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| author | jakub <jakub@138bc75d-0d04-0410-961f-82ee72b054a4> | 2013-05-04 12:41:52 +0000 |
|---|---|---|
| committer | jakub <jakub@138bc75d-0d04-0410-961f-82ee72b054a4> | 2013-05-04 12:41:52 +0000 |
| commit | fd304a932522a0d854fbe316429753f001e5b7de (patch) | |
| tree | 268423f878efbc6f96e2577bc8b63cfd72fe0f6a /gcc/combine.c | |
| parent | 36c30f9e6ff19c50712b8635e83d8f5caefc5f49 (diff) | |
| download | gcc-fd304a932522a0d854fbe316429753f001e5b7de.tar.gz | |
* combine.c (combine_simplify_rtx) <case SUBREG>: If nonzero_bits
on op shows all bits zero in mode of a lowpart subreg, return zero.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@198595 138bc75d-0d04-0410-961f-82ee72b054a4
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index 0792ba3b6f4..b737bc5529f 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -5417,6 +5417,17 @@ combine_simplify_rtx (rtx x, enum machine_mode op0_mode, int in_dest, SUBREG_BYTE (x)); if (temp) return temp; + + /* If op is known to have all lower bits zero, the result is zero. */ + if (!in_dest + && SCALAR_INT_MODE_P (mode) + && SCALAR_INT_MODE_P (op0_mode) + && GET_MODE_PRECISION (mode) < GET_MODE_PRECISION (op0_mode) + && subreg_lowpart_offset (mode, op0_mode) == SUBREG_BYTE (x) + && HWI_COMPUTABLE_MODE_P (op0_mode) + && (nonzero_bits (SUBREG_REG (x), op0_mode) + & GET_MODE_MASK (mode)) == 0) + return CONST0_RTX (mode); } /* Don't change the mode of the MEM if that would change the meaning |