[gcc r16-1284] cselim: change how to detect no load/stores after store in single_trailing_store_in_bb

[Andrew Pinski via Gcc-cvs]

https://gcc.gnu.org/g:4f88f1593fac1f9b32045f7d97170913f93986f6

commit r16-1284-g4f88f1593fac1f9b32045f7d97170913f93986f6
Author: Andrew Pinski <quic_apin...@quicinc.com>
Date:   Fri Jun 6 11:07:57 2025 -0700

    cselim: change how to detect no load/stores after store in 
single_trailing_store_in_bb
    
    So the current code iterates through the uses of the vdef of the store to 
see if there
    is an use of the vdef inside the bb. Except in this case we know the only 
usage will
    be a phi node, so change the loop into calling single_imm_use and then 
checking if the
    usage statement was the PHI node.
    
    Bootstrapped and tested on x86_64-linux-gnu.
    
    Also did a quick test by adding a return false after the checks of 
single_trailing_store_in_bb
    in cond_if_else_store_replacement to make sure this code still does the 
correct thing.
    
    gcc/ChangeLog:
    
            * tree-ssa-phiopt.cc (single_trailing_store_in_bb): Add vphi 
argument.
            Check for single use of the vdef of the store instead of a loop
            and check vdef's single use statement is the same as vphi.
            (cond_if_else_store_replacement): Update call to 
single_trailing_store_in_bb.
    
    Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>

Diff:
---
 gcc/tree-ssa-phiopt.cc | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index 381c048fc3d5..1e770cb0e805 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -3708,10 +3708,11 @@ cond_if_else_store_replacement_1 (basic_block then_bb, 
basic_block else_bb,
 }
 
 /* Return the single store in BB with VDEF or NULL if there are
-   other stores in the BB or loads following the store.  */
+   other stores in the BB or loads following the store. VPHI is
+   where the only use of the vdef should be.  */
 
 static gimple *
-single_trailing_store_in_bb (basic_block bb, tree vdef)
+single_trailing_store_in_bb (basic_block bb, tree vdef, gphi *vphi)
 {
   if (SSA_NAME_IS_DEFAULT_DEF (vdef))
     return NULL;
@@ -3726,13 +3727,14 @@ single_trailing_store_in_bb (basic_block bb, tree vdef)
       && gimple_code (SSA_NAME_DEF_STMT (gimple_vuse (store))) != GIMPLE_PHI)
     return NULL;
 
-  /* Verify there is no load or store after the store.  */
+  /* Verify there is no load or store after the store, the vdef of the store
+     should only be used by the vphi joining the 2 bbs.  */
   use_operand_p use_p;
-  imm_use_iterator imm_iter;
-  FOR_EACH_IMM_USE_FAST (use_p, imm_iter, gimple_vdef (store))
-    if (USE_STMT (use_p) != store
-       && gimple_bb (USE_STMT (use_p)) == bb)
-      return NULL;
+  gimple *use_stmt;
+  if (!single_imm_use (gimple_vdef (store), &use_p, &use_stmt))
+    return NULL;
+  if (use_stmt != vphi)
+    return NULL;
 
   return store;
 }
@@ -3778,10 +3780,10 @@ cond_if_else_store_replacement (basic_block then_bb, 
basic_block else_bb,
     return false;
   tree then_vdef = PHI_ARG_DEF_FROM_EDGE (vphi, single_succ_edge (then_bb));
   tree else_vdef = PHI_ARG_DEF_FROM_EDGE (vphi, single_succ_edge (else_bb));
-  gimple *then_assign = single_trailing_store_in_bb (then_bb, then_vdef);
+  gimple *then_assign = single_trailing_store_in_bb (then_bb, then_vdef, vphi);
   if (then_assign)
     {
-      gimple *else_assign = single_trailing_store_in_bb (else_bb, else_vdef);
+      gimple *else_assign = single_trailing_store_in_bb (else_bb, else_vdef, 
vphi);
       if (else_assign)
        return cond_if_else_store_replacement_1 (then_bb, else_bb, join_bb,
                                                 then_assign, else_assign, 
vphi);