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| author | Ian Lance Taylor <iant@google.com> | 2007-02-01 16:43:20 +0000 |
|---|---|---|
| committer | Ian Lance Taylor <ian@gcc.gnu.org> | 2007-02-01 16:43:20 +0000 |
| commit | 0e6c5b58543978b3dc16cdfeb653df6997d4e800 (patch) | |
| tree | 8ba597196a731bc04276e1b1d25a8f8fd4ff95ea /gcc | |
| parent | c0d919fa35e2af4aedb4c0e50c73778795d3f0b4 (diff) | |
| download | gcc-0e6c5b58543978b3dc16cdfeb653df6997d4e800.zip gcc-0e6c5b58543978b3dc16cdfeb653df6997d4e800.tar.gz gcc-0e6c5b58543978b3dc16cdfeb653df6997d4e800.tar.bz2 | |
lower-subreg.c (simplify_gen_subreg_concatn): If we ask for the high part of a paradoxical subreg, return a constant zero.
* lower-subreg.c (simplify_gen_subreg_concatn): If we ask for the
high part of a paradoxical subreg, return a constant zero.
From-SVN: r121466
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/lower-subreg.c | 19 |
2 files changed, 23 insertions, 1 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 0a3ee33..a935ee4 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2007-02-01 Ian Lance Taylor <iant@google.com> + + * lower-subreg.c (simplify_gen_subreg_concatn): If we ask for the + high part of a paradoxical subreg, return a constant zero. + 2007-02-01 Zdenek Dvorak <dvorakz@suse.cz> * toplev.c (lang_dependent_init): Call init_set_costs. diff --git a/gcc/lower-subreg.c b/gcc/lower-subreg.c index 7227624..ce9cfc5 100644 --- a/gcc/lower-subreg.c +++ b/gcc/lower-subreg.c @@ -372,6 +372,8 @@ static rtx simplify_gen_subreg_concatn (enum machine_mode outermode, rtx op, enum machine_mode innermode, unsigned int byte) { + rtx ret; + /* We have to handle generating a SUBREG of a SUBREG of a CONCATN. If OP is a SUBREG of a CONCATN, then it must be a simple mode change with the same size and offset 0, or it must extract a @@ -405,9 +407,24 @@ simplify_gen_subreg_concatn (enum machine_mode outermode, rtx op, gcc_assert (op != NULL_RTX); gcc_assert (innermode == GET_MODE (op)); } + if (GET_CODE (op) == CONCATN) return simplify_subreg_concatn (outermode, op, byte); - return simplify_gen_subreg (outermode, op, innermode, byte); + + ret = simplify_gen_subreg (outermode, op, innermode, byte); + + /* If we see an insn like (set (reg:DI) (subreg:DI (reg:SI) 0)) then + resolve_simple_move will ask for the high part of the paradoxical + subreg, which does not have a value. Just return a zero. */ + if (ret == NULL_RTX + && GET_CODE (op) == SUBREG + && SUBREG_BYTE (op) == 0 + && (GET_MODE_SIZE (innermode) + > GET_MODE_SIZE (GET_MODE (SUBREG_REG (op))))) + return CONST0_RTX (outermode); + + gcc_assert (ret != NULL_RTX); + return ret; } /* Return whether we should resolve X into the registers into which it |