[Bug rtl-optimization/117191] [avr][dse2][lra] wrong dead store elimination

[denisc at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117191

--- Comment #8 from denisc at gcc dot gnu.org ---
I forgot to add condition for "except those that refer to the return value"

The patch:

diff --git a/gcc/lra-spills.cc b/gcc/lra-spills.cc
index c149c3388cd..2f86ec0026c 100644
--- a/gcc/lra-spills.cc
+++ b/gcc/lra-spills.cc
@@ -741,10 +741,20 @@ lra_final_code_change (void)
              delete_insn (insn);
              continue;
            }
-         if (GET_CODE (pat) == CLOBBER && LRA_TEMP_CLOBBER_P (pat))
+         if (GET_CODE (pat) == CLOBBER
+             && (LRA_TEMP_CLOBBER_P (pat)
+                 || ((!MEM_P (XEXP (pat, 0))
+                      || GET_MODE (XEXP (pat, 0)) != BLKmode
+                      || (GET_CODE (XEXP (XEXP (pat, 0), 0)) != SCRATCH
+                          && XEXP (XEXP (pat, 0), 0) != stack_pointer_rtx))
+                     && (!REG_P (XEXP (pat, 0))
+                         || !REG_FUNCTION_VALUE_P (XEXP (pat, 0))))))
            {
-             /* Remove clobbers temporarily created in LRA.  We don't
-                need them anymore and don't want to waste compiler
+             /* Remove clobbers temporarily created in LRA and clobbers with
+                registers spilled to memory except those that refer to the
+                return value and the special mem:BLK CLOBBERs added to prevent
+                the scheduler from misarranging variable-array code.
+                We don't need them anymore and don't want to waste compiler
                 time processing them in a few subsequent passes.  */
              lra_invalidate_insn_data (insn);
              delete_insn (insn);