toplev.c (rest_of_compilation): Call purge_hard_subreg_sets to remove all SETs of SUBREGs of hard registers.

2000-09-15  Andrew Haley  <aph@redhat.com>

        * toplev.c (rest_of_compilation): Call purge_hard_subreg_sets to
        remove all SETs of SUBREGs of hard registers.
        * function.c (purge_hard_subreg_sets): New function.
        (purge_single_hard_subreg_set): New function.
        * rtl.h: (purge_hard_subreg_sets): New function.

From-SVN: r36511

4 files changed, 82 insertions, 4 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 4c0edc7..4e99ee9 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2000-09-15  Andrew Haley  <aph@redhat.com>
+
+	* toplev.c (rest_of_compilation): Call purge_hard_subreg_sets to
+	remove all SETs of SUBREGs of hard registers.
+ 	* function.c (purge_hard_subreg_sets): New function.
+	(purge_single_hard_subreg_set): New function.
+	* rtl.h: (purge_hard_subreg_sets): New function.
+
 2000-09-18  Richard Henderson  <rth@cygnus.com>
 
 	* config/ia64/ia64-protos.h: Update.
diff --git a/gcc/function.c b/gcc/function.c
index 6a9bdc9..969887f 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -294,6 +294,7 @@ static void emit_return_into_block PARAMS ((basic_block, rtx));
 static void put_addressof_into_stack PARAMS ((rtx, struct hash_table *));
 static boolean purge_addressof_1 PARAMS ((rtx *, rtx, int, int,
 					  struct hash_table *));
+static void purge_single_hard_subreg_set PARAMS ((rtx));
 #ifdef HAVE_epilogue
 static void keep_stack_depressed PARAMS ((rtx));
 #endif
@@ -3393,6 +3394,71 @@ purge_addressof (insns)
   unshare_all_rtl_again (get_insns ());
 }
 
+/* Convert a SET of a hard subreg to a set of the appropriet hard
+   register.  A subroutine of purge_hard_subreg_sets.  */
+
+static void
+purge_single_hard_subreg_set (pattern)
+     rtx pattern;
+{
+  rtx reg = SET_DEST (pattern);
+  enum machine_mode mode = GET_MODE (SET_DEST (pattern));
+  int word = 0;
+		  
+  while (GET_CODE (reg) == SUBREG)
+    {
+      word += SUBREG_WORD (reg);
+      reg = SUBREG_REG (reg);
+    }
+	      
+  if (REGNO (reg) < FIRST_PSEUDO_REGISTER)
+    {
+      reg = gen_rtx_REG (mode, REGNO (reg) + word);
+      SET_DEST (pattern) = reg;
+    }
+}
+
+/* Eliminate all occurrences of SETs of hard subregs from INSNS.  The
+   only such SETs that we expect to see are those left in because
+   integrate can't handle sets of parts of a return value register.
+
+   We don't use alter_subreg because we only want to eliminate subregs
+   of hard registers.  */
+
+void
+purge_hard_subreg_sets (insn)
+     rtx insn;
+{
+  for (; insn; insn = NEXT_INSN (insn))
+    {
+      if (INSN_P (insn))
+	{
+	  rtx pattern = PATTERN (insn);
+	  switch (GET_CODE (pattern))
+	    {
+	    case SET:
+	      if (GET_CODE (SET_DEST (pattern)) == SUBREG)
+		purge_single_hard_subreg_set (pattern);
+	      break;	      
+	    case PARALLEL:
+	      {
+		int j;
+		for (j = XVECLEN (pattern, 0) - 1; j >= 0; j--)
+		  {
+		    rtx inner_pattern = XVECEXP (pattern, 0, j);
+		    if (GET_CODE (inner_pattern) == SET
+			&& GET_CODE (SET_DEST (inner_pattern)) == SUBREG)
+		      purge_single_hard_subreg_set (inner_pattern);
+		  }
+	      }
+	      break;
+	    default:
+	      break;
+	    }
+	}
+    }
+}
+
 /* Pass through the INSNS of function FNDECL and convert virtual register
    references to hard register references.  */
 
diff --git a/gcc/rtl.h b/gcc/rtl.h
index a866595..190e971 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -1776,6 +1776,7 @@ extern void preserve_rtl_expr_result			PARAMS ((rtx));
 extern void mark_temp_addr_taken			PARAMS ((rtx));
 extern void update_temp_slot_address			PARAMS ((rtx, rtx));
 extern void purge_addressof				PARAMS ((rtx));
+extern void purge_hard_subreg_sets			PARAMS ((rtx));
 
 /* In reload.c */
 extern int operands_match_p		PARAMS ((rtx, rtx));
diff --git a/gcc/toplev.c b/gcc/toplev.c
index 333cde6..74e0e3eb 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -2829,11 +2829,14 @@ rest_of_compilation (decl)
   if (! DECL_DEFER_OUTPUT (decl))
     TREE_ASM_WRITTEN (decl) = 1;
 
-  /* Now that integrate will no longer see our rtl, we need not distinguish
-     between the return value of this function and the return value of called
-     functions.  */
+  /* Now that integrate will no longer see our rtl, we need not
+     distinguish between the return value of this function and the
+     return value of called functions.  Also, we can remove all SETs
+     of subregs of hard registers; they are only here because of
+     integrate.*/
   rtx_equal_function_value_matters = 0;
-
+  purge_hard_subreg_sets (get_insns ());
+  
   /* Don't return yet if -Wreturn-type; we need to do jump_optimize.  */
   if ((rtl_dump_and_exit || flag_syntax_only) && !warn_return_type)
     goto exit_rest_of_compilation;