Add -mgeneral-regs-only option

X86 Linux kernel is compiled only with integer instructions.  Currently,

-mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -mno-80387
-mno-fp-ret-in-387  -mskip-rax-setup

is used to compile kernel.  If we add another non-integer feature, it
has to be turned off.  We can add a -mgeneral-regs-only option, similar
to AArch64, to disable all non-integer features so that kernel doesn't
need a long list and the same option will work for future compilers.
It can also be used to compile interrupt handler.

gcc/

	PR target/70738
	* common/config/i386/i386-common.c
	(OPTION_MASK_ISA_GENERAL_REGS_ONLY_UNSET): New.
	(ix86_handle_option): Disable MPX, MMX, SSE and x87 instructions
	for -mgeneral-regs-only.
	* config/i386/i386.c (ix86_option_override_internal): Don't
	enable x87 instructions if only the general registers are
	allowed.
	* config/i386/i386.opt: Add -mgeneral-regs-only.
	* doc/invoke.texi: Document -mgeneral-regs-only.

gcc/testsuite/

	PR target/70738
	* gcc.target/i386/pr70738-1.c: Likewise.
	* gcc.target/i386/pr70738-2.c: Likewise.
	* gcc.target/i386/pr70738-3.c: Likewise.
	* gcc.target/i386/pr70738-4.c: Likewise.
	* gcc.target/i386/pr70738-5.c: Likewise.
	* gcc.target/i386/pr70738-6.c: Likewise.
	* gcc.target/i386/pr70738-7.c: Likewise.
	* gcc.target/i386/pr70738-8.c: Likewise.
	* gcc.target/i386/pr70738-9.c: Likewise.

From-SVN: r236520

15 files changed, 193 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 67d7bf8..0a5526d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,16 @@
+2016-05-20  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR target/70738
+	* common/config/i386/i386-common.c
+	(OPTION_MASK_ISA_GENERAL_REGS_ONLY_UNSET): New.
+	(ix86_handle_option): Disable MPX, MMX, SSE and x87 instructions
+	for -mgeneral-regs-only.
+	* config/i386/i386.c (ix86_option_override_internal): Don't
+	enable x87 instructions if only the general registers are
+	allowed.
+	* config/i386/i386.opt: Add -mgeneral-regs-only.
+	* doc/invoke.texi: Document -mgeneral-regs-only.
+
 2016-05-20  David Malcolm  <dmalcolm@redhat.com>
 
 	* calls.c (maybe_complain_about_tail_call): New function.
diff --git a/gcc/common/config/i386/i386-common.c b/gcc/common/config/i386/i386-common.c
index cc65c8c..b150c9e 100644
--- a/gcc/common/config/i386/i386-common.c
+++ b/gcc/common/config/i386/i386-common.c
@@ -223,6 +223,11 @@ along with GCC; see the file COPYING3.  If not see
 #define OPTION_MASK_ISA_RDRND_UNSET OPTION_MASK_ISA_RDRND
 #define OPTION_MASK_ISA_F16C_UNSET OPTION_MASK_ISA_F16C
 
+#define OPTION_MASK_ISA_GENERAL_REGS_ONLY_UNSET \
+  (OPTION_MASK_ISA_MMX_UNSET \
+   | OPTION_MASK_ISA_SSE_UNSET \
+   | OPTION_MASK_ISA_MPX)
+
 /* Implement TARGET_HANDLE_OPTION.  */
 
 bool
@@ -236,6 +241,21 @@ ix86_handle_option (struct gcc_options *opts,
 
   switch (code)
     {
+    case OPT_mgeneral_regs_only:
+      if (value)
+	{
+	  /* Disable MPX, MMX, SSE and x87 instructions if only the
+	     general registers are allowed..  */
+	  opts->x_ix86_isa_flags
+	    &= ~OPTION_MASK_ISA_GENERAL_REGS_ONLY_UNSET;
+	  opts->x_ix86_isa_flags_explicit
+	    |= OPTION_MASK_ISA_GENERAL_REGS_ONLY_UNSET;
+	  opts->x_target_flags &= ~MASK_80387;
+	}
+      else
+	gcc_unreachable ();
+      return true;
+
     case OPT_mmmx:
       if (value)
 	{
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index cecea11..af434ec 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -5337,7 +5337,10 @@ ix86_option_override_internal (bool main_args_p,
 	    && !(opts->x_ix86_isa_flags_explicit & OPTION_MASK_ISA_PKU))
 	  opts->x_ix86_isa_flags |= OPTION_MASK_ISA_PKU;
 
