[PATCH] Restrict conditional SLSR candidates to CAND_MULTs
Bill Schmidt
wschmidt@linux.vnet.ibm.com
Tue May 7 18:12:00 GMT 2013
The intent of conditional candidate processing in SLSR was always to
apply it only to CAND_MULT candidates [(base + index) * stride].
However, I neglected to actually enforce this, leading to wrong code
generated for CAND_ADD candidates. This patch adds the restriction.
My previous "fix" wasn't sufficient; at the time I thought we were
handling CAND_ADD candidates improperly, when in reality we shouldn't
have been handling them at all. So this patch also backs out that
change, which becomes dead code with the CAND_MULT restriction.
I've verified this fixes the pr33017.c and vect-28.c tests. I haven't
yet reproduced the remaining Fortran problems, but I am hopeful that
this will fix those as well. If you see these have been fixed, please
let me know; otherwise I will work on reproducing them.
Bootstrapped and tested on powerpc64-unknown-linux-gnu, -m32/-m64, with
no new regressions. Ok for trunk?
Thanks,
Bill
2013-05-07 Bill Schmidt <wschmidt@linux.vnet.ibm.com>
* gimple-ssa-strength-reduction.c (find_phi_def): Revert former "fix."
(alloc_cand_and_find_basis): Restrict conditional candidate
processing to CAND_MULTs.
Index: gcc/gimple-ssa-strength-reduction.c
===================================================================
--- gcc/gimple-ssa-strength-reduction.c (revision 198682)
+++ gcc/gimple-ssa-strength-reduction.c (working copy)
@@ -415,32 +415,16 @@ cand_chain_hasher::equal (const value_type *chain1
static hash_table <cand_chain_hasher> base_cand_map;
/* Look in the candidate table for a CAND_PHI that defines BASE and
- return it if found; otherwise return NULL. GS is the candidate
- statement with BASE, INDEX, and STRIDE. If GS is a CAND_ADD with
- an index of 1 and an SSA name for STRIDE, we must be careful that
- we haven't commuted the operands for this candidate. STRIDE must
- correspond to the second addend of GS for the eventual transformation
- to be legal. If not, return NULL. */
+ return it if found; otherwise return NULL. */
static cand_idx
-find_phi_def (gimple gs, enum cand_kind kind, tree base,
- double_int index, tree stride)
+find_phi_def (tree base)
{
slsr_cand_t c;
if (TREE_CODE (base) != SSA_NAME)
return 0;
- /* If we've commuted the operands (so "y + z" is represented as
- "z + (1 * y)"), we don't have the pattern we're looking for.
- Bail out to avoid doing a wrong replacement downstream. */
- if (kind == CAND_ADD
- && index.is_one ()
- && TREE_CODE (stride) == SSA_NAME
- && gimple_assign_rhs_code (gs) == PLUS_EXPR
- && stride != gimple_assign_rhs2 (gs))
- return 0;
-
c = base_cand_from_table (base);
if (!c || c->kind != CAND_PHI)
@@ -583,7 +567,7 @@ alloc_cand_and_find_basis (enum cand_kind kind, gi
c->next_interp = 0;
c->dependent = 0;
c->sibling = 0;
- c->def_phi = find_phi_def (gs, kind, base, index, stride);
+ c->def_phi = kind == CAND_MULT ? find_phi_def (base) : 0;
c->dead_savings = savings;
cand_vec.safe_push (c);
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