[PATCH, nds32] Committed: Remove some features that are not available yet in nds32 port of GNU binutils package.

[PATCH, nds32] Committed: Remove some features that are not available yet in nds32 port of GNU binutils package.

[Chung-Ju Wu]

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Hi, all,

The nds32 target supports two features, fp-as-gp and ex9, designed
for code size optimizations.  They are majorly performed by linker
so that compiler is merely to give some hints or directives with
-mforce-fp-as-gp, -mforbid-fp-as-gp, and -mex9 options.

However, those two features are not available yet in the current
nds32 port of GNU binutils package.  For consistency concern, I think
it would be better to remove them from gcc trunk as well for now.

Committed as Rev. 219576: https://gcc.gnu.org/r219576


gcc/ChangeLog

2015-01-14  Chung-Ju Wu  <jasonwucj@gmail.com>

        * config/nds32/nds32.opt (mforce-fp-as-gp): Remove.
        (mforbid-fp-as-gp): Remove.
        (mex9): Remove.
        * config/nds32/nds32-fp-as-gp.c (nds32_have_prologue_p): Remove.
        (nds32_symbol_load_store_p): Remove.
        (nds32_fp_as_gp_check_available): Clean up implementation.
        * config/nds32/nds32.h (LINK_SPEC): Remove -mforce-as-gp and -mex9
        cases.
        * config/nds32/nds32.c (nds32_asm_file_start): No need to consider
        fp-as-gp and ex9 cases.


Best regards,
jasonwucj

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diff --git a/gcc/config/nds32/nds32-fp-as-gp.c b/gcc/config/nds32/nds32-fp-as-gp.c
index f68a8e3..c8fa836 100644
--- a/gcc/config/nds32/nds32-fp-as-gp.c
+++ b/gcc/config/nds32/nds32-fp-as-gp.c
@@ -68,55 +68,6 @@
 
