Add -malign-data={abi|compat|cachineline}

Add -malign-data={abi|compat,cachineline} to control how GCC aligns
variables.  "compat" uses increased alignment value compatible with
GCC 4.8 and earlier, "abi" uses alignment value as specified by the
psABI, and "cacheline" uses increased alignment value to match the
cache line size.  "compat" is the default.

gcc/

	PR target/61296
	* config/i386/i386-opts.h (ix86_align_data): New enum.
	* config/i386/i386.c (ix86_data_alignment): Return the ABI
	alignment value for -malign-data=abi, the cachine line size
	for -malign-data=cachineline and the older GCC compatible
	alignment value for for -malign-data=compat.
	* config/i386/i386.opt (malign-data=): New.
	* doc/invoke.texi: Document -malign-data=.

gcc/testsuite/

	PR target/61296
	* gcc.target/i386/pr61296-2.c: New.
	* gcc.target/i386/pr61296-2.c: Likewise.
	* gcc.target/i386/pr61296-3.c: Likewise.
	* gcc.target/i386/pr61296-4.c: Likewise.
	* gcc.target/i386/pr61296-5.c: Likewise.
	* gcc.target/i386/pr61296-6.c: Likewise.
	* gcc.target/i386/pr61296-7.c: Likewise.

Co-Authored-By: Jakub Jelinek <jakub@redhat.com>
Co-Authored-By: Uros Bizjak <ubizjak@gmail.com>

From-SVN: r218818

13 files changed, 253 insertions, 3 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7b3c4aa..663669b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,16 @@
+2014-12-17  H.J. Lu  <hongjiu.lu@intel.com>
+	    Jakub Jelinek  <jakub@redhat.com>
+	    Uros Bizjak  <ubizjak@gmail.com>
+
+	PR target/61296
+	* config/i386/i386-opts.h (ix86_align_data): New enum.
+	* config/i386/i386.c (ix86_data_alignment): Return the ABI
+	alignment value for -malign-data=abi, the cachine line size
+	for -malign-data=cachineline and the older GCC compatible
+	alignment value for for -malign-data=compat.
+	* config/i386/i386.opt (malign-data=): New.
+	* doc/invoke.texi: Document -malign-data=.
+
 2014-12-17  Marek Polacek  <polacek@redhat.com>
 
 	PR middle-end/63568
diff --git a/gcc/config/i386/i386-opts.h b/gcc/config/i386/i386-opts.h
index 47a34db..455df43 100644
--- a/gcc/config/i386/i386-opts.h
+++ b/gcc/config/i386/i386-opts.h
@@ -77,6 +77,12 @@ enum pmode {
   PMODE_DI 	/* Pmode == DImode. */
 };
 
+enum ix86_align_data {
+  ix86_align_data_type_compat,
+  ix86_align_data_type_abi,
+  ix86_align_data_type_cacheline
+};
+
 enum asm_dialect {
   ASM_ATT,
   ASM_INTEL
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 72c1219..17ef751 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -27191,8 +27191,7 @@ ix86_data_alignment (tree type, int align, bool opt)
      those compilers, ensure we don't decrease alignment from what we
      used to assume.  */
 
-  int max_align_compat
-    = optimize_size ? BITS_PER_WORD : MIN (256, MAX_OFILE_ALIGNMENT);
+  int max_align_compat = MIN (256, MAX_OFILE_ALIGNMENT);
 
   /* A data structure, equal or greater than the size of a cache line
      (64 bytes in the Pentium 4 and other recent Intel processors, including
@@ -27205,6 +27204,13 @@ ix86_data_alignment (tree type, int align, bool opt)
   if (max_align < BITS_PER_WORD)
     max_align = BITS_PER_WORD;
 
+  switch (ix86_align_data_type)
+    {
+    case ix86_align_data_type_abi: opt = false; break;
+    case ix86_align_data_type_compat: max_align = BITS_PER_WORD; break;
+    case ix86_align_data_type_cacheline: break;
+    }
+
   if (opt
       && AGGREGATE_TYPE_P (type)
       && TYPE_SIZE (type)
diff --git a/gcc/config/i386/i386.opt b/gcc/config/i386/i386.opt
index b1c6319..3d54bfa 100644
--- a/gcc/config/i386/i386.opt
+++ b/gcc/config/i386/i386.opt
@@ -221,6 +221,23 @@ malign-stringops
 Target RejectNegative Report InverseMask(NO_ALIGN_STRINGOPS, ALIGN_STRINGOPS) Save
 Align destination of the string operations
 
