad6ac538021aaf (patch) | |
| tree | 29fdccad56796b5a6ffd64e9312a9a999448b6fd /gcc/cp/constexpr.cc | |
| parent | 3cb27b85a7b977958d53e1a29596ba211d21dde2 (diff) | |
| download | gcc-72c243017dee611bf3c32ea7bfad6ac538021aaf.zip gcc-72c243017dee611bf3c32ea7bfad6ac538021aaf.tar.gz gcc-72c243017dee611bf3c32ea7bfad6ac538021aaf.tar.bz2 | |
PR middle-end/98420: Don't fold x - x to 0.0 with -frounding-math
This patch addresses PR middle-end/98420, which is inappropriate constant
folding of x - x to 0.0 (in match.pd) when -frounding-math is specified.
Specifically, x - x may be -0.0 with FE_DOWNWARD as the rounding mode.
To summarize, the desired IEEE behaviour, x - x for floating point x,
(1) can't be folded to 0.0 by default, due to the possibility of NaN or Inf
(2) can be folded to 0.0 with -ffinite-math-only
(3) can't be folded to 0.0 with -ffinite-math-only -frounding-math
(4) can be folded with -ffinite-math-only -frounding-math -fno-signed-zeros
2022-03-12 Roger Sayle <roger@nextmovesoftware.com>
gcc/ChangeLog
PR middle-end/98420
* match.pd (minus @0 @0): Additional checks for -fno-rounding-math
(the defaut) or -fno-signed-zeros.
gcc/testsuite/ChangeLog
PR middle-end/98420
* gcc.dg/pr98420.c: New test case.
Diffstat (limited to 'gcc/cp/constexpr.cc')
0 files changed, 0 insertions, 0 deletions