[gcc r14-4667] i386: Allow -mlarge-data-threshold with -mcmodel=large

[gcc r14-4667] i386: Allow -mlarge-data-threshold with -mcmodel=large

[Uros Bizjak]

https://gcc.gnu.org/g:1a64156c7e25813afa8d4d8bbeb0590cad91cf55

commit r14-4667-g1a64156c7e25813afa8d4d8bbeb0590cad91cf55
Author: Uros Bizjak <ubizjak@gmail.com>
Date:   Mon Oct 16 22:22:28 2023 +0200

    i386: Allow -mlarge-data-threshold with -mcmodel=large
    
    From: Fangrui Song <maskray@google.com>
    
    When using -mcmodel=medium, large data objects larger than the
    -mlarge-data-threshold threshold are placed into large data sections
    (.lrodata, .ldata, .lbss and some variants).  GNU ld and ld.lld 17 place
    .l* sections into separate output sections.  If small and medium code
    model object files are mixed, the .l* sections won't exert relocation
    overflow pressure on sections in object files built with -mcmodel=small.
    
    However, when using -mcmodel=large, -mlarge-data-threshold doesn't
    apply.  This means that the .rodata/.data/.bss sections may exert
    relocation overflow pressure on sections in -mcmodel=small object files.
    
    This patch allows -mcmodel=large to generate .l* sections and drops an
    unneeded documentation restriction that the value must be the same.
    
    Link: https://groups.google.com/g/x86-64-abi/c/jnQdJeabxiU
    ("Large data sections for the large code model")
    
    Signed-off-by: Fangrui Song <maskray@google.com>
    
    gcc/ChangeLog:
    
            * config/i386/i386.cc (ix86_can_inline_p):
            Handle CM_LARGE and CM_LARGE_PIC.
            (x86_elf_aligned_decl_common): Ditto.
            (x86_output_aligned_bss): Ditto.
            * config/i386/i386.opt: Update doc for -mlarge-data-threshold=.
            * doc/invoke.texi: Update doc for -mlarge-data-threshold=.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/i386/large-data.c: New test.

Diff:
---
 gcc/config/i386/i386.cc                    |  9 ++++++---
 gcc/config/i386/i386.opt                   |  2 +-
 gcc/doc/invoke.texi                        |  6 +++---
 gcc/testsuite/gcc.target/i386/large-data.c | 13 +++++++++++++
 4 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 8251b67e2d6d..641e76803355 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -663,7 +663,8 @@ ix86_can_inline_p (tree caller, tree callee)
 static bool
 ix86_in_large_data_p (tree exp)
 {
-  if (ix86_cmodel != CM_MEDIUM && ix86_cmodel != CM_MEDIUM_PIC)
+  if (ix86_cmodel != CM_MEDIUM && ix86_cmodel != CM_MEDIUM_PIC
+      && ix86_cmodel != CM_LARGE && ix86_cmodel != CM_LARGE_PIC)
     return false;
 
   if (exp == NULL_TREE)
@@ -874,7 +875,8 @@ x86_elf_aligned_decl_common (FILE *file, tree decl,
 			const char *name, unsigned HOST_WIDE_INT size,
 			unsigned align)
 {
-  if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC)
+  if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC
+       || ix86_cmodel == CM_LARGE || ix86_cmodel == CM_LARGE_PIC)
       && size > (unsigned int)ix86_section_threshold)
     {
       switch_to_section (get_named_section (decl, ".lbss", 0));
@@ -895,7 +897,8 @@ void
 x86_output_aligned_bss (FILE *file, tree decl, const char *name,
 		       	unsigned HOST_WIDE_INT size, unsigned align)
 {
-  if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC)
+  if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC
+       || ix86_cmodel == CM_LARGE || ix86_cmodel == CM_LARGE_PIC)
       && size > (unsigned int)ix86_section_threshold)
     switch_to_section (get_named_section (decl, ".lbss", 0));
   else
diff --git a/gcc/config/i386/i386.opt b/gcc/config/i386/i386.opt
index b8382c480998..0c3b8f4b6218 100644
--- a/gcc/config/i386/i386.opt
+++ b/gcc/config/i386/i386.opt
@@ -282,7 +282,7 @@ Branches are this expensive (arbitrary units).
 
 mlarge-data-threshold=
 Target RejectNegative Joined UInteger Var(ix86_section_threshold) Init(DEFAULT_LARGE_SECTION_THRESHOLD)
--mlarge-data-threshold=<number>	Data greater than given threshold will go into .ldata section in x86-64 medium model.
+-mlarge-data-threshold=<number>	Data greater than given threshold will go into a large data section in x86-64 medium and large code models.
 
 mcmodel=
 Target RejectNegative Joined Enum(cmodel) Var(ix86_cmodel) Init(CM_32)
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index a26dc5aae69f..2a500c1baeea 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -33398,9 +33398,9 @@ the cache line size.  @samp{compat} is the default.
 
 @opindex mlarge-data-threshold
 @item -mlarge-data-threshold=@var{threshold}
-When @option{-mcmodel=medium} is specified, data objects larger than
-@var{threshold} are placed in the large data section.  This value must be the
-same across all objects linked into the binary, and defaults to 65535.
+When @option{-mcmodel=medium} or @option{-mcmodel=large} is specified, data
+objects larger than @var{threshold} are placed in large data sections.  The
+default is 65535.
 
 @opindex mrtd
 @item -mrtd
diff --git a/gcc/testsuite/gcc.target/i386/large-data.c b/gcc/testsuite/gcc.target/i386/large-data.c
new file mode 100644
index 000000000000..bdd4acd30b8b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/large-data.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target lp64 } */
+/* { dg-options "-O2 -mcmodel=large -mlarge-data-threshold=4" } */
+/* { dg-final { scan-assembler {\.lbss} } } */
+/* { dg-final { scan-assembler {\.bss} } } */
+/* { dg-final { scan-assembler {\.ldata} } } */
+/* { dg-final { scan-assembler {\.data} } } */
+/* { dg-final { scan-assembler {\.lrodata} } } */
+/* { dg-final { scan-assembler {\.rodata} } } */
+
+const char rodata_a[] = "abc", rodata_b[] = "abcd";
+char data_a[4] = {1}, data_b[5] = {1};
+char bss_a[4], bss_b[5];