Hi,
found in slp-reduc-7.c, this patch prevents optimizing e.g.
COND_LEN_ADD ({-1, ... }, a, 0, c, len, bias)
unconditionally into just "a".
Currently, we assume that COND_LEN operations can be optimized similarly
to COND operations. As the length is part of the mask (and usually not
compile-time constant), we must not perform any optimization that relies
on just the mask being "true".
Bootstrap and testsuite are unchanged on aarch64 and x86.
Regards
Robin
gcc/ChangeLog:
* gimple-match-exports.cc (maybe_resimplify_conditional_op):
Check for length masking.
---
gcc/gimple-match-exports.cc | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/gcc/gimple-match-exports.cc b/gcc/gimple-match-exports.cc
index b36027b0bad..73be9f4f4c3 100644
--- a/gcc/gimple-match-exports.cc
+++ b/gcc/gimple-match-exports.cc
@@ -262,7 +262,8 @@ maybe_resimplify_conditional_op (gimple_seq *seq,
gimple_match_op *res_op,
if (!res_op->cond.cond)
return false;
- if (!res_op->cond.else_value
+ if (!res_op->cond.len
+ && !res_op->cond.else_value
&& res_op->code.is_tree_code ())
{
/* The "else" value doesn't matter. If the "then" value is a
@@ -301,9 +302,12 @@ maybe_resimplify_conditional_op (gimple_seq *seq,
gimple_match_op *res_op,
/* If the "then" value is a gimple value and the "else" value matters,
create a VEC_COND_EXPR between them, then see if it can be further
- simplified. */
+ simplified.
+ Don't do this if we have a COND_LEN_ as that would make us lose the
+ length masking. */
gimple_match_op new_op;
- if (res_op->cond.else_value
+ if (!res_op->cond.len
+ && res_op->cond.else_value
&& VECTOR_TYPE_P (res_op->type)
&& gimple_simplified_result_is_gimple_val (res_op))
{
@@ -314,7 +318,7 @@ maybe_resimplify_conditional_op (gimple_seq *seq,
gimple_match_op *res_op,
return gimple_resimplify3 (seq, res_op, valueize);
}
- /* Otherwise try rewriting the operation as an IFN_COND_* call.
+ /* Otherwise try rewriting the operation as an IFN_COND_(LEN_)* call.
Again, this isn't a simplification in itself, since it's what
RES_OP already described. */
if (convert_conditional_op (res_op, &new_op))
--
2.41.0