-	if (!(opts_set->x_target_flags & MASK_80387))
+	/* Don't enable x87 instructions if only the general registers
+	   are allowed.  */
+	if (!(opts_set->x_target_flags & MASK_GENERAL_REGS_ONLY)
+	    && !(opts_set->x_target_flags & MASK_80387))
 	  {
 	    if (processor_alias_table[i].flags & PTA_NO_80387)
 	      opts->x_target_flags &= ~MASK_80387;
diff --git a/gcc/config/i386/i386.opt b/gcc/config/i386/i386.opt
index 36dd4bd..d12b29a 100644
--- a/gcc/config/i386/i386.opt
+++ b/gcc/config/i386/i386.opt
@@ -897,3 +897,7 @@ Enum(stack_protector_guard) String(global) Value(SSP_GLOBAL)
 mmitigate-rop
 Target Var(flag_mitigate_rop) Init(0)
 Attempt to avoid generating instruction sequences containing ret bytes.
+
+mgeneral-regs-only
+Target Report RejectNegative Mask(GENERAL_REGS_ONLY) Save
+Generate code which uses only the general registers.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index f3d087f..926e1e6 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -1172,7 +1172,7 @@ See RS/6000 and PowerPC Options.
 -msse2avx -mfentry -mrecord-mcount -mnop-mcount -m8bit-idiv @gol
 -mavx256-split-unaligned-load -mavx256-split-unaligned-store @gol
 -malign-data=@var{type} -mstack-protector-guard=@var{guard} @gol
--mmitigate-rop}
+-mmitigate-rop -mgeneral-regs-only}
 
 @emph{x86 Windows Options}
 @gccoptlist{-mconsole -mcygwin -mno-cygwin -mdll @gol
@@ -24264,6 +24264,12 @@ opcodes, to mitigate against certain forms of attack. At the moment,
 this option is limited in what it can do and should not be relied
 on to provide serious protection.
 
+@item -mgeneral-regs-only
+@opindex mgeneral-regs-only
+Generate code that uses only the general-purpose registers.  This
+prevents the compiler from using floating-point, vector, mask and bound
+registers.
+
 @end table
 
 These @samp{-m} switches are supported in addition to the above
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 323e69f..25edf4a 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,16 @@
+2016-05-20  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR target/70738
+	* gcc.target/i386/pr70738-1.c: Likewise.
+	* gcc.target/i386/pr70738-2.c: Likewise.
+	* gcc.target/i386/pr70738-3.c: Likewise.
+	* gcc.target/i386/pr70738-4.c: Likewise.
+	* gcc.target/i386/pr70738-5.c: Likewise.
+	* gcc.target/i386/pr70738-6.c: Likewise.
+	* gcc.target/i386/pr70738-7.c: Likewise.
+	* gcc.target/i386/pr70738-8.c: Likewise.
+	* gcc.target/i386/pr70738-9.c: Likewise.
+
 2016-05-20  Bill Seurer  <seurer@linux.vnet.ibm.com>
 
