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| author | James Greenhalgh <james.greenhalgh@arm.com> | 2017-12-12 11:27:54 +0000 |
|---|---|---|
| committer | James Greenhalgh <jgreenhalgh@gcc.gnu.org> | 2017-12-12 11:27:54 +0000 |
| commit | c5060cadf030f6517a1552bf0fc263cb03eb96c4 (patch) | |
| tree | 1ef03d795f5e00306bb2200aa40cf082fc59bb06 /gcc/combine.c | |
| parent | 49e6a6c023d1b91c90d3fbdf16adf20dff246156 (diff) | |
| download | gcc-c5060cadf030f6517a1552bf0fc263cb03eb96c4.zip gcc-c5060cadf030f6517a1552bf0fc263cb03eb96c4.tar.gz gcc-c5060cadf030f6517a1552bf0fc263cb03eb96c4.tar.bz2 | |
[Patch combine] Don't create vector mode ZERO_EXTEND from subregs
The code in simplify set to handle transforming the paradoxical subreg
expression:
(set FOO (subreg:M (mem:N BAR) 0))
in to:
(set FOO (zero_extend:M (mem:N BAR)))
Does not consider the case where M is a vector mode, allowing it to
construct (for example):
(zero_extend:V4SI (mem:SI))
For one, this has the wrong semantics - but fortunately we fail long
before then in expand_compound_operation.
We need to explicitly reject vector modes from this transformation.
gcc/
* combine.c (simplify_set): Do not transform subregs to zero_extends
if the destination mode is a vector mode.
From-SVN: r255578
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index f4e9445..b6410c3 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -6962,11 +6962,13 @@ simplify_set (rtx x) /* If we have (set FOO (subreg:M (mem:N BAR) 0)) with M wider than N, this would require a paradoxical subreg. Replace the subreg with a - zero_extend to avoid the reload that would otherwise be required. */ + zero_extend to avoid the reload that would otherwise be required. + Don't do this for vector modes, as the transformation is incorrect. */ enum rtx_code extend_op; if (paradoxical_subreg_p (src) && MEM_P (SUBREG_REG (src)) + && !VECTOR_MODE_P (GET_MODE (src)) && (extend_op = load_extend_op (GET_MODE (SUBREG_REG (src)))) != UNKNOWN) { SUBST (SET_SRC (x), |