* combine.c (make_extraction): Check TRULY_NOOP_TRUNCATION before

	creating LHS paradoxical subregs.  Fix surrounding returns to
	use NULL_RTX rather than 0.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@149401 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6fefd14..4007a66 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2009-07-08  Adam Nemet  <anemet@caviumnetworks.com>
+
+       * combine.c (make_extraction): Check TRULY_NOOP_TRUNCATION before
+       creating LHS paradoxical subregs.  Fix surrounding returns to
+       use NULL_RTX rather than 0.
+
 2009-07-08  DJ Delorie  <dj@redhat.com>
 
        * config/mep/mep.c: (mep_option_can_inline_p): New.
@@ -36,9 +42,9 @@
        * optabs.h (optab_libfunc): Ditto.
        * tree.h (tree_expr_nonzero_warnv_p): Ditto.
        * tree-flow.h (vect_can_force_dr_alignment_p,
-       get_vectype_for_scalar_type): Ditto.    
+       get_vectype_for_scalar_type): Ditto.
        (vectorize_loops): Move prototype to ...
-       * tree-vectorizer.h: ... here. Also, adjust comment. 
+       * tree-vectorizer.h: ... here. Also, adjust comment.
        (vect_set_verbosity_level): Remove duplicate prototype.
        * tree-ssa-loop.c: Include tree-vectorizer.h.
        * Makefile.in (tree-ssa-loop.o): Depend on tree-vectorizer.h.
@@ -57,7 +63,7 @@
        * config/mep/intrinsics.md: Regenerated.
        * config/mep/mep.c (mep_interrupt_saved_reg): Save IVC2 control
        registers when asm() or calls are detected.
-       
+
 2009-07-08  Manuel López-Ibáñez  <manu@gcc.gnu.org>
 
        PR c++/31246
@@ -66,7 +72,7 @@
        * gimple (gimple_build_call_from_tree): Likewise.
        * tree-cfg.c (remove_useless_stmts_warn_notreached): Check
        no_warning flag before warning.
-       
+
 2009-07-07  Manuel López-Ibáñez  <manu@gcc.gnu.org>
 
        * tree.c (set_expr_locus): Remove.
@@ -152,7 +158,7 @@
        * config/mep/intrinsics.md: Regenerate.
        * config/mep/intrinsics.h: Regenerate.
        * config/mep/mep-intrin.h: Regenerate.
-       
+
 2009-07-07  Manuel López-Ibáñez  <manu@gcc.gnu.org>
 
        * c-lex.c: Replace %H by an explicit location. Update all calls.
@@ -248,7 +254,7 @@
        PR target/40587
        * ira.c (build_insn_chain): Use DF_LR_OUT instead of
        df_get_live_out.
-       
+
 2009-07-03  Richard Guenther  <rguenther@suse.de>
 
        PR tree-optimization/40640
@@ -363,16 +369,16 @@
        * config/mep/intrinsics.md: Regenerate.
        * config/mep/intrinsics.h: Regenerate.
        * config/mep/mep-intrin.h: Regenerate.
-       
+
 2009-07-01  Anthony Green  <green@moxielogic.com>
 
        * config/moxie/moxie.c (moxie_expand_prologue): Use dec
        instruction when possible.
        (moxie_expand_prologue): Ditto.  Also, save an instruction and
-       some complexity by popping off of $r12 instead of $sp.  
+       some complexity by popping off of $r12 instead of $sp.
        * config/moxie/moxie.md (movsi_pop): Don't assume $sp.  Take two
        operands.
-       
+
 2009-07-01  Richard Henderson  <rth@redhat.com>
 
        PR bootstrap/40347

diff --git a/gcc/combine.c b/gcc/combine.c
index a4f0d66..a781484 100644 (file)
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -6692,18 +6692,25 @@ make_extraction (enum machine_mode mode, rtx inner, HOST_WIDE_INT pos,
       inner = adjust_address_nv (inner, wanted_inner_mode, offset);
     }
 
-  /* If INNER is not memory, we can always get it into the proper mode.  If we
-     are changing its mode, POS must be a constant and smaller than the size
-     of the new mode.  */
+  /* If INNER is not memory, get it into the proper mode.  If we are changing
+     its mode, POS must be a constant and smaller than the size of the new
+     mode.  */
   else if (!MEM_P (inner))
     {
+      /* On the LHS, don't create paradoxical subregs implicitely truncating
+        the register unless TRULY_NOOP_TRUNCATION.  */
+      if (in_dest
+         && !TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (GET_MODE (inner)),
+                                    GET_MODE_BITSIZE (wanted_inner_mode)))
+       return NULL_RTX;
+
       if (GET_MODE (inner) != wanted_inner_mode
          && (pos_rtx != 0
              || orig_pos + len > GET_MODE_BITSIZE (wanted_inner_mode)))
-       return 0;
+       return NULL_RTX;
 
       if (orig_pos < 0)
-       return 0;
+       return NULL_RTX;
 
       inner = force_to_mode (inner, wanted_inner_mode,
                             pos_rtx