[gcc(refs/users/aoliva/heads/testme)] cselib: lookup mem addr during invalidation

[Alexandre Oliva]

https://gcc.gnu.org/g:32412f32c74a26a83ddc92649354f132102fff77

commit 32412f32c74a26a83ddc92649354f132102fff77
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Thu Nov 27 22:28:53 2025 -0300

    cselib: lookup mem addr during invalidation
    
    When processing stores for e.g. parameters passed on the stack, as in
    gcc.dg/pr117239.c, each store invalidates other stores pertaining to
    the same argument, because we can tell they refer to the same object,
    but not that the offsets don't overlap.  The reason for that is that
    the mem_rtx being invalidated is canonicalized to an SP offset, while
    those in the cselib table have canonical values as addresses, and
    alias.cc can't resolve SP to values to compare the offsets.
    
    With this change, pr117239.c doesn't require -fschedule-insns to fail,
    with the PR117239 fixes reverted.
    
    
    While at that, rework dump_cselib_table to not crash when
    cselib_preserved_hash_table is not allocated, and to remove the
    extraneous indirection from dump_cselib_val that made it inconvenient
    to call from a debugger.
    
    
    for  gcc/ChangeLog
    
            * cselib.cc (cselib_invalidate_mem): Lookup the address as
            part of canonicalizing it.
            (dump_cselib_val): Split out of and rename to...
            (dump_cselib_val_ptr): ... this.
            (dump_cselib_table): Adjust.

Diff:
---
 gcc/cselib.cc | 31 +++++++++++++++++++++++++------
 1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/gcc/cselib.cc b/gcc/cselib.cc
index 7f1991b09c3c..c6628abf2a98 100644
--- a/gcc/cselib.cc
+++ b/gcc/cselib.cc
@@ -2623,6 +2623,14 @@ cselib_invalidate_mem (rtx mem_rtx)
   rtx mem_addr;
 
   mem_addr = canon_rtx (get_addr (XEXP (mem_rtx, 0)));
+  /* Resolve MEM_ADDR to a VALUE_RTX, so that canon_anti_dependence can compare
+     offsets from the same base, even for SP-based addresses.  */
+  if ((v = cselib_lookup (mem_addr, GET_MODE (mem_addr),
+			  0, GET_MODE (mem_rtx))))
+    {
+      mem_addr = v->val_rtx;
+      mem_rtx = replace_equiv_address_nv (mem_rtx, mem_addr);
+    }
   mem_rtx = canon_rtx (mem_rtx);
 
   vp = &first_containing_mem;
@@ -3459,12 +3467,11 @@ cselib_finish (void)
   next_uid = 0;
 }
 
-/* Dump the cselib_val *X to FILE *OUT.  */
+/* Dump the cselib_val V to FILE *OUT.  */
 
 int
-dump_cselib_val (cselib_val **x, FILE *out)
+dump_cselib_val (cselib_val *v, FILE *out)
 {
-  cselib_val *v = *x;
   bool need_lf = true;
 
   print_inline_rtx (out, v->val_rtx, 0);
@@ -3533,15 +3540,27 @@ dump_cselib_val (cselib_val **x, FILE *out)
   return 1;
 }
 
+/* Dump the cselib_val *X to FILE *OUT.  */
+
+static int
+dump_cselib_val_ptr (cselib_val **x, FILE *out)
+{
+  cselib_val *v = *x;
+  return dump_cselib_val (v, out);
+}
+
 /* Dump to OUT everything in the CSELIB table.  */
 
 void
 dump_cselib_table (FILE *out)
 {
   fprintf (out, "cselib hash table:\n");
-  cselib_hash_table->traverse <FILE *, dump_cselib_val> (out);
-  fprintf (out, "cselib preserved hash table:\n");
-  cselib_preserved_hash_table->traverse <FILE *, dump_cselib_val> (out);
+  cselib_hash_table->traverse <FILE *, dump_cselib_val_ptr> (out);
+  if (cselib_preserved_hash_table)
+    {
+      fprintf (out, "cselib preserved hash table:\n");
+      cselib_preserved_hash_table->traverse <FILE *, dump_cselib_val_ptr> (out);
+    }
   if (first_containing_mem != &dummy_val)
     {
       fputs ("first mem ", out);