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| author | John Wehle <john@feith.com> | 2001-11-09 05:27:51 +0000 |
|---|---|---|
| committer | John Wehle <wehle@gcc.gnu.org> | 2001-11-09 05:27:51 +0000 |
| commit | 11b161d06979925862bcbaf1945a8a03a1272625 (patch) | |
| tree | 5ea49b0b7937215806e9fc55e17820acf7ca6a76 /gcc/fold-const.c | |
| parent | 702020d6585adb08b31c395ece13c9120d865549 (diff) | |
| download | gcc-11b161d06979925862bcbaf1945a8a03a1272625.zip gcc-11b161d06979925862bcbaf1945a8a03a1272625.tar.gz gcc-11b161d06979925862bcbaf1945a8a03a1272625.tar.bz2 | |
fold-const.c (lshift_double): Honor PREC.
* fold-const.c (lshift_double): Honor PREC.
(rshift_double): Likewise.
From-SVN: r46872
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 57 |
1 files changed, 49 insertions, 8 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 05be225..a60930b 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -383,6 +383,8 @@ lshift_double (l1, h1, count, prec, lv, hv, arith) HOST_WIDE_INT *hv; int arith; { + unsigned HOST_WIDE_INT signmask; + if (count < 0) { rshift_double (l1, h1, -count, prec, lv, hv, arith); @@ -412,6 +414,26 @@ lshift_double (l1, h1, count, prec, lv, hv, arith) | (l1 >> (HOST_BITS_PER_WIDE_INT - count - 1) >> 1)); *lv = l1 << count; } + + /* Sign extend all bits that are beyond the precision. */ + + signmask = -((prec > HOST_BITS_PER_WIDE_INT + ? (*hv >> (prec - HOST_BITS_PER_WIDE_INT - 1)) + : (*lv >> (prec - 1))) & 1); + + if (prec >= 2 * HOST_BITS_PER_WIDE_INT) + ; + else if (prec >= HOST_BITS_PER_WIDE_INT) + { + *hv &= ~((HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT)); + *hv |= signmask << (prec - HOST_BITS_PER_WIDE_INT); + } + else + { + *hv = signmask; + *lv &= ~((unsigned HOST_WIDE_INT) (-1) << prec); + *lv |= signmask << prec; + } } /* Shift the doubleword integer in L1, H1 right by COUNT places @@ -423,7 +445,7 @@ void rshift_double (l1, h1, count, prec, lv, hv, arith) unsigned HOST_WIDE_INT l1; HOST_WIDE_INT h1, count; - unsigned int prec ATTRIBUTE_UNUSED; + unsigned int prec; unsigned HOST_WIDE_INT *lv; HOST_WIDE_INT *hv; int arith; @@ -443,21 +465,40 @@ rshift_double (l1, h1, count, prec, lv, hv, arith) { /* Shifting by the host word size is undefined according to the ANSI standard, so we must handle this as a special case. */ - *hv = signmask; - *lv = signmask; + *hv = 0; + *lv = 0; } else if (count >= HOST_BITS_PER_WIDE_INT) { - *hv = signmask; - *lv = ((signmask << (2 * HOST_BITS_PER_WIDE_INT - count - 1) << 1) - | ((unsigned HOST_WIDE_INT) h1 >> (count - HOST_BITS_PER_WIDE_INT))); + *hv = 0; + *lv = (unsigned HOST_WIDE_INT) h1 >> (count - HOST_BITS_PER_WIDE_INT); } else { + *hv = (unsigned HOST_WIDE_INT) h1 >> count; *lv = ((l1 >> count) | ((unsigned HOST_WIDE_INT) h1 << (HOST_BITS_PER_WIDE_INT - count - 1) << 1)); - *hv = ((signmask << (HOST_BITS_PER_WIDE_INT - count)) - | ((unsigned HOST_WIDE_INT) h1 >> count)); + } + + /* Zero / sign extend all bits that are beyond the precision. */ + + if (count >= (HOST_WIDE_INT)prec) + { + *hv = signmask; + *lv = signmask; + } + else if ((prec - count) >= 2 * HOST_BITS_PER_WIDE_INT) + ; + else if ((prec - count) >= HOST_BITS_PER_WIDE_INT) + { + *hv &= ~((HOST_WIDE_INT) (-1) << (prec - count - HOST_BITS_PER_WIDE_INT)); + *hv |= signmask << (prec - count - HOST_BITS_PER_WIDE_INT); + } + else + { + *hv = signmask; + *lv &= ~((unsigned HOST_WIDE_INT) (-1) << (prec - count)); + *lv |= signmask << (prec - count); } } |