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| author | Eric Botcazou <ebotcazou@gcc.gnu.org> | 2004-02-28 07:33:10 +0000 |
|---|---|---|
| committer | Eric Botcazou <ebotcazou@gcc.gnu.org> | 2004-02-28 07:33:10 +0000 |
| commit | 68a1a5da2b17865bb90a28ba13a117092b82b608 (patch) | |
| tree | b0b51a7b4b105517f87b91d4760b368e2419d4b7 /gcc/fold-const.c | |
| parent | a10016d3b08ca2318ff1ce9e35ac5d9e0124d965 (diff) | |
| download | gcc-68a1a5da2b17865bb90a28ba13a117092b82b608.zip gcc-68a1a5da2b17865bb90a28ba13a117092b82b608.tar.gz gcc-68a1a5da2b17865bb90a28ba13a117092b82b608.tar.bz2 | |
fold-const.c (fold): Strip NOPs that change the signedness for RSHIFT too.
* fold-const.c (fold): Strip NOPs that change the signedness
for RSHIFT too. Expand comment.
From-SVN: r78603
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 9178a344..04452de 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -5423,14 +5423,20 @@ fold (tree expr) if (op == 0) continue; /* Valid for CALL_EXPR, at least. */ - if (kind == '<' || code == RSHIFT_EXPR) - { - /* Signedness matters here. Perhaps we can refine this - later. */ - STRIP_SIGN_NOPS (op); - } + /* Strip any conversions that don't change the mode. This is + safe for every expression, except for a comparison expression + because its signedness is derived from its operands. So, in + the latter case, only strip conversions that don't change the + signedness. + + Note that this is done as an internal manipulation within the + constant folder, in order to find the simplest representation + of the arguments so that their form can be studied. In any + cases, the appropriate type conversions should be put back in + the tree that will get out of the constant folder. */ + if (kind == '<') + STRIP_SIGN_NOPS (op); else - /* Strip any conversions that don't change the mode. */ STRIP_NOPS (op); if (TREE_CODE (op) == COMPLEX_CST) |