[gcc r15-3633] Fix factor_out_conditional_operation heuristics for constants

[Andrew Pinski]

https://gcc.gnu.org/g:8ed8c342fba682286159f56d0e53a05db95762a0

commit r15-3633-g8ed8c342fba682286159f56d0e53a05db95762a0
Author: Andrew Pinski <quic_apinski@quicinc.com>
Date:   Wed Sep 11 22:10:53 2024 -0700

    Fix factor_out_conditional_operation heuristics for constants
    
    While working on a different patch, I noticed the heuristics were not
    doing the right thing if there was statements before the NOP/PREDICTs.
    (LABELS don't have other statements before them).
    
    This fixes that oversight which was added in r15-3334-gceda727dafba6e.
    
    Bootstrapped and tested on x86_64-linux-gnu.
    
    gcc/ChangeLog:
    
            * tree-ssa-phiopt.cc (factor_out_conditional_operation): Instead
            of just ignorning a NOP/PREDICT, skip over them before checking
            the heuristics.
    
    Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>

Diff:
---
 gcc/tree-ssa-phiopt.cc | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index 5710bc32e611..e5413e405722 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -332,15 +332,17 @@ factor_out_conditional_operation (edge e0, edge e1, gphi *phi,
 	{
 	  gsi = gsi_for_stmt (arg0_def_stmt);
 	  gsi_prev_nondebug (&gsi);
+	  /* Ignore nops, predicates and labels. */
+	  while (!gsi_end_p (gsi)
+		  && (gimple_code (gsi_stmt (gsi)) == GIMPLE_NOP
+		      || gimple_code (gsi_stmt (gsi)) == GIMPLE_PREDICT
+		      || gimple_code (gsi_stmt (gsi)) == GIMPLE_LABEL))
+	    gsi_prev_nondebug (&gsi);
+
 	  if (!gsi_end_p (gsi))
 	    {
 	      gimple *stmt = gsi_stmt (gsi);
-	      /* Ignore nops, predicates and labels. */
-	      if (gimple_code (stmt) == GIMPLE_NOP
-		  || gimple_code (stmt) == GIMPLE_PREDICT
-		  || gimple_code (stmt) == GIMPLE_LABEL)
-		;
-	      else if (gassign *assign = dyn_cast <gassign *> (stmt))
+	      if (gassign *assign = dyn_cast <gassign *> (stmt))
 		{
 		  tree lhs = gimple_assign_lhs (assign);
 		  enum tree_code ass_code