rs6000: -mreadonly-in-sdata (PR82411)

This adds a new option -mreadonly-in-sdata (on by default) that
controls whether readonly data can be put in sdata.  (For EABI this
does nothing, readonly data is put in sdata2 as usual).


	PR target/82411
	* config/rs6000/rs6000.c (rs6000_elf_in_small_data_p): Don't put
	readonly data in sdata, if that is disabled.
	* config/rs6000/sysv4.opt (mreadonly-in-sdata): New option.
	* doc/invoke.texi (RS/6000 and PowerPC Options): Document
	-mreadonly-in-sdata option.

gcc/testsuite/
	PR target/82411
	* gcc.target/powerpc/ppc-sdata-2.c: Skip if -mno-readonly-in-sdata.

From-SVN: r258340

gcc/ChangeLog

+2018-03-07  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	PR target/82411
+	* config/rs6000/rs6000.c (rs6000_elf_in_small_data_p): Don't put
+	readonly data in sdata, if that is disabled.
+	* config/rs6000/sysv4.opt (mreadonly-in-sdata): New option.
+	* doc/invoke.texi (RS/6000 and PowerPC Options): Document
+	-mreadonly-in-sdata option.
+
 2018-03-07  Martin Sebor  <msebor@redhat.com>
 
 	PR tree-optimization/84468

gcc/config/rs6000/rs6000.c

@@ -33259,6 +33259,11 @@ rs6000_elf_in_small_data_p (const_tree decl)
     }
   else
     {
+      /* If we are told not to put readonly data in sdata, then don't.  */
+      if (TREE_READONLY (decl) && rs6000_sdata != SDATA_EABI
+	  && !rs6000_readonly_in_sdata)
+	return false;
+
       HOST_WIDE_INT size = int_size_in_bytes (TREE_TYPE (decl));
 
       if (size > 0

gcc/config/rs6000/sysv4.opt

@@ -27,6 +27,10 @@ msdata=
 Target RejectNegative Joined Var(rs6000_sdata_name)
 Select method for sdata handling.
 
+mreadonly-in-sdata
+Target Report Var(rs6000_readonly_in_sdata) Init(1) Save
+Allow readonly data in sdata.
+
 mtls-size=
 Target RejectNegative Joined Var(rs6000_tls_size) Enum(rs6000_tls_size)
 Specify bit size of immediate TLS offsets.

gcc/doc/invoke.texi

@@ -1087,7 +1087,7 @@ See RS/6000 and PowerPC Options.
 -mdlmzb  -mno-dlmzb @gol
 -mprototype  -mno-prototype @gol
 -msim  -mmvme  -mads  -myellowknife  -memb  -msdata @gol
--msdata=@var{opt}  -mvxworks  -G @var{num} @gol
+-msdata=@var{opt}  -mreadonly-in-sdata  -mvxworks  -G @var{num} @gol
 -mrecip  -mrecip=@var{opt}  -mno-recip  -mrecip-precision @gol
 -mno-recip-precision @gol
 -mveclibabi=@var{type}  -mfriz  -mno-friz @gol
@@ -24114,6 +24114,13 @@ On embedded PowerPC systems, put all initialized global and static data
 in the @code{.data} section, and all uninitialized data in the
 @code{.bss} section.
 
+@item -mreadonly-in-sdata
+@itemx -mreadonly-in-sdata
+@opindex mreadonly-in-sdata
+@opindex mno-readonly-in-sdata
+Put read-only objects in the @code{.sdata} section as well.  This is the
+default.
+
 @item -mblock-move-inline-limit=@var{num}
 @opindex mblock-move-inline-limit
 Inline all block moves (such as calls to @code{memcpy} or structure

gcc/testsuite/ChangeLog

+2018-03-07  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	PR target/82411
+	* gcc.target/powerpc/ppc-sdata-2.c: Skip if -mno-readonly-in-sdata.
+
 2018-03-07  Martin Sebor  <msebor@redhat.com>
 
 	PR tree-optimization/84468

gcc/testsuite/gcc.target/powerpc/ppc-sdata-2.c

@@ -5,6 +5,7 @@
 /* { dg-final { scan-assembler-not "\\.section\[ \t\]\\.sdata2," } } */
 /* { dg-final { scan-assembler "sdat@sdarel\\(13\\)" } } */
 /* { dg-final { scan-assembler "sdat2@sdarel\\(13\\)" } } */
+/* { dg-skip-if "" { *-*-* } { "-mno-readonly-in-sdata" } { "" } } */
 
 
 int sdat = 2;