 /* ------------------------------------------------------------------------ */
 
-/* A helper function to check if this function should contain prologue.  */
-static int
-nds32_have_prologue_p (void)
-{
-  int i;
-
-  for (i = 0; i < 28; i++)
-    if (NDS32_REQUIRED_CALLEE_SAVED_P (i))
-      return 1;
-
-  return (flag_pic
-	  || NDS32_REQUIRED_CALLEE_SAVED_P (FP_REGNUM)
-	  || NDS32_REQUIRED_CALLEE_SAVED_P (LP_REGNUM));
-}
-
-/* Return true if is load/store with SYMBOL_REF addressing mode
-   and memory mode is SImode.  */
-static bool
-nds32_symbol_load_store_p (rtx_insn *insn)
-{
-  rtx mem_src = NULL_RTX;
-
-  switch (get_attr_type (insn))
-    {
-    case TYPE_LOAD:
-      mem_src = SET_SRC (PATTERN (insn));
-      break;
-    case TYPE_STORE:
-      mem_src = SET_DEST (PATTERN (insn));
-      break;
-    default:
-      break;
-    }
-
-  /* Find load/store insn with addressing mode is SYMBOL_REF.  */
-  if (mem_src != NULL_RTX)
-    {
-      if ((GET_CODE (mem_src) == ZERO_EXTEND)
-	  || (GET_CODE (mem_src) == SIGN_EXTEND))
-	mem_src = XEXP (mem_src, 0);
-
-      if ((GET_CODE (XEXP (mem_src, 0)) == SYMBOL_REF)
-	   || (GET_CODE (XEXP (mem_src, 0)) == LO_SUM))
-	return true;
-    }
-
-  return false;
-}
-
 /* Function to determine whether it is worth to do fp_as_gp optimization.
    Return 0: It is NOT worth to do fp_as_gp optimization.
    Return 1: It is APPROXIMATELY worth to do fp_as_gp optimization.
@@ -125,106 +76,6 @@ nds32_symbol_load_store_p (rtx_insn *insn)
 int
 nds32_fp_as_gp_check_available (void)
 {
-  /* If there exists ANY of following conditions,
-     we DO NOT perform fp_as_gp optimization:
-       1. TARGET_FORBID_FP_AS_GP is set
-          regardless of the TARGET_FORCE_FP_AS_GP.
-       2. User explicitly uses 'naked' attribute.
-       3. Not optimize for size.
-       4. Need frame pointer.
-       5. If $fp is already required to be saved,
-          it means $fp is already choosen by register allocator.
-          Thus we better not to use it for fp_as_gp optimization.
-       6. This function is a vararg function.
-          DO NOT apply fp_as_gp optimization on this function
-          because it may change and break stack frame.
-       7. The epilogue is empty.
-          This happens when the function uses exit()
-          or its attribute is no_return.
-          In that case, compiler will not expand epilogue
-          so that we have no chance to output .omit_fp_end directive.  */
-  if (TARGET_FORBID_FP_AS_GP
-      || lookup_attribute ("naked", DECL_ATTRIBUTES (current_function_decl))
-      || !optimize_size
-      || frame_pointer_needed
-      || NDS32_REQUIRED_CALLEE_SAVED_P (FP_REGNUM)
-      || (cfun->stdarg == 1)
-      || (find_fallthru_edge (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) == NULL))
-    return 0;
-
-  /* Now we can check the possibility of using fp_as_gp optimization.  */
-  if (TARGET_FORCE_FP_AS_GP)
-    {
-      /* User explicitly issues -mforce-fp-as-gp option.  */
-      df_set_regs_ever_live (FP_REGNUM, 1);
-      return 1;
-    }
-  else
-    {
-      /* In the following we are going to evaluate whether
-         it is worth to do fp_as_gp optimization.  */
-      int good_gain     = 0;
-      int symbol_count  = 0;
-
-      int threshold;
-      rtx_insn *insn;
-
-      /* We check if there already requires prologue.
-         Note that $gp will be saved in prologue for PIC code generation.
-         After that, we can set threshold by the existence of prologue.
-         Each fp-implied instruction will gain 2-byte code size
-         from gp-aware instruction, so we have following heuristics.  */
-      if (flag_pic
-	  || nds32_have_prologue_p ())
-	{
-	  /* Have-prologue:
-	       Compiler already intends to generate prologue content,
-	       so the fp_as_gp optimization will only insert
-	       'la $fp,_FP_BASE_' instruction, which will be
-	       converted into 4-byte instruction at link time.
-	       The threshold is "3" symbol accesses, 2 + 2 + 2 > 4.  */
-	  threshold = 3;
-	}
-      else
-	{
-	  /* None-prologue:
-	       Compiler originally does not generate prologue content,
-	       so the fp_as_gp optimization will NOT ONLY insert
-	       'la $fp,_FP_BASE' instruction, but also causes
-	       push/pop instructions.
-	       If we are using v3push (push25/pop25),
-	       the threshold is "5" symbol accesses, 5*2 > 4 + 2 + 2;
-	       If we are using normal push (smw/lmw),
-	       the threshold is "5+2" symbol accesses 7*2 > 4 + 4 + 4.  */
-	  threshold = 5 + (TARGET_V3PUSH ? 0 : 2);
-	}
-
-      /* We would like to traverse every instruction in this function.
-         So we need to have push_topmost_sequence()/pop_topmost_sequence()
-         surrounding our for-loop evaluation.  */
-      push_topmost_sequence ();
-      /* Counting the insn number which the addressing mode is symbol.  */
-      for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
-	{
-	  if (single_set (insn) && nds32_symbol_load_store_p (insn))
-	    symbol_count++;
-
-	  if (symbol_count == threshold)
-	    {
-	      good_gain = 1;
-	      break;
-	    }
-	}
-      pop_topmost_sequence ();
-
-      /* Enable fp_as_gp optimization when potential gain is good enough.  */
-      if (good_gain)
-	{
-	  df_set_regs_ever_live (FP_REGNUM, 1);
-	  return 1;
-	}
-    }
-
   /* By default we return 0.  */
   return 0;
 }
diff --git a/gcc/config/nds32/nds32.c b/gcc/config/nds32/nds32.c
index 62fc02c..0ef9b94 100644
--- a/gcc/config/nds32/nds32.c
+++ b/gcc/config/nds32/nds32.c
@@ -2186,26 +2186,6 @@ nds32_asm_file_start (void)
 			 "for checking inconsistency on interrupt handler\n");
   fprintf (asm_out_file, "\t.vec_size\t%d\n", nds32_isr_vector_size);
 
