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| author | John Carr <jfc@mit.edu> | 1998-02-01 01:49:32 +0000 |
|---|---|---|
| committer | Jeff Law <law@gcc.gnu.org> | 1998-01-31 18:49:32 -0700 |
| commit | 6e0ef100dad74b006895619fbaf1fac7aeff06ee (patch) | |
| tree | 82fd0412e3cc32ed274e427aafbfb4113ea2baa2 /gcc/combine.c | |
| parent | 8821a725d65a1509cb76153f32e4bdcddb4a30dc (diff) | |
| download | gcc-6e0ef100dad74b006895619fbaf1fac7aeff06ee.zip gcc-6e0ef100dad74b006895619fbaf1fac7aeff06ee.tar.gz gcc-6e0ef100dad74b006895619fbaf1fac7aeff06ee.tar.bz2 | |
combine.c (simplify_shift_const): (lshiftrt (truncate (lshiftrt))) is (truncate (lshiftrt)).
* combine.c (simplify_shift_const): (lshiftrt (truncate (lshiftrt)))
is (truncate (lshiftrt)).
From-SVN: r17570
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index 3bcea7d..017cf12 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -8787,6 +8787,28 @@ simplify_shift_const (x, code, result_mode, varop, count) continue; } break; + + case TRUNCATE: + /* Change (lshiftrt (truncate (lshiftrt))) to (truncate (lshiftrt)) + if the truncate does not affect the value. */ + if (code == LSHIFTRT + && GET_CODE (XEXP (varop, 0)) == LSHIFTRT + && GET_CODE (XEXP (XEXP (varop, 0), 1)) == CONST_INT + && (INTVAL (XEXP (XEXP (varop, 0), 1)) + >= (GET_MODE_BITSIZE (GET_MODE (XEXP (varop, 0))) - GET_MODE_BITSIZE (varop)))) + { + rtx varop_inner = XEXP (varop, 0); + + varop_inner = gen_rtx_combine (LSHIFTRT, + GET_MODE (varop_inner), + XEXP (varop_inner, 0), + GEN_INT (count + INTVAL (XEXP (varop_inner, 1)))); + varop = gen_rtx_combine (TRUNCATE, GET_MODE (varop), + varop_inner); + count = 0; + continue; + } + break; default: break; |