Since 4c4a180d, LTO has turned off flag_pic when linking a fixed
position executable. This results in flag_pic being zero in
rs6000_file_start, and no definition of ".LCTOC1".
However, when we get to actually emitting code, flag_pic may be on
again, and references made to ".LCTOC1". How flag_pic comes to be
enabled again is quite a story. It goes like this.. If a function is
compiled with -fPIC then sysv4.h SUBTARGET_OVERRIDE_OPTIONS will set
TARGET_RELOCATABLE. Conversely, if TARGET_RELOCATABLE is set and
flag_pic is zero, then SUBTARGET_OVERRIDE_OPTIONS will set flag_pic=2.
It also happens that TARGET_RELOCATABLE is a bit in rs6000_isa_flags,
which is handled by rs6000_function_specific_save and
rs6000_function_specific_restore. That last fact means lto streaming
keeps track of the state of TARGET_RELOCATABLE for functions, and when
options are restored for a given function we'll set flag_pic=2 if the
function was originally compiled with -fPIC. That's bad because it
defeats the purpose of the 4c4a180d lto change, resulting in worse
optimization of ppc32 executables. What's more, we don't seem to turn
off flag_pic once it is on.
We should really untangle the flag_pic/TARGET_RELOCATABLE mess, but
that change is probably a little dangerous for stage4. Instead, this
patch removes the toc symbol initialization from file_start and does
so when the first item is emitted to the toc, or after the function
epilogue in the cases where we emit code to initialize a toc pointer
but don't actually use it (-O0 mostly, I think).
Bootstrapped and regression tested powerpc64-linux biarch with all
languages enabled. OK to apply?
PR target/68662
* config/rs6000/rs6000.c (need_toc_init): New var, set it
whenever toc_label_name used.
(rs6000_file_start): Don't set up toc section here,
(rs6000_output_function_epilogue): do so here instead,
(rs6000_xcoff_file_start): and here.
* config/rs6000/rs6000.md (load_toc_aix_si): Set need_toc_init.
(load_toc_aix_di): Likewise.
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 4704d00..4ea4efb 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -209,7 +209,7 @@ tree rs6000_builtin_types[RS6000_BTI_MAX];
tree rs6000_builtin_decls[RS6000_BUILTIN_COUNT];
/* Flag to say the TOC is initialized */
-int toc_initialized;
+int toc_initialized, need_toc_init;
char toc_label_name[10];
/* Cached value of rs6000_variable_issue. This is cached in
@@ -5682,13 +5682,6 @@ rs6000_file_start (void)
if (DEFAULT_ABI == ABI_ELFv2)
fprintf (file, "\t.abiversion 2\n");
-
- if (DEFAULT_ABI == ABI_AIX || DEFAULT_ABI == ABI_ELFv2
- || (TARGET_ELF && flag_pic == 2))
- {
- switch_to_section (toc_section);
- switch_to_section (text_section);
- }
}
@@ -20375,6 +20368,7 @@ rs6000_output_addr_const_extra (FILE *file, rtx x)
{
putc ('-', file);
assemble_name (file, toc_label_name);
+ need_toc_init = 1;
}
else if (TARGET_ELF)
fputs ("@toc", file);
@@ -24003,7 +23997,10 @@ rs6000_emit_load_toc_table (int fromprolog)
ASM_GENERATE_INTERNAL_LABEL (buf, "L", CODE_LABEL_NUMBER (lab));
lab = gen_rtx_SYMBOL_REF (Pmode, ggc_strdup (buf));
if (flag_pic == 2)
- got = gen_rtx_SYMBOL_REF (Pmode, ggc_strdup (toc_label_name));
+ {
+ got = gen_rtx_SYMBOL_REF (Pmode, ggc_strdup (toc_label_name));
+ need_toc_init = 1;
+ }
else
got = rs6000_got_sym ();
tmp1 = tmp2 = dest;
@@ -24048,6 +24045,7 @@ rs6000_emit_load_toc_table (int fromprolog)
rtx tocsym, lab;
tocsym = gen_rtx_SYMBOL_REF (Pmode, ggc_strdup (toc_label_name));
+ need_toc_init = 1;
lab = gen_label_rtx ();
emit_insn (gen_load_toc_v4_PIC_1b (tocsym, lab));
emit_move_insn (dest, gen_rtx_REG (Pmode, LR_REGNO));
@@ -24062,6 +24060,7 @@ rs6000_emit_load_toc_table (int fromprolog)
/* This is for AIX code running in non-PIC ELF32. */
rtx realsym = gen_rtx_SYMBOL_REF (Pmode, ggc_strdup (toc_label_name));
+ need_toc_init = 1;
emit_insn (gen_elf_high (dest, realsym));
emit_insn (gen_elf_low (dest, dest, realsym));
}
@@ -27598,6 +27597,17 @@ rs6000_output_function_epilogue (FILE *file,
fputs ("\t.align 2\n", file);
}
+
+ /* Arrange to define .LCTOC1 label, if not already done. */
+ if (need_toc_init)
+ {
+ need_toc_init = 0;
+ if (!toc_initialized)
+ {
+ switch_to_section (toc_section);
+ switch_to_section (current_function_section ());
+ }
+ }
}
/* -fsplit-stack support. */
@@ -31745,6 +31755,7 @@ rs6000_elf_declare_function_name (FILE *file, const
char *name, tree decl)
fprintf (file, "\t.long ");
assemble_name (file, toc_label_name);
+ need_toc_init = 1;
putc ('-', file);
ASM_GENERATE_INTERNAL_LABEL (buf, "LCF", rs6000_pic_labelno);
assemble_name (file, buf);
@@ -32137,6 +32148,7 @@ rs6000_xcoff_file_start (void)
fputc ('\n', asm_out_file);
if (write_symbols != NO_DEBUG)
switch_to_section (private_data_section);
+ switch_to_section (toc_section);
switch_to_section (text_section);
if (profile_flag)
fprintf (asm_out_file, "\t.extern %s\n", RS6000_MCOUNT);
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 6e22c52..fe19853 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -9475,6 +9475,8 @@
"*
{
char buf[30];
+ extern int need_toc_init;
+ need_toc_init = 1;
ASM_GENERATE_INTERNAL_LABEL (buf, \"LCTOC\", 1);
operands[1] = gen_rtx_SYMBOL_REF (Pmode, ggc_strdup (buf));
operands[2] = gen_rtx_REG (Pmode, 2);
@@ -9492,6 +9494,8 @@
"*
{
char buf[30];
+ extern int need_toc_init;
+ need_toc_init = 1;
#ifdef TARGET_RELOCATABLE
ASM_GENERATE_INTERNAL_LABEL (buf, \"LCTOC\",
!TARGET_MINIMAL_TOC || TARGET_RELOCATABLE);
--
Alan Modra
Australia Development Lab, IBM
