* gcse.c (local_cprop_find_used_regs): New.

        (local_cprop_pass): Use it.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@62555 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9f89508..8898bea 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2003-02-07  Richard Henderson  <rth@redhat.com>
+
+       PR 9226
+        * gcse.c (local_cprop_find_used_regs): New.
+        (local_cprop_pass): Use it.
+
 2003-02-07  Fred Fish  <fnf@intrinsity.com>
 
        * mips-tfile.c (parse_def): Parenthesize assignments to fix

diff --git a/gcc/gcse.c b/gcc/gcse.c
index 3adaf5c..2cc7f0b 100644 (file)
--- a/gcc/gcse.c
+++ b/gcc/gcse.c
@@ -706,6 +706,7 @@ static void free_insn_expr_list_list        PARAMS ((rtx *));
 static void clear_modify_mem_tables    PARAMS ((void));
 static void free_modify_mem_tables     PARAMS ((void));
 static rtx gcse_emit_move_after                PARAMS ((rtx, rtx, rtx));
+static void local_cprop_find_used_regs PARAMS ((rtx *, void *));
 static bool do_local_cprop             PARAMS ((rtx, rtx, int, rtx*));
 static bool adjust_libcall_notes       PARAMS ((rtx, rtx, rtx, rtx*));
 static void local_cprop_pass           PARAMS ((int));
@@ -4258,6 +4259,53 @@ cprop_insn (insn, alter_jumps)
   return changed;
 }
 
+/* Like find_used_regs, but avoid recording uses that appear in
+   input-output contexts such as zero_extract or pre_dec.  This
+   restricts the cases we consider to those for which local cprop
+   can legitimately make replacements.  */
+
+static void
+local_cprop_find_used_regs (xptr, data)
+     rtx *xptr;
+     void *data;
+{
+  rtx x = *xptr;
+
+  if (x == 0)
+    return;
+
+  switch (GET_CODE (x))
+    {
+    case ZERO_EXTRACT:
+    case SIGN_EXTRACT:
+    case STRICT_LOW_PART:
+      return;
+
+    case PRE_DEC:
+    case PRE_INC:
+    case POST_DEC:
+    case POST_INC:
+    case PRE_MODIFY:
+    case POST_MODIFY:
+      /* Can only legitimately appear this early in the context of
+        stack pushes for function arguments, but handle all of the
+        codes nonetheless.  */
+      return;
+
+    case SUBREG:
+      /* Setting a subreg of a register larger than word_mode leaves
+        the non-written words unchanged.  */
+      if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) > BITS_PER_WORD)
+       return;
+      break;
+
+    default:
+      break;
+    }
+
+  find_used_regs (xptr, data);
+}
+  
 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
    their REG_EQUAL notes need updating.  */
 
@@ -4413,9 +4461,9 @@ local_cprop_pass (alter_jumps)
          do
            {
              reg_use_count = 0;
-             note_uses (&PATTERN (insn), find_used_regs, NULL);
+             note_uses (&PATTERN (insn), local_cprop_find_used_regs, NULL);
              if (note)
-               find_used_regs (&XEXP (note, 0), NULL);
+               local_cprop_find_used_regs (&XEXP (note, 0), NULL);
 
              for (reg_used = &reg_use_table[0]; reg_use_count > 0;
                   reg_used++, reg_use_count--)