+malign-data=
+Target RejectNegative Joined Var(ix86_align_data_type) Enum(ix86_align_data) Init(ix86_align_data_type_compat)
+Use the given data alignment
+
+Enum
+Name(ix86_align_data) Type(enum ix86_align_data)
+Known data alignment choices (for use with the -malign-data= option):
+
+EnumValue
+Enum(ix86_align_data) String(compat) Value(ix86_align_data_type_compat)
+
+EnumValue
+Enum(ix86_align_data) String(abi) Value(ix86_align_data_type_abi)
+
+EnumValue
+Enum(ix86_align_data) String(cacheline) Value(ix86_align_data_type_cacheline)
+
 march=
 Target RejectNegative Joined Var(ix86_arch_string)
 Generate code for given CPU
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 19422d7..15068da 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -701,7 +701,7 @@ Objective-C and Objective-C++ Dialects}.
 -m32 -m64 -mx32 -m16 -mlarge-data-threshold=@var{num} @gol
 -msse2avx -mfentry -mrecord-mcount -mnop-mcount -m8bit-idiv @gol
 -mavx256-split-unaligned-load -mavx256-split-unaligned-store @gol
--mstack-protector-guard=@var{guard}}
+-malign-data=@var{type} -mstack-protector-guard=@var{guard}}
 
 @emph{i386 and x86-64 Windows Options}
 @gccoptlist{-mconsole -mcygwin -mno-cygwin -mdll @gol
@@ -15682,6 +15682,14 @@ as well as modifying the function calling convention for functions taking
 @code{long double}.  Hence they are not binary-compatible
 with code compiled without that switch.
 
+@item -malign-data=@var{type}
+@opindex malign-data
+Control how GCC aligns variables.  Supported values for @var{type} are
+@samp{compat} uses increased alignment value compatible uses GCC 4.8
+and earlier, @samp{abi} uses alignment value as specified by the
+psABI, and @samp{cacheline} uses increased alignment value to match
+the cache line size.  @samp{compat} is the default.
+
 @item -mlarge-data-threshold=@var{threshold}
 @opindex mlarge-data-threshold
 When @option{-mcmodel=medium} is specified, data objects larger than
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 3b04479..24c5143 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,14 @@
+2014-12-17  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR target/61296
+	* gcc.target/i386/pr61296-2.c: New.
+	* gcc.target/i386/pr61296-2.c: Likewise.
+	* gcc.target/i386/pr61296-3.c: Likewise.
+	* gcc.target/i386/pr61296-4.c: Likewise.
+	* gcc.target/i386/pr61296-5.c: Likewise.
+	* gcc.target/i386/pr61296-6.c: Likewise.
+	* gcc.target/i386/pr61296-7.c: Likewise.
+
 2014-12-17  Tejas Belagod  <tejas.belagod@arm.com>
 
 	PR testsuite/64328
diff --git a/gcc/testsuite/gcc.target/i386/pr61296-1.c b/gcc/testsuite/gcc.target/i386/pr61296-1.c
new file mode 100644
index 0000000..751dee0
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr61296-1.c
@@ -0,0 +1,27 @@
+/* PR target/61296 */
+/* { dg-do compile { target { *-*-linux* } } } */
+/* { dg-options "-O2" } */
+
+struct foo
+{
+  char i1[8];
+  char i2[8];
+  char i3[8];
+  char i4[8];
+  char i5[8];
+  char i6[8];
+  char i7[8];
+  char i8[8];
+  char i9[8];
+  char i10[8];
+  char i11[8];
+  char i12[8];
+  char i13[8];
+  char i14[8];
+  char i15[8];
+  char i16[8];
+};
+
+struct foo x = { 1 };
+
+/* { dg-final { scan-assembler ".align\[ \t]*32\[^:]*\[\n\r]x:" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr61296-2.c b/gcc/testsuite/gcc.target/i386/pr61296-2.c
new file mode 100644
index 0000000..5999555
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr61296-2.c
@@ -0,0 +1,27 @@
+/* PR target/61296 */
+/* { dg-do compile { target { *-*-linux* } } } */
+/* { dg-options "-O2 -malign-data=cacheline" } */
+
+struct foo
+{
+  char i1[8];
+  char i2[8];
+  char i3[8];
+  char i4[8];
+  char i5[8];
+  char i6[8];
+  char i7[8];
+  char i8[8];
+  char i9[8];
+  char i10[8];
+  char i11[8];
+  char i12[8];
+  char i13[8];
+  char i14[8];
+  char i15[8];
+  char i16[8];
+};
+
+struct foo x = { 1 };
+
+/* { dg-final { scan-assembler ".align\[ \t]*64\[^:]*\[\n\r]x:" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr61296-3.c b/gcc/testsuite/gcc.target/i386/pr61296-3.c
new file mode 100644
index 0000000..d0152f7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr61296-3.c
@@ -0,0 +1,27 @@
+/* PR target/61296 */
+/* { dg-do compile { target { *-*-linux* } } } */
+/* { dg-options "-O2 -malign-data=abi" } */
+
+struct foo
+{
+  char i1[8];
+  char i2[8];
+  char i3[8];
+  char i4[8];
+  char i5[8];
+  char i6[8];
+  char i7[8];
+  char i8[8];
+  char i9[8];
+  char i10[8];
+  char i11[8];
+  char i12[8];
+  char i13[8];
+  char i14[8];
+  char i15[8];
+  char i16[8];
+};
+
+struct foo x = { 1 };
+
+/* { dg-final { scan-assembler-not ".align\[ \t]*\[0-9\]+\[^:]*\[\n\r]x:" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr61296-4.c b/gcc/testsuite/gcc.target/i386/pr61296-4.c
new file mode 100644
index 0000000..95e1ac6
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr61296-4.c
@@ -0,0 +1,27 @@
+/* PR target/61296 */
+/* { dg-do compile { target { *-*-linux* } } } */
+/* { dg-options "-O2 -malign-data=cacheline -malign-data=abi" } */
+
+struct foo
+{
+  char i1[8];
+  char i2[8];
+  char i3[8];
+  char i4[8];
+  char i5[8];
+  char i6[8];
+  char i7[8];
+  char i8[8];
+  char i9[8];
+  char i10[8];
+  char i11[8];
+  char i12[8];
+  char i13[8];
+  char i14[8];
+  char i15[8];
+  char i16[8];
+};
+
+struct foo x = { 1 };
+
+/* { dg-final { scan-assembler-not ".align\[ \t]*\[0-9\]+\[^:]*\[\n\r]x:" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr61296-5.c b/gcc/testsuite/gcc.target/i386/pr61296-5.c
new file mode 100644
index 0000000..5caa77c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr61296-5.c
@@ -0,0 +1,27 @@
+/* PR target/61296 */
+/* { dg-do compile { target { *-*-linux* } } } */
+/* { dg-options "-O2 -malign-data=abi -malign-data=cacheline" } */
+
+struct foo
+{
+  char i1[8];
+  char i2[8];
+  char i3[8];
+  char i4[8];
+  char i5[8];
+  char i6[8];
+  char i7[8];
+  char i8[8];
+  char i9[8];
+  char i10[8];
+  char i11[8];
+  char i12[8];
+  char i13[8];
+  char i14[8];
+  char i15[8];
+  char i16[8];
+};
+
+struct foo x = { 1 };
+
+/* { dg-final { scan-assembler ".align\[ \t]*64\[^:]*\[\n\r]x:" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr61296-6.c b/gcc/testsuite/gcc.target/i386/pr61296-6.c
new file mode 100644
index 0000000..8e0d535
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr61296-6.c
@@ -0,0 +1,27 @@
+/* PR target/61296 */
+/* { dg-do compile { target { *-*-linux* } } } */
+/* { dg-options "-O2 -malign-data=cacheline -malign-data=compat" } */
+
+struct foo
+{
+  char i1[8];
+  char i2[8];
+  char i3[8];
+  char i4[8];
+  char i5[8];
+  char i6[8];
+  char i7[8];
+  char i8[8];
+  char i9[8];
+  char i10[8];
+  char i11[8];
+  char i12[8];
+  char i13[8];
+  char i14[8];
+  char i15[8];
+  char i16[8];
+};
+
+struct foo x = { 1 };
+
+/* { dg-final { scan-assembler ".align\[ \t]*32\[^:]*\[\n\r]x:" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr61296-7.c b/gcc/testsuite/gcc.target/i386/pr61296-7.c
new file mode 100644
index 0000000..6a67c90
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr61296-7.c
@@ -0,0 +1,27 @@
+/* PR target/61296 */
+/* { dg-do compile { target { *-*-linux* } } } */
+/* { dg-options "-O2 -malign-data=compat -malign-data=abi" } */
+
+struct foo
+{
+  char i1[8];
+  char i2[8];
+  char i3[8];
+  char i4[8];
+  char i5[8];
+  char i6[8];
+  char i7[8];
+  char i8[8];
+  char i9[8];
+  char i10[8];
+  char i11[8];
+  char i12[8];
+  char i13[8];
+  char i14[8];
+  char i15[8];
+  char i16[8];
+};
+
+struct foo x = { 1 };
+
+/* { dg-final { scan-assembler-not ".align\[ \t]*\[0-9\]+\[^:]*\[\n\r]x:" } } */