-  /* If user enables '-mforce-fp-as-gp' or compiles programs with -Os,
-     the compiler may produce 'la $fp,_FP_BASE_' instruction
-     at prologue for fp-as-gp optimization.
-     We should emit weak reference of _FP_BASE_ to avoid undefined reference
-     in case user does not pass '--relax' option to linker.  */
-  if (TARGET_FORCE_FP_AS_GP || optimize_size)
-    {
-      fprintf (asm_out_file, "\t! This weak reference is required to do "
-			     "fp-as-gp link time optimization\n");
-      fprintf (asm_out_file, "\t.weak\t_FP_BASE_\n");
-    }
-  /* If user enables '-mex9', we should emit relaxation directive
-     to tell linker that this file is allowed to do ex9 optimization.  */
-  if (TARGET_EX9)
-    {
-      fprintf (asm_out_file, "\t! This relaxation directive is required "
-			     "to do ex9 link time optimization\n");
-      fprintf (asm_out_file, "\t.relax\tex9\n");
-    }
-
   fprintf (asm_out_file, "\t! ------------------------------------\n");
 
   if (TARGET_ISA_V2)
@@ -2739,12 +2719,6 @@ nds32_option_override (void)
 	fixed_regs[r] = call_used_regs[r] = 1;
     }
 
-  /* See if user explicitly would like to use fp-as-gp optimization.
-     If so, we must prevent $fp from being allocated
-     during register allocation.  */
-  if (TARGET_FORCE_FP_AS_GP)
-    fixed_regs[FP_REGNUM] = call_used_regs[FP_REGNUM] = 1;
-
   if (!TARGET_16_BIT)
     {
       /* Under no 16 bit ISA, we need to strictly disable TARGET_V3PUSH.  */
diff --git a/gcc/config/nds32/nds32.h b/gcc/config/nds32/nds32.h
index 4a271cf..7f74159 100644
--- a/gcc/config/nds32/nds32.h
+++ b/gcc/config/nds32/nds32.h
@@ -381,13 +381,10 @@ enum nds32_builtins
 #define ASM_SPEC \
   " %{mbig-endian:-EB} %{mlittle-endian:-EL}"
 
-/* If user issues -mrelax, -mforce-fp-as-gp, or -mex9,
-   we need to pass '--relax' to linker.
-   Besides, for -mex9, we need to further pass '--mex9'.  */
+/* If user issues -mrelax, we need to pass '--relax' to linker.  */
 #define LINK_SPEC \
   " %{mbig-endian:-EB} %{mlittle-endian:-EL}" \
-  " %{mrelax|mforce-fp-as-gp|mex9:--relax}" \
-  " %{mex9:--mex9}"
+  " %{mrelax:--relax}"
 
 #define LIB_SPEC \
   " -lc -lgloss"
diff --git a/gcc/config/nds32/nds32.opt b/gcc/config/nds32/nds32.opt
index 6653982..ffaab90 100644
--- a/gcc/config/nds32/nds32.opt
+++ b/gcc/config/nds32/nds32.opt
@@ -95,18 +95,6 @@ Enum(nds32_cmodel_type) String(medium) Value(CMODEL_MEDIUM)
 EnumValue
 Enum(nds32_cmodel_type) String(large) Value(CMODEL_LARGE)
 
-mforce-fp-as-gp
-Target Report Mask(FORCE_FP_AS_GP)
-Prevent $fp being allocated during register allocation so that compiler is able to force performing fp-as-gp optimization.
-
-mforbid-fp-as-gp
-Target Report Mask(FORBID_FP_AS_GP)
-Forbid using $fp to access static and global variables.  This option strictly forbids fp-as-gp optimization regardless of '-mforce-fp-as-gp'.
-
-mex9
-Target Report Mask(EX9)
-Use special directives to guide linker doing ex9 optimization.
-
 mctor-dtor
 Target Report
 Enable constructor/destructor feature.
-- 
1.9.0