 	* gcc.target/powerpc/vec-addec.c: New test.
diff --git a/gcc/testsuite/gcc.target/i386/pr70738-1.c b/gcc/testsuite/gcc.target/i386/pr70738-1.c
new file mode 100644
index 0000000..19381c2
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr70738-1.c
@@ -0,0 +1,9 @@
+/* { dg-do compile { target { ! ia32 } } } */
+/* { dg-options "-msse2 -mgeneral-regs-only" } */
+
+typedef int int32x2_t __attribute__ ((__vector_size__ ((8))));
+
+int32x2_t test (int32x2_t a, int32x2_t b)
+{ /* { dg-error "SSE register return with SSE disabled" } */
+  return a + b;
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr70738-2.c b/gcc/testsuite/gcc.target/i386/pr70738-2.c
new file mode 100644
index 0000000..8b90904
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr70738-2.c
@@ -0,0 +1,10 @@
+/* { dg-do compile { target ia32 } } */
+/* { dg-options "-mmmx -mgeneral-regs-only" } */
+
+typedef int int32x2_t __attribute__ ((__vector_size__ ((8))));
+
+int32x2_t
+test (int32x2_t a, int32x2_t b) /* { dg-warning "MMX vector argument without MMX enabled" } */
+{ /* { dg-warning "MMX vector return without MMX enabled" } */
+  return a + b;
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr70738-3.c b/gcc/testsuite/gcc.target/i386/pr70738-3.c
new file mode 100644
index 0000000..1ac3adb
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr70738-3.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-msse2 -mgeneral-regs-only" } */
+
+typedef int int32x4_t __attribute__ ((__vector_size__ ((16))));
+extern int32x4_t c;
+
+void
+test (int32x4_t a, int32x4_t b) /* { dg-warning "SSE vector argument without SSE enabled" } */
+{
+  c = a + b;
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr70738-4.c b/gcc/testsuite/gcc.target/i386/pr70738-4.c
new file mode 100644
index 0000000..c6d20f2
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr70738-4.c
@@ -0,0 +1,10 @@
+/* { dg-do compile { target ia32 } } */
+/* { dg-options "-msse2 -mgeneral-regs-only" } */
+
+typedef int int32x4_t __attribute__ ((__vector_size__ ((16))));
+
+int32x4_t
+test (int32x4_t a, int32x4_t b) /* { dg-warning "SSE vector argument without SSE enabled" } */
+{ /* { dg-warning "SSE vector return without SSE enabled" } */
+  return a + b;
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr70738-5.c b/gcc/testsuite/gcc.target/i386/pr70738-5.c
new file mode 100644
index 0000000..8b43809
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr70738-5.c
@@ -0,0 +1,16 @@
+/* { dg-do compile { target { ! ia32 } } } */
+/* { dg-options "-msse2 -mgeneral-regs-only" } */
+
+#include <stdarg.h>
+
+typedef int int32x2_t __attribute__ ((__vector_size__ ((8))));
+
+int
+test (int i, ...)
+{
+  va_list argp;
+  va_start (argp, i);
+  int32x2_t x = (int32x2_t) {0, 1};
+  x += va_arg (argp, int32x2_t); /* { dg-error "SSE register argument with SSE disabled" } */
+  return x[0] + x[1];
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr70738-6.c b/gcc/testsuite/gcc.target/i386/pr70738-6.c
new file mode 100644
index 0000000..3bccabb
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr70738-6.c
@@ -0,0 +1,10 @@
+/* { dg-do compile { target { ! ia32 } } } */
+/* { dg-options "-msse2 -mgeneral-regs-only" } */
+
+extern float a, b, c;
+
+void
+foo (void)
+{
+  c = a * b; /* { dg-error "SSE register return with SSE disabled" } */
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr70738-7.c b/gcc/testsuite/gcc.target/i386/pr70738-7.c
new file mode 100644
index 0000000..2e5b49f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr70738-7.c
@@ -0,0 +1,13 @@
+/* { dg-do compile { target ia32 } } */
+/* { dg-options "-msse2 -mgeneral-regs-only" } */
+
+extern float a, b, c;
+
+void
+foo (void)
+{
+  c = a * b;
+}
+
+/* { dg-final { scan-assembler-not "mulss" } } */
+/* { dg-final { scan-assembler "call\[ \t\]__mulsf3" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr70738-8.c b/gcc/testsuite/gcc.target/i386/pr70738-8.c
new file mode 100644
index 0000000..0740460
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr70738-8.c
@@ -0,0 +1,30 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -mgeneral-regs-only" } */
+
+extern void abort ();
+
+int
+dec (int a, int b)
+{
+  return a + b;
+}
+
+int
+cal (int a, int b)
+{
+  int sum1 = a * b;
+  int sum2 = a / b;
+  int sum = dec (sum1, sum2);
+  return a + b + sum + sum1 + sum2;
+}
+
+int
+main (int argc, char **argv)
+{
+  int ret = cal (2, 1);
+
+  if (ret != 11)
+    abort ();
+
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr70738-9.c b/gcc/testsuite/gcc.target/i386/pr70738-9.c
new file mode 100644
index 0000000..c71f0b0
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr70738-9.c
@@ -0,0 +1,23 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -mgeneral-regs-only" } */
+
+extern void abort ();
+
+int
+cal (int a, int b)
+{
+  int sum = a + b;
+  int sum1 = a * b;
+  return (a + b + sum + sum1);
+}
+
+int
+main (int argc, char **argv)
+{
+  int ret = cal (1, 2);
+
+  if (ret != 8)
+    abort ();
+
+  return 0;
+}