Re: [Patch 1/2 PR78561] Rename get_pool_size to get_pool_size_upper_bound

[Jeff Law]

On 12/01/2016 08:29 AM, James Greenhalgh wrote:


Hi,

There's no functional change in this patch, just a rename.

The size recorded in "offset" is only ever incremented as we add new items
to the constant pool. But this information can become stale where those
constant pool entries would not get emitted.

Thus, it is only ever an upper bound on the size of the constant pool.

The only uses of get_pool_size are in rs6000 and there it is only used to
check whether a constant pool might be output - but explicitly renaming the
function to make it clear that you're getting an upper bound rather than the
real size can only be good for programmers using the interface.

OK?

Thanks,
James

---
2016-12-01  James Greenhalgh  

PR rtl-optimization/78561
* config/rs6000/rs6000.c (rs6000_reg_live_or_pic_offset_p) Rename
get_pool_size to get_pool_size_upper_bound.
(rs6000_stack_info): Likewise.
(rs6000_emit_prologue): Likewise.
(rs6000_elf_declare_function_name): Likewise.
(rs6000_set_up_by_prologue): Likewise.
(rs6000_can_eliminate): Likewise, reformat spaces to tabs.
* output.h (get_pool_size): Rename to...
(get_pool_size_upper_bound): ...This.
* varasm.c (get_pool_size): Rename to...
(get_pool_size_upper_bound): ...This.


Both parts of the fix for 78561 are OK.

Thanks,
Jeff

[Patch 1/2 PR78561] Rename get_pool_size to get_pool_size_upper_bound

[James Greenhalgh]

Hi,

There's no functional change in this patch, just a rename.

The size recorded in "offset" is only ever incremented as we add new items
to the constant pool. But this information can become stale where those
constant pool entries would not get emitted.

Thus, it is only ever an upper bound on the size of the constant pool.

The only uses of get_pool_size are in rs6000 and there it is only used to
check whether a constant pool might be output - but explicitly renaming the
function to make it clear that you're getting an upper bound rather than the
real size can only be good for programmers using the interface.

OK?

Thanks,
James

---
2016-12-01  James Greenhalgh  

PR rtl-optimization/78561
* config/rs6000/rs6000.c (rs6000_reg_live_or_pic_offset_p) Rename
get_pool_size to get_pool_size_upper_bound.
(rs6000_stack_info): Likewise.
(rs6000_emit_prologue): Likewise.
(rs6000_elf_declare_function_name): Likewise.
(rs6000_set_up_by_prologue): Likewise.
(rs6000_can_eliminate): Likewise, reformat spaces to tabs.
* output.h (get_pool_size): Rename to...
(get_pool_size_upper_bound): ...This.
* varasm.c (get_pool_size): Rename to...
(get_pool_size_upper_bound): ...This.

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 0a6a784..7e965f9 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -25456,7 +25456,7 @@ rs6000_reg_live_or_pic_offset_p (int reg)
   if (TARGET_TOC && TARGET_MINIMAL_TOC
 	  && (crtl->calls_eh_return
 	  || df_regs_ever_live_p (reg)
-	  || get_pool_size ()))
+	  || get_pool_size_upper_bound ()))
 	return true;
 
   if ((DEFAULT_ABI == ABI_V4 || DEFAULT_ABI == ABI_DARWIN)
@@ -26262,7 +26262,7 @@ rs6000_stack_info (void)
 #ifdef TARGET_RELOCATABLE
   || (DEFAULT_ABI == ABI_V4
 	  && (TARGET_RELOCATABLE || flag_pic > 1)
-	  && get_pool_size () != 0)
+	  && get_pool_size_upper_bound () != 0)
 #endif
   || rs6000_ra_ever_killed ())
 info->lr_save_p = 1;
@@ -28039,7 +28039,8 @@ rs6000_emit_prologue (void)
   cfun->machine->r2_setup_needed = df_regs_ever_live_p (TOC_REGNUM);
 
   /* With -mminimal-toc we may generate an extra use of r2 below.  */
-  if (TARGET_TOC && TARGET_MINIMAL_TOC && get_pool_size () != 0)
+  if (TARGET_TOC && TARGET_MINIMAL_TOC
+	  && get_pool_size_upper_bound () != 0)
 	cfun->machine->r2_setup_needed = true;
 }
 
@@ -28894,7 +28895,8 @@ rs6000_emit_prologue (void)
 
   /* If we are using RS6000_PIC_OFFSET_TABLE_REGNUM, we need to set it up.  */
   if (!TARGET_SINGLE_PIC_BASE
-  && ((TARGET_TOC && TARGET_MINIMAL_TOC && get_pool_size () != 0)
+  && ((TARGET_TOC && TARGET_MINIMAL_TOC
+	   && get_pool_size_upper_bound () != 0)
 	  || (DEFAULT_ABI == ABI_V4
 	  && (flag_pic == 1 || (flag_pic && TARGET_SECURE_PLT))
 	  && df_regs_ever_live_p (RS6000_PIC_OFFSET_TABLE_REGNUM
@@ -34961,7 +34963,7 @@ rs6000_elf_declare_function_name (FILE *file, const char *name, tree decl)
   if (DEFAULT_ABI == ABI_V4
   && (TARGET_RELOCATABLE || flag_pic > 1)
   && !TARGET_SECURE_PLT
-  && (get_pool_size () != 0 || crtl->profile)
+  && (get_pool_size_upper_bound () != 0 || crtl->profile)
   && uses_TOC ())
 {
   char buf[256];
@@ -37444,10 +37446,11 @@ static bool
 rs6000_can_eliminate (const int from, const int to)
 {
   return (from == ARG_POINTER_REGNUM && to == STACK_POINTER_REGNUM
-  ? ! frame_pointer_needed
-  : from == RS6000_PIC_OFFSET_TABLE_REGNUM
-? ! TARGET_MINIMAL_TOC || TARGET_NO_TOC || get_pool_size () == 0
-: true);
+	  ? ! frame_pointer_needed
+	  : from == RS6000_PIC_OFFSET_TABLE_REGNUM
+	? ! TARGET_MINIMAL_TOC || TARGET_NO_TOC
+		|| get_pool_size_upper_bound () == 0
+	: true);
 }
 
 /* Define the offset between two registers, FROM to be eliminated and its
@@ -38983,7 +38986,7 @@ rs6000_set_up_by_prologue (struct hard_reg_set_container *set)
   if (!TARGET_SINGLE_PIC_BASE
   && TARGET_TOC
   && TARGET_MINIMAL_TOC
-  && get_pool_size () != 0)
+  && get_pool_size_upper_bound () != 0)
 add_to_hard_reg_set (>set, Pmode, RS6000_PIC_OFFSET_TABLE_REGNUM);
   if (cfun->machine->split_stack_argp_used)
 add_to_hard_reg_set (>set, Pmode, 12);
diff --git a/gcc/output.h b/gcc/output.h
index 0924499..7186dc1 100644
--- a/gcc/output.h
+++ b/gcc/output.h
@@ -287,8 +287,11 @@ extern void assemble_real (REAL_VALUE_TYPE, machine_mode, unsigned,
 /* Write the address of the entity given by SYMBOL to SEC.  */
 extern void assemble_addr_to_section (rtx, section *);
 
-/* Return the size of the constant pool.  */
-extern int get_pool_size (void);
+/* Return the maximum size of the constant pool.  This may be larger
+   than the final size of the constant pool, as entries may be added to
+   the constant pool which become unreferenced, or otherwise not need
